text: /* vi:set ts=8 sts=4 sw=4:
   *
   * Handling of regular expressions: vim_regcomp(), vim_regexec(), vim_regsub()
   *
   * NOTICE:
   *
   * This is NOT the original regular expression code as written by Henry
   * Spencer.  This code has been modified specifically for use with the VIM
   * editor, and should not be used separately from Vim.  If you want a good
   * regular expression library, get the original code.  The copyright notice
   * that follows is from the original.
   *
   * END NOTICE
   *
   *	Copyright (c) 1986 by University of Toronto.
   *	Written by Henry Spencer.  Not derived from licensed software.
   *
   *	Permission is granted to anyone to use this software for any
   *	purpose on any computer system, and to redistribute it freely,
   *	subject to the following restrictions:
   *
   *	1. The author is not responsible for the consequences of use of
   *		this software, no matter how awful, even if they arise
   *		from defects in it.
   *
   *	2. The origin of this software must not be misrepresented, either
   *		by explicit claim or by omission.
   *
   *	3. Altered versions must be plainly marked as such, and must not
   *		be misrepresented as being the original software.
   *
   * Beware that some of this code is subtly aware of the way operator
   * precedence is structured in regular expressions.  Serious changes in
   * regular-expression syntax might require a total rethink.
   *
   * Changes have been made by Tony Andrews, Olaf 'Rhialto' Seibert, Robert
   * Webb, Ciaran McCreesh and Bram Moolenaar.
   * Named character class support added by Walter Briscoe (1998 Jul 01)
   */
  
  /* Uncomment the first if you do not want to see debugging logs or files
   * related to regular expressions, even when compiling with -DDEBUG.
   * Uncomment the second to get the regexp debugging. */
  /* #undef REGEXP_DEBUG */
  /* #define REGEXP_DEBUG */
  
  #include "vim.h"
  
  #ifdef REGEXP_DEBUG
  /* show/save debugging data when BT engine is used */
  # define BT_REGEXP_DUMP
  /* save the debugging data to a file instead of displaying it */
  # define BT_REGEXP_LOG
  # define BT_REGEXP_DEBUG_LOG
  # define BT_REGEXP_DEBUG_LOG_NAME       "bt_regexp_debug.log"
  #endif
  
  /*
   * The "internal use only" fields in regexp.h are present to pass info from
   * compile to execute that permits the execute phase to run lots faster on
   * simple cases.  They are:
   *
   * regstart	char that must begin a match; NUL if none obvious; Can be a
   *		multi-byte character.
   * reganch	is the match anchored (at beginning-of-line only)?
   * regmust	string (pointer into program) that match must include, or NULL
   * regmlen	length of regmust string
   * regflags	RF_ values or'ed together
   *
   * Regstart and reganch permit very fast decisions on suitable starting points
   * for a match, cutting down the work a lot.  Regmust permits fast rejection
   * of lines that cannot possibly match.  The regmust tests are costly enough
   * that vim_regcomp() supplies a regmust only if the r.e. contains something
   * potentially expensive (at present, the only such thing detected is * or +
   * at the start of the r.e., which can involve a lot of backup).  Regmlen is
   * supplied because the test in vim_regexec() needs it and vim_regcomp() is
   * computing it anyway.
   */
  
  /*
   * Structure for regexp "program".  This is essentially a linear encoding
   * of a nondeterministic finite-state machine (aka syntax charts or
   * "railroad normal form" in parsing technology).  Each node is an opcode
   * plus a "next" pointer, possibly plus an operand.  "Next" pointers of
   * all nodes except BRANCH and BRACES_COMPLEX implement concatenation; a "next"
   * pointer with a BRANCH on both ends of it is connecting two alternatives.
   * (Here we have one of the subtle syntax dependencies:	an individual BRANCH
   * (as opposed to a collection of them) is never concatenated with anything
   * because of operator precedence).  The "next" pointer of a BRACES_COMPLEX
   * node points to the node after the stuff to be repeated.
   * The operand of some types of node is a literal string; for others, it is a
   * node leading into a sub-FSM.  In particular, the operand of a BRANCH node
   * is the first node of the branch.
   * (NB this is *not* a tree structure: the tail of the branch connects to the
   * thing following the set of BRANCHes.)
   *
   * pattern	is coded like:
   *
   *			  +-----------------+
   *			  |		    V
   * <aa>\|<bb>	BRANCH <aa> BRANCH <bb> --> END
   *		     |	    ^	 |	    ^
   *		     +------+	 +----------+
   *
   *
   *		       +------------------+
   *		       V		  |
   * <aa>*	BRANCH BRANCH <aa> --> BACK BRANCH --> NOTHING --> END
   *		     |	    |		    ^			   ^
   *		     |	    +---------------+			   |
   *		     +---------------------------------------------+
   *
   *
   *		       +----------------------+
   *		       V		      |
   * <aa>\+	BRANCH <aa> --> BRANCH --> BACK  BRANCH --> NOTHING --> END
   *		     |		     |		 ^			^
   *		     |		     +-----------+			|
   *		     +--------------------------------------------------+
   *
   *
   *					+-------------------------+
   *					V			  |
   * <aa>\{}	BRANCH BRACE_LIMITS --> BRACE_COMPLEX <aa> --> BACK  END
   *		     |				    |		     ^
   *		     |				    +----------------+
   *		     +-----------------------------------------------+
   *
   *
   * <aa>\@!<bb>	BRANCH NOMATCH <aa> --> END  <bb> --> END
   *		     |	     |		      ^       ^
   *		     |	     +----------------+       |
   *		     +--------------------------------+
   *
   *						      +---------+
   *						      |		V
   * \z[abc]	BRANCH BRANCH  a  BRANCH  b  BRANCH  c	BRANCH	NOTHING --> END
   *		     |	    |	       |	  |	^		    ^
   *		     |	    |	       |	  +-----+		    |
   *		     |	    |	       +----------------+		    |
   *		     |	    +---------------------------+		    |
   *		     +------------------------------------------------------+
   *
   * They all start with a BRANCH for "\|" alternatives, even when there is only
   * one alternative.
   */
  
  /*
   * The opcodes are:
   */
  
  /* definition	number		   opnd?    meaning */
  #define END             0       /*	End of program or NOMATCH operand. */
  #define BOL             1       /*	Match "" at beginning of line. */
  #define EOL             2       /*	Match "" at end of line. */
  #define BRANCH          3       /* node Match this alternative, or the
                                   *	next... */
  #define BACK            4       /*	Match "", "next" ptr points backward. */
  #define EXACTLY         5       /* str	Match this string. */
  #define NOTHING         6       /*	Match empty string. */
  #define STAR            7       /* node Match this (simple) thing 0 or more
                                   *	times. */
  #define PLUS            8       /* node Match this (simple) thing 1 or more
                                   *	times. */
  #define MATCH           9       /* node match the operand zero-width */
  #define NOMATCH         10      /* node check for no match with operand */
  #define BEHIND          11      /* node look behind for a match with operand */
  #define NOBEHIND        12      /* node look behind for no match with operand */
  #define SUBPAT          13      /* node match the operand here */
  #define BRACE_SIMPLE    14      /* node Match this (simple) thing between m and
                                   *	n times (\{m,n\}). */
  #define BOW             15      /*	Match "" after [^a-zA-Z0-9_] */
  #define EOW             16      /*	Match "" at    [^a-zA-Z0-9_] */
  #define BRACE_LIMITS    17      /* nr nr  define the min & max for BRACE_SIMPLE
                                   *	and BRACE_COMPLEX. */
  #define NEWL            18      /*	Match line-break */
  #define BHPOS           19      /*	End position for BEHIND or NOBEHIND */
  
  
  /* character classes: 20-48 normal, 50-78 include a line-break */
  #define ADD_NL          30
  #define FIRST_NL        ANY + ADD_NL
  #define ANY             20      /*	Match any one character. */
  #define ANYOF           21      /* str	Match any character in this string. */
  #define ANYBUT          22      /* str	Match any character not in this
                                   *	string. */
  #define IDENT           23      /*	Match identifier char */
  #define SIDENT          24      /*	Match identifier char but no digit */
  #define KWORD           25      /*	Match keyword char */
  #define SKWORD          26      /*	Match word char but no digit */
  #define FNAME           27      /*	Match file name char */
  #define SFNAME          28      /*	Match file name char but no digit */
  #define PRINT           29      /*	Match printable char */
  #define SPRINT          30      /*	Match printable char but no digit */
  #define WHITE           31      /*	Match whitespace char */
  #define NWHITE          32      /*	Match non-whitespace char */
  #define DIGIT           33      /*	Match digit char */
  #define NDIGIT          34      /*	Match non-digit char */
  #define HEX             35      /*	Match hex char */
  #define NHEX            36      /*	Match non-hex char */
  #define OCTAL           37      /*	Match octal char */
  #define NOCTAL          38      /*	Match non-octal char */
  #define WORD            39      /*	Match word char */
  #define NWORD           40      /*	Match non-word char */
  #define HEAD            41      /*	Match head char */
  #define NHEAD           42      /*	Match non-head char */
  #define ALPHA           43      /*	Match alpha char */
  #define NALPHA          44      /*	Match non-alpha char */
  #define LOWER           45      /*	Match lowercase char */
  #define NLOWER          46      /*	Match non-lowercase char */
  #define UPPER           47      /*	Match uppercase char */
  #define NUPPER          48      /*	Match non-uppercase char */
  #define LAST_NL         NUPPER + ADD_NL
  #define WITH_NL(op)     ((op) >= FIRST_NL && (op) <= LAST_NL)
  
  #define MOPEN           80  /* -89	 Mark this point in input as start of
                               *	 \( subexpr.  MOPEN + 0 marks start of
                               *	 match. */
  #define MCLOSE          90  /* -99	 Analogous to MOPEN.  MCLOSE + 0 marks
                               *	 end of match. */
  #define BACKREF         100 /* -109 node Match same string again \1-\9 */
  
  # define ZOPEN          110 /* -119	 Mark this point in input as start of
                               *	 \z( subexpr. */
  # define ZCLOSE         120 /* -129	 Analogous to ZOPEN. */
  # define ZREF           130 /* -139 node Match external submatch \z1-\z9 */
  
  #define BRACE_COMPLEX   140 /* -149 node Match nodes between m & n times */
  
  #define NOPEN           150     /*	Mark this point in input as start of
                                   \%( subexpr. */
  #define NCLOSE          151     /*	Analogous to NOPEN. */
  
  #define MULTIBYTECODE   200     /* mbc	Match one multi-byte character */
  #define RE_BOF          201     /*	Match "" at beginning of file. */
  #define RE_EOF          202     /*	Match "" at end of file. */
  #define CURSOR          203     /*	Match location of cursor. */
  
  #define RE_LNUM         204     /* nr cmp  Match line number */
  #define RE_COL          205     /* nr cmp  Match column number */
  #define RE_VCOL         206     /* nr cmp  Match virtual column number */
  
  #define RE_MARK         207     /* mark cmp  Match mark position */
  #define RE_VISUAL       208     /*	Match Visual area */
  
  /*
   * Magic characters have a special meaning, they don't match literally.
   * Magic characters are negative.  This separates them from literal characters
   * (possibly multi-byte).  Only ASCII characters can be Magic.
   */
  #define Magic(x)        ((int)(x) - 256)
  #define un_Magic(x)     ((x) + 256)
  #define is_Magic(x)     ((x) < 0)
  
  static int no_Magic __ARGS((int x));
  static int toggle_Magic __ARGS((int x));
  
  static int no_Magic(x)
  int x;
  {
    if (is_Magic(x))
      return un_Magic(x);
    return x;
  }
  
  static int toggle_Magic(x)
  int x;
  {
    if (is_Magic(x))
      return un_Magic(x);
    return Magic(x);
  }
  
  /*
   * The first byte of the regexp internal "program" is actually this magic
   * number; the start node begins in the second byte.  It's used to catch the
   * most severe mutilation of the program by the caller.
   */
  
  #define REGMAGIC        0234
  
  /*
   * Opcode notes:
   *
   * BRANCH	The set of branches constituting a single choice are hooked
   *		together with their "next" pointers, since precedence prevents
   *		anything being concatenated to any individual branch.  The
   *		"next" pointer of the last BRANCH in a choice points to the
   *		thing following the whole choice.  This is also where the
   *		final "next" pointer of each individual branch points; each
   *		branch starts with the operand node of a BRANCH node.
   *
   * BACK		Normal "next" pointers all implicitly point forward; BACK
   *		exists to make loop structures possible.
   *
   * STAR,PLUS	'=', and complex '*' and '+', are implemented as circular
   *		BRANCH structures using BACK.  Simple cases (one character
   *		per match) are implemented with STAR and PLUS for speed
   *		and to minimize recursive plunges.
   *
   * BRACE_LIMITS	This is always followed by a BRACE_SIMPLE or BRACE_COMPLEX
   *		node, and defines the min and max limits to be used for that
   *		node.
   *
   * MOPEN,MCLOSE	...are numbered at compile time.
   * ZOPEN,ZCLOSE	...ditto
   */
  
  /*
   * A node is one char of opcode followed by two chars of "next" pointer.
   * "Next" pointers are stored as two 8-bit bytes, high order first.  The
   * value is a positive offset from the opcode of the node containing it.
   * An operand, if any, simply follows the node.  (Note that much of the
   * code generation knows about this implicit relationship.)
   *
   * Using two bytes for the "next" pointer is vast overkill for most things,
   * but allows patterns to get big without disasters.
   */
  #define OP(p)           ((int)*(p))
  #define NEXT(p)         (((*((p) + 1) & 0377) << 8) + (*((p) + 2) & 0377))
  #define OPERAND(p)      ((p) + 3)
  /* Obtain an operand that was stored as four bytes, MSB first. */
  #define OPERAND_MIN(p)  (((long)(p)[3] << 24) + ((long)(p)[4] << 16) \
                           + ((long)(p)[5] << 8) + (long)(p)[6])
  /* Obtain a second operand stored as four bytes. */
  #define OPERAND_MAX(p)  OPERAND_MIN((p) + 4)
  /* Obtain a second single-byte operand stored after a four bytes operand. */
  #define OPERAND_CMP(p)  (p)[7]
  
  /*
   * Utility definitions.
   */
  #define UCHARAT(p)      ((int)*(char_u *)(p))
  
  /* Used for an error (down from) vim_regcomp(): give the error message, set
   * rc_did_emsg and return NULL */
  #define EMSG_RET_NULL(m) return (EMSG(m), rc_did_emsg = TRUE, (void *)NULL)
  #define EMSG_RET_FAIL(m) return (EMSG(m), rc_did_emsg = TRUE, FAIL)
  #define EMSG2_RET_NULL(m, \
                         c) return (EMSG2((m), \
                                        (c) ? "" : "\\"), rc_did_emsg = TRUE, \
                                    (void *)NULL)
  #define EMSG2_RET_FAIL(m, \
                         c) return (EMSG2((m), \
                                        (c) ? "" : "\\"), rc_did_emsg = TRUE, \
                                    FAIL)
  #define EMSG_ONE_RET_NULL EMSG2_RET_NULL(_( \
          "E369: invalid item in %s%%[]"), reg_magic == MAGIC_ALL)
  
  #define MAX_LIMIT       (32767L << 16L)
  
  static int re_multi_type __ARGS((int));
  static int cstrncmp __ARGS((char_u *s1, char_u *s2, int *n));
  static char_u *cstrchr __ARGS((char_u *, int));
  
  #ifdef BT_REGEXP_DUMP
  static void regdump __ARGS((char_u *, bt_regprog_T *));
  #endif
  #ifdef REGEXP_DEBUG
  static char_u   *regprop __ARGS((char_u *));
  #endif
  
  static char_u e_missingbracket[] = N_("E769: Missing ] after %s[");
  static char_u e_unmatchedpp[] = N_("E53: Unmatched %s%%(");
  static char_u e_unmatchedp[] = N_("E54: Unmatched %s(");
  static char_u e_unmatchedpar[] = N_("E55: Unmatched %s)");
  static char_u e_z_not_allowed[] = N_("E66: \\z( not allowed here");
  static char_u e_z1_not_allowed[] = N_("E67: \\z1 et al. not allowed here");
  static char_u e_missing_sb[] = N_("E69: Missing ] after %s%%[");
  static char_u e_empty_sb[]  = N_("E70: Empty %s%%[]");
  #define NOT_MULTI       0
  #define MULTI_ONE       1
  #define MULTI_MULT      2
  /*
   * Return NOT_MULTI if c is not a "multi" operator.
   * Return MULTI_ONE if c is a single "multi" operator.
   * Return MULTI_MULT if c is a multi "multi" operator.
   */
  static int re_multi_type(c)
  int c;
  {
    if (c == Magic('@') || c == Magic('=') || c == Magic('?'))
      return MULTI_ONE;
    if (c == Magic('*') || c == Magic('+') || c == Magic('{'))
      return MULTI_MULT;
    return NOT_MULTI;
  }
  
  /*
   * Flags to be passed up and down.
   */
  #define HASWIDTH        0x1     /* Known never to match null string. */
  #define SIMPLE          0x2     /* Simple enough to be STAR/PLUS operand. */
  #define SPSTART         0x4     /* Starts with * or +. */
  #define HASNL           0x8     /* Contains some \n. */
  #define HASLOOKBH       0x10    /* Contains "\@<=" or "\@<!". */
  #define WORST           0       /* Worst case. */
  
  /*
   * When regcode is set to this value, code is not emitted and size is computed
   * instead.
   */
  #define JUST_CALC_SIZE  ((char_u *) -1)
  
  static char_u           *reg_prev_sub = NULL;
  
  /*
   * REGEXP_INRANGE contains all characters which are always special in a []
   * range after '\'.
   * REGEXP_ABBR contains all characters which act as abbreviations after '\'.
   * These are:
   *  \n	- New line (NL).
   *  \r	- Carriage Return (CR).
   *  \t	- Tab (TAB).
   *  \e	- Escape (ESC).
   *  \b	- Backspace (Ctrl_H).
   *  \d  - Character code in decimal, eg \d123
   *  \o	- Character code in octal, eg \o80
   *  \x	- Character code in hex, eg \x4a
   *  \u	- Multibyte character code, eg \u20ac
   *  \U	- Long multibyte character code, eg \U12345678
   */
  static char_u REGEXP_INRANGE[] = "]^-n\\";
  static char_u REGEXP_ABBR[] = "nrtebdoxuU";
  
  static int backslash_trans __ARGS((int c));
  static int get_char_class __ARGS((char_u **pp));
  static int get_equi_class __ARGS((char_u **pp));
  static void reg_equi_class __ARGS((int c));
  static int get_coll_element __ARGS((char_u **pp));
  static char_u   *skip_anyof __ARGS((char_u *p));
  static void init_class_tab __ARGS((void));
  
  /*
   * Translate '\x' to its control character, except "\n", which is Magic.
   */
  static int backslash_trans(c)
  int c;
  {
    switch (c) {
    case 'r':   return CAR;
    case 't':   return TAB;
    case 'e':   return ESC;
    case 'b':   return BS;
    }
    return c;
  }
  
  /*
   * Check for a character class name "[:name:]".  "pp" points to the '['.
   * Returns one of the CLASS_ items. CLASS_NONE means that no item was
   * recognized.  Otherwise "pp" is advanced to after the item.
   */
  static int get_char_class(pp)
  char_u      **pp;
  {
    static const char *(class_names[]) =
    {
      "alnum:]",
  #define CLASS_ALNUM 0
      "alpha:]",
  #define CLASS_ALPHA 1
      "blank:]",
  #define CLASS_BLANK 2
      "cntrl:]",
  #define CLASS_CNTRL 3
      "digit:]",
  #define CLASS_DIGIT 4
      "graph:]",
  #define CLASS_GRAPH 5
      "lower:]",
  #define CLASS_LOWER 6
      "print:]",
  #define CLASS_PRINT 7
      "punct:]",
  #define CLASS_PUNCT 8
      "space:]",
  #define CLASS_SPACE 9
      "upper:]",
  #define CLASS_UPPER 10
      "xdigit:]",
  #define CLASS_XDIGIT 11
      "tab:]",
  #define CLASS_TAB 12
      "return:]",
  #define CLASS_RETURN 13
      "backspace:]",
  #define CLASS_BACKSPACE 14
      "escape:]",
  #define CLASS_ESCAPE 15
    };
  #define CLASS_NONE 99
    int i;
  
    if ((*pp)[1] == ':') {
      for (i = 0; i < (int)(sizeof(class_names) / sizeof(*class_names)); ++i)
        if (STRNCMP(*pp + 2, class_names[i], STRLEN(class_names[i])) == 0) {
          *pp += STRLEN(class_names[i]) + 2;
          return i;
        }
    }
    return CLASS_NONE;
  }
  
  /*
   * Specific version of character class functions.
   * Using a table to keep this fast.
   */
  static short class_tab[256];
  
  #define     RI_DIGIT    0x01
  #define     RI_HEX      0x02
  #define     RI_OCTAL    0x04
  #define     RI_WORD     0x08
  #define     RI_HEAD     0x10
  #define     RI_ALPHA    0x20
  #define     RI_LOWER    0x40
  #define     RI_UPPER    0x80
  #define     RI_WHITE    0x100
  
  static void init_class_tab()                 {
    int i;
    static int done = FALSE;
  
    if (done)
      return;
  
    for (i = 0; i < 256; ++i) {
      if (i >= '0' && i <= '7')
        class_tab[i] = RI_DIGIT + RI_HEX + RI_OCTAL + RI_WORD;
      else if (i >= '8' && i <= '9')
        class_tab[i] = RI_DIGIT + RI_HEX + RI_WORD;
      else if (i >= 'a' && i <= 'f')
        class_tab[i] = RI_HEX + RI_WORD + RI_HEAD + RI_ALPHA + RI_LOWER;
      else if (i >= 'g' && i <= 'z')
        class_tab[i] = RI_WORD + RI_HEAD + RI_ALPHA + RI_LOWER;
      else if (i >= 'A' && i <= 'F')
        class_tab[i] = RI_HEX + RI_WORD + RI_HEAD + RI_ALPHA + RI_UPPER;
      else if (i >= 'G' && i <= 'Z')
        class_tab[i] = RI_WORD + RI_HEAD + RI_ALPHA + RI_UPPER;
      else if (i == '_')
        class_tab[i] = RI_WORD + RI_HEAD;
      else
        class_tab[i] = 0;
    }
    class_tab[' '] |= RI_WHITE;
    class_tab['\t'] |= RI_WHITE;
    done = TRUE;
  }
  
  # define ri_digit(c)    (c < 0x100 && (class_tab[c] & RI_DIGIT))
  # define ri_hex(c)      (c < 0x100 && (class_tab[c] & RI_HEX))
  # define ri_octal(c)    (c < 0x100 && (class_tab[c] & RI_OCTAL))
  # define ri_word(c)     (c < 0x100 && (class_tab[c] & RI_WORD))
  # define ri_head(c)     (c < 0x100 && (class_tab[c] & RI_HEAD))
  # define ri_alpha(c)    (c < 0x100 && (class_tab[c] & RI_ALPHA))
  # define ri_lower(c)    (c < 0x100 && (class_tab[c] & RI_LOWER))
  # define ri_upper(c)    (c < 0x100 && (class_tab[c] & RI_UPPER))
  # define ri_white(c)    (c < 0x100 && (class_tab[c] & RI_WHITE))
  
  /* flags for regflags */
  #define RF_ICASE    1   /* ignore case */
  #define RF_NOICASE  2   /* don't ignore case */
  #define RF_HASNL    4   /* can match a NL */
  #define RF_ICOMBINE 8   /* ignore combining characters */
  #define RF_LOOKBH   16  /* uses "\@<=" or "\@<!" */
  
  /*
   * Global work variables for vim_regcomp().
   */
  
  static char_u   *regparse;      /* Input-scan pointer. */
  static int prevchr_len;         /* byte length of previous char */
  static int num_complex_braces;      /* Complex \{...} count */
  static int regnpar;             /* () count. */
  static int regnzpar;            /* \z() count. */
  static int re_has_z;            /* \z item detected */
  static char_u   *regcode;       /* Code-emit pointer, or JUST_CALC_SIZE */
  static long regsize;            /* Code size. */
  static int reg_toolong;         /* TRUE when offset out of range */
  static char_u had_endbrace[NSUBEXP];    /* flags, TRUE if end of () found */
  static unsigned regflags;       /* RF_ flags for prog */
  static long brace_min[10];      /* Minimums for complex brace repeats */
  static long brace_max[10];      /* Maximums for complex brace repeats */
  static int brace_count[10];      /* Current counts for complex brace repeats */
  static int had_eol;             /* TRUE when EOL found by vim_regcomp() */
  static int one_exactly = FALSE;         /* only do one char for EXACTLY */
  
  static int reg_magic;           /* magicness of the pattern: */
  #define MAGIC_NONE      1       /* "\V" very unmagic */
  #define MAGIC_OFF       2       /* "\M" or 'magic' off */
  #define MAGIC_ON        3       /* "\m" or 'magic' */
  #define MAGIC_ALL       4       /* "\v" very magic */
  
  static int reg_string;          /* matching with a string instead of a buffer
                                     line */
  static int reg_strict;          /* "[abc" is illegal */
  
  /*
   * META contains all characters that may be magic, except '^' and '$'.
   */
  
  /* META[] is used often enough to justify turning it into a table. */
  static char_u META_flags[] = {
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    /*		   %  &     (  )  *  +	      .    */
    0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 0,
    /*     1  2  3	4  5  6  7  8  9	<  =  >  ? */
    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1,
    /*  @  A     C	D     F     H  I     K	L  M	 O */
    1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1,
    /*  P	     S	   U  V  W  X	  Z  [		 _ */
    1, 0, 0, 1, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 0, 1,
    /*     a     c	d     f     h  i     k	l  m  n  o */
    0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1,
    /*  p	     s	   u  v  w  x	  z  {	|     ~    */
    1, 0, 0, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1
  };
  
  static int curchr;              /* currently parsed character */
  /* Previous character.  Note: prevchr is sometimes -1 when we are not at the
   * start, eg in /[ ^I]^ the pattern was never found even if it existed,
   * because ^ was taken to be magic -- webb */
  static int prevchr;
  static int prevprevchr;         /* previous-previous character */
  static int nextchr;             /* used for ungetchr() */
  
  /* arguments for reg() */
  #define REG_NOPAREN     0       /* toplevel reg() */
  #define REG_PAREN       1       /* \(\) */
  #define REG_ZPAREN      2       /* \z(\) */
  #define REG_NPAREN      3       /* \%(\) */
  
  typedef struct {
    char_u     *regparse;
    int prevchr_len;
    int curchr;
    int prevchr;
    int prevprevchr;
    int nextchr;
    int at_start;
    int prev_at_start;
    int regnpar;
  } parse_state_T;
  
  /*
   * Forward declarations for vim_regcomp()'s friends.
   */
  static void initchr __ARGS((char_u *));
  static void save_parse_state __ARGS((parse_state_T *ps));
  static void restore_parse_state __ARGS((parse_state_T *ps));
  static int getchr __ARGS((void));
  static void skipchr_keepstart __ARGS((void));
  static int peekchr __ARGS((void));
  static void skipchr __ARGS((void));
  static void ungetchr __ARGS((void));
  static int gethexchrs __ARGS((int maxinputlen));
  static int getoctchrs __ARGS((void));
  static int getdecchrs __ARGS((void));
  static int coll_get_char __ARGS((void));
  static void regcomp_start __ARGS((char_u *expr, int flags));
  static char_u   *reg __ARGS((int, int *));
  static char_u   *regbranch __ARGS((int *flagp));
  static char_u   *regconcat __ARGS((int *flagp));
  static char_u   *regpiece __ARGS((int *));
  static char_u   *regatom __ARGS((int *));
  static char_u   *regnode __ARGS((int));
  static int use_multibytecode __ARGS((int c));
  static int prog_magic_wrong __ARGS((void));
  static char_u   *regnext __ARGS((char_u *));
  static void regc __ARGS((int b));
  static void regmbc __ARGS((int c));
  # define REGMBC(x) regmbc(x);
  # define CASEMBC(x) case x:
  static void reginsert __ARGS((int, char_u *));
  static void reginsert_nr __ARGS((int op, long val, char_u *opnd));
  static void reginsert_limits __ARGS((int, long, long, char_u *));
  static char_u   *re_put_long __ARGS((char_u *pr, long_u val));
  static int read_limits __ARGS((long *, long *));
  static void regtail __ARGS((char_u *, char_u *));
  static void regoptail __ARGS((char_u *, char_u *));
  
  static regengine_T bt_regengine;
  static regengine_T nfa_regengine;
  
  /*
   * Return TRUE if compiled regular expression "prog" can match a line break.
   */
  int re_multiline(prog)
  regprog_T *prog;
  {
    return prog->regflags & RF_HASNL;
  }
  
  /*
   * Return TRUE if compiled regular expression "prog" looks before the start
   * position (pattern contains "\@<=" or "\@<!").
   */
  int re_lookbehind(prog)
  regprog_T *prog;
  {
    return prog->regflags & RF_LOOKBH;
  }
  
  /*
   * Check for an equivalence class name "[=a=]".  "pp" points to the '['.
   * Returns a character representing the class. Zero means that no item was
   * recognized.  Otherwise "pp" is advanced to after the item.
   */
  static int get_equi_class(pp)
  char_u      **pp;
  {
    int c;
    int l = 1;
    char_u      *p = *pp;
  
    if (p[1] == '=') {
      if (has_mbyte)
        l = (*mb_ptr2len)(p + 2);
      if (p[l + 2] == '=' && p[l + 3] == ']') {
        if (has_mbyte)
          c = mb_ptr2char(p + 2);
        else
          c = p[2];
        *pp += l + 4;
        return c;
      }
    }
    return 0;
  }
  
  
  /*
   * Produce the bytes for equivalence class "c".
   * Currently only handles latin1, latin9 and utf-8.
   * NOTE: When changing this function, also change nfa_emit_equi_class()
   */
  static void reg_equi_class(c)
  int c;
  {
    if (enc_utf8 || STRCMP(p_enc, "latin1") == 0
        || STRCMP(p_enc, "iso-8859-15") == 0) {
      switch (c) {
      case 'A': case '\300': case '\301': case '\302':
        CASEMBC(0x100) CASEMBC(0x102) CASEMBC(0x104) CASEMBC(0x1cd)
        CASEMBC(0x1de) CASEMBC(0x1e0) CASEMBC(0x1ea2)
      case '\303': case '\304': case '\305':
        regmbc('A'); regmbc('\300'); regmbc('\301');
        regmbc('\302'); regmbc('\303'); regmbc('\304');
        regmbc('\305');
        REGMBC(0x100) REGMBC(0x102) REGMBC(0x104)
        REGMBC(0x1cd) REGMBC(0x1de) REGMBC(0x1e0)
        REGMBC(0x1ea2)
        return;
      case 'B': CASEMBC(0x1e02) CASEMBC(0x1e06)
        regmbc('B'); REGMBC(0x1e02) REGMBC(0x1e06)
        return;
      case 'C': case '\307':
        CASEMBC(0x106) CASEMBC(0x108) CASEMBC(0x10a) CASEMBC(0x10c)
        regmbc('C'); regmbc('\307');
        REGMBC(0x106) REGMBC(0x108) REGMBC(0x10a)
        REGMBC(0x10c)
        return;
      case 'D': CASEMBC(0x10e) CASEMBC(0x110) CASEMBC(0x1e0a)
        CASEMBC(0x1e0e) CASEMBC(0x1e10)
        regmbc('D'); REGMBC(0x10e) REGMBC(0x110)
        REGMBC(0x1e0a) REGMBC(0x1e0e) REGMBC(0x1e10)
        return;
      case 'E': case '\310': case '\311': case '\312': case '\313':
        CASEMBC(0x112) CASEMBC(0x114) CASEMBC(0x116) CASEMBC(0x118)
        CASEMBC(0x11a) CASEMBC(0x1eba) CASEMBC(0x1ebc)
        regmbc('E'); regmbc('\310'); regmbc('\311');
        regmbc('\312'); regmbc('\313');
        REGMBC(0x112) REGMBC(0x114) REGMBC(0x116)
        REGMBC(0x118) REGMBC(0x11a) REGMBC(0x1eba)
        REGMBC(0x1ebc)
        return;
      case 'F': CASEMBC(0x1e1e)
        regmbc('F'); REGMBC(0x1e1e)
        return;
      case 'G': CASEMBC(0x11c) CASEMBC(0x11e) CASEMBC(0x120)
        CASEMBC(0x122) CASEMBC(0x1e4) CASEMBC(0x1e6) CASEMBC(0x1f4)
        CASEMBC(0x1e20)
        regmbc('G'); REGMBC(0x11c) REGMBC(0x11e)
        REGMBC(0x120) REGMBC(0x122) REGMBC(0x1e4)
        REGMBC(0x1e6) REGMBC(0x1f4) REGMBC(0x1e20)
        return;
      case 'H': CASEMBC(0x124) CASEMBC(0x126) CASEMBC(0x1e22)
        CASEMBC(0x1e26) CASEMBC(0x1e28)
        regmbc('H'); REGMBC(0x124) REGMBC(0x126)
        REGMBC(0x1e22) REGMBC(0x1e26) REGMBC(0x1e28)
        return;
      case 'I': case '\314': case '\315': case '\316': case '\317':
        CASEMBC(0x128) CASEMBC(0x12a) CASEMBC(0x12c) CASEMBC(0x12e)
        CASEMBC(0x130) CASEMBC(0x1cf) CASEMBC(0x1ec8)
        regmbc('I'); regmbc('\314'); regmbc('\315');
        regmbc('\316'); regmbc('\317');
        REGMBC(0x128) REGMBC(0x12a) REGMBC(0x12c)
        REGMBC(0x12e) REGMBC(0x130) REGMBC(0x1cf)
        REGMBC(0x1ec8)
        return;
      case 'J': CASEMBC(0x134)
        regmbc('J'); REGMBC(0x134)
        return;
      case 'K': CASEMBC(0x136) CASEMBC(0x1e8) CASEMBC(0x1e30)
        CASEMBC(0x1e34)
        regmbc('K'); REGMBC(0x136) REGMBC(0x1e8)
        REGMBC(0x1e30) REGMBC(0x1e34)
        return;
      case 'L': CASEMBC(0x139) CASEMBC(0x13b) CASEMBC(0x13d)
        CASEMBC(0x13f) CASEMBC(0x141) CASEMBC(0x1e3a)
        regmbc('L'); REGMBC(0x139) REGMBC(0x13b)
        REGMBC(0x13d) REGMBC(0x13f) REGMBC(0x141)
        REGMBC(0x1e3a)
        return;
      case 'M': CASEMBC(0x1e3e) CASEMBC(0x1e40)
        regmbc('M'); REGMBC(0x1e3e) REGMBC(0x1e40)
        return;
      case 'N': case '\321':
        CASEMBC(0x143) CASEMBC(0x145) CASEMBC(0x147) CASEMBC(0x1e44)
        CASEMBC(0x1e48)
        regmbc('N'); regmbc('\321');
        REGMBC(0x143) REGMBC(0x145) REGMBC(0x147)
        REGMBC(0x1e44) REGMBC(0x1e48)
        return;
      case 'O': case '\322': case '\323': case '\324': case '\325':
      case '\326': case '\330':
        CASEMBC(0x14c) CASEMBC(0x14e) CASEMBC(0x150) CASEMBC(0x1a0)
        CASEMBC(0x1d1) CASEMBC(0x1ea) CASEMBC(0x1ec) CASEMBC(0x1ece)
        regmbc('O'); regmbc('\322'); regmbc('\323');
        regmbc('\324'); regmbc('\325'); regmbc('\326');
        regmbc('\330');
        REGMBC(0x14c) REGMBC(0x14e) REGMBC(0x150)
        REGMBC(0x1a0) REGMBC(0x1d1) REGMBC(0x1ea)
        REGMBC(0x1ec) REGMBC(0x1ece)
        return;
      case 'P': case 0x1e54: case 0x1e56:
        regmbc('P'); REGMBC(0x1e54) REGMBC(0x1e56)
        return;
      case 'R': CASEMBC(0x154) CASEMBC(0x156) CASEMBC(0x158)
        CASEMBC(0x1e58) CASEMBC(0x1e5e)
        regmbc('R'); REGMBC(0x154) REGMBC(0x156) REGMBC(0x158)
        REGMBC(0x1e58) REGMBC(0x1e5e)
        return;
      case 'S': CASEMBC(0x15a) CASEMBC(0x15c) CASEMBC(0x15e)
        CASEMBC(0x160) CASEMBC(0x1e60)
        regmbc('S'); REGMBC(0x15a) REGMBC(0x15c)
        REGMBC(0x15e) REGMBC(0x160) REGMBC(0x1e60)
        return;
      case 'T': CASEMBC(0x162) CASEMBC(0x164) CASEMBC(0x166)
        CASEMBC(0x1e6a) CASEMBC(0x1e6e)
        regmbc('T'); REGMBC(0x162) REGMBC(0x164)
        REGMBC(0x166) REGMBC(0x1e6a) REGMBC(0x1e6e)
        return;
      case 'U': case '\331': case '\332': case '\333': case '\334':
        CASEMBC(0x168) CASEMBC(0x16a) CASEMBC(0x16c) CASEMBC(0x16e)
        CASEMBC(0x170) CASEMBC(0x172) CASEMBC(0x1af) CASEMBC(0x1d3)
        CASEMBC(0x1ee6)
        regmbc('U'); regmbc('\331'); regmbc('\332');
        regmbc('\333'); regmbc('\334');
        REGMBC(0x168) REGMBC(0x16a) REGMBC(0x16c)
        REGMBC(0x16e) REGMBC(0x170) REGMBC(0x172)
        REGMBC(0x1af) REGMBC(0x1d3) REGMBC(0x1ee6)
        return;
      case 'V': CASEMBC(0x1e7c)
        regmbc('V'); REGMBC(0x1e7c)
        return;
      case 'W': CASEMBC(0x174) CASEMBC(0x1e80) CASEMBC(0x1e82)
        CASEMBC(0x1e84) CASEMBC(0x1e86)
        regmbc('W'); REGMBC(0x174) REGMBC(0x1e80)
        REGMBC(0x1e82) REGMBC(0x1e84) REGMBC(0x1e86)
        return;
      case 'X': CASEMBC(0x1e8a) CASEMBC(0x1e8c)
        regmbc('X'); REGMBC(0x1e8a) REGMBC(0x1e8c)
        return;
      case 'Y': case '\335':
        CASEMBC(0x176) CASEMBC(0x178) CASEMBC(0x1e8e) CASEMBC(0x1ef2)
        CASEMBC(0x1ef6) CASEMBC(0x1ef8)
        regmbc('Y'); regmbc('\335');
        REGMBC(0x176) REGMBC(0x178) REGMBC(0x1e8e)
        REGMBC(0x1ef2) REGMBC(0x1ef6) REGMBC(0x1ef8)
        return;
      case 'Z': CASEMBC(0x179) CASEMBC(0x17b) CASEMBC(0x17d)
        CASEMBC(0x1b5) CASEMBC(0x1e90) CASEMBC(0x1e94)
        regmbc('Z'); REGMBC(0x179) REGMBC(0x17b)
        REGMBC(0x17d) REGMBC(0x1b5) REGMBC(0x1e90)
        REGMBC(0x1e94)
        return;
      case 'a': case '\340': case '\341': case '\342':
      case '\343': case '\344': case '\345':
        CASEMBC(0x101) CASEMBC(0x103) CASEMBC(0x105) CASEMBC(0x1ce)
        CASEMBC(0x1df) CASEMBC(0x1e1) CASEMBC(0x1ea3)
        regmbc('a'); regmbc('\340'); regmbc('\341');
        regmbc('\342'); regmbc('\343'); regmbc('\344');
        regmbc('\345');
        REGMBC(0x101) REGMBC(0x103) REGMBC(0x105)
        REGMBC(0x1ce) REGMBC(0x1df) REGMBC(0x1e1)
        REGMBC(0x1ea3)
        return;
      case 'b': CASEMBC(0x1e03) CASEMBC(0x1e07)
        regmbc('b'); REGMBC(0x1e03) REGMBC(0x1e07)
        return;
      case 'c': case '\347':
        CASEMBC(0x107) CASEMBC(0x109) CASEMBC(0x10b) CASEMBC(0x10d)
        regmbc('c'); regmbc('\347');
        REGMBC(0x107) REGMBC(0x109) REGMBC(0x10b)
        REGMBC(0x10d)
        return;
      case 'd': CASEMBC(0x10f) CASEMBC(0x111) CASEMBC(0x1d0b)
        CASEMBC(0x1e11)
        regmbc('d'); REGMBC(0x10f) REGMBC(0x111)
        REGMBC(0x1e0b) REGMBC(0x01e0f) REGMBC(0x1e11)
        return;
      case 'e': case '\350': case '\351': case '\352': case '\353':
        CASEMBC(0x113) CASEMBC(0x115) CASEMBC(0x117) CASEMBC(0x119)
        CASEMBC(0x11b) CASEMBC(0x1ebb) CASEMBC(0x1ebd)
        regmbc('e'); regmbc('\350'); regmbc('\351');
        regmbc('\352'); regmbc('\353');
        REGMBC(0x113) REGMBC(0x115) REGMBC(0x117)
        REGMBC(0x119) REGMBC(0x11b) REGMBC(0x1ebb)
        REGMBC(0x1ebd)
        return;
      case 'f': CASEMBC(0x1e1f)
        regmbc('f'); REGMBC(0x1e1f)
        return;
      case 'g': CASEMBC(0x11d) CASEMBC(0x11f) CASEMBC(0x121)
        CASEMBC(0x123) CASEMBC(0x1e5) CASEMBC(0x1e7) CASEMBC(0x1f5)
        CASEMBC(0x1e21)
        regmbc('g'); REGMBC(0x11d) REGMBC(0x11f)
        REGMBC(0x121) REGMBC(0x123) REGMBC(0x1e5)
        REGMBC(0x1e7) REGMBC(0x1f5) REGMBC(0x1e21)
        return;
      case 'h': CASEMBC(0x125) CASEMBC(0x127) CASEMBC(0x1e23)
        CASEMBC(0x1e27) CASEMBC(0x1e29) CASEMBC(0x1e96)
        regmbc('h'); REGMBC(0x125) REGMBC(0x127)
        REGMBC(0x1e23) REGMBC(0x1e27) REGMBC(0x1e29)
        REGMBC(0x1e96)
        return;
      case 'i': case '\354': case '\355': case '\356': case '\357':
        CASEMBC(0x129) CASEMBC(0x12b) CASEMBC(0x12d) CASEMBC(0x12f)
        CASEMBC(0x1d0) CASEMBC(0x1ec9)
        regmbc('i'); regmbc('\354'); regmbc('\355');
        regmbc('\356'); regmbc('\357');
        REGMBC(0x129) REGMBC(0x12b) REGMBC(0x12d)
        REGMBC(0x12f) REGMBC(0x1d0) REGMBC(0x1ec9)
        return;
      case 'j': CASEMBC(0x135) CASEMBC(0x1f0)
        regmbc('j'); REGMBC(0x135) REGMBC(0x1f0)
        return;
      case 'k': CASEMBC(0x137) CASEMBC(0x1e9) CASEMBC(0x1e31)
        CASEMBC(0x1e35)
        regmbc('k'); REGMBC(0x137) REGMBC(0x1e9)
        REGMBC(0x1e31) REGMBC(0x1e35)
        return;
      case 'l': CASEMBC(0x13a) CASEMBC(0x13c) CASEMBC(0x13e)
        CASEMBC(0x140) CASEMBC(0x142) CASEMBC(0x1e3b)
        regmbc('l'); REGMBC(0x13a) REGMBC(0x13c)
        REGMBC(0x13e) REGMBC(0x140) REGMBC(0x142)
        REGMBC(0x1e3b)
        return;
      case 'm': CASEMBC(0x1e3f) CASEMBC(0x1e41)
        regmbc('m'); REGMBC(0x1e3f) REGMBC(0x1e41)
        return;
      case 'n': case '\361':
        CASEMBC(0x144) CASEMBC(0x146) CASEMBC(0x148) CASEMBC(0x149)
        CASEMBC(0x1e45) CASEMBC(0x1e49)
        regmbc('n'); regmbc('\361');
        REGMBC(0x144) REGMBC(0x146) REGMBC(0x148)
        REGMBC(0x149) REGMBC(0x1e45) REGMBC(0x1e49)
        return;
      case 'o': case '\362': case '\363': case '\364': case '\365':
      case '\366': case '\370':
        CASEMBC(0x14d) CASEMBC(0x14f) CASEMBC(0x151) CASEMBC(0x1a1)
        CASEMBC(0x1d2) CASEMBC(0x1eb) CASEMBC(0x1ed) CASEMBC(0x1ecf)
        regmbc('o'); regmbc('\362'); regmbc('\363');
        regmbc('\364'); regmbc('\365'); regmbc('\366');
        regmbc('\370');
        REGMBC(0x14d) REGMBC(0x14f) REGMBC(0x151)
        REGMBC(0x1a1) REGMBC(0x1d2) REGMBC(0x1eb)
        REGMBC(0x1ed) REGMBC(0x1ecf)
        return;
      case 'p': CASEMBC(0x1e55) CASEMBC(0x1e57)
        regmbc('p'); REGMBC(0x1e55) REGMBC(0x1e57)
        return;
      case 'r': CASEMBC(0x155) CASEMBC(0x157) CASEMBC(0x159)
        CASEMBC(0x1e59) CASEMBC(0x1e5f)
        regmbc('r'); REGMBC(0x155) REGMBC(0x157) REGMBC(0x159)
        REGMBC(0x1e59) REGMBC(0x1e5f)
        return;
      case 's': CASEMBC(0x15b) CASEMBC(0x15d) CASEMBC(0x15f)
        CASEMBC(0x161) CASEMBC(0x1e61)
        regmbc('s'); REGMBC(0x15b) REGMBC(0x15d)
        REGMBC(0x15f) REGMBC(0x161) REGMBC(0x1e61)
        return;
      case 't': CASEMBC(0x163) CASEMBC(0x165) CASEMBC(0x167)
        CASEMBC(0x1e6b) CASEMBC(0x1e6f) CASEMBC(0x1e97)
        regmbc('t'); REGMBC(0x163) REGMBC(0x165) REGMBC(0x167)
        REGMBC(0x1e6b) REGMBC(0x1e6f) REGMBC(0x1e97)
        return;
      case 'u': case '\371': case '\372': case '\373': case '\374':
        CASEMBC(0x169) CASEMBC(0x16b) CASEMBC(0x16d) CASEMBC(0x16f)
        CASEMBC(0x171) CASEMBC(0x173) CASEMBC(0x1b0) CASEMBC(0x1d4)
        CASEMBC(0x1ee7)
        regmbc('u'); regmbc('\371'); regmbc('\372');
        regmbc('\373'); regmbc('\374');
        REGMBC(0x169) REGMBC(0x16b) REGMBC(0x16d)
        REGMBC(0x16f) REGMBC(0x171) REGMBC(0x173)
        REGMBC(0x1b0) REGMBC(0x1d4) REGMBC(0x1ee7)
        return;
      case 'v': CASEMBC(0x1e7d)
        regmbc('v'); REGMBC(0x1e7d)
        return;
      case 'w': CASEMBC(0x175) CASEMBC(0x1e81) CASEMBC(0x1e83)
        CASEMBC(0x1e85) CASEMBC(0x1e87) CASEMBC(0x1e98)
        regmbc('w'); REGMBC(0x175) REGMBC(0x1e81)
        REGMBC(0x1e83) REGMBC(0x1e85) REGMBC(0x1e87)
        REGMBC(0x1e98)
        return;
      case 'x': CASEMBC(0x1e8b) CASEMBC(0x1e8d)
        regmbc('x'); REGMBC(0x1e8b) REGMBC(0x1e8d)
        return;
      case 'y': case '\375': case '\377':
        CASEMBC(0x177) CASEMBC(0x1e8f) CASEMBC(0x1e99)
        CASEMBC(0x1ef3) CASEMBC(0x1ef7) CASEMBC(0x1ef9)
        regmbc('y'); regmbc('\375'); regmbc('\377');
        REGMBC(0x177) REGMBC(0x1e8f) REGMBC(0x1e99)
        REGMBC(0x1ef3) REGMBC(0x1ef7) REGMBC(0x1ef9)
        return;
      case 'z': CASEMBC(0x17a) CASEMBC(0x17c) CASEMBC(0x17e)
        CASEMBC(0x1b6) CASEMBC(0x1e91) CASEMBC(0x1e95)
        regmbc('z'); REGMBC(0x17a) REGMBC(0x17c)
        REGMBC(0x17e) REGMBC(0x1b6) REGMBC(0x1e91)
        REGMBC(0x1e95)
        return;
      }
    }
    regmbc(c);
  }
  
  /*
   * Check for a collating element "[.a.]".  "pp" points to the '['.
   * Returns a character. Zero means that no item was recognized.  Otherwise
   * "pp" is advanced to after the item.
   * Currently only single characters are recognized!
   */
  static int get_coll_element(pp)
  char_u      **pp;
  {
    int c;
    int l = 1;
    char_u      *p = *pp;
  
    if (p[1] == '.') {
      if (has_mbyte)
        l = (*mb_ptr2len)(p + 2);
      if (p[l + 2] == '.' && p[l + 3] == ']') {
        if (has_mbyte)
          c = mb_ptr2char(p + 2);
        else
          c = p[2];
        *pp += l + 4;
        return c;
      }
    }
    return 0;
  }
  
  static void get_cpo_flags __ARGS((void));
  static int reg_cpo_lit; /* 'cpoptions' contains 'l' flag */
  static int reg_cpo_bsl; /* 'cpoptions' contains '\' flag */
  
  static void get_cpo_flags()                 {
    reg_cpo_lit = vim_strchr(p_cpo, CPO_LITERAL) != NULL;
    reg_cpo_bsl = vim_strchr(p_cpo, CPO_BACKSL) != NULL;
  }
  
  /*
   * Skip over a "[]" range.
   * "p" must point to the character after the '['.
   * The returned pointer is on the matching ']', or the terminating NUL.
   */
  static char_u * skip_anyof(p)
  char_u      *p;
  {
    int l;
  
    if (*p == '^')        /* Complement of range. */
      ++p;
    if (*p == ']' || *p == '-')
      ++p;
    while (*p != NUL && *p != ']') {
      if (has_mbyte && (l = (*mb_ptr2len)(p)) > 1)
        p += l;
      else if (*p == '-')  {
        ++p;
        if (*p != ']' && *p != NUL)
          mb_ptr_adv(p);
      } else if (*p == '\\'
                 && !reg_cpo_bsl
                 && (vim_strchr(REGEXP_INRANGE, p[1]) != NULL
                     || (!reg_cpo_lit && vim_strchr(REGEXP_ABBR, p[1]) != NULL)))
        p += 2;
      else if (*p == '[') {
        if (get_char_class(&p) == CLASS_NONE
            && get_equi_class(&p) == 0
            && get_coll_element(&p) == 0)
          ++p;         /* It was not a class name */
      } else
        ++p;
    }
  
    return p;
  }
  
  /*
   * Skip past regular expression.
   * Stop at end of "startp" or where "dirc" is found ('/', '?', etc).
   * Take care of characters with a backslash in front of it.
   * Skip strings inside [ and ].
   * When "newp" is not NULL and "dirc" is '?', make an allocated copy of the
   * expression and change "\?" to "?".  If "*newp" is not NULL the expression
   * is changed in-place.
   */
  char_u * skip_regexp(startp, dirc, magic, newp)
  char_u      *startp;
  int dirc;
  int magic;
  char_u      **newp;
  {
    int mymagic;
    char_u      *p = startp;
  
    if (magic)
      mymagic = MAGIC_ON;
    else
      mymagic = MAGIC_OFF;
    get_cpo_flags();
  
    for (; p[0] != NUL; mb_ptr_adv(p)) {
      if (p[0] == dirc)           /* found end of regexp */
        break;
      if ((p[0] == '[' && mymagic >= MAGIC_ON)
          || (p[0] == '\\' && p[1] == '[' && mymagic <= MAGIC_OFF)) {
        p = skip_anyof(p + 1);
        if (p[0] == NUL)
          break;
      } else if (p[0] == '\\' && p[1] != NUL)   {
        if (dirc == '?' && newp != NULL && p[1] == '?') {
          /* change "\?" to "?", make a copy first. */
          if (*newp == NULL) {
            *newp = vim_strsave(startp);
            if (*newp != NULL)
              p = *newp + (p - startp);
          }
          if (*newp != NULL)
            STRMOVE(p, p + 1);
          else
            ++p;
        } else
          ++p;            /* skip next character */
        if (*p == 'v')
          mymagic = MAGIC_ALL;
        else if (*p == 'V')
          mymagic = MAGIC_NONE;
      }
    }
    return p;
  }
  
  static regprog_T  *bt_regcomp __ARGS((char_u *expr, int re_flags));
  static void bt_regfree __ARGS((regprog_T *prog));
  
  /*
   * bt_regcomp() - compile a regular expression into internal code for the
   * traditional back track matcher.
   * Returns the program in allocated space.  Returns NULL for an error.
   *
   * We can't allocate space until we know how big the compiled form will be,
   * but we can't compile it (and thus know how big it is) until we've got a
   * place to put the code.  So we cheat:  we compile it twice, once with code
   * generation turned off and size counting turned on, and once "for real".
   * This also means that we don't allocate space until we are sure that the
   * thing really will compile successfully, and we never have to move the
   * code and thus invalidate pointers into it.  (Note that it has to be in
   * one piece because vim_free() must be able to free it all.)
   *
   * Whether upper/lower case is to be ignored is decided when executing the
   * program, it does not matter here.
   *
   * Beware that the optimization-preparation code in here knows about some
   * of the structure of the compiled regexp.
   * "re_flags": RE_MAGIC and/or RE_STRING.
   */
  static regprog_T * bt_regcomp(expr, re_flags)
  char_u      *expr;
  int re_flags;
  {
    bt_regprog_T    *r;
    char_u      *scan;
    char_u      *longest;
    int len;
    int flags;
  
    if (expr == NULL)
      EMSG_RET_NULL(_(e_null));
  
    init_class_tab();
  
    /*
     * First pass: determine size, legality.
     */
    regcomp_start(expr, re_flags);
    regcode = JUST_CALC_SIZE;
    regc(REGMAGIC);
    if (reg(REG_NOPAREN, &flags) == NULL)
      return NULL;
  
    /* Small enough for pointer-storage convention? */
  #ifdef SMALL_MALLOC             /* 16 bit storage allocation */
    if (regsize >= 65536L - 256L)
      EMSG_RET_NULL(_("E339: Pattern too long"));
  #endif
  
    /* Allocate space. */
    r = (bt_regprog_T *)lalloc(sizeof(bt_regprog_T) + regsize, TRUE);
    if (r == NULL)
      return NULL;
  
    /*
     * Second pass: emit code.
     */
    regcomp_start(expr, re_flags);
    regcode = r->program;
    regc(REGMAGIC);
    if (reg(REG_NOPAREN, &flags) == NULL || reg_toolong) {
      vim_free(r);
      if (reg_toolong)
        EMSG_RET_NULL(_("E339: Pattern too long"));
      return NULL;
    }
  
    /* Dig out information for optimizations. */
    r->regstart = NUL;            /* Worst-case defaults. */
    r->reganch = 0;
    r->regmust = NULL;
    r->regmlen = 0;
    r->regflags = regflags;
    if (flags & HASNL)
      r->regflags |= RF_HASNL;
    if (flags & HASLOOKBH)
      r->regflags |= RF_LOOKBH;
    /* Remember whether this pattern has any \z specials in it. */
    r->reghasz = re_has_z;
    scan = r->program + 1;        /* First BRANCH. */
    if (OP(regnext(scan)) == END) {   /* Only one top-level choice. */
      scan = OPERAND(scan);
  
      /* Starting-point info. */
      if (OP(scan) == BOL || OP(scan) == RE_BOF) {
        r->reganch++;
        scan = regnext(scan);
      }
  
      if (OP(scan) == EXACTLY) {
        if (has_mbyte)
          r->regstart = (*mb_ptr2char)(OPERAND(scan));
        else
          r->regstart = *OPERAND(scan);
      } else if ((OP(scan) == BOW
                  || OP(scan) == EOW
                  || OP(scan) == NOTHING
                  || OP(scan) == MOPEN + 0 || OP(scan) == NOPEN
                  || OP(scan) == MCLOSE + 0 || OP(scan) == NCLOSE)
                 && OP(regnext(scan)) == EXACTLY) {
        if (has_mbyte)
          r->regstart = (*mb_ptr2char)(OPERAND(regnext(scan)));
        else
          r->regstart = *OPERAND(regnext(scan));
      }
  
      /*
       * If there's something expensive in the r.e., find the longest
       * literal string that must appear and make it the regmust.  Resolve
       * ties in favor of later strings, since the regstart check works
       * with the beginning of the r.e. and avoiding duplication
       * strengthens checking.  Not a strong reason, but sufficient in the
       * absence of others.
       */
      /*
       * When the r.e. starts with BOW, it is faster to look for a regmust
       * first. Used a lot for "#" and "*" commands. (Added by mool).
       */
      if ((flags & SPSTART || OP(scan) == BOW || OP(scan) == EOW)
          && !(flags & HASNL)) {
        longest = NULL;
        len = 0;
        for (; scan != NULL; scan = regnext(scan))
          if (OP(scan) == EXACTLY && STRLEN(OPERAND(scan)) >= (size_t)len) {
            longest = OPERAND(scan);
            len = (int)STRLEN(OPERAND(scan));
          }
        r->regmust = longest;
        r->regmlen = len;
      }
    }
  #ifdef BT_REGEXP_DUMP
    regdump(expr, r);
  #endif
    r->engine = &bt_regengine;
    return (regprog_T *)r;
  }
  
  /*
   * Free a compiled regexp program, returned by bt_regcomp().
   */
  static void bt_regfree(prog)
  regprog_T   *prog;
  {
    vim_free(prog);
  }
  
  /*
   * Setup to parse the regexp.  Used once to get the length and once to do it.
   */
  static void regcomp_start(expr, re_flags)
  char_u      *expr;
  int re_flags;                       /* see vim_regcomp() */
  {
    initchr(expr);
    if (re_flags & RE_MAGIC)
      reg_magic = MAGIC_ON;
    else
      reg_magic = MAGIC_OFF;
    reg_string = (re_flags & RE_STRING);
    reg_strict = (re_flags & RE_STRICT);
    get_cpo_flags();
  
    num_complex_braces = 0;
    regnpar = 1;
    vim_memset(had_endbrace, 0, sizeof(had_endbrace));
    regnzpar = 1;
    re_has_z = 0;
    regsize = 0L;
    reg_toolong = FALSE;
    regflags = 0;
    had_eol = FALSE;
  }
  
  /*
   * Check if during the previous call to vim_regcomp the EOL item "$" has been
   * found.  This is messy, but it works fine.
   */
  int vim_regcomp_had_eol()         {
    return had_eol;
  }
  
  /*
   * Parse regular expression, i.e. main body or parenthesized thing.
   *
   * Caller must absorb opening parenthesis.
   *
   * Combining parenthesis handling with the base level of regular expression
   * is a trifle forced, but the need to tie the tails of the branches to what
   * follows makes it hard to avoid.
   */
  static char_u * reg(paren, flagp)
  int paren;              /* REG_NOPAREN, REG_PAREN, REG_NPAREN or REG_ZPAREN */
  int         *flagp;
  {
    char_u      *ret;
    char_u      *br;
    char_u      *ender;
    int parno = 0;
    int flags;
  
    *flagp = HASWIDTH;            /* Tentatively. */
  
    if (paren == REG_ZPAREN) {
      /* Make a ZOPEN node. */
      if (regnzpar >= NSUBEXP)
        EMSG_RET_NULL(_("E50: Too many \\z("));
      parno = regnzpar;
      regnzpar++;
      ret = regnode(ZOPEN + parno);
    } else if (paren == REG_PAREN)    {
      /* Make a MOPEN node. */
      if (regnpar >= NSUBEXP)
        EMSG2_RET_NULL(_("E51: Too many %s("), reg_magic == MAGIC_ALL);
      parno = regnpar;
      ++regnpar;
      ret = regnode(MOPEN + parno);
    } else if (paren == REG_NPAREN)   {
      /* Make a NOPEN node. */
      ret = regnode(NOPEN);
    } else
      ret = NULL;
  
    /* Pick up the branches, linking them together. */
    br = regbranch(&flags);
    if (br == NULL)
      return NULL;
    if (ret != NULL)
      regtail(ret, br);           /* [MZ]OPEN -> first. */
    else
      ret = br;
    /* If one of the branches can be zero-width, the whole thing can.
     * If one of the branches has * at start or matches a line-break, the
     * whole thing can. */
    if (!(flags & HASWIDTH))
      *flagp &= ~HASWIDTH;
    *flagp |= flags & (SPSTART | HASNL | HASLOOKBH);
    while (peekchr() == Magic('|')) {
      skipchr();
      br = regbranch(&flags);
      if (br == NULL || reg_toolong)
        return NULL;
      regtail(ret, br);           /* BRANCH -> BRANCH. */
      if (!(flags & HASWIDTH))
        *flagp &= ~HASWIDTH;
      *flagp |= flags & (SPSTART | HASNL | HASLOOKBH);
    }
  
    /* Make a closing node, and hook it on the end. */
    ender = regnode(
        paren == REG_ZPAREN ? ZCLOSE + parno :
        paren == REG_PAREN ? MCLOSE + parno :
        paren == REG_NPAREN ? NCLOSE : END);
    regtail(ret, ender);
  
    /* Hook the tails of the branches to the closing node. */
    for (br = ret; br != NULL; br = regnext(br))
      regoptail(br, ender);
  
    /* Check for proper termination. */
    if (paren != REG_NOPAREN && getchr() != Magic(')')) {
      if (paren == REG_ZPAREN)
        EMSG_RET_NULL(_("E52: Unmatched \\z("));
      else if (paren == REG_NPAREN)
        EMSG2_RET_NULL(_(e_unmatchedpp), reg_magic == MAGIC_ALL);
      else
        EMSG2_RET_NULL(_(e_unmatchedp), reg_magic == MAGIC_ALL);
    } else if (paren == REG_NOPAREN && peekchr() != NUL)   {
      if (curchr == Magic(')'))
        EMSG2_RET_NULL(_(e_unmatchedpar), reg_magic == MAGIC_ALL);
      else
        EMSG_RET_NULL(_(e_trailing));             /* "Can't happen". */
      /* NOTREACHED */
    }
    /*
     * Here we set the flag allowing back references to this set of
     * parentheses.
     */
    if (paren == REG_PAREN)
      had_endbrace[parno] = TRUE;         /* have seen the close paren */
    return ret;
  }
  
  /*
   * Parse one alternative of an | operator.
   * Implements the & operator.
   */
  static char_u * regbranch(flagp)
  int         *flagp;
  {
    char_u      *ret;
    char_u      *chain = NULL;
    char_u      *latest;
    int flags;
  
    *flagp = WORST | HASNL;               /* Tentatively. */
  
    ret = regnode(BRANCH);
    for (;; ) {
      latest = regconcat(&flags);
      if (latest == NULL)
        return NULL;
      /* If one of the branches has width, the whole thing has.  If one of
       * the branches anchors at start-of-line, the whole thing does.
       * If one of the branches uses look-behind, the whole thing does. */
      *flagp |= flags & (HASWIDTH | SPSTART | HASLOOKBH);
      /* If one of the branches doesn't match a line-break, the whole thing
       * doesn't. */
      *flagp &= ~HASNL | (flags & HASNL);
      if (chain != NULL)
        regtail(chain, latest);
      if (peekchr() != Magic('&'))
        break;
      skipchr();
      regtail(latest, regnode(END));     /* operand ends */
      if (reg_toolong)
        break;
      reginsert(MATCH, latest);
      chain = latest;
    }
  
    return ret;
  }
  
  /*
   * Parse one alternative of an | or & operator.
   * Implements the concatenation operator.
   */
  static char_u * regconcat(flagp)
  int         *flagp;
  {
    char_u      *first = NULL;
    char_u      *chain = NULL;
    char_u      *latest;
    int flags;
    int cont = TRUE;
  
    *flagp = WORST;               /* Tentatively. */
  
    while (cont) {
      switch (peekchr()) {
      case NUL:
      case Magic('|'):
      case Magic('&'):
      case Magic(')'):
        cont = FALSE;
        break;
      case Magic('Z'):
        regflags |= RF_ICOMBINE;
        skipchr_keepstart();
        break;
      case Magic('c'):
        regflags |= RF_ICASE;
        skipchr_keepstart();
        break;
      case Magic('C'):
        regflags |= RF_NOICASE;
        skipchr_keepstart();
        break;
      case Magic('v'):
        reg_magic = MAGIC_ALL;
        skipchr_keepstart();
        curchr = -1;
        break;
      case Magic('m'):
        reg_magic = MAGIC_ON;
        skipchr_keepstart();
        curchr = -1;
        break;
      case Magic('M'):
        reg_magic = MAGIC_OFF;
        skipchr_keepstart();
        curchr = -1;
        break;
      case Magic('V'):
        reg_magic = MAGIC_NONE;
        skipchr_keepstart();
        curchr = -1;
        break;
      default:
        latest = regpiece(&flags);
        if (latest == NULL || reg_toolong)
          return NULL;
        *flagp |= flags & (HASWIDTH | HASNL | HASLOOKBH);
        if (chain == NULL)                        /* First piece. */
          *flagp |= flags & SPSTART;
        else
          regtail(chain, latest);
        chain = latest;
        if (first == NULL)
          first = latest;
        break;
      }
    }
    if (first == NULL)            /* Loop ran zero times. */
      first = regnode(NOTHING);
    return first;
  }
  
  /*
   * Parse something followed by possible [*+=].
   *
   * Note that the branching code sequences used for = and the general cases
   * of * and + are somewhat optimized:  they use the same NOTHING node as
   * both the endmarker for their branch list and the body of the last branch.
   * It might seem that this node could be dispensed with entirely, but the
   * endmarker role is not redundant.
   */
  static char_u * regpiece(flagp)
  int             *flagp;
  {
    char_u          *ret;
    int op;
    char_u          *next;
    int flags;
    long minval;
    long maxval;
  
    ret = regatom(&flags);
    if (ret == NULL)
      return NULL;
  
    op = peekchr();
    if (re_multi_type(op) == NOT_MULTI) {
      *flagp = flags;
      return ret;
    }
    /* default flags */
    *flagp = (WORST | SPSTART | (flags & (HASNL | HASLOOKBH)));
  
    skipchr();
    switch (op) {
    case Magic('*'):
      if (flags & SIMPLE)
        reginsert(STAR, ret);
      else {
        /* Emit x* as (x&|), where & means "self". */
        reginsert(BRANCH, ret);           /* Either x */
        regoptail(ret, regnode(BACK));            /* and loop */
        regoptail(ret, ret);              /* back */
        regtail(ret, regnode(BRANCH));            /* or */
        regtail(ret, regnode(NOTHING));           /* null. */
      }
      break;
  
    case Magic('+'):
      if (flags & SIMPLE)
        reginsert(PLUS, ret);
      else {
        /* Emit x+ as x(&|), where & means "self". */
        next = regnode(BRANCH);           /* Either */
        regtail(ret, next);
        regtail(regnode(BACK), ret);              /* loop back */
        regtail(next, regnode(BRANCH));           /* or */
        regtail(ret, regnode(NOTHING));           /* null. */
      }
      *flagp = (WORST | HASWIDTH | (flags & (HASNL | HASLOOKBH)));
      break;
  
    case Magic('@'):
    {
      int lop = END;
      int nr;
  
      nr = getdecchrs();
      switch (no_Magic(getchr())) {
      case '=': lop = MATCH; break;                                 /* \@= */
      case '!': lop = NOMATCH; break;                               /* \@! */
      case '>': lop = SUBPAT; break;                                /* \@> */
      case '<': switch (no_Magic(getchr())) {
        case '=': lop = BEHIND; break;                               /* \@<= */
        case '!': lop = NOBEHIND; break;                             /* \@<! */
      }
      }
      if (lop == END)
        EMSG2_RET_NULL(_("E59: invalid character after %s@"),
            reg_magic == MAGIC_ALL);
      /* Look behind must match with behind_pos. */
      if (lop == BEHIND || lop == NOBEHIND) {
        regtail(ret, regnode(BHPOS));
        *flagp |= HASLOOKBH;
      }
      regtail(ret, regnode(END));             /* operand ends */
      if (lop == BEHIND || lop == NOBEHIND) {
        if (nr < 0)
          nr = 0;                 /* no limit is same as zero limit */
        reginsert_nr(lop, nr, ret);
      } else
        reginsert(lop, ret);
      break;
    }
  
    case Magic('?'):
    case Magic('='):
      /* Emit x= as (x|) */
      reginsert(BRANCH, ret);                     /* Either x */
      regtail(ret, regnode(BRANCH));              /* or */
      next = regnode(NOTHING);                    /* null. */
      regtail(ret, next);
      regoptail(ret, next);
      break;
  
    case Magic('{'):
      if (!read_limits(&minval, &maxval))
        return NULL;
      if (flags & SIMPLE) {
        reginsert(BRACE_SIMPLE, ret);
        reginsert_limits(BRACE_LIMITS, minval, maxval, ret);
      } else   {
        if (num_complex_braces >= 10)
          EMSG2_RET_NULL(_("E60: Too many complex %s{...}s"),
              reg_magic == MAGIC_ALL);
        reginsert(BRACE_COMPLEX + num_complex_braces, ret);
        regoptail(ret, regnode(BACK));
        regoptail(ret, ret);
        reginsert_limits(BRACE_LIMITS, minval, maxval, ret);
        ++num_complex_braces;
      }
      if (minval > 0 && maxval > 0)
        *flagp = (HASWIDTH | (flags & (HASNL | HASLOOKBH)));
      break;
    }
    if (re_multi_type(peekchr()) != NOT_MULTI) {
      /* Can't have a multi follow a multi. */
      if (peekchr() == Magic('*'))
        sprintf((char *)IObuff, _("E61: Nested %s*"),
            reg_magic >= MAGIC_ON ? "" : "\\");
      else
        sprintf((char *)IObuff, _("E62: Nested %s%c"),
            reg_magic == MAGIC_ALL ? "" : "\\", no_Magic(peekchr()));
      EMSG_RET_NULL(IObuff);
    }
  
    return ret;
  }
  
  /* When making changes to classchars also change nfa_classcodes. */
  static char_u   *classchars = (char_u *)".iIkKfFpPsSdDxXoOwWhHaAlLuU";
  static int classcodes[] = {
    ANY, IDENT, SIDENT, KWORD, SKWORD,
    FNAME, SFNAME, PRINT, SPRINT,
    WHITE, NWHITE, DIGIT, NDIGIT,
    HEX, NHEX, OCTAL, NOCTAL,
    WORD, NWORD, HEAD, NHEAD,
    ALPHA, NALPHA, LOWER, NLOWER,
    UPPER, NUPPER
  };
  
  /*
   * Parse the lowest level.
   *
   * Optimization:  gobbles an entire sequence of ordinary characters so that
   * it can turn them into a single node, which is smaller to store and
   * faster to run.  Don't do this when one_exactly is set.
   */
  static char_u * regatom(flagp)
  int            *flagp;
  {
    char_u          *ret;
    int flags;
    int c;
    char_u          *p;
    int extra = 0;
  
    *flagp = WORST;               /* Tentatively. */
  
    c = getchr();
    switch (c) {
    case Magic('^'):
      ret = regnode(BOL);
      break;
  
    case Magic('$'):
      ret = regnode(EOL);
      had_eol = TRUE;
      break;
  
    case Magic('<'):
      ret = regnode(BOW);
      break;
  
    case Magic('>'):
      ret = regnode(EOW);
      break;
  
    case Magic('_'):
      c = no_Magic(getchr());
      if (c == '^') {             /* "\_^" is start-of-line */
        ret = regnode(BOL);
        break;
      }
      if (c == '$') {             /* "\_$" is end-of-line */
        ret = regnode(EOL);
        had_eol = TRUE;
        break;
      }
  
      extra = ADD_NL;
      *flagp |= HASNL;
  
      /* "\_[" is character range plus newline */
      if (c == '[')
        goto collection;
  
    /* "\_x" is character class plus newline */
    /*FALLTHROUGH*/
  
    /*
     * Character classes.
     */
    case Magic('.'):
    case Magic('i'):
    case Magic('I'):
    case Magic('k'):
    case Magic('K'):
    case Magic('f'):
    case Magic('F'):
    case Magic('p'):
    case Magic('P'):
    case Magic('s'):
    case Magic('S'):
    case Magic('d'):
    case Magic('D'):
    case Magic('x'):
    case Magic('X'):
    case Magic('o'):
    case Magic('O'):
    case Magic('w'):
    case Magic('W'):
    case Magic('h'):
    case Magic('H'):
    case Magic('a'):
    case Magic('A'):
    case Magic('l'):
    case Magic('L'):
    case Magic('u'):
    case Magic('U'):
      p = vim_strchr(classchars, no_Magic(c));
      if (p == NULL)
        EMSG_RET_NULL(_("E63: invalid use of \\_"));
      /* When '.' is followed by a composing char ignore the dot, so that
       * the composing char is matched here. */
      if (enc_utf8 && c == Magic('.') && utf_iscomposing(peekchr())) {
        c = getchr();
        goto do_multibyte;
      }
      ret = regnode(classcodes[p - classchars] + extra);
      *flagp |= HASWIDTH | SIMPLE;
      break;
  
    case Magic('n'):
      if (reg_string) {
        /* In a string "\n" matches a newline character. */
        ret = regnode(EXACTLY);
        regc(NL);
        regc(NUL);
        *flagp |= HASWIDTH | SIMPLE;
      } else   {
        /* In buffer text "\n" matches the end of a line. */
        ret = regnode(NEWL);
        *flagp |= HASWIDTH | HASNL;
      }
      break;
  
    case Magic('('):
      if (one_exactly)
        EMSG_ONE_RET_NULL;
      ret = reg(REG_PAREN, &flags);
      if (ret == NULL)
        return NULL;
      *flagp |= flags & (HASWIDTH | SPSTART | HASNL | HASLOOKBH);
      break;
  
    case NUL:
    case Magic('|'):
    case Magic('&'):
    case Magic(')'):
      if (one_exactly)
        EMSG_ONE_RET_NULL;
      EMSG_RET_NULL(_(e_internal));       /* Supposed to be caught earlier. */
    /* NOTREACHED */
  
    case Magic('='):
    case Magic('?'):
    case Magic('+'):
    case Magic('@'):
    case Magic('{'):
    case Magic('*'):
      c = no_Magic(c);
      sprintf((char *)IObuff, _("E64: %s%c follows nothing"),
          (c == '*' ? reg_magic >= MAGIC_ON : reg_magic == MAGIC_ALL)
          ? "" : "\\", c);
      EMSG_RET_NULL(IObuff);
    /* NOTREACHED */
  
    case Magic('~'):              /* previous substitute pattern */
      if (reg_prev_sub != NULL) {
        char_u      *lp;
  
        ret = regnode(EXACTLY);
        lp = reg_prev_sub;
        while (*lp != NUL)
          regc(*lp++);
        regc(NUL);
        if (*reg_prev_sub != NUL) {
          *flagp |= HASWIDTH;
          if ((lp - reg_prev_sub) == 1)
            *flagp |= SIMPLE;
        }
      } else
        EMSG_RET_NULL(_(e_nopresub));
      break;
  
    case Magic('1'):
    case Magic('2'):
    case Magic('3'):
    case Magic('4'):
    case Magic('5'):
    case Magic('6'):
    case Magic('7'):
    case Magic('8'):
    case Magic('9'):
    {
      int refnum;
  
      refnum = c - Magic('0');
      /*
       * Check if the back reference is legal. We must have seen the
       * close brace.
       * TODO: Should also check that we don't refer to something
       * that is repeated (+*=): what instance of the repetition
       * should we match?
       */
      if (!had_endbrace[refnum]) {
        /* Trick: check if "@<=" or "@<!" follows, in which case
         * the \1 can appear before the referenced match. */
        for (p = regparse; *p != NUL; ++p)
          if (p[0] == '@' && p[1] == '<'
              && (p[2] == '!' || p[2] == '='))
            break;
        if (*p == NUL)
          EMSG_RET_NULL(_("E65: Illegal back reference"));
      }
      ret = regnode(BACKREF + refnum);
    }
    break;
  
    case Magic('z'):
    {
      c = no_Magic(getchr());
      switch (c) {
      case '(': if (reg_do_extmatch != REX_SET)
          EMSG_RET_NULL(_(e_z_not_allowed));
        if (one_exactly)
          EMSG_ONE_RET_NULL;
        ret = reg(REG_ZPAREN, &flags);
        if (ret == NULL)
          return NULL;
        *flagp |= flags & (HASWIDTH|SPSTART|HASNL|HASLOOKBH);
        re_has_z = REX_SET;
        break;
  
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9': if (reg_do_extmatch != REX_USE)
          EMSG_RET_NULL(_(e_z1_not_allowed));
        ret = regnode(ZREF + c - '0');
        re_has_z = REX_USE;
        break;
  
      case 's': ret = regnode(MOPEN + 0);
        break;
  
      case 'e': ret = regnode(MCLOSE + 0);
        break;
  
      default:  EMSG_RET_NULL(_("E68: Invalid character after \\z"));
      }
    }
    break;
  
    case Magic('%'):
    {
      c = no_Magic(getchr());
      switch (c) {
      /* () without a back reference */
      case '(':
        if (one_exactly)
          EMSG_ONE_RET_NULL;
        ret = reg(REG_NPAREN, &flags);
        if (ret == NULL)
          return NULL;
        *flagp |= flags & (HASWIDTH | SPSTART | HASNL | HASLOOKBH);
        break;
  
      /* Catch \%^ and \%$ regardless of where they appear in the
       * pattern -- regardless of whether or not it makes sense. */
      case '^':
        ret = regnode(RE_BOF);
        break;
  
      case '$':
        ret = regnode(RE_EOF);
        break;
  
      case '#':
        ret = regnode(CURSOR);
        break;
  
      case 'V':
        ret = regnode(RE_VISUAL);
        break;
  
      /* \%[abc]: Emit as a list of branches, all ending at the last
       * branch which matches nothing. */
      case '[':
        if (one_exactly)                          /* doesn't nest */
          EMSG_ONE_RET_NULL;
        {
          char_u    *lastbranch;
          char_u    *lastnode = NULL;
          char_u    *br;
  
          ret = NULL;
          while ((c = getchr()) != ']') {
            if (c == NUL)
              EMSG2_RET_NULL(_(e_missing_sb),
                  reg_magic == MAGIC_ALL);
            br = regnode(BRANCH);
            if (ret == NULL)
              ret = br;
            else
              regtail(lastnode, br);
  
            ungetchr();
            one_exactly = TRUE;
            lastnode = regatom(flagp);
            one_exactly = FALSE;
            if (lastnode == NULL)
              return NULL;
          }
          if (ret == NULL)
            EMSG2_RET_NULL(_(e_empty_sb),
                reg_magic == MAGIC_ALL);
          lastbranch = regnode(BRANCH);
          br = regnode(NOTHING);
          if (ret != JUST_CALC_SIZE) {
            regtail(lastnode, br);
            regtail(lastbranch, br);
            /* connect all branches to the NOTHING
             * branch at the end */
            for (br = ret; br != lastnode; ) {
              if (OP(br) == BRANCH) {
                regtail(br, lastbranch);
                br = OPERAND(br);
              } else
                br = regnext(br);
            }
          }
          *flagp &= ~(HASWIDTH | SIMPLE);
          break;
        }
  
      case 'd':               /* %d123 decimal */
      case 'o':               /* %o123 octal */
      case 'x':               /* %xab hex 2 */
      case 'u':               /* %uabcd hex 4 */
      case 'U':               /* %U1234abcd hex 8 */
      {
        int i;
  
        switch (c) {
        case 'd': i = getdecchrs(); break;
        case 'o': i = getoctchrs(); break;
        case 'x': i = gethexchrs(2); break;
        case 'u': i = gethexchrs(4); break;
        case 'U': i = gethexchrs(8); break;
        default:  i = -1; break;
        }
  
        if (i < 0)
          EMSG2_RET_NULL(
              _("E678: Invalid character after %s%%[dxouU]"),
              reg_magic == MAGIC_ALL);
        if (use_multibytecode(i))
          ret = regnode(MULTIBYTECODE);
        else
          ret = regnode(EXACTLY);
        if (i == 0)
          regc(0x0a);
        else
          regmbc(i);
        regc(NUL);
        *flagp |= HASWIDTH;
        break;
      }
  
      default:
        if (VIM_ISDIGIT(c) || c == '<' || c == '>'
            || c == '\'') {
          long_u n = 0;
          int cmp;
  
          cmp = c;
          if (cmp == '<' || cmp == '>')
            c = getchr();
          while (VIM_ISDIGIT(c)) {
            n = n * 10 + (c - '0');
            c = getchr();
          }
          if (c == '\'' && n == 0) {
            /* "\%'m", "\%<'m" and "\%>'m": Mark */
            c = getchr();
            ret = regnode(RE_MARK);
            if (ret == JUST_CALC_SIZE)
              regsize += 2;
            else {
              *regcode++ = c;
              *regcode++ = cmp;
            }
            break;
          } else if (c == 'l' || c == 'c' || c == 'v')   {
            if (c == 'l')
              ret = regnode(RE_LNUM);
            else if (c == 'c')
              ret = regnode(RE_COL);
            else
              ret = regnode(RE_VCOL);
            if (ret == JUST_CALC_SIZE)
              regsize += 5;
            else {
              /* put the number and the optional
               * comparator after the opcode */
              regcode = re_put_long(regcode, n);
              *regcode++ = cmp;
            }
            break;
          }
        }
  
        EMSG2_RET_NULL(_("E71: Invalid character after %s%%"),
            reg_magic == MAGIC_ALL);
      }
    }
    break;
  
    case Magic('['):
  collection:
      {
        char_u      *lp;
  
        /*
         * If there is no matching ']', we assume the '[' is a normal
         * character.  This makes 'incsearch' and ":help [" work.
         */
        lp = skip_anyof(regparse);
        if (*lp == ']') {         /* there is a matching ']' */
          int startc = -1;                /* > 0 when next '-' is a range */
          int endc;
  
          /*
           * In a character class, different parsing rules apply.
           * Not even \ is special anymore, nothing is.
           */
          if (*regparse == '^') {             /* Complement of range. */
            ret = regnode(ANYBUT + extra);
            regparse++;
          } else
            ret = regnode(ANYOF + extra);
  
          /* At the start ']' and '-' mean the literal character. */
          if (*regparse == ']' || *regparse == '-') {
            startc = *regparse;
            regc(*regparse++);
          }
  
          while (*regparse != NUL && *regparse != ']') {
            if (*regparse == '-') {
              ++regparse;
              /* The '-' is not used for a range at the end and
               * after or before a '\n'. */
              if (*regparse == ']' || *regparse == NUL
                  || startc == -1
                  || (regparse[0] == '\\' && regparse[1] == 'n')) {
                regc('-');
                startc = '-';                     /* [--x] is a range */
              } else   {
                /* Also accept "a-[.z.]" */
                endc = 0;
                if (*regparse == '[')
                  endc = get_coll_element(&regparse);
                if (endc == 0) {
                  if (has_mbyte)
                    endc = mb_ptr2char_adv(&regparse);
                  else
                    endc = *regparse++;
                }
  
                /* Handle \o40, \x20 and \u20AC style sequences */
                if (endc == '\\' && !reg_cpo_lit && !reg_cpo_bsl)
                  endc = coll_get_char();
  
                if (startc > endc)
                  EMSG_RET_NULL(_(e_invrange));
                if (has_mbyte && ((*mb_char2len)(startc) > 1
                                  || (*mb_char2len)(endc) > 1)) {
                  /* Limit to a range of 256 chars */
                  if (endc > startc + 256)
                    EMSG_RET_NULL(_(e_invrange));
                  while (++startc <= endc)
                    regmbc(startc);
                } else   {
                  while (++startc <= endc)
                    regc(startc);
                }
                startc = -1;
              }
            }
            /*
             * Only "\]", "\^", "\]" and "\\" are special in Vi.  Vim
             * accepts "\t", "\e", etc., but only when the 'l' flag in
             * 'cpoptions' is not included.
             * Posix doesn't recognize backslash at all.
             */
            else if (*regparse == '\\'
                     && !reg_cpo_bsl
                     && (vim_strchr(REGEXP_INRANGE, regparse[1]) != NULL
                         || (!reg_cpo_lit
                             && vim_strchr(REGEXP_ABBR,
                                 regparse[1]) != NULL))) {
              regparse++;
              if (*regparse == 'n') {
                /* '\n' in range: also match NL */
                if (ret != JUST_CALC_SIZE) {
                  /* Using \n inside [^] does not change what
                   * matches. "[^\n]" is the same as ".". */
                  if (*ret == ANYOF) {
                    *ret = ANYOF + ADD_NL;
                    *flagp |= HASNL;
                  }
                  /* else: must have had a \n already */
                }
                regparse++;
                startc = -1;
              } else if (*regparse == 'd'
                         || *regparse == 'o'
                         || *regparse == 'x'
                         || *regparse == 'u'
                         || *regparse == 'U') {
                startc = coll_get_char();
                if (startc == 0)
                  regc(0x0a);
                else
                  regmbc(startc);
              } else   {
                startc = backslash_trans(*regparse++);
                regc(startc);
              }
            } else if (*regparse == '[')   {
              int c_class;
              int cu;
  
              c_class = get_char_class(&regparse);
              startc = -1;
              /* Characters assumed to be 8 bits! */
              switch (c_class) {
              case CLASS_NONE:
                c_class = get_equi_class(&regparse);
                if (c_class != 0) {
                  /* produce equivalence class */
                  reg_equi_class(c_class);
                } else if ((c_class =
                              get_coll_element(&regparse)) != 0) {
                  /* produce a collating element */
                  regmbc(c_class);
                } else   {
                  /* literal '[', allow [[-x] as a range */
                  startc = *regparse++;
                  regc(startc);
                }
                break;
              case CLASS_ALNUM:
                for (cu = 1; cu <= 255; cu++)
                  if (isalnum(cu))
                    regc(cu);
                break;
              case CLASS_ALPHA:
                for (cu = 1; cu <= 255; cu++)
                  if (isalpha(cu))
                    regc(cu);
                break;
              case CLASS_BLANK:
                regc(' ');
                regc('\t');
                break;
              case CLASS_CNTRL:
                for (cu = 1; cu <= 255; cu++)
                  if (iscntrl(cu))
                    regc(cu);
                break;
              case CLASS_DIGIT:
                for (cu = 1; cu <= 255; cu++)
                  if (VIM_ISDIGIT(cu))
                    regc(cu);
                break;
              case CLASS_GRAPH:
                for (cu = 1; cu <= 255; cu++)
                  if (isgraph(cu))
                    regc(cu);
                break;
              case CLASS_LOWER:
                for (cu = 1; cu <= 255; cu++)
                  if (MB_ISLOWER(cu))
                    regc(cu);
                break;
              case CLASS_PRINT:
                for (cu = 1; cu <= 255; cu++)
                  if (vim_isprintc(cu))
                    regc(cu);
                break;
              case CLASS_PUNCT:
                for (cu = 1; cu <= 255; cu++)
                  if (ispunct(cu))
                    regc(cu);
                break;
              case CLASS_SPACE:
                for (cu = 9; cu <= 13; cu++)
                  regc(cu);
                regc(' ');
                break;
              case CLASS_UPPER:
                for (cu = 1; cu <= 255; cu++)
                  if (MB_ISUPPER(cu))
                    regc(cu);
                break;
              case CLASS_XDIGIT:
                for (cu = 1; cu <= 255; cu++)
                  if (vim_isxdigit(cu))
                    regc(cu);
                break;
              case CLASS_TAB:
                regc('\t');
                break;
              case CLASS_RETURN:
                regc('\r');
                break;
              case CLASS_BACKSPACE:
                regc('\b');
                break;
              case CLASS_ESCAPE:
                regc('\033');
                break;
              }
            } else   {
              if (has_mbyte) {
                int len;
  
                /* produce a multibyte character, including any
                 * following composing characters */
                startc = mb_ptr2char(regparse);
                len = (*mb_ptr2len)(regparse);
                if (enc_utf8 && utf_char2len(startc) != len)
                  startc = -1;                    /* composing chars */
                while (--len >= 0)
                  regc(*regparse++);
              } else   {
                startc = *regparse++;
                regc(startc);
              }
            }
          }
          regc(NUL);
          prevchr_len = 1;                /* last char was the ']' */
          if (*regparse != ']')
            EMSG_RET_NULL(_(e_toomsbra));                 /* Cannot happen? */
          skipchr();                  /* let's be friends with the lexer again */
          *flagp |= HASWIDTH | SIMPLE;
          break;
        } else if (reg_strict)
          EMSG2_RET_NULL(_(e_missingbracket), reg_magic > MAGIC_OFF);
      }
    /* FALLTHROUGH */
  
    default:
    {
      int len;
  
      /* A multi-byte character is handled as a separate atom if it's
       * before a multi and when it's a composing char. */
      if (use_multibytecode(c)) {
  do_multibyte:
        ret = regnode(MULTIBYTECODE);
        regmbc(c);
        *flagp |= HASWIDTH | SIMPLE;
        break;
      }
  
      ret = regnode(EXACTLY);
  
      /*
       * Append characters as long as:
       * - there is no following multi, we then need the character in
       *   front of it as a single character operand
       * - not running into a Magic character
       * - "one_exactly" is not set
       * But always emit at least one character.  Might be a Multi,
       * e.g., a "[" without matching "]".
       */
      for (len = 0; c != NUL && (len == 0
                                 || (re_multi_type(peekchr()) == NOT_MULTI
                                     && !one_exactly
                                     && !is_Magic(c))); ++len) {
        c = no_Magic(c);
        if (has_mbyte) {
          regmbc(c);
          if (enc_utf8) {
            int l;
  
            /* Need to get composing character too. */
            for (;; ) {
              l = utf_ptr2len(regparse);
              if (!UTF_COMPOSINGLIKE(regparse, regparse + l))
                break;
              regmbc(utf_ptr2char(regparse));
              skipchr();
            }
          }
        } else
          regc(c);
        c = getchr();
      }
      ungetchr();
  
      regc(NUL);
      *flagp |= HASWIDTH;
      if (len == 1)
        *flagp |= SIMPLE;
    }
    break;
    }
  
    return ret;
  }
  
  /*
   * Return TRUE if MULTIBYTECODE should be used instead of EXACTLY for
   * character "c".
   */
  static int use_multibytecode(c)
  int c;
  {
    return has_mbyte && (*mb_char2len)(c) > 1
           && (re_multi_type(peekchr()) != NOT_MULTI
               || (enc_utf8 && utf_iscomposing(c)));
  }
  
  /*
   * Emit a node.
   * Return pointer to generated code.
   */
  static char_u * regnode(op)
  int op;
  {
    char_u  *ret;
  
    ret = regcode;
    if (ret == JUST_CALC_SIZE)
      regsize += 3;
    else {
      *regcode++ = op;
      *regcode++ = NUL;                   /* Null "next" pointer. */
      *regcode++ = NUL;
    }
    return ret;
  }
  
  /*
   * Emit (if appropriate) a byte of code
   */
  static void regc(b)
  int b;
  {
    if (regcode == JUST_CALC_SIZE)
      regsize++;
    else
      *regcode++ = b;
  }
  
  /*
   * Emit (if appropriate) a multi-byte character of code
   */
  static void regmbc(c)
  int c;
  {
    if (!has_mbyte && c > 0xff)
      return;
    if (regcode == JUST_CALC_SIZE)
      regsize += (*mb_char2len)(c);
    else
      regcode += (*mb_char2bytes)(c, regcode);
  }
  
  /*
   * Insert an operator in front of already-emitted operand
   *
   * Means relocating the operand.
   */
  static void reginsert(op, opnd)
  int op;
  char_u     *opnd;
  {
    char_u      *src;
    char_u      *dst;
    char_u      *place;
  
    if (regcode == JUST_CALC_SIZE) {
      regsize += 3;
      return;
    }
    src = regcode;
    regcode += 3;
    dst = regcode;
    while (src > opnd)
      *--dst = *--src;
  
    place = opnd;                 /* Op node, where operand used to be. */
    *place++ = op;
    *place++ = NUL;
    *place = NUL;
  }
  
  /*
   * Insert an operator in front of already-emitted operand.
   * Add a number to the operator.
   */
  static void reginsert_nr(op, val, opnd)
  int op;
  long val;
  char_u      *opnd;
  {
    char_u      *src;
    char_u      *dst;
    char_u      *place;
  
    if (regcode == JUST_CALC_SIZE) {
      regsize += 7;
      return;
    }
    src = regcode;
    regcode += 7;
    dst = regcode;
    while (src > opnd)
      *--dst = *--src;
  
    place = opnd;                 /* Op node, where operand used to be. */
    *place++ = op;
    *place++ = NUL;
    *place++ = NUL;
    place = re_put_long(place, (long_u)val);
  }
  
  /*
   * Insert an operator in front of already-emitted operand.
   * The operator has the given limit values as operands.  Also set next pointer.
   *
   * Means relocating the operand.
   */
  static void reginsert_limits(op, minval, maxval, opnd)
  int op;
  long minval;
  long maxval;
  char_u      *opnd;
  {
    char_u      *src;
    char_u      *dst;
    char_u      *place;
  
    if (regcode == JUST_CALC_SIZE) {
      regsize += 11;
      return;
    }
    src = regcode;
    regcode += 11;
    dst = regcode;
    while (src > opnd)
      *--dst = *--src;
  
    place = opnd;                 /* Op node, where operand used to be. */
    *place++ = op;
    *place++ = NUL;
    *place++ = NUL;
    place = re_put_long(place, (long_u)minval);
    place = re_put_long(place, (long_u)maxval);
    regtail(opnd, place);
  }
  
  /*
   * Write a long as four bytes at "p" and return pointer to the next char.
   */
  static char_u * re_put_long(p, val)
  char_u      *p;
  long_u val;
  {
    *p++ = (char_u) ((val >> 24) & 0377);
    *p++ = (char_u) ((val >> 16) & 0377);
    *p++ = (char_u) ((val >> 8) & 0377);
    *p++ = (char_u) (val & 0377);
    return p;
  }
  
  /*
   * Set the next-pointer at the end of a node chain.
   */
  static void regtail(p, val)
  char_u      *p;
  char_u      *val;
  {
    char_u      *scan;
    char_u      *temp;
    int offset;
  
    if (p == JUST_CALC_SIZE)
      return;
  
    /* Find last node. */
    scan = p;
    for (;; ) {
      temp = regnext(scan);
      if (temp == NULL)
        break;
      scan = temp;
    }
  
    if (OP(scan) == BACK)
      offset = (int)(scan - val);
    else
      offset = (int)(val - scan);
    /* When the offset uses more than 16 bits it can no longer fit in the two
     * bytes available.  Use a global flag to avoid having to check return
     * values in too many places. */
    if (offset > 0xffff)
      reg_toolong = TRUE;
    else {
      *(scan + 1) = (char_u) (((unsigned)offset >> 8) & 0377);
      *(scan + 2) = (char_u) (offset & 0377);
    }
  }
  
  /*
   * Like regtail, on item after a BRANCH; nop if none.
   */
  static void regoptail(p, val)
  char_u      *p;
  char_u      *val;
  {
    /* When op is neither BRANCH nor BRACE_COMPLEX0-9, it is "operandless" */
    if (p == NULL || p == JUST_CALC_SIZE
        || (OP(p) != BRANCH
            && (OP(p) < BRACE_COMPLEX || OP(p) > BRACE_COMPLEX + 9)))
      return;
    regtail(OPERAND(p), val);
  }
  
  /*
   * Functions for getting characters from the regexp input.
   */
  
  static int at_start;            /* True when on the first character */
  static int prev_at_start;       /* True when on the second character */
  
  /*
   * Start parsing at "str".
   */
  static void initchr(str)
  char_u *str;
  {
    regparse = str;
    prevchr_len = 0;
    curchr = prevprevchr = prevchr = nextchr = -1;
    at_start = TRUE;
    prev_at_start = FALSE;
  }
  
  /*
   * Save the current parse state, so that it can be restored and parsing
   * starts in the same state again.
   */
  static void save_parse_state(ps)
  parse_state_T *ps;
  {
    ps->regparse = regparse;
    ps->prevchr_len = prevchr_len;
    ps->curchr = curchr;
    ps->prevchr = prevchr;
    ps->prevprevchr = prevprevchr;
    ps->nextchr = nextchr;
    ps->at_start = at_start;
    ps->prev_at_start = prev_at_start;
    ps->regnpar = regnpar;
  }
  
  /*
   * Restore a previously saved parse state.
   */
  static void restore_parse_state(ps)
  parse_state_T *ps;
  {
    regparse = ps->regparse;
    prevchr_len = ps->prevchr_len;
    curchr = ps->curchr;
    prevchr = ps->prevchr;
    prevprevchr = ps->prevprevchr;
    nextchr = ps->nextchr;
    at_start = ps->at_start;
    prev_at_start = ps->prev_at_start;
    regnpar = ps->regnpar;
  }
  
  
  /*
   * Get the next character without advancing.
   */
  static int peekchr()                {
    static int after_slash = FALSE;
  
    if (curchr == -1) {
      switch (curchr = regparse[0]) {
      case '.':
      case '[':
      case '~':
        /* magic when 'magic' is on */
        if (reg_magic >= MAGIC_ON)
          curchr = Magic(curchr);
        break;
      case '(':
      case ')':
      case '{':
      case '%':
      case '+':
      case '=':
      case '?':
      case '@':
      case '!':
      case '&':
      case '|':
      case '<':
      case '>':
      case '#':           /* future ext. */
      case '"':           /* future ext. */
      case '\'':          /* future ext. */
      case ',':           /* future ext. */
      case '-':           /* future ext. */
      case ':':           /* future ext. */
      case ';':           /* future ext. */
      case '`':           /* future ext. */
      case '/':           /* Can't be used in / command */
        /* magic only after "\v" */
        if (reg_magic == MAGIC_ALL)
          curchr = Magic(curchr);
        break;
      case '*':
        /* * is not magic as the very first character, eg "?*ptr", when
         * after '^', eg "/^*ptr" and when after "\(", "\|", "\&".  But
         * "\(\*" is not magic, thus must be magic if "after_slash" */
        if (reg_magic >= MAGIC_ON
            && !at_start
            && !(prev_at_start && prevchr == Magic('^'))
            && (after_slash
                || (prevchr != Magic('(')
                    && prevchr != Magic('&')
                    && prevchr != Magic('|'))))
          curchr = Magic('*');
        break;
      case '^':
        /* '^' is only magic as the very first character and if it's after
         * "\(", "\|", "\&' or "\n" */
        if (reg_magic >= MAGIC_OFF
            && (at_start
                || reg_magic == MAGIC_ALL
                || prevchr == Magic('(')
                || prevchr == Magic('|')
                || prevchr == Magic('&')
                || prevchr == Magic('n')
                || (no_Magic(prevchr) == '('
                    && prevprevchr == Magic('%')))) {
          curchr = Magic('^');
          at_start = TRUE;
          prev_at_start = FALSE;
        }
        break;
      case '$':
        /* '$' is only magic as the very last char and if it's in front of
         * either "\|", "\)", "\&", or "\n" */
        if (reg_magic >= MAGIC_OFF) {
          char_u *p = regparse + 1;
  
          /* ignore \c \C \m and \M after '$' */
          while (p[0] == '\\' && (p[1] == 'c' || p[1] == 'C'
                                  || p[1] == 'm' || p[1] == 'M' || p[1] == 'Z'))
            p += 2;
          if (p[0] == NUL
              || (p[0] == '\\'
                  && (p[1] == '|' || p[1] == '&' || p[1] == ')'
                      || p[1] == 'n'))
              || reg_magic == MAGIC_ALL)
            curchr = Magic('$');
        }
        break;
      case '\\':
      {
        int c = regparse[1];
  
        if (c == NUL)
          curchr = '\\';                  /* trailing '\' */
        else if (
          c <= '~' && META_flags[c]
          ) {
          /*
           * META contains everything that may be magic sometimes,
           * except ^ and $ ("\^" and "\$" are only magic after
           * "\v").  We now fetch the next character and toggle its
           * magicness.  Therefore, \ is so meta-magic that it is
           * not in META.
           */
          curchr = -1;
          prev_at_start = at_start;
          at_start = FALSE;               /* be able to say "/\*ptr" */
          ++regparse;
          ++after_slash;
          peekchr();
          --regparse;
          --after_slash;
          curchr = toggle_Magic(curchr);
        } else if (vim_strchr(REGEXP_ABBR, c))   {
          /*
           * Handle abbreviations, like "\t" for TAB -- webb
           */
          curchr = backslash_trans(c);
        } else if (reg_magic == MAGIC_NONE && (c == '$' || c == '^'))
          curchr = toggle_Magic(c);
        else {
          /*
           * Next character can never be (made) magic?
           * Then backslashing it won't do anything.
           */
          if (has_mbyte)
            curchr = (*mb_ptr2char)(regparse + 1);
          else
            curchr = c;
        }
        break;
      }
  
      default:
        if (has_mbyte)
          curchr = (*mb_ptr2char)(regparse);
      }
    }
  
    return curchr;
  }
  
  /*
   * Eat one lexed character.  Do this in a way that we can undo it.
   */
  static void skipchr()                 {
    /* peekchr() eats a backslash, do the same here */
    if (*regparse == '\\')
      prevchr_len = 1;
    else
      prevchr_len = 0;
    if (regparse[prevchr_len] != NUL) {
      if (enc_utf8)
        /* exclude composing chars that mb_ptr2len does include */
        prevchr_len += utf_ptr2len(regparse + prevchr_len);
      else if (has_mbyte)
        prevchr_len += (*mb_ptr2len)(regparse + prevchr_len);
      else
        ++prevchr_len;
    }
    regparse += prevchr_len;
    prev_at_start = at_start;
    at_start = FALSE;
    prevprevchr = prevchr;
    prevchr = curchr;
    curchr = nextchr;         /* use previously unget char, or -1 */
    nextchr = -1;
  }
  
  /*
   * Skip a character while keeping the value of prev_at_start for at_start.
   * prevchr and prevprevchr are also kept.
   */
  static void skipchr_keepstart()                 {
    int as = prev_at_start;
    int pr = prevchr;
    int prpr = prevprevchr;
  
    skipchr();
    at_start = as;
    prevchr = pr;
    prevprevchr = prpr;
  }
  
  /*
   * Get the next character from the pattern. We know about magic and such, so
   * therefore we need a lexical analyzer.
   */
  static int getchr()                {
    int chr = peekchr();
  
    skipchr();
    return chr;
  }
  
  /*
   * put character back.  Works only once!
   */
  static void ungetchr()                 {
    nextchr = curchr;
    curchr = prevchr;
    prevchr = prevprevchr;
    at_start = prev_at_start;
    prev_at_start = FALSE;
  
    /* Backup regparse, so that it's at the same position as before the
     * getchr(). */
    regparse -= prevchr_len;
  }
  
  /*
   * Get and return the value of the hex string at the current position.
   * Return -1 if there is no valid hex number.
   * The position is updated:
   *     blahblah\%x20asdf
   *	   before-^ ^-after
   * The parameter controls the maximum number of input characters. This will be
   * 2 when reading a \%x20 sequence and 4 when reading a \%u20AC sequence.
   */
  static int gethexchrs(maxinputlen)
  int maxinputlen;
  {
    int nr = 0;
    int c;
    int i;
  
    for (i = 0; i < maxinputlen; ++i) {
      c = regparse[0];
      if (!vim_isxdigit(c))
        break;
      nr <<= 4;
      nr |= hex2nr(c);
      ++regparse;
    }
  
    if (i == 0)
      return -1;
    return nr;
  }
  
  /*
   * Get and return the value of the decimal string immediately after the
   * current position. Return -1 for invalid.  Consumes all digits.
   */
  static int getdecchrs()                {
    int nr = 0;
    int c;
    int i;
  
    for (i = 0;; ++i) {
      c = regparse[0];
      if (c < '0' || c > '9')
        break;
      nr *= 10;
      nr += c - '0';
      ++regparse;
      curchr = -1;     /* no longer valid */
    }
  
    if (i == 0)
      return -1;
    return nr;
  }
  
  /*
   * get and return the value of the octal string immediately after the current
   * position. Return -1 for invalid, or 0-255 for valid. Smart enough to handle
   * numbers > 377 correctly (for example, 400 is treated as 40) and doesn't
   * treat 8 or 9 as recognised characters. Position is updated:
   *     blahblah\%o210asdf
   *	   before-^  ^-after
   */
  static int getoctchrs()                {
    int nr = 0;
    int c;
    int i;
  
    for (i = 0; i < 3 && nr < 040; ++i) {
      c = regparse[0];
      if (c < '0' || c > '7')
        break;
      nr <<= 3;
      nr |= hex2nr(c);
      ++regparse;
    }
  
    if (i == 0)
      return -1;
    return nr;
  }
  
  /*
   * Get a number after a backslash that is inside [].
   * When nothing is recognized return a backslash.
   */
  static int coll_get_char()                {
    int nr = -1;
  
    switch (*regparse++) {
    case 'd': nr = getdecchrs(); break;
    case 'o': nr = getoctchrs(); break;
    case 'x': nr = gethexchrs(2); break;
    case 'u': nr = gethexchrs(4); break;
    case 'U': nr = gethexchrs(8); break;
    }
    if (nr < 0) {
      /* If getting the number fails be backwards compatible: the character
       * is a backslash. */
      --regparse;
      nr = '\\';
    }
    return nr;
  }
  
  /*
   * read_limits - Read two integers to be taken as a minimum and maximum.
   * If the first character is '-', then the range is reversed.
   * Should end with 'end'.  If minval is missing, zero is default, if maxval is
   * missing, a very big number is the default.
   */
  static int read_limits(minval, maxval)
  long        *minval;
  long        *maxval;
  {
    int reverse = FALSE;
    char_u      *first_char;
    long tmp;
  
    if (*regparse == '-') {
      /* Starts with '-', so reverse the range later */
      regparse++;
      reverse = TRUE;
    }
    first_char = regparse;
    *minval = getdigits(&regparse);
    if (*regparse == ',') {           /* There is a comma */
      if (vim_isdigit(*++regparse))
        *maxval = getdigits(&regparse);
      else
        *maxval = MAX_LIMIT;
    } else if (VIM_ISDIGIT(*first_char))
      *maxval = *minval;              /* It was \{n} or \{-n} */
    else
      *maxval = MAX_LIMIT;            /* It was \{} or \{-} */
    if (*regparse == '\\')
      regparse++;         /* Allow either \{...} or \{...\} */
    if (*regparse != '}') {
      sprintf((char *)IObuff, _("E554: Syntax error in %s{...}"),
          reg_magic == MAGIC_ALL ? "" : "\\");
      EMSG_RET_FAIL(IObuff);
    }
  
    /*
     * Reverse the range if there was a '-', or make sure it is in the right
     * order otherwise.
     */
    if ((!reverse && *minval > *maxval) || (reverse && *minval < *maxval)) {
      tmp = *minval;
      *minval = *maxval;
      *maxval = tmp;
    }
    skipchr();            /* let's be friends with the lexer again */
    return OK;
  }
  
  /*
   * vim_regexec and friends
   */
  
  /*
   * Global work variables for vim_regexec().
   */
  
  /* The current match-position is remembered with these variables: */
  static linenr_T reglnum;        /* line number, relative to first line */
  static char_u   *regline;       /* start of current line */
  static char_u   *reginput;      /* current input, points into "regline" */
  
  static int need_clear_subexpr;          /* subexpressions still need to be
                                           * cleared */
  static int need_clear_zsubexpr = FALSE;         /* extmatch subexpressions
                                                   * still need to be cleared */
  
  /*
   * Structure used to save the current input state, when it needs to be
   * restored after trying a match.  Used by reg_save() and reg_restore().
   * Also stores the length of "backpos".
   */
  typedef struct {
    union {
      char_u  *ptr;       /* reginput pointer, for single-line regexp */
      lpos_T pos;         /* reginput pos, for multi-line regexp */
    } rs_u;
    int rs_len;
  } regsave_T;
  
  /* struct to save start/end pointer/position in for \(\) */
  typedef struct {
    union {
      char_u  *ptr;
      lpos_T pos;
    } se_u;
  } save_se_T;
  
  /* used for BEHIND and NOBEHIND matching */
  typedef struct regbehind_S {
    regsave_T save_after;
    regsave_T save_behind;
    int save_need_clear_subexpr;
    save_se_T save_start[NSUBEXP];
    save_se_T save_end[NSUBEXP];
  } regbehind_T;
  
  static char_u   *reg_getline __ARGS((linenr_T lnum));
  static long bt_regexec_both __ARGS((char_u *line, colnr_T col, proftime_T *tm));
  static long regtry __ARGS((bt_regprog_T *prog, colnr_T col));
  static void cleanup_subexpr __ARGS((void));
  static void cleanup_zsubexpr __ARGS((void));
  static void save_subexpr __ARGS((regbehind_T *bp));
  static void restore_subexpr __ARGS((regbehind_T *bp));
  static void reg_nextline __ARGS((void));
  static void reg_save __ARGS((regsave_T *save, garray_T *gap));
  static void reg_restore __ARGS((regsave_T *save, garray_T *gap));
  static int reg_save_equal __ARGS((regsave_T *save));
  static void save_se_multi __ARGS((save_se_T *savep, lpos_T *posp));
  static void save_se_one __ARGS((save_se_T *savep, char_u **pp));
  
  /* Save the sub-expressions before attempting a match. */
  #define save_se(savep, posp, pp) \
    REG_MULTI ? save_se_multi((savep), (posp)) : save_se_one((savep), (pp))
  
  /* After a failed match restore the sub-expressions. */
  #define restore_se(savep, posp, pp) { \
      if (REG_MULTI) \
        *(posp) = (savep)->se_u.pos; \
      else \
        *(pp) = (savep)->se_u.ptr; }
  
  static int re_num_cmp __ARGS((long_u val, char_u *scan));
  static int match_with_backref __ARGS((linenr_T start_lnum, colnr_T start_col,
                                        linenr_T end_lnum, colnr_T end_col,
                                        int *bytelen));
  static int regmatch __ARGS((char_u *prog));
  static int regrepeat __ARGS((char_u *p, long maxcount));
  
  #ifdef REGEXP_DEBUG
  int regnarrate = 0;
  #endif
  
  /*
   * Internal copy of 'ignorecase'.  It is set at each call to vim_regexec().
   * Normally it gets the value of "rm_ic" or "rmm_ic", but when the pattern
   * contains '\c' or '\C' the value is overruled.
   */
  static int ireg_ic;
  
  /*
   * Similar to ireg_ic, but only for 'combining' characters.  Set with \Z flag
   * in the regexp.  Defaults to false, always.
   */
  static int ireg_icombine;
  
  /*
   * Copy of "rmm_maxcol": maximum column to search for a match.  Zero when
   * there is no maximum.
   */
  static colnr_T ireg_maxcol;
  
  /*
   * Sometimes need to save a copy of a line.  Since alloc()/free() is very
   * slow, we keep one allocated piece of memory and only re-allocate it when
   * it's too small.  It's freed in bt_regexec_both() when finished.
   */
  static char_u   *reg_tofree = NULL;
  static unsigned reg_tofreelen;
  
  /*
   * These variables are set when executing a regexp to speed up the execution.
   * Which ones are set depends on whether a single-line or multi-line match is
   * done:
   *			single-line		multi-line
   * reg_match		&regmatch_T		NULL
   * reg_mmatch		NULL			&regmmatch_T
   * reg_startp		reg_match->startp	<invalid>
   * reg_endp		reg_match->endp		<invalid>
   * reg_startpos		<invalid>		reg_mmatch->startpos
   * reg_endpos		<invalid>		reg_mmatch->endpos
   * reg_win		NULL			window in which to search
   * reg_buf		curbuf			buffer in which to search
   * reg_firstlnum	<invalid>		first line in which to search
   * reg_maxline		0			last line nr
   * reg_line_lbr		FALSE or TRUE		FALSE
   */
  static regmatch_T       *reg_match;
  static regmmatch_T      *reg_mmatch;
  static char_u           **reg_startp = NULL;
  static char_u           **reg_endp = NULL;
  static lpos_T           *reg_startpos = NULL;
  static lpos_T           *reg_endpos = NULL;
  static win_T            *reg_win;
  static buf_T            *reg_buf;
  static linenr_T reg_firstlnum;
  static linenr_T reg_maxline;
  static int reg_line_lbr;                    /* "\n" in string is line break */
  
  /* Values for rs_state in regitem_T. */
  typedef enum regstate_E {
    RS_NOPEN = 0          /* NOPEN and NCLOSE */
    , RS_MOPEN            /* MOPEN + [0-9] */
    , RS_MCLOSE           /* MCLOSE + [0-9] */
    , RS_ZOPEN            /* ZOPEN + [0-9] */
    , RS_ZCLOSE           /* ZCLOSE + [0-9] */
    , RS_BRANCH           /* BRANCH */
    , RS_BRCPLX_MORE      /* BRACE_COMPLEX and trying one more match */
    , RS_BRCPLX_LONG      /* BRACE_COMPLEX and trying longest match */
    , RS_BRCPLX_SHORT     /* BRACE_COMPLEX and trying shortest match */
    , RS_NOMATCH          /* NOMATCH */
    , RS_BEHIND1          /* BEHIND / NOBEHIND matching rest */
    , RS_BEHIND2          /* BEHIND / NOBEHIND matching behind part */
    , RS_STAR_LONG        /* STAR/PLUS/BRACE_SIMPLE longest match */
    , RS_STAR_SHORT       /* STAR/PLUS/BRACE_SIMPLE shortest match */
  } regstate_T;
  
  /*
   * When there are alternatives a regstate_T is put on the regstack to remember
   * what we are doing.
   * Before it may be another type of item, depending on rs_state, to remember
   * more things.
   */
  typedef struct regitem_S {
    regstate_T rs_state;          /* what we are doing, one of RS_ above */
    char_u      *rs_scan;         /* current node in program */
    union {
      save_se_T sesave;
      regsave_T regsave;
    } rs_un;                      /* room for saving reginput */
    short rs_no;                  /* submatch nr or BEHIND/NOBEHIND */
  } regitem_T;
  
  static regitem_T *regstack_push __ARGS((regstate_T state, char_u *scan));
  static void regstack_pop __ARGS((char_u **scan));
  
  /* used for STAR, PLUS and BRACE_SIMPLE matching */
  typedef struct regstar_S {
    int nextb;                    /* next byte */
    int nextb_ic;                 /* next byte reverse case */
    long count;
    long minval;
    long maxval;
  } regstar_T;
  
  /* used to store input position when a BACK was encountered, so that we now if
   * we made any progress since the last time. */
  typedef struct backpos_S {
    char_u      *bp_scan;         /* "scan" where BACK was encountered */
    regsave_T bp_pos;             /* last input position */
  } backpos_T;
  
  /*
   * "regstack" and "backpos" are used by regmatch().  They are kept over calls
   * to avoid invoking malloc() and free() often.
   * "regstack" is a stack with regitem_T items, sometimes preceded by regstar_T
   * or regbehind_T.
   * "backpos_T" is a table with backpos_T for BACK
   */
  static garray_T regstack = {0, 0, 0, 0, NULL};
  static garray_T backpos = {0, 0, 0, 0, NULL};
  
  /*
   * Both for regstack and backpos tables we use the following strategy of
   * allocation (to reduce malloc/free calls):
   * - Initial size is fairly small.
   * - When needed, the tables are grown bigger (8 times at first, double after
   *   that).
   * - After executing the match we free the memory only if the array has grown.
   *   Thus the memory is kept allocated when it's at the initial size.
   * This makes it fast while not keeping a lot of memory allocated.
   * A three times speed increase was observed when using many simple patterns.
   */
  #define REGSTACK_INITIAL        2048
  #define BACKPOS_INITIAL         64
  
  #if defined(EXITFREE) || defined(PROTO)
  void free_regexp_stuff()          {
    ga_clear(&regstack);
    ga_clear(&backpos);
    vim_free(reg_tofree);
    vim_free(reg_prev_sub);
  }
  
  #endif
  
  /*
   * Get pointer to the line "lnum", which is relative to "reg_firstlnum".
   */
  static char_u * reg_getline(lnum)
  linenr_T lnum;
  {
    /* when looking behind for a match/no-match lnum is negative.  But we
     * can't go before line 1 */
    if (reg_firstlnum + lnum < 1)
      return NULL;
    if (lnum > reg_maxline)
      /* Must have matched the "\n" in the last line. */
      return (char_u *)"";
    return ml_get_buf(reg_buf, reg_firstlnum + lnum, FALSE);
  }
  
  static regsave_T behind_pos;
  
  static char_u   *reg_startzp[NSUBEXP];  /* Workspace to mark beginning */
  static char_u   *reg_endzp[NSUBEXP];    /*   and end of \z(...\) matches */
  static lpos_T reg_startzpos[NSUBEXP];   /* idem, beginning pos */
  static lpos_T reg_endzpos[NSUBEXP];     /* idem, end pos */
  
  /* TRUE if using multi-line regexp. */
  #define REG_MULTI       (reg_match == NULL)
  
  static int bt_regexec __ARGS((regmatch_T *rmp, char_u *line, colnr_T col));
  
  /*
   * Match a regexp against a string.
   * "rmp->regprog" is a compiled regexp as returned by vim_regcomp().
   * Uses curbuf for line count and 'iskeyword'.
   *
   * Return TRUE if there is a match, FALSE if not.
   */
  static int bt_regexec(rmp, line, col)
  regmatch_T  *rmp;
  char_u      *line;      /* string to match against */
  colnr_T col;            /* column to start looking for match */
  {
    reg_match = rmp;
    reg_mmatch = NULL;
    reg_maxline = 0;
    reg_line_lbr = FALSE;
    reg_buf = curbuf;
    reg_win = NULL;
    ireg_ic = rmp->rm_ic;
    ireg_icombine = FALSE;
    ireg_maxcol = 0;
    return bt_regexec_both(line, col, NULL) != 0;
  }
  
  #if defined(FEAT_MODIFY_FNAME) || defined(FEAT_EVAL) \
    || defined(FIND_REPLACE_DIALOG) || defined(PROTO)
  
  static int bt_regexec_nl __ARGS((regmatch_T *rmp, char_u *line, colnr_T col));
  
  /*
   * Like vim_regexec(), but consider a "\n" in "line" to be a line break.
   */
  static int bt_regexec_nl(rmp, line, col)
  regmatch_T  *rmp;
  char_u      *line;      /* string to match against */
  colnr_T col;            /* column to start looking for match */
  {
    reg_match = rmp;
    reg_mmatch = NULL;
    reg_maxline = 0;
    reg_line_lbr = TRUE;
    reg_buf = curbuf;
    reg_win = NULL;
    ireg_ic = rmp->rm_ic;
    ireg_icombine = FALSE;
    ireg_maxcol = 0;
    return bt_regexec_both(line, col, NULL) != 0;
  }
  #endif
  
  static long bt_regexec_multi __ARGS((regmmatch_T *rmp, win_T *win, buf_T *buf,
                                       linenr_T lnum, colnr_T col,
                                       proftime_T *tm));
  
  /*
   * Match a regexp against multiple lines.
   * "rmp->regprog" is a compiled regexp as returned by vim_regcomp().
   * Uses curbuf for line count and 'iskeyword'.
   *
   * Return zero if there is no match.  Return number of lines contained in the
   * match otherwise.
   */
  static long bt_regexec_multi(rmp, win, buf, lnum, col, tm)
  regmmatch_T *rmp;
  win_T       *win;               /* window in which to search or NULL */
  buf_T       *buf;               /* buffer in which to search */
  linenr_T lnum;                  /* nr of line to start looking for match */
  colnr_T col;                    /* column to start looking for match */
  proftime_T  *tm;                /* timeout limit or NULL */
  {
    long r;
  
    reg_match = NULL;
    reg_mmatch = rmp;
    reg_buf = buf;
    reg_win = win;
    reg_firstlnum = lnum;
    reg_maxline = reg_buf->b_ml.ml_line_count - lnum;
    reg_line_lbr = FALSE;
    ireg_ic = rmp->rmm_ic;
    ireg_icombine = FALSE;
    ireg_maxcol = rmp->rmm_maxcol;
  
    r = bt_regexec_both(NULL, col, tm);
  
    return r;
  }
  
  /*
   * Match a regexp against a string ("line" points to the string) or multiple
   * lines ("line" is NULL, use reg_getline()).
   */
  static long bt_regexec_both(line, col, tm)
  char_u      *line;
  colnr_T col;                    /* column to start looking for match */
  proftime_T  *tm UNUSED;         /* timeout limit or NULL */
  {
    bt_regprog_T        *prog;
    char_u      *s;
    long retval = 0L;
  
    /* Create "regstack" and "backpos" if they are not allocated yet.
     * We allocate *_INITIAL amount of bytes first and then set the grow size
     * to much bigger value to avoid many malloc calls in case of deep regular
     * expressions.  */
    if (regstack.ga_data == NULL) {
      /* Use an item size of 1 byte, since we push different things
       * onto the regstack. */
      ga_init2(&regstack, 1, REGSTACK_INITIAL);
      ga_grow(&regstack, REGSTACK_INITIAL);
      regstack.ga_growsize = REGSTACK_INITIAL * 8;
    }
  
    if (backpos.ga_data == NULL) {
      ga_init2(&backpos, sizeof(backpos_T), BACKPOS_INITIAL);
      ga_grow(&backpos, BACKPOS_INITIAL);
      backpos.ga_growsize = BACKPOS_INITIAL * 8;
    }
  
    if (REG_MULTI) {
      prog = (bt_regprog_T *)reg_mmatch->regprog;
      line = reg_getline((linenr_T)0);
      reg_startpos = reg_mmatch->startpos;
      reg_endpos = reg_mmatch->endpos;
    } else   {
      prog = (bt_regprog_T *)reg_match->regprog;
      reg_startp = reg_match->startp;
      reg_endp = reg_match->endp;
    }
  
    /* Be paranoid... */
    if (prog == NULL || line == NULL) {
      EMSG(_(e_null));
      goto theend;
    }
  
    /* Check validity of program. */
    if (prog_magic_wrong())
      goto theend;
  
    /* If the start column is past the maximum column: no need to try. */
    if (ireg_maxcol > 0 && col >= ireg_maxcol)
      goto theend;
  
    /* If pattern contains "\c" or "\C": overrule value of ireg_ic */
    if (prog->regflags & RF_ICASE)
      ireg_ic = TRUE;
    else if (prog->regflags & RF_NOICASE)
      ireg_ic = FALSE;
  
    /* If pattern contains "\Z" overrule value of ireg_icombine */
    if (prog->regflags & RF_ICOMBINE)
      ireg_icombine = TRUE;
  
    /* If there is a "must appear" string, look for it. */
    if (prog->regmust != NULL) {
      int c;
  
      if (has_mbyte)
        c = (*mb_ptr2char)(prog->regmust);
      else
        c = *prog->regmust;
      s = line + col;
  
      /*
       * This is used very often, esp. for ":global".  Use three versions of
       * the loop to avoid overhead of conditions.
       */
      if (!ireg_ic
          && !has_mbyte
          )
        while ((s = vim_strbyte(s, c)) != NULL) {
          if (cstrncmp(s, prog->regmust, &prog->regmlen) == 0)
            break;                        /* Found it. */
          ++s;
        }
      else if (!ireg_ic || (!enc_utf8 && mb_char2len(c) > 1))
        while ((s = vim_strchr(s, c)) != NULL) {
          if (cstrncmp(s, prog->regmust, &prog->regmlen) == 0)
            break;                        /* Found it. */
          mb_ptr_adv(s);
        }
      else
        while ((s = cstrchr(s, c)) != NULL) {
          if (cstrncmp(s, prog->regmust, &prog->regmlen) == 0)
            break;                        /* Found it. */
          mb_ptr_adv(s);
        }
      if (s == NULL)              /* Not present. */
        goto theend;
    }
  
    regline = line;
    reglnum = 0;
    reg_toolong = FALSE;
  
    /* Simplest case: Anchored match need be tried only once. */
    if (prog->reganch) {
      int c;
  
      if (has_mbyte)
        c = (*mb_ptr2char)(regline + col);
      else
        c = regline[col];
      if (prog->regstart == NUL
          || prog->regstart == c
          || (ireg_ic && ((
                            (enc_utf8 && utf_fold(prog->regstart) == utf_fold(c)))
                          || (c < 255 && prog->regstart < 255 &&
                              MB_TOLOWER(prog->regstart) == MB_TOLOWER(c)))))
        retval = regtry(prog, col);
      else
        retval = 0;
    } else   {
      int tm_count = 0;
      /* Messy cases:  unanchored match. */
      while (!got_int) {
        if (prog->regstart != NUL) {
          /* Skip until the char we know it must start with.
           * Used often, do some work to avoid call overhead. */
          if (!ireg_ic
              && !has_mbyte
              )
            s = vim_strbyte(regline + col, prog->regstart);
          else
            s = cstrchr(regline + col, prog->regstart);
          if (s == NULL) {
            retval = 0;
            break;
          }
          col = (int)(s - regline);
        }
  
        /* Check for maximum column to try. */
        if (ireg_maxcol > 0 && col >= ireg_maxcol) {
          retval = 0;
          break;
        }
  
        retval = regtry(prog, col);
        if (retval > 0)
          break;
  
        /* if not currently on the first line, get it again */
        if (reglnum != 0) {
          reglnum = 0;
          regline = reg_getline((linenr_T)0);
        }
        if (regline[col] == NUL)
          break;
        if (has_mbyte)
          col += (*mb_ptr2len)(regline + col);
        else
          ++col;
        /* Check for timeout once in a twenty times to avoid overhead. */
        if (tm != NULL && ++tm_count == 20) {
          tm_count = 0;
          if (profile_passed_limit(tm))
            break;
        }
      }
    }
  
  theend:
    /* Free "reg_tofree" when it's a bit big.
     * Free regstack and backpos if they are bigger than their initial size. */
    if (reg_tofreelen > 400) {
      vim_free(reg_tofree);
      reg_tofree = NULL;
    }
    if (regstack.ga_maxlen > REGSTACK_INITIAL)
      ga_clear(&regstack);
    if (backpos.ga_maxlen > BACKPOS_INITIAL)
      ga_clear(&backpos);
  
    return retval;
  }
  
  static reg_extmatch_T *make_extmatch __ARGS((void));
  
  /*
   * Create a new extmatch and mark it as referenced once.
   */
  static reg_extmatch_T * make_extmatch()                             {
    reg_extmatch_T      *em;
  
    em = (reg_extmatch_T *)alloc_clear((unsigned)sizeof(reg_extmatch_T));
    if (em != NULL)
      em->refcnt = 1;
    return em;
  }
  
  /*
   * Add a reference to an extmatch.
   */
  reg_extmatch_T * ref_extmatch(em)
  reg_extmatch_T      *em;
  {
    if (em != NULL)
      em->refcnt++;
    return em;
  }
  
  /*
   * Remove a reference to an extmatch.  If there are no references left, free
   * the info.
   */
  void unref_extmatch(em)
  reg_extmatch_T      *em;
  {
    int i;
  
    if (em != NULL && --em->refcnt <= 0) {
      for (i = 0; i < NSUBEXP; ++i)
        vim_free(em->matches[i]);
      vim_free(em);
    }
  }
  
  /*
   * regtry - try match of "prog" with at regline["col"].
   * Returns 0 for failure, number of lines contained in the match otherwise.
   */
  static long regtry(prog, col)
  bt_regprog_T    *prog;
  colnr_T col;
  {
    reginput = regline + col;
    need_clear_subexpr = TRUE;
    /* Clear the external match subpointers if necessary. */
    if (prog->reghasz == REX_SET)
      need_clear_zsubexpr = TRUE;
  
    if (regmatch(prog->program + 1) == 0)
      return 0;
  
    cleanup_subexpr();
    if (REG_MULTI) {
      if (reg_startpos[0].lnum < 0) {
        reg_startpos[0].lnum = 0;
        reg_startpos[0].col = col;
      }
      if (reg_endpos[0].lnum < 0) {
        reg_endpos[0].lnum = reglnum;
        reg_endpos[0].col = (int)(reginput - regline);
      } else
        /* Use line number of "\ze". */
        reglnum = reg_endpos[0].lnum;
    } else   {
      if (reg_startp[0] == NULL)
        reg_startp[0] = regline + col;
      if (reg_endp[0] == NULL)
        reg_endp[0] = reginput;
    }
    /* Package any found \z(...\) matches for export. Default is none. */
    unref_extmatch(re_extmatch_out);
    re_extmatch_out = NULL;
  
    if (prog->reghasz == REX_SET) {
      int i;
  
      cleanup_zsubexpr();
      re_extmatch_out = make_extmatch();
      for (i = 0; i < NSUBEXP; i++) {
        if (REG_MULTI) {
          /* Only accept single line matches. */
          if (reg_startzpos[i].lnum >= 0
              && reg_endzpos[i].lnum == reg_startzpos[i].lnum)
            re_extmatch_out->matches[i] =
              vim_strnsave(reg_getline(reg_startzpos[i].lnum)
                  + reg_startzpos[i].col,
                  reg_endzpos[i].col - reg_startzpos[i].col);
        } else   {
          if (reg_startzp[i] != NULL && reg_endzp[i] != NULL)
            re_extmatch_out->matches[i] =
              vim_strnsave(reg_startzp[i],
                  (int)(reg_endzp[i] - reg_startzp[i]));
        }
      }
    }
    return 1 + reglnum;
  }
  
  static int reg_prev_class __ARGS((void));
  
  /*
   * Get class of previous character.
   */
  static int reg_prev_class()                {
    if (reginput > regline)
      return mb_get_class_buf(reginput - 1
          - (*mb_head_off)(regline, reginput - 1), reg_buf);
    return -1;
  }
  
  static int reg_match_visual __ARGS((void));
  
  /*
   * Return TRUE if the current reginput position matches the Visual area.
   */
  static int reg_match_visual()                {
    pos_T top, bot;
    linenr_T lnum;
    colnr_T col;
    win_T       *wp = reg_win == NULL ? curwin : reg_win;
    int mode;
    colnr_T start, end;
    colnr_T start2, end2;
    colnr_T cols;
  
    /* Check if the buffer is the current buffer. */
    if (reg_buf != curbuf || VIsual.lnum == 0)
      return FALSE;
  
    if (VIsual_active) {
      if (lt(VIsual, wp->w_cursor)) {
        top = VIsual;
        bot = wp->w_cursor;
      } else   {
        top = wp->w_cursor;
        bot = VIsual;
      }
      mode = VIsual_mode;
    } else   {
      if (lt(curbuf->b_visual.vi_start, curbuf->b_visual.vi_end)) {
        top = curbuf->b_visual.vi_start;
        bot = curbuf->b_visual.vi_end;
      } else   {
        top = curbuf->b_visual.vi_end;
        bot = curbuf->b_visual.vi_start;
      }
      mode = curbuf->b_visual.vi_mode;
    }
    lnum = reglnum + reg_firstlnum;
    if (lnum < top.lnum || lnum > bot.lnum)
      return FALSE;
  
    if (mode == 'v') {
      col = (colnr_T)(reginput - regline);
      if ((lnum == top.lnum && col < top.col)
          || (lnum == bot.lnum && col >= bot.col + (*p_sel != 'e')))
        return FALSE;
    } else if (mode == Ctrl_V)   {
      getvvcol(wp, &top, &start, NULL, &end);
      getvvcol(wp, &bot, &start2, NULL, &end2);
      if (start2 < start)
        start = start2;
      if (end2 > end)
        end = end2;
      if (top.col == MAXCOL || bot.col == MAXCOL)
        end = MAXCOL;
      cols = win_linetabsize(wp, regline, (colnr_T)(reginput - regline));
      if (cols < start || cols > end - (*p_sel == 'e'))
        return FALSE;
    }
    return TRUE;
  }
  
  #define ADVANCE_REGINPUT() mb_ptr_adv(reginput)
  
  /*
   * The arguments from BRACE_LIMITS are stored here.  They are actually local
   * to regmatch(), but they are here to reduce the amount of stack space used
   * (it can be called recursively many times).
   */
  static long bl_minval;
  static long bl_maxval;
  
  /*
   * regmatch - main matching routine
   *
   * Conceptually the strategy is simple: Check to see whether the current node
   * matches, push an item onto the regstack and loop to see whether the rest
   * matches, and then act accordingly.  In practice we make some effort to
   * avoid using the regstack, in particular by going through "ordinary" nodes
   * (that don't need to know whether the rest of the match failed) by a nested
   * loop.
   *
   * Returns TRUE when there is a match.  Leaves reginput and reglnum just after
   * the last matched character.
   * Returns FALSE when there is no match.  Leaves reginput and reglnum in an
   * undefined state!
   */
  static int regmatch(scan)
  char_u      *scan;              /* Current node. */
  {
    char_u        *next;          /* Next node. */
    int op;
    int c;
    regitem_T     *rp;
    int no;
    int status;                   /* one of the RA_ values: */
  #define RA_FAIL         1       /* something failed, abort */
  #define RA_CONT         2       /* continue in inner loop */
  #define RA_BREAK        3       /* break inner loop */
  #define RA_MATCH        4       /* successful match */
  #define RA_NOMATCH      5       /* didn't match */
  
    /* Make "regstack" and "backpos" empty.  They are allocated and freed in
     * bt_regexec_both() to reduce malloc()/free() calls. */
    regstack.ga_len = 0;
    backpos.ga_len = 0;
  
    /*
     * Repeat until "regstack" is empty.
     */
    for (;; ) {
      /* Some patterns may take a long time to match, e.g., "\([a-z]\+\)\+Q".
       * Allow interrupting them with CTRL-C. */
      fast_breakcheck();
  
  #ifdef REGEXP_DEBUG
      if (scan != NULL && regnarrate) {
        mch_errmsg((char *)regprop(scan));
        mch_errmsg("(\n");
      }
  #endif
  
      /*
       * Repeat for items that can be matched sequentially, without using the
       * regstack.
       */
      for (;; ) {
        if (got_int || scan == NULL) {
          status = RA_FAIL;
          break;
        }
        status = RA_CONT;
  
  #ifdef REGEXP_DEBUG
        if (regnarrate) {
          mch_errmsg((char *)regprop(scan));
          mch_errmsg("...\n");
          if (re_extmatch_in != NULL) {
            int i;
  
            mch_errmsg(_("External submatches:\n"));
            for (i = 0; i < NSUBEXP; i++) {
              mch_errmsg("    \"");
              if (re_extmatch_in->matches[i] != NULL)
                mch_errmsg((char *)re_extmatch_in->matches[i]);
              mch_errmsg("\"\n");
            }
          }
        }
  #endif
        next = regnext(scan);
  
        op = OP(scan);
        /* Check for character class with NL added. */
        if (!reg_line_lbr && WITH_NL(op) && REG_MULTI
            && *reginput == NUL && reglnum <= reg_maxline) {
          reg_nextline();
        } else if (reg_line_lbr && WITH_NL(op) && *reginput == '\n')   {
          ADVANCE_REGINPUT();
        } else   {
          if (WITH_NL(op))
            op -= ADD_NL;
          if (has_mbyte)
            c = (*mb_ptr2char)(reginput);
          else
            c = *reginput;
          switch (op) {
          case BOL:
            if (reginput != regline)
              status = RA_NOMATCH;
            break;
  
          case EOL:
            if (c != NUL)
              status = RA_NOMATCH;
            break;
  
          case RE_BOF:
            /* We're not at the beginning of the file when below the first
             * line where we started, not at the start of the line or we
             * didn't start at the first line of the buffer. */
            if (reglnum != 0 || reginput != regline
                || (REG_MULTI && reg_firstlnum > 1))
              status = RA_NOMATCH;
            break;
  
          case RE_EOF:
            if (reglnum != reg_maxline || c != NUL)
              status = RA_NOMATCH;
            break;
  
          case CURSOR:
            /* Check if the buffer is in a window and compare the
             * reg_win->w_cursor position to the match position. */
            if (reg_win == NULL
                || (reglnum + reg_firstlnum != reg_win->w_cursor.lnum)
                || ((colnr_T)(reginput - regline) != reg_win->w_cursor.col))
              status = RA_NOMATCH;
            break;
  
          case RE_MARK:
            /* Compare the mark position to the match position. */
          {
            int mark = OPERAND(scan)[0];
            int cmp = OPERAND(scan)[1];
            pos_T   *pos;
  
            pos = getmark_buf(reg_buf, mark, FALSE);
            if (pos == NULL                    /* mark doesn't exist */
                || pos->lnum <= 0              /* mark isn't set in reg_buf */
                || (pos->lnum == reglnum + reg_firstlnum
                    ? (pos->col == (colnr_T)(reginput - regline)
                       ? (cmp == '<' || cmp == '>')
                       : (pos->col < (colnr_T)(reginput - regline)
                          ? cmp != '>'
                          : cmp != '<'))
                    : (pos->lnum < reglnum + reg_firstlnum
                       ? cmp != '>'
                       : cmp != '<')))
              status = RA_NOMATCH;
          }
          break;
  
          case RE_VISUAL:
            if (!reg_match_visual())
              status = RA_NOMATCH;
            break;
  
          case RE_LNUM:
            if (!REG_MULTI || !re_num_cmp((long_u)(reglnum + reg_firstlnum),
                    scan))
              status = RA_NOMATCH;
            break;
  
          case RE_COL:
            if (!re_num_cmp((long_u)(reginput - regline) + 1, scan))
              status = RA_NOMATCH;
            break;
  
          case RE_VCOL:
            if (!re_num_cmp((long_u)win_linetabsize(
                        reg_win == NULL ? curwin : reg_win,
                        regline, (colnr_T)(reginput - regline)) + 1, scan))
              status = RA_NOMATCH;
            break;
  
          case BOW:       /* \<word; reginput points to w */
            if (c == NUL)         /* Can't match at end of line */
              status = RA_NOMATCH;
            else if (has_mbyte) {
              int this_class;
  
              /* Get class of current and previous char (if it exists). */
              this_class = mb_get_class_buf(reginput, reg_buf);
              if (this_class <= 1)
                status = RA_NOMATCH;        /* not on a word at all */
              else if (reg_prev_class() == this_class)
                status = RA_NOMATCH;        /* previous char is in same word */
            } else   {
              if (!vim_iswordc_buf(c, reg_buf) || (reginput > regline
                                                   && vim_iswordc_buf(reginput[-1
                                                       ], reg_buf)))
                status = RA_NOMATCH;
            }
            break;
  
          case EOW:       /* word\>; reginput points after d */
            if (reginput == regline)      /* Can't match at start of line */
              status = RA_NOMATCH;
            else if (has_mbyte) {
              int this_class, prev_class;
  
              /* Get class of current and previous char (if it exists). */
              this_class = mb_get_class_buf(reginput, reg_buf);
              prev_class = reg_prev_class();
              if (this_class == prev_class
                  || prev_class == 0 || prev_class == 1)
                status = RA_NOMATCH;
            } else   {
              if (!vim_iswordc_buf(reginput[-1], reg_buf)
                  || (reginput[0] != NUL && vim_iswordc_buf(c, reg_buf)))
                status = RA_NOMATCH;
            }
            break;   /* Matched with EOW */
  
          case ANY:
            /* ANY does not match new lines. */
            if (c == NUL)
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case IDENT:
            if (!vim_isIDc(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case SIDENT:
            if (VIM_ISDIGIT(*reginput) || !vim_isIDc(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case KWORD:
            if (!vim_iswordp_buf(reginput, reg_buf))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case SKWORD:
            if (VIM_ISDIGIT(*reginput) || !vim_iswordp_buf(reginput, reg_buf))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case FNAME:
            if (!vim_isfilec(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case SFNAME:
            if (VIM_ISDIGIT(*reginput) || !vim_isfilec(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case PRINT:
            if (!vim_isprintc(PTR2CHAR(reginput)))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case SPRINT:
            if (VIM_ISDIGIT(*reginput) || !vim_isprintc(PTR2CHAR(reginput)))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case WHITE:
            if (!vim_iswhite(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case NWHITE:
            if (c == NUL || vim_iswhite(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case DIGIT:
            if (!ri_digit(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case NDIGIT:
            if (c == NUL || ri_digit(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case HEX:
            if (!ri_hex(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case NHEX:
            if (c == NUL || ri_hex(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case OCTAL:
            if (!ri_octal(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case NOCTAL:
            if (c == NUL || ri_octal(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case WORD:
            if (!ri_word(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case NWORD:
            if (c == NUL || ri_word(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case HEAD:
            if (!ri_head(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case NHEAD:
            if (c == NUL || ri_head(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case ALPHA:
            if (!ri_alpha(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case NALPHA:
            if (c == NUL || ri_alpha(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case LOWER:
            if (!ri_lower(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case NLOWER:
            if (c == NUL || ri_lower(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case UPPER:
            if (!ri_upper(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case NUPPER:
            if (c == NUL || ri_upper(c))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case EXACTLY:
          {
            int len;
            char_u  *opnd;
  
            opnd = OPERAND(scan);
            /* Inline the first byte, for speed. */
            if (*opnd != *reginput
                && (!ireg_ic || (
                      !enc_utf8 &&
                      MB_TOLOWER(*opnd) != MB_TOLOWER(*reginput))))
              status = RA_NOMATCH;
            else if (*opnd == NUL) {
              /* match empty string always works; happens when "~" is
               * empty. */
            } else if (opnd[1] == NUL
                       && !(enc_utf8 && ireg_ic)
                       )
              ++reginput;                 /* matched a single char */
            else {
              len = (int)STRLEN(opnd);
              /* Need to match first byte again for multi-byte. */
              if (cstrncmp(opnd, reginput, &len) != 0)
                status = RA_NOMATCH;
              /* Check for following composing character. */
              else if (enc_utf8
                       && UTF_COMPOSINGLIKE(reginput, reginput + len)) {
                /* raaron: This code makes a composing character get
                 * ignored, which is the correct behavior (sometimes)
                 * for voweled Hebrew texts. */
                if (!ireg_icombine)
                  status = RA_NOMATCH;
              } else
                reginput += len;
            }
          }
          break;
  
          case ANYOF:
          case ANYBUT:
            if (c == NUL)
              status = RA_NOMATCH;
            else if ((cstrchr(OPERAND(scan), c) == NULL) == (op == ANYOF))
              status = RA_NOMATCH;
            else
              ADVANCE_REGINPUT();
            break;
  
          case MULTIBYTECODE:
            if (has_mbyte) {
              int i, len;
              char_u  *opnd;
              int opndc = 0, inpc;
  
              opnd = OPERAND(scan);
              /* Safety check (just in case 'encoding' was changed since
               * compiling the program). */
              if ((len = (*mb_ptr2len)(opnd)) < 2) {
                status = RA_NOMATCH;
                break;
              }
              if (enc_utf8)
                opndc = mb_ptr2char(opnd);
              if (enc_utf8 && utf_iscomposing(opndc)) {
                /* When only a composing char is given match at any
                 * position where that composing char appears. */
                status = RA_NOMATCH;
                for (i = 0; reginput[i] != NUL; i += utf_char2len(inpc)) {
                  inpc = mb_ptr2char(reginput + i);
                  if (!utf_iscomposing(inpc)) {
                    if (i > 0)
                      break;
                  } else if (opndc == inpc)   {
                    /* Include all following composing chars. */
                    len = i + mb_ptr2len(reginput + i);
                    status = RA_MATCH;
                    break;
                  }
                }
              } else
                for (i = 0; i < len; ++i)
                  if (opnd[i] != reginput[i]) {
                    status = RA_NOMATCH;
                    break;
                  }
              reginput += len;
            } else
              status = RA_NOMATCH;
            break;
  
          case NOTHING:
            break;
  
          case BACK:
          {
            int i;
            backpos_T       *bp;
  
            /*
             * When we run into BACK we need to check if we don't keep
             * looping without matching any input.  The second and later
             * times a BACK is encountered it fails if the input is still
             * at the same position as the previous time.
             * The positions are stored in "backpos" and found by the
             * current value of "scan", the position in the RE program.
             */
            bp = (backpos_T *)backpos.ga_data;
            for (i = 0; i < backpos.ga_len; ++i)
              if (bp[i].bp_scan == scan)
                break;
            if (i == backpos.ga_len) {
              /* First time at this BACK, make room to store the pos. */
              if (ga_grow(&backpos, 1) == FAIL)
                status = RA_FAIL;
              else {
                /* get "ga_data" again, it may have changed */
                bp = (backpos_T *)backpos.ga_data;
                bp[i].bp_scan = scan;
                ++backpos.ga_len;
              }
            } else if (reg_save_equal(&bp[i].bp_pos))
              /* Still at same position as last time, fail. */
              status = RA_NOMATCH;
  
            if (status != RA_FAIL && status != RA_NOMATCH)
              reg_save(&bp[i].bp_pos, &backpos);
          }
          break;
  
          case MOPEN + 0:     /* Match start: \zs */
          case MOPEN + 1:     /* \( */
          case MOPEN + 2:
          case MOPEN + 3:
          case MOPEN + 4:
          case MOPEN + 5:
          case MOPEN + 6:
          case MOPEN + 7:
          case MOPEN + 8:
          case MOPEN + 9:
          {
            no = op - MOPEN;
            cleanup_subexpr();
            rp = regstack_push(RS_MOPEN, scan);
            if (rp == NULL)
              status = RA_FAIL;
            else {
              rp->rs_no = no;
              save_se(&rp->rs_un.sesave, &reg_startpos[no],
                  &reg_startp[no]);
              /* We simply continue and handle the result when done. */
            }
          }
          break;
  
          case NOPEN:         /* \%( */
          case NCLOSE:        /* \) after \%( */
            if (regstack_push(RS_NOPEN, scan) == NULL)
              status = RA_FAIL;
            /* We simply continue and handle the result when done. */
            break;
  
          case ZOPEN + 1:
          case ZOPEN + 2:
          case ZOPEN + 3:
          case ZOPEN + 4:
          case ZOPEN + 5:
          case ZOPEN + 6:
          case ZOPEN + 7:
          case ZOPEN + 8:
          case ZOPEN + 9:
          {
            no = op - ZOPEN;
            cleanup_zsubexpr();
            rp = regstack_push(RS_ZOPEN, scan);
            if (rp == NULL)
              status = RA_FAIL;
            else {
              rp->rs_no = no;
              save_se(&rp->rs_un.sesave, &reg_startzpos[no],
                  &reg_startzp[no]);
              /* We simply continue and handle the result when done. */
            }
          }
          break;
  
          case MCLOSE + 0:    /* Match end: \ze */
          case MCLOSE + 1:    /* \) */
          case MCLOSE + 2:
          case MCLOSE + 3:
          case MCLOSE + 4:
          case MCLOSE + 5:
          case MCLOSE + 6:
          case MCLOSE + 7:
          case MCLOSE + 8:
          case MCLOSE + 9:
          {
            no = op - MCLOSE;
            cleanup_subexpr();
            rp = regstack_push(RS_MCLOSE, scan);
            if (rp == NULL)
              status = RA_FAIL;
            else {
              rp->rs_no = no;
              save_se(&rp->rs_un.sesave, &reg_endpos[no], &reg_endp[no]);
              /* We simply continue and handle the result when done. */
            }
          }
          break;
  
          case ZCLOSE + 1:    /* \) after \z( */
          case ZCLOSE + 2:
          case ZCLOSE + 3:
          case ZCLOSE + 4:
          case ZCLOSE + 5:
          case ZCLOSE + 6:
          case ZCLOSE + 7:
          case ZCLOSE + 8:
          case ZCLOSE + 9:
          {
            no = op - ZCLOSE;
            cleanup_zsubexpr();
            rp = regstack_push(RS_ZCLOSE, scan);
            if (rp == NULL)
              status = RA_FAIL;
            else {
              rp->rs_no = no;
              save_se(&rp->rs_un.sesave, &reg_endzpos[no],
                  &reg_endzp[no]);
              /* We simply continue and handle the result when done. */
            }
          }
          break;
  
          case BACKREF + 1:
          case BACKREF + 2:
          case BACKREF + 3:
          case BACKREF + 4:
          case BACKREF + 5:
          case BACKREF + 6:
          case BACKREF + 7:
          case BACKREF + 8:
          case BACKREF + 9:
          {
            int len;
  
            no = op - BACKREF;
            cleanup_subexpr();
            if (!REG_MULTI) {             /* Single-line regexp */
              if (reg_startp[no] == NULL || reg_endp[no] == NULL) {
                /* Backref was not set: Match an empty string. */
                len = 0;
              } else   {
                /* Compare current input with back-ref in the same
                 * line. */
                len = (int)(reg_endp[no] - reg_startp[no]);
                if (cstrncmp(reg_startp[no], reginput, &len) != 0)
                  status = RA_NOMATCH;
              }
            } else   {                            /* Multi-line regexp */
              if (reg_startpos[no].lnum < 0 || reg_endpos[no].lnum < 0) {
                /* Backref was not set: Match an empty string. */
                len = 0;
              } else   {
                if (reg_startpos[no].lnum == reglnum
                    && reg_endpos[no].lnum == reglnum) {
                  /* Compare back-ref within the current line. */
                  len = reg_endpos[no].col - reg_startpos[no].col;
                  if (cstrncmp(regline + reg_startpos[no].col,
                          reginput, &len) != 0)
                    status = RA_NOMATCH;
                } else   {
                  /* Messy situation: Need to compare between two
                   * lines. */
                  int r = match_with_backref(
                      reg_startpos[no].lnum,
                      reg_startpos[no].col,
                      reg_endpos[no].lnum,
                      reg_endpos[no].col,
                      &len);
  
                  if (r != RA_MATCH)
                    status = r;
                }
              }
            }
  
            /* Matched the backref, skip over it. */
            reginput += len;
          }
          break;
  
          case ZREF + 1:
          case ZREF + 2:
          case ZREF + 3:
          case ZREF + 4:
          case ZREF + 5:
          case ZREF + 6:
          case ZREF + 7:
          case ZREF + 8:
          case ZREF + 9:
          {
            int len;
  
            cleanup_zsubexpr();
            no = op - ZREF;
            if (re_extmatch_in != NULL
                && re_extmatch_in->matches[no] != NULL) {
              len = (int)STRLEN(re_extmatch_in->matches[no]);
              if (cstrncmp(re_extmatch_in->matches[no],
                      reginput, &len) != 0)
                status = RA_NOMATCH;
              else
                reginput += len;
            } else   {
              /* Backref was not set: Match an empty string. */
            }
          }
          break;
  
          case BRANCH:
          {
            if (OP(next) != BRANCH)       /* No choice. */
              next = OPERAND(scan);               /* Avoid recursion. */
            else {
              rp = regstack_push(RS_BRANCH, scan);
              if (rp == NULL)
                status = RA_FAIL;
              else
                status = RA_BREAK;                /* rest is below */
            }
          }
          break;
  
          case BRACE_LIMITS:
          {
            if (OP(next) == BRACE_SIMPLE) {
              bl_minval = OPERAND_MIN(scan);
              bl_maxval = OPERAND_MAX(scan);
            } else if (OP(next) >= BRACE_COMPLEX
                       && OP(next) < BRACE_COMPLEX + 10) {
              no = OP(next) - BRACE_COMPLEX;
              brace_min[no] = OPERAND_MIN(scan);
              brace_max[no] = OPERAND_MAX(scan);
              brace_count[no] = 0;
            } else   {
              EMSG(_(e_internal));                    /* Shouldn't happen */
              status = RA_FAIL;
            }
          }
          break;
  
          case BRACE_COMPLEX + 0:
          case BRACE_COMPLEX + 1:
          case BRACE_COMPLEX + 2:
          case BRACE_COMPLEX + 3:
          case BRACE_COMPLEX + 4:
          case BRACE_COMPLEX + 5:
          case BRACE_COMPLEX + 6:
          case BRACE_COMPLEX + 7:
          case BRACE_COMPLEX + 8:
          case BRACE_COMPLEX + 9:
          {
            no = op - BRACE_COMPLEX;
            ++brace_count[no];
  
            /* If not matched enough times yet, try one more */
            if (brace_count[no] <= (brace_min[no] <= brace_max[no]
                                    ? brace_min[no] : brace_max[no])) {
              rp = regstack_push(RS_BRCPLX_MORE, scan);
              if (rp == NULL)
                status = RA_FAIL;
              else {
                rp->rs_no = no;
                reg_save(&rp->rs_un.regsave, &backpos);
                next = OPERAND(scan);
                /* We continue and handle the result when done. */
              }
              break;
            }
  
            /* If matched enough times, may try matching some more */
            if (brace_min[no] <= brace_max[no]) {
              /* Range is the normal way around, use longest match */
              if (brace_count[no] <= brace_max[no]) {
                rp = regstack_push(RS_BRCPLX_LONG, scan);
                if (rp == NULL)
                  status = RA_FAIL;
                else {
                  rp->rs_no = no;
                  reg_save(&rp->rs_un.regsave, &backpos);
                  next = OPERAND(scan);
                  /* We continue and handle the result when done. */
                }
              }
            } else   {
              /* Range is backwards, use shortest match first */
              if (brace_count[no] <= brace_min[no]) {
                rp = regstack_push(RS_BRCPLX_SHORT, scan);
                if (rp == NULL)
                  status = RA_FAIL;
                else {
                  reg_save(&rp->rs_un.regsave, &backpos);
                  /* We continue and handle the result when done. */
                }
              }
            }
          }
          break;
  
          case BRACE_SIMPLE:
          case STAR:
          case PLUS:
          {
            regstar_T rst;
  
            /*
             * Lookahead to avoid useless match attempts when we know
             * what character comes next.
             */
            if (OP(next) == EXACTLY) {
              rst.nextb = *OPERAND(next);
              if (ireg_ic) {
                if (MB_ISUPPER(rst.nextb))
                  rst.nextb_ic = MB_TOLOWER(rst.nextb);
                else
                  rst.nextb_ic = MB_TOUPPER(rst.nextb);
              } else
                rst.nextb_ic = rst.nextb;
            } else   {
              rst.nextb = NUL;
              rst.nextb_ic = NUL;
            }
            if (op != BRACE_SIMPLE) {
              rst.minval = (op == STAR) ? 0 : 1;
              rst.maxval = MAX_LIMIT;
            } else   {
              rst.minval = bl_minval;
              rst.maxval = bl_maxval;
            }
  
            /*
             * When maxval > minval, try matching as much as possible, up
             * to maxval.  When maxval < minval, try matching at least the
             * minimal number (since the range is backwards, that's also
             * maxval!).
             */
            rst.count = regrepeat(OPERAND(scan), rst.maxval);
            if (got_int) {
              status = RA_FAIL;
              break;
            }
            if (rst.minval <= rst.maxval
                ? rst.count >= rst.minval : rst.count >= rst.maxval) {
              /* It could match.  Prepare for trying to match what
               * follows.  The code is below.  Parameters are stored in
               * a regstar_T on the regstack. */
              if ((long)((unsigned)regstack.ga_len >> 10) >= p_mmp) {
                EMSG(_(e_maxmempat));
                status = RA_FAIL;
              } else if (ga_grow(&regstack, sizeof(regstar_T)) == FAIL)
                status = RA_FAIL;
              else {
                regstack.ga_len += sizeof(regstar_T);
                rp = regstack_push(rst.minval <= rst.maxval
                    ? RS_STAR_LONG : RS_STAR_SHORT, scan);
                if (rp == NULL)
                  status = RA_FAIL;
                else {
                  *(((regstar_T *)rp) - 1) = rst;
                  status = RA_BREAK;                  /* skip the restore bits */
                }
              }
            } else
              status = RA_NOMATCH;
  
          }
          break;
  
          case NOMATCH:
          case MATCH:
          case SUBPAT:
            rp = regstack_push(RS_NOMATCH, scan);
            if (rp == NULL)
              status = RA_FAIL;
            else {
              rp->rs_no = op;
              reg_save(&rp->rs_un.regsave, &backpos);
              next = OPERAND(scan);
              /* We continue and handle the result when done. */
            }
            break;
  
          case BEHIND:
          case NOBEHIND:
            /* Need a bit of room to store extra positions. */
            if ((long)((unsigned)regstack.ga_len >> 10) >= p_mmp) {
              EMSG(_(e_maxmempat));
              status = RA_FAIL;
            } else if (ga_grow(&regstack, sizeof(regbehind_T)) == FAIL)
              status = RA_FAIL;
            else {
              regstack.ga_len += sizeof(regbehind_T);
              rp = regstack_push(RS_BEHIND1, scan);
              if (rp == NULL)
                status = RA_FAIL;
              else {
                /* Need to save the subexpr to be able to restore them
                 * when there is a match but we don't use it. */
                save_subexpr(((regbehind_T *)rp) - 1);
  
                rp->rs_no = op;
                reg_save(&rp->rs_un.regsave, &backpos);
                /* First try if what follows matches.  If it does then we
                 * check the behind match by looping. */
              }
            }
            break;
  
          case BHPOS:
            if (REG_MULTI) {
              if (behind_pos.rs_u.pos.col != (colnr_T)(reginput - regline)
                  || behind_pos.rs_u.pos.lnum != reglnum)
                status = RA_NOMATCH;
            } else if (behind_pos.rs_u.ptr != reginput)
              status = RA_NOMATCH;
            break;
  
          case NEWL:
            if ((c != NUL || !REG_MULTI || reglnum > reg_maxline
                 || reg_line_lbr) && (c != '\n' || !reg_line_lbr))
              status = RA_NOMATCH;
            else if (reg_line_lbr)
              ADVANCE_REGINPUT();
            else
              reg_nextline();
            break;
  
          case END:
            status = RA_MATCH;    /* Success! */
            break;
  
          default:
            EMSG(_(e_re_corr));
  #ifdef REGEXP_DEBUG
            printf("Illegal op code %d\n", op);
  #endif
            status = RA_FAIL;
            break;
          }
        }
  
        /* If we can't continue sequentially, break the inner loop. */
        if (status != RA_CONT)
          break;
  
        /* Continue in inner loop, advance to next item. */
        scan = next;
  
      } /* end of inner loop */
  
      /*
       * If there is something on the regstack execute the code for the state.
       * If the state is popped then loop and use the older state.
       */
      while (regstack.ga_len > 0 && status != RA_FAIL) {
        rp = (regitem_T *)((char *)regstack.ga_data + regstack.ga_len) - 1;
        switch (rp->rs_state) {
        case RS_NOPEN:
          /* Result is passed on as-is, simply pop the state. */
          regstack_pop(&scan);
          break;
  
        case RS_MOPEN:
          /* Pop the state.  Restore pointers when there is no match. */
          if (status == RA_NOMATCH)
            restore_se(&rp->rs_un.sesave, &reg_startpos[rp->rs_no],
                &reg_startp[rp->rs_no]);
          regstack_pop(&scan);
          break;
  
        case RS_ZOPEN:
          /* Pop the state.  Restore pointers when there is no match. */
          if (status == RA_NOMATCH)
            restore_se(&rp->rs_un.sesave, &reg_startzpos[rp->rs_no],
                &reg_startzp[rp->rs_no]);
          regstack_pop(&scan);
          break;
  
        case RS_MCLOSE:
          /* Pop the state.  Restore pointers when there is no match. */
          if (status == RA_NOMATCH)
            restore_se(&rp->rs_un.sesave, &reg_endpos[rp->rs_no],
                &reg_endp[rp->rs_no]);
          regstack_pop(&scan);
          break;
  
        case RS_ZCLOSE:
          /* Pop the state.  Restore pointers when there is no match. */
          if (status == RA_NOMATCH)
            restore_se(&rp->rs_un.sesave, &reg_endzpos[rp->rs_no],
                &reg_endzp[rp->rs_no]);
          regstack_pop(&scan);
          break;
  
        case RS_BRANCH:
          if (status == RA_MATCH)
            /* this branch matched, use it */
            regstack_pop(&scan);
          else {
            if (status != RA_BREAK) {
              /* After a non-matching branch: try next one. */
              reg_restore(&rp->rs_un.regsave, &backpos);
              scan = rp->rs_scan;
            }
            if (scan == NULL || OP(scan) != BRANCH) {
              /* no more branches, didn't find a match */
              status = RA_NOMATCH;
              regstack_pop(&scan);
            } else   {
              /* Prepare to try a branch. */
              rp->rs_scan = regnext(scan);
              reg_save(&rp->rs_un.regsave, &backpos);
              scan = OPERAND(scan);
            }
          }
          break;
  
        case RS_BRCPLX_MORE:
          /* Pop the state.  Restore pointers when there is no match. */
          if (status == RA_NOMATCH) {
            reg_restore(&rp->rs_un.regsave, &backpos);
            --brace_count[rp->rs_no];             /* decrement match count */
          }
          regstack_pop(&scan);
          break;
  
        case RS_BRCPLX_LONG:
          /* Pop the state.  Restore pointers when there is no match. */
          if (status == RA_NOMATCH) {
            /* There was no match, but we did find enough matches. */
            reg_restore(&rp->rs_un.regsave, &backpos);
            --brace_count[rp->rs_no];
            /* continue with the items after "\{}" */
            status = RA_CONT;
          }
          regstack_pop(&scan);
          if (status == RA_CONT)
            scan = regnext(scan);
          break;
  
        case RS_BRCPLX_SHORT:
          /* Pop the state.  Restore pointers when there is no match. */
          if (status == RA_NOMATCH)
            /* There was no match, try to match one more item. */
            reg_restore(&rp->rs_un.regsave, &backpos);
          regstack_pop(&scan);
          if (status == RA_NOMATCH) {
            scan = OPERAND(scan);
            status = RA_CONT;
          }
          break;
  
        case RS_NOMATCH:
          /* Pop the state.  If the operand matches for NOMATCH or
          * doesn't match for MATCH/SUBPAT, we fail.  Otherwise backup,
          * except for SUBPAT, and continue with the next item. */
          if (status == (rp->rs_no == NOMATCH ? RA_MATCH : RA_NOMATCH))
            status = RA_NOMATCH;
          else {
            status = RA_CONT;
            if (rp->rs_no != SUBPAT)              /* zero-width */
              reg_restore(&rp->rs_un.regsave, &backpos);
          }
          regstack_pop(&scan);
          if (status == RA_CONT)
            scan = regnext(scan);
          break;
  
        case RS_BEHIND1:
          if (status == RA_NOMATCH) {
            regstack_pop(&scan);
            regstack.ga_len -= sizeof(regbehind_T);
          } else   {
            /* The stuff after BEHIND/NOBEHIND matches.  Now try if
             * the behind part does (not) match before the current
             * position in the input.  This must be done at every
             * position in the input and checking if the match ends at
             * the current position. */
  
            /* save the position after the found match for next */
            reg_save(&(((regbehind_T *)rp) - 1)->save_after, &backpos);
  
            /* Start looking for a match with operand at the current
             * position.  Go back one character until we find the
             * result, hitting the start of the line or the previous
             * line (for multi-line matching).
             * Set behind_pos to where the match should end, BHPOS
             * will match it.  Save the current value. */
            (((regbehind_T *)rp) - 1)->save_behind = behind_pos;
            behind_pos = rp->rs_un.regsave;
  
            rp->rs_state = RS_BEHIND2;
  
            reg_restore(&rp->rs_un.regsave, &backpos);
            scan = OPERAND(rp->rs_scan) + 4;
          }
          break;
  
        case RS_BEHIND2:
          /*
           * Looping for BEHIND / NOBEHIND match.
           */
          if (status == RA_MATCH && reg_save_equal(&behind_pos)) {
            /* found a match that ends where "next" started */
            behind_pos = (((regbehind_T *)rp) - 1)->save_behind;
            if (rp->rs_no == BEHIND)
              reg_restore(&(((regbehind_T *)rp) - 1)->save_after,
                  &backpos);
            else {
              /* But we didn't want a match.  Need to restore the
               * subexpr, because what follows matched, so they have
               * been set. */
              status = RA_NOMATCH;
              restore_subexpr(((regbehind_T *)rp) - 1);
            }
            regstack_pop(&scan);
            regstack.ga_len -= sizeof(regbehind_T);
          } else   {
            long limit;
  
            /* No match or a match that doesn't end where we want it: Go
             * back one character.  May go to previous line once. */
            no = OK;
            limit = OPERAND_MIN(rp->rs_scan);
            if (REG_MULTI) {
              if (limit > 0
                  && ((rp->rs_un.regsave.rs_u.pos.lnum
                       < behind_pos.rs_u.pos.lnum
                       ? (colnr_T)STRLEN(regline)
                       : behind_pos.rs_u.pos.col)
                      - rp->rs_un.regsave.rs_u.pos.col >= limit))
                no = FAIL;
              else if (rp->rs_un.regsave.rs_u.pos.col == 0) {
                if (rp->rs_un.regsave.rs_u.pos.lnum
                    < behind_pos.rs_u.pos.lnum
                    || reg_getline(
                        --rp->rs_un.regsave.rs_u.pos.lnum)
                    == NULL)
                  no = FAIL;
                else {
                  reg_restore(&rp->rs_un.regsave, &backpos);
                  rp->rs_un.regsave.rs_u.pos.col =
                    (colnr_T)STRLEN(regline);
                }
              } else   {
                if (has_mbyte)
                  rp->rs_un.regsave.rs_u.pos.col -=
                    (*mb_head_off)(regline, regline
                                   + rp->rs_un.regsave.rs_u.pos.col - 1) + 1;
                else
                  --rp->rs_un.regsave.rs_u.pos.col;
              }
            } else   {
              if (rp->rs_un.regsave.rs_u.ptr == regline)
                no = FAIL;
              else {
                mb_ptr_back(regline, rp->rs_un.regsave.rs_u.ptr);
                if (limit > 0 && (long)(behind_pos.rs_u.ptr
                                        - rp->rs_un.regsave.rs_u.ptr) > limit)
                  no = FAIL;
              }
            }
            if (no == OK) {
              /* Advanced, prepare for finding match again. */
              reg_restore(&rp->rs_un.regsave, &backpos);
              scan = OPERAND(rp->rs_scan) + 4;
              if (status == RA_MATCH) {
                /* We did match, so subexpr may have been changed,
                 * need to restore them for the next try. */
                status = RA_NOMATCH;
                restore_subexpr(((regbehind_T *)rp) - 1);
              }
            } else   {
              /* Can't advance.  For NOBEHIND that's a match. */
              behind_pos = (((regbehind_T *)rp) - 1)->save_behind;
              if (rp->rs_no == NOBEHIND) {
                reg_restore(&(((regbehind_T *)rp) - 1)->save_after,
                    &backpos);
                status = RA_MATCH;
              } else   {
                /* We do want a proper match.  Need to restore the
                 * subexpr if we had a match, because they may have
                 * been set. */
                if (status == RA_MATCH) {
                  status = RA_NOMATCH;
                  restore_subexpr(((regbehind_T *)rp) - 1);
                }
              }
              regstack_pop(&scan);
              regstack.ga_len -= sizeof(regbehind_T);
            }
          }
          break;
  
        case RS_STAR_LONG:
        case RS_STAR_SHORT:
        {
          regstar_T           *rst = ((regstar_T *)rp) - 1;
  
          if (status == RA_MATCH) {
            regstack_pop(&scan);
            regstack.ga_len -= sizeof(regstar_T);
            break;
          }
  
          /* Tried once already, restore input pointers. */
          if (status != RA_BREAK)
            reg_restore(&rp->rs_un.regsave, &backpos);
  
          /* Repeat until we found a position where it could match. */
          for (;; ) {
            if (status != RA_BREAK) {
              /* Tried first position already, advance. */
              if (rp->rs_state == RS_STAR_LONG) {
                /* Trying for longest match, but couldn't or
                 * didn't match -- back up one char. */
                if (--rst->count < rst->minval)
                  break;
                if (reginput == regline) {
                  /* backup to last char of previous line */
                  --reglnum;
                  regline = reg_getline(reglnum);
                  /* Just in case regrepeat() didn't count
                   * right. */
                  if (regline == NULL)
                    break;
                  reginput = regline + STRLEN(regline);
                  fast_breakcheck();
                } else
                  mb_ptr_back(regline, reginput);
              } else   {
                /* Range is backwards, use shortest match first.
                 * Careful: maxval and minval are exchanged!
                 * Couldn't or didn't match: try advancing one
                 * char. */
                if (rst->count == rst->minval
                    || regrepeat(OPERAND(rp->rs_scan), 1L) == 0)
                  break;
                ++rst->count;
              }
              if (got_int)
                break;
            } else
              status = RA_NOMATCH;
  
            /* If it could match, try it. */
            if (rst->nextb == NUL || *reginput == rst->nextb
                || *reginput == rst->nextb_ic) {
              reg_save(&rp->rs_un.regsave, &backpos);
              scan = regnext(rp->rs_scan);
              status = RA_CONT;
              break;
            }
          }
          if (status != RA_CONT) {
            /* Failed. */
            regstack_pop(&scan);
            regstack.ga_len -= sizeof(regstar_T);
            status = RA_NOMATCH;
          }
        }
        break;
        }
  
        /* If we want to continue the inner loop or didn't pop a state
         * continue matching loop */
        if (status == RA_CONT || rp == (regitem_T *)
            ((char *)regstack.ga_data + regstack.ga_len) - 1)
          break;
      }
  
      /* May need to continue with the inner loop, starting at "scan". */
      if (status == RA_CONT)
        continue;
  
      /*
       * If the regstack is empty or something failed we are done.
       */
      if (regstack.ga_len == 0 || status == RA_FAIL) {
        if (scan == NULL) {
          /*
           * We get here only if there's trouble -- normally "case END" is
           * the terminating point.
           */
          EMSG(_(e_re_corr));
  #ifdef REGEXP_DEBUG
          printf("Premature EOL\n");
  #endif
        }
        if (status == RA_FAIL)
          got_int = TRUE;
        return status == RA_MATCH;
      }
  
    } /* End of loop until the regstack is empty. */
  
    /* NOTREACHED */
  }
  
  /*
   * Push an item onto the regstack.
   * Returns pointer to new item.  Returns NULL when out of memory.
   */
  static regitem_T * regstack_push(state, scan)
  regstate_T state;
  char_u      *scan;
  {
    regitem_T   *rp;
  
    if ((long)((unsigned)regstack.ga_len >> 10) >= p_mmp) {
      EMSG(_(e_maxmempat));
      return NULL;
    }
    if (ga_grow(&regstack, sizeof(regitem_T)) == FAIL)
      return NULL;
  
    rp = (regitem_T *)((char *)regstack.ga_data + regstack.ga_len);
    rp->rs_state = state;
    rp->rs_scan = scan;
  
    regstack.ga_len += sizeof(regitem_T);
    return rp;
  }
  
  /*
   * Pop an item from the regstack.
   */
  static void regstack_pop(scan)
  char_u      **scan;
  {
    regitem_T   *rp;
  
    rp = (regitem_T *)((char *)regstack.ga_data + regstack.ga_len) - 1;
    *scan = rp->rs_scan;
  
    regstack.ga_len -= sizeof(regitem_T);
  }
  
  /*
   * regrepeat - repeatedly match something simple, return how many.
   * Advances reginput (and reglnum) to just after the matched chars.
   */
  static int regrepeat(p, maxcount)
  char_u      *p;
  long maxcount;              /* maximum number of matches allowed */
  {
    long count = 0;
    char_u      *scan;
    char_u      *opnd;
    int mask;
    int testval = 0;
  
    scan = reginput;          /* Make local copy of reginput for speed. */
    opnd = OPERAND(p);
    switch (OP(p)) {
    case ANY:
    case ANY + ADD_NL:
      while (count < maxcount) {
        /* Matching anything means we continue until end-of-line (or
         * end-of-file for ANY + ADD_NL), only limited by maxcount. */
        while (*scan != NUL && count < maxcount) {
          ++count;
          mb_ptr_adv(scan);
        }
        if (!REG_MULTI || !WITH_NL(OP(p)) || reglnum > reg_maxline
            || reg_line_lbr || count == maxcount)
          break;
        ++count;                  /* count the line-break */
        reg_nextline();
        scan = reginput;
        if (got_int)
          break;
      }
      break;
  
    case IDENT:
    case IDENT + ADD_NL:
      testval = TRUE;
    /*FALLTHROUGH*/
    case SIDENT:
    case SIDENT + ADD_NL:
      while (count < maxcount) {
        if (vim_isIDc(PTR2CHAR(scan)) && (testval || !VIM_ISDIGIT(*scan))) {
          mb_ptr_adv(scan);
        } else if (*scan == NUL)   {
          if (!REG_MULTI || !WITH_NL(OP(p)) || reglnum > reg_maxline
              || reg_line_lbr)
            break;
          reg_nextline();
          scan = reginput;
          if (got_int)
            break;
        } else if (reg_line_lbr && *scan == '\n' && WITH_NL(OP(p)))
          ++scan;
        else
          break;
        ++count;
      }
      break;
  
    case KWORD:
    case KWORD + ADD_NL:
      testval = TRUE;
    /*FALLTHROUGH*/
    case SKWORD:
    case SKWORD + ADD_NL:
      while (count < maxcount) {
        if (vim_iswordp_buf(scan, reg_buf)
            && (testval || !VIM_ISDIGIT(*scan))) {
          mb_ptr_adv(scan);
        } else if (*scan == NUL)   {
          if (!REG_MULTI || !WITH_NL(OP(p)) || reglnum > reg_maxline
              || reg_line_lbr)
            break;
          reg_nextline();
          scan = reginput;
          if (got_int)
            break;
        } else if (reg_line_lbr && *scan == '\n' && WITH_NL(OP(p)))
          ++scan;
        else
          break;
        ++count;
      }
      break;
  
    case FNAME:
    case FNAME + ADD_NL:
      testval = TRUE;
    /*FALLTHROUGH*/
    case SFNAME:
    case SFNAME + ADD_NL:
      while (count < maxcount) {
        if (vim_isfilec(PTR2CHAR(scan)) && (testval || !VIM_ISDIGIT(*scan))) {
          mb_ptr_adv(scan);
        } else if (*scan == NUL)   {
          if (!REG_MULTI || !WITH_NL(OP(p)) || reglnum > reg_maxline
              || reg_line_lbr)
            break;
          reg_nextline();
          scan = reginput;
          if (got_int)
            break;
        } else if (reg_line_lbr && *scan == '\n' && WITH_NL(OP(p)))
          ++scan;
        else
          break;
        ++count;
      }
      break;
  
    case PRINT:
    case PRINT + ADD_NL:
      testval = TRUE;
    /*FALLTHROUGH*/
    case SPRINT:
    case SPRINT + ADD_NL:
      while (count < maxcount) {
        if (*scan == NUL) {
          if (!REG_MULTI || !WITH_NL(OP(p)) || reglnum > reg_maxline
              || reg_line_lbr)
            break;
          reg_nextline();
          scan = reginput;
          if (got_int)
            break;
        } else if (vim_isprintc(PTR2CHAR(scan)) == 1
                   && (testval || !VIM_ISDIGIT(*scan))) {
          mb_ptr_adv(scan);
        } else if (reg_line_lbr && *scan == '\n' && WITH_NL(OP(p)))
          ++scan;
        else
          break;
        ++count;
      }
      break;
  
    case WHITE:
    case WHITE + ADD_NL:
      testval = mask = RI_WHITE;
  do_class:
      while (count < maxcount) {
        int l;
        if (*scan == NUL) {
          if (!REG_MULTI || !WITH_NL(OP(p)) || reglnum > reg_maxline
              || reg_line_lbr)
            break;
          reg_nextline();
          scan = reginput;
          if (got_int)
            break;
        } else if (has_mbyte && (l = (*mb_ptr2len)(scan)) > 1)   {
          if (testval != 0)
            break;
          scan += l;
        } else if ((class_tab[*scan] & mask) == testval)
          ++scan;
        else if (reg_line_lbr && *scan == '\n' && WITH_NL(OP(p)))
          ++scan;
        else
          break;
        ++count;
      }
      break;
  
    case NWHITE:
    case NWHITE + ADD_NL:
      mask = RI_WHITE;
      goto do_class;
    case DIGIT:
    case DIGIT + ADD_NL:
      testval = mask = RI_DIGIT;
      goto do_class;
    case NDIGIT:
    case NDIGIT + ADD_NL:
      mask = RI_DIGIT;
      goto do_class;
    case HEX:
    case HEX + ADD_NL:
      testval = mask = RI_HEX;
      goto do_class;
    case NHEX:
    case NHEX + ADD_NL:
      mask = RI_HEX;
      goto do_class;
    case OCTAL:
    case OCTAL + ADD_NL:
      testval = mask = RI_OCTAL;
      goto do_class;
    case NOCTAL:
    case NOCTAL + ADD_NL:
      mask = RI_OCTAL;
      goto do_class;
    case WORD:
    case WORD + ADD_NL:
      testval = mask = RI_WORD;
      goto do_class;
    case NWORD:
    case NWORD + ADD_NL:
      mask = RI_WORD;
      goto do_class;
    case HEAD:
    case HEAD + ADD_NL:
      testval = mask = RI_HEAD;
      goto do_class;
    case NHEAD:
    case NHEAD + ADD_NL:
      mask = RI_HEAD;
      goto do_class;
    case ALPHA:
    case ALPHA + ADD_NL:
      testval = mask = RI_ALPHA;
      goto do_class;
    case NALPHA:
    case NALPHA + ADD_NL:
      mask = RI_ALPHA;
      goto do_class;
    case LOWER:
    case LOWER + ADD_NL:
      testval = mask = RI_LOWER;
      goto do_class;
    case NLOWER:
    case NLOWER + ADD_NL:
      mask = RI_LOWER;
      goto do_class;
    case UPPER:
    case UPPER + ADD_NL:
      testval = mask = RI_UPPER;
      goto do_class;
    case NUPPER:
    case NUPPER + ADD_NL:
      mask = RI_UPPER;
      goto do_class;
  
    case EXACTLY:
    {
      int cu, cl;
  
      /* This doesn't do a multi-byte character, because a MULTIBYTECODE
       * would have been used for it.  It does handle single-byte
       * characters, such as latin1. */
      if (ireg_ic) {
        cu = MB_TOUPPER(*opnd);
        cl = MB_TOLOWER(*opnd);
        while (count < maxcount && (*scan == cu || *scan == cl)) {
          count++;
          scan++;
        }
      } else   {
        cu = *opnd;
        while (count < maxcount && *scan == cu) {
          count++;
          scan++;
        }
      }
      break;
    }
  
    case MULTIBYTECODE:
    {
      int i, len, cf = 0;
  
      /* Safety check (just in case 'encoding' was changed since
       * compiling the program). */
      if ((len = (*mb_ptr2len)(opnd)) > 1) {
        if (ireg_ic && enc_utf8)
          cf = utf_fold(utf_ptr2char(opnd));
        while (count < maxcount) {
          for (i = 0; i < len; ++i)
            if (opnd[i] != scan[i])
              break;
          if (i < len && (!ireg_ic || !enc_utf8
                          || utf_fold(utf_ptr2char(scan)) != cf))
            break;
          scan += len;
          ++count;
        }
      }
    }
    break;
  
    case ANYOF:
    case ANYOF + ADD_NL:
      testval = TRUE;
    /*FALLTHROUGH*/
  
    case ANYBUT:
    case ANYBUT + ADD_NL:
      while (count < maxcount) {
        int len;
        if (*scan == NUL) {
          if (!REG_MULTI || !WITH_NL(OP(p)) || reglnum > reg_maxline
              || reg_line_lbr)
            break;
          reg_nextline();
          scan = reginput;
          if (got_int)
            break;
        } else if (reg_line_lbr && *scan == '\n' && WITH_NL(OP(p)))
          ++scan;
        else if (has_mbyte && (len = (*mb_ptr2len)(scan)) > 1) {
          if ((cstrchr(opnd, (*mb_ptr2char)(scan)) == NULL) == testval)
            break;
          scan += len;
        } else   {
          if ((cstrchr(opnd, *scan) == NULL) == testval)
            break;
          ++scan;
        }
        ++count;
      }
      break;
  
    case NEWL:
      while (count < maxcount
             && ((*scan == NUL && reglnum <= reg_maxline && !reg_line_lbr
                  && REG_MULTI) || (*scan == '\n' && reg_line_lbr))) {
        count++;
        if (reg_line_lbr)
          ADVANCE_REGINPUT();
        else
          reg_nextline();
        scan = reginput;
        if (got_int)
          break;
      }
      break;
  
    default:                      /* Oh dear.  Called inappropriately. */
      EMSG(_(e_re_corr));
  #ifdef REGEXP_DEBUG
      printf("Called regrepeat with op code %d\n", OP(p));
  #endif
      break;
    }
  
    reginput = scan;
  
    return (int)count;
  }
  
  /*
   * regnext - dig the "next" pointer out of a node
   * Returns NULL when calculating size, when there is no next item and when
   * there is an error.
   */
  static char_u * regnext(p)
  char_u  *p;
  {
    int offset;
  
    if (p == JUST_CALC_SIZE || reg_toolong)
      return NULL;
  
    offset = NEXT(p);
    if (offset == 0)
      return NULL;
  
    if (OP(p) == BACK)
      return p - offset;
    else
      return p + offset;
  }
  
  /*
   * Check the regexp program for its magic number.
   * Return TRUE if it's wrong.
   */
  static int prog_magic_wrong()                {
    regprog_T   *prog;
  
    prog = REG_MULTI ? reg_mmatch->regprog : reg_match->regprog;
    if (prog->engine == &nfa_regengine)
      /* For NFA matcher we don't check the magic */
      return FALSE;
  
    if (UCHARAT(((bt_regprog_T *)prog)->program) != REGMAGIC) {
      EMSG(_(e_re_corr));
      return TRUE;
    }
    return FALSE;
  }
  
  /*
   * Cleanup the subexpressions, if this wasn't done yet.
   * This construction is used to clear the subexpressions only when they are
   * used (to increase speed).
   */
  static void cleanup_subexpr()                 {
    if (need_clear_subexpr) {
      if (REG_MULTI) {
        /* Use 0xff to set lnum to -1 */
        vim_memset(reg_startpos, 0xff, sizeof(lpos_T) * NSUBEXP);
        vim_memset(reg_endpos, 0xff, sizeof(lpos_T) * NSUBEXP);
      } else   {
        vim_memset(reg_startp, 0, sizeof(char_u *) * NSUBEXP);
        vim_memset(reg_endp, 0, sizeof(char_u *) * NSUBEXP);
      }
      need_clear_subexpr = FALSE;
    }
  }
  
  static void cleanup_zsubexpr()                 {
    if (need_clear_zsubexpr) {
      if (REG_MULTI) {
        /* Use 0xff to set lnum to -1 */
        vim_memset(reg_startzpos, 0xff, sizeof(lpos_T) * NSUBEXP);
        vim_memset(reg_endzpos, 0xff, sizeof(lpos_T) * NSUBEXP);
      } else   {
        vim_memset(reg_startzp, 0, sizeof(char_u *) * NSUBEXP);
        vim_memset(reg_endzp, 0, sizeof(char_u *) * NSUBEXP);
      }
      need_clear_zsubexpr = FALSE;
    }
  }
  
  /*
   * Save the current subexpr to "bp", so that they can be restored
   * later by restore_subexpr().
   */
  static void save_subexpr(bp)
  regbehind_T *bp;
  {
    int i;
  
    /* When "need_clear_subexpr" is set we don't need to save the values, only
     * remember that this flag needs to be set again when restoring. */
    bp->save_need_clear_subexpr = need_clear_subexpr;
    if (!need_clear_subexpr) {
      for (i = 0; i < NSUBEXP; ++i) {
        if (REG_MULTI) {
          bp->save_start[i].se_u.pos = reg_startpos[i];
          bp->save_end[i].se_u.pos = reg_endpos[i];
        } else   {
          bp->save_start[i].se_u.ptr = reg_startp[i];
          bp->save_end[i].se_u.ptr = reg_endp[i];
        }
      }
    }
  }
  
  /*
   * Restore the subexpr from "bp".
   */
  static void restore_subexpr(bp)
  regbehind_T *bp;
  {
    int i;
  
    /* Only need to restore saved values when they are not to be cleared. */
    need_clear_subexpr = bp->save_need_clear_subexpr;
    if (!need_clear_subexpr) {
      for (i = 0; i < NSUBEXP; ++i) {
        if (REG_MULTI) {
          reg_startpos[i] = bp->save_start[i].se_u.pos;
          reg_endpos[i] = bp->save_end[i].se_u.pos;
        } else   {
          reg_startp[i] = bp->save_start[i].se_u.ptr;
          reg_endp[i] = bp->save_end[i].se_u.ptr;
        }
      }
    }
  }
  
  /*
   * Advance reglnum, regline and reginput to the next line.
   */
  static void reg_nextline()                 {
    regline = reg_getline(++reglnum);
    reginput = regline;
    fast_breakcheck();
  }
  
  /*
   * Save the input line and position in a regsave_T.
   */
  static void reg_save(save, gap)
  regsave_T   *save;
  garray_T    *gap;
  {
    if (REG_MULTI) {
      save->rs_u.pos.col = (colnr_T)(reginput - regline);
      save->rs_u.pos.lnum = reglnum;
    } else
      save->rs_u.ptr = reginput;
    save->rs_len = gap->ga_len;
  }
  
  /*
   * Restore the input line and position from a regsave_T.
   */
  static void reg_restore(save, gap)
  regsave_T   *save;
  garray_T    *gap;
  {
    if (REG_MULTI) {
      if (reglnum != save->rs_u.pos.lnum) {
        /* only call reg_getline() when the line number changed to save
         * a bit of time */
        reglnum = save->rs_u.pos.lnum;
        regline = reg_getline(reglnum);
      }
      reginput = regline + save->rs_u.pos.col;
    } else
      reginput = save->rs_u.ptr;
    gap->ga_len = save->rs_len;
  }
  
  /*
   * Return TRUE if current position is equal to saved position.
   */
  static int reg_save_equal(save)
  regsave_T   *save;
  {
    if (REG_MULTI)
      return reglnum == save->rs_u.pos.lnum
             && reginput == regline + save->rs_u.pos.col;
    return reginput == save->rs_u.ptr;
  }
  
  /*
   * Tentatively set the sub-expression start to the current position (after
   * calling regmatch() they will have changed).  Need to save the existing
   * values for when there is no match.
   * Use se_save() to use pointer (save_se_multi()) or position (save_se_one()),
   * depending on REG_MULTI.
   */
  static void save_se_multi(savep, posp)
  save_se_T   *savep;
  lpos_T      *posp;
  {
    savep->se_u.pos = *posp;
    posp->lnum = reglnum;
    posp->col = (colnr_T)(reginput - regline);
  }
  
  static void save_se_one(savep, pp)
  save_se_T   *savep;
  char_u      **pp;
  {
    savep->se_u.ptr = *pp;
    *pp = reginput;
  }
  
  /*
   * Compare a number with the operand of RE_LNUM, RE_COL or RE_VCOL.
   */
  static int re_num_cmp(val, scan)
  long_u val;
  char_u      *scan;
  {
    long_u n = OPERAND_MIN(scan);
  
    if (OPERAND_CMP(scan) == '>')
      return val > n;
    if (OPERAND_CMP(scan) == '<')
      return val < n;
    return val == n;
  }
  
  /*
   * Check whether a backreference matches.
   * Returns RA_FAIL, RA_NOMATCH or RA_MATCH.
   * If "bytelen" is not NULL, it is set to the byte length of the match in the
   * last line.
   */
  static int match_with_backref(start_lnum, start_col, end_lnum, end_col, bytelen)
  linenr_T start_lnum;
  colnr_T start_col;
  linenr_T end_lnum;
  colnr_T end_col;
  int      *bytelen;
  {
    linenr_T clnum = start_lnum;
    colnr_T ccol = start_col;
    int len;
    char_u      *p;
  
    if (bytelen != NULL)
      *bytelen = 0;
    for (;; ) {
      /* Since getting one line may invalidate the other, need to make copy.
       * Slow! */
      if (regline != reg_tofree) {
        len = (int)STRLEN(regline);
        if (reg_tofree == NULL || len >= (int)reg_tofreelen) {
          len += 50;              /* get some extra */
          vim_free(reg_tofree);
          reg_tofree = alloc(len);
          if (reg_tofree == NULL)
            return RA_FAIL;           /* out of memory!*/
          reg_tofreelen = len;
        }
        STRCPY(reg_tofree, regline);
        reginput = reg_tofree + (reginput - regline);
        regline = reg_tofree;
      }
  
      /* Get the line to compare with. */
      p = reg_getline(clnum);
      if (clnum == end_lnum)
        len = end_col - ccol;
      else
        len = (int)STRLEN(p + ccol);
  
      if (cstrncmp(p + ccol, reginput, &len) != 0)
        return RA_NOMATCH;        /* doesn't match */
      if (bytelen != NULL)
        *bytelen += len;
      if (clnum == end_lnum)
        break;                    /* match and at end! */
      if (reglnum >= reg_maxline)
        return RA_NOMATCH;        /* text too short */
  
      /* Advance to next line. */
      reg_nextline();
      if (bytelen != NULL)
        *bytelen = 0;
      ++clnum;
      ccol = 0;
      if (got_int)
        return RA_FAIL;
    }
  
    /* found a match!  Note that regline may now point to a copy of the line,
     * that should not matter. */
    return RA_MATCH;
  }
  
  #ifdef BT_REGEXP_DUMP
  
  /*
   * regdump - dump a regexp onto stdout in vaguely comprehensible form
   */
  static void regdump(pattern, r)
  char_u      *pattern;
  bt_regprog_T        *r;
  {
    char_u  *s;
    int op = EXACTLY;             /* Arbitrary non-END op. */
    char_u  *next;
    char_u  *end = NULL;
    FILE    *f;
  
  #ifdef BT_REGEXP_LOG
    f = fopen("bt_regexp_log.log", "a");
  #else
    f = stdout;
  #endif
    if (f == NULL)
      return;
    fprintf(f, "-------------------------------------\n\r\nregcomp(%s):\r\n",
        pattern);
  
    s = r->program + 1;
    /*
     * Loop until we find the END that isn't before a referred next (an END
     * can also appear in a NOMATCH operand).
     */
    while (op != END || s <= end) {
      op = OP(s);
      fprintf(f, "%2d%s", (int)(s - r->program), regprop(s));     /* Where, what. */
      next = regnext(s);
      if (next == NULL)           /* Next ptr. */
        fprintf(f, "(0)");
      else
        fprintf(f, "(%d)", (int)((s - r->program) + (next - s)));
      if (end < next)
        end = next;
      if (op == BRACE_LIMITS) {
        /* Two ints */
        fprintf(f, " minval %ld, maxval %ld", OPERAND_MIN(s), OPERAND_MAX(s));
        s += 8;
      } else if (op == BEHIND || op == NOBEHIND)   {
        /* one int */
        fprintf(f, " count %ld", OPERAND_MIN(s));
        s += 4;
      } else if (op == RE_LNUM || op == RE_COL || op == RE_VCOL)   {
        /* one int plus comperator */
        fprintf(f, " count %ld", OPERAND_MIN(s));
        s += 5;
      }
      s += 3;
      if (op == ANYOF || op == ANYOF + ADD_NL
          || op == ANYBUT || op == ANYBUT + ADD_NL
          || op == EXACTLY) {
        /* Literal string, where present. */
        fprintf(f, "\nxxxxxxxxx\n");
        while (*s != NUL)
          fprintf(f, "%c", *s++);
        fprintf(f, "\nxxxxxxxxx\n");
        s++;
      }
      fprintf(f, "\r\n");
    }
  
    /* Header fields of interest. */
    if (r->regstart != NUL)
      fprintf(f, "start `%s' 0x%x; ", r->regstart < 256
          ? (char *)transchar(r->regstart)
          : "multibyte", r->regstart);
    if (r->reganch)
      fprintf(f, "anchored; ");
    if (r->regmust != NULL)
      fprintf(f, "must have \"%s\"", r->regmust);
    fprintf(f, "\r\n");
  
  #ifdef BT_REGEXP_LOG
    fclose(f);
  #endif
  }
  #endif      /* BT_REGEXP_DUMP */
  
  #ifdef REGEXP_DEBUG
  /*
   * regprop - printable representation of opcode
   */
  static char_u * regprop(op)
  char_u         *op;
  {
    char            *p;
    static char buf[50];
  
    STRCPY(buf, ":");
  
    switch ((int) OP(op)) {
    case BOL:
      p = "BOL";
      break;
    case EOL:
      p = "EOL";
      break;
    case RE_BOF:
      p = "BOF";
      break;
    case RE_EOF:
      p = "EOF";
      break;
    case CURSOR:
      p = "CURSOR";
      break;
    case RE_VISUAL:
      p = "RE_VISUAL";
      break;
    case RE_LNUM:
      p = "RE_LNUM";
      break;
    case RE_MARK:
      p = "RE_MARK";
      break;
    case RE_COL:
      p = "RE_COL";
      break;
    case RE_VCOL:
      p = "RE_VCOL";
      break;
    case BOW:
      p = "BOW";
      break;
    case EOW:
      p = "EOW";
      break;
    case ANY:
      p = "ANY";
      break;
    case ANY + ADD_NL:
      p = "ANY+NL";
      break;
    case ANYOF:
      p = "ANYOF";
      break;
    case ANYOF + ADD_NL:
      p = "ANYOF+NL";
      break;
    case ANYBUT:
      p = "ANYBUT";
      break;
    case ANYBUT + ADD_NL:
      p = "ANYBUT+NL";
      break;
    case IDENT:
      p = "IDENT";
      break;
    case IDENT + ADD_NL:
      p = "IDENT+NL";
      break;
    case SIDENT:
      p = "SIDENT";
      break;
    case SIDENT + ADD_NL:
      p = "SIDENT+NL";
      break;
    case KWORD:
      p = "KWORD";
      break;
    case KWORD + ADD_NL:
      p = "KWORD+NL";
      break;
    case SKWORD:
      p = "SKWORD";
      break;
    case SKWORD + ADD_NL:
      p = "SKWORD+NL";
      break;
    case FNAME:
      p = "FNAME";
      break;
    case FNAME + ADD_NL:
      p = "FNAME+NL";
      break;
    case SFNAME:
      p = "SFNAME";
      break;
    case SFNAME + ADD_NL:
      p = "SFNAME+NL";
      break;
    case PRINT:
      p = "PRINT";
      break;
    case PRINT + ADD_NL:
      p = "PRINT+NL";
      break;
    case SPRINT:
      p = "SPRINT";
      break;
    case SPRINT + ADD_NL:
      p = "SPRINT+NL";
      break;
    case WHITE:
      p = "WHITE";
      break;
    case WHITE + ADD_NL:
      p = "WHITE+NL";
      break;
    case NWHITE:
      p = "NWHITE";
      break;
    case NWHITE + ADD_NL:
      p = "NWHITE+NL";
      break;
    case DIGIT:
      p = "DIGIT";
      break;
    case DIGIT + ADD_NL:
      p = "DIGIT+NL";
      break;
    case NDIGIT:
      p = "NDIGIT";
      break;
    case NDIGIT + ADD_NL:
      p = "NDIGIT+NL";
      break;
    case HEX:
      p = "HEX";
      break;
    case HEX + ADD_NL:
      p = "HEX+NL";
      break;
    case NHEX:
      p = "NHEX";
      break;
    case NHEX + ADD_NL:
      p = "NHEX+NL";
      break;
    case OCTAL:
      p = "OCTAL";
      break;
    case OCTAL + ADD_NL:
      p = "OCTAL+NL";
      break;
    case NOCTAL:
      p = "NOCTAL";
      break;
    case NOCTAL + ADD_NL:
      p = "NOCTAL+NL";
      break;
    case WORD:
      p = "WORD";
      break;
    case WORD + ADD_NL:
      p = "WORD+NL";
      break;
    case NWORD:
      p = "NWORD";
      break;
    case NWORD + ADD_NL:
      p = "NWORD+NL";
      break;
    case HEAD:
      p = "HEAD";
      break;
    case HEAD + ADD_NL:
      p = "HEAD+NL";
      break;
    case NHEAD:
      p = "NHEAD";
      break;
    case NHEAD + ADD_NL:
      p = "NHEAD+NL";
      break;
    case ALPHA:
      p = "ALPHA";
      break;
    case ALPHA + ADD_NL:
      p = "ALPHA+NL";
      break;
    case NALPHA:
      p = "NALPHA";
      break;
    case NALPHA + ADD_NL:
      p = "NALPHA+NL";
      break;
    case LOWER:
      p = "LOWER";
      break;
    case LOWER + ADD_NL:
      p = "LOWER+NL";
      break;
    case NLOWER:
      p = "NLOWER";
      break;
    case NLOWER + ADD_NL:
      p = "NLOWER+NL";
      break;
    case UPPER:
      p = "UPPER";
      break;
    case UPPER + ADD_NL:
      p = "UPPER+NL";
      break;
    case NUPPER:
      p = "NUPPER";
      break;
    case NUPPER + ADD_NL:
      p = "NUPPER+NL";
      break;
    case BRANCH:
      p = "BRANCH";
      break;
    case EXACTLY:
      p = "EXACTLY";
      break;
    case NOTHING:
      p = "NOTHING";
      break;
    case BACK:
      p = "BACK";
      break;
    case END:
      p = "END";
      break;
    case MOPEN + 0:
      p = "MATCH START";
      break;
    case MOPEN + 1:
    case MOPEN + 2:
    case MOPEN + 3:
    case MOPEN + 4:
    case MOPEN + 5:
    case MOPEN + 6:
    case MOPEN + 7:
    case MOPEN + 8:
    case MOPEN + 9:
      sprintf(buf + STRLEN(buf), "MOPEN%d", OP(op) - MOPEN);
      p = NULL;
      break;
    case MCLOSE + 0:
      p = "MATCH END";
      break;
    case MCLOSE + 1:
    case MCLOSE + 2:
    case MCLOSE + 3:
    case MCLOSE + 4:
    case MCLOSE + 5:
    case MCLOSE + 6:
    case MCLOSE + 7:
    case MCLOSE + 8:
    case MCLOSE + 9:
      sprintf(buf + STRLEN(buf), "MCLOSE%d", OP(op) - MCLOSE);
      p = NULL;
      break;
    case BACKREF + 1:
    case BACKREF + 2:
    case BACKREF + 3:
    case BACKREF + 4:
    case BACKREF + 5:
    case BACKREF + 6:
    case BACKREF + 7:
    case BACKREF + 8:
    case BACKREF + 9:
      sprintf(buf + STRLEN(buf), "BACKREF%d", OP(op) - BACKREF);
      p = NULL;
      break;
    case NOPEN:
      p = "NOPEN";
      break;
    case NCLOSE:
      p = "NCLOSE";
      break;
    case ZOPEN + 1:
    case ZOPEN + 2:
    case ZOPEN + 3:
    case ZOPEN + 4:
    case ZOPEN + 5:
    case ZOPEN + 6:
    case ZOPEN + 7:
    case ZOPEN + 8:
    case ZOPEN + 9:
      sprintf(buf + STRLEN(buf), "ZOPEN%d", OP(op) - ZOPEN);
      p = NULL;
      break;
    case ZCLOSE + 1:
    case ZCLOSE + 2:
    case ZCLOSE + 3:
    case ZCLOSE + 4:
    case ZCLOSE + 5:
    case ZCLOSE + 6:
    case ZCLOSE + 7:
    case ZCLOSE + 8:
    case ZCLOSE + 9:
      sprintf(buf + STRLEN(buf), "ZCLOSE%d", OP(op) - ZCLOSE);
      p = NULL;
      break;
    case ZREF + 1:
    case ZREF + 2:
    case ZREF + 3:
    case ZREF + 4:
    case ZREF + 5:
    case ZREF + 6:
    case ZREF + 7:
    case ZREF + 8:
    case ZREF + 9:
      sprintf(buf + STRLEN(buf), "ZREF%d", OP(op) - ZREF);
      p = NULL;
      break;
    case STAR:
      p = "STAR";
      break;
    case PLUS:
      p = "PLUS";
      break;
    case NOMATCH:
      p = "NOMATCH";
      break;
    case MATCH:
      p = "MATCH";
      break;
    case BEHIND:
      p = "BEHIND";
      break;
    case NOBEHIND:
      p = "NOBEHIND";
      break;
    case SUBPAT:
      p = "SUBPAT";
      break;
    case BRACE_LIMITS:
      p = "BRACE_LIMITS";
      break;
    case BRACE_SIMPLE:
      p = "BRACE_SIMPLE";
      break;
    case BRACE_COMPLEX + 0:
    case BRACE_COMPLEX + 1:
    case BRACE_COMPLEX + 2:
    case BRACE_COMPLEX + 3:
    case BRACE_COMPLEX + 4:
    case BRACE_COMPLEX + 5:
    case BRACE_COMPLEX + 6:
    case BRACE_COMPLEX + 7:
    case BRACE_COMPLEX + 8:
    case BRACE_COMPLEX + 9:
      sprintf(buf + STRLEN(buf), "BRACE_COMPLEX%d", OP(op) - BRACE_COMPLEX);
      p = NULL;
      break;
    case MULTIBYTECODE:
      p = "MULTIBYTECODE";
      break;
    case NEWL:
      p = "NEWL";
      break;
    default:
      sprintf(buf + STRLEN(buf), "corrupt %d", OP(op));
      p = NULL;
      break;
    }
    if (p != NULL)
      STRCAT(buf, p);
    return (char_u *)buf;
  }
  #endif      /* REGEXP_DEBUG */
  
  static void mb_decompose __ARGS((int c, int *c1, int *c2, int *c3));
  
  typedef struct {
    int a, b, c;
  } decomp_T;
  
  
  /* 0xfb20 - 0xfb4f */
  static decomp_T decomp_table[0xfb4f-0xfb20+1] =
  {
    {0x5e2,0,0},                  /* 0xfb20	alt ayin */
    {0x5d0,0,0},                  /* 0xfb21	alt alef */
    {0x5d3,0,0},                  /* 0xfb22	alt dalet */
    {0x5d4,0,0},                  /* 0xfb23	alt he */
    {0x5db,0,0},                  /* 0xfb24	alt kaf */
    {0x5dc,0,0},                  /* 0xfb25	alt lamed */
    {0x5dd,0,0},                  /* 0xfb26	alt mem-sofit */
    {0x5e8,0,0},                  /* 0xfb27	alt resh */
    {0x5ea,0,0},                  /* 0xfb28	alt tav */
    {'+', 0, 0},                  /* 0xfb29	alt plus */
    {0x5e9, 0x5c1, 0},            /* 0xfb2a	shin+shin-dot */
    {0x5e9, 0x5c2, 0},            /* 0xfb2b	shin+sin-dot */
    {0x5e9, 0x5c1, 0x5bc},        /* 0xfb2c	shin+shin-dot+dagesh */
    {0x5e9, 0x5c2, 0x5bc},        /* 0xfb2d	shin+sin-dot+dagesh */
    {0x5d0, 0x5b7, 0},            /* 0xfb2e	alef+patah */
    {0x5d0, 0x5b8, 0},            /* 0xfb2f	alef+qamats */
    {0x5d0, 0x5b4, 0},            /* 0xfb30	alef+hiriq */
    {0x5d1, 0x5bc, 0},            /* 0xfb31	bet+dagesh */
    {0x5d2, 0x5bc, 0},            /* 0xfb32	gimel+dagesh */
    {0x5d3, 0x5bc, 0},            /* 0xfb33	dalet+dagesh */
    {0x5d4, 0x5bc, 0},            /* 0xfb34	he+dagesh */
    {0x5d5, 0x5bc, 0},            /* 0xfb35	vav+dagesh */
    {0x5d6, 0x5bc, 0},            /* 0xfb36	zayin+dagesh */
    {0xfb37, 0, 0},               /* 0xfb37 -- UNUSED */
    {0x5d8, 0x5bc, 0},            /* 0xfb38	tet+dagesh */
    {0x5d9, 0x5bc, 0},            /* 0xfb39	yud+dagesh */
    {0x5da, 0x5bc, 0},            /* 0xfb3a	kaf sofit+dagesh */
    {0x5db, 0x5bc, 0},            /* 0xfb3b	kaf+dagesh */
    {0x5dc, 0x5bc, 0},            /* 0xfb3c	lamed+dagesh */
    {0xfb3d, 0, 0},               /* 0xfb3d -- UNUSED */
    {0x5de, 0x5bc, 0},            /* 0xfb3e	mem+dagesh */
    {0xfb3f, 0, 0},               /* 0xfb3f -- UNUSED */
    {0x5e0, 0x5bc, 0},            /* 0xfb40	nun+dagesh */
    {0x5e1, 0x5bc, 0},            /* 0xfb41	samech+dagesh */
    {0xfb42, 0, 0},               /* 0xfb42 -- UNUSED */
    {0x5e3, 0x5bc, 0},            /* 0xfb43	pe sofit+dagesh */
    {0x5e4, 0x5bc,0},             /* 0xfb44	pe+dagesh */
    {0xfb45, 0, 0},               /* 0xfb45 -- UNUSED */
    {0x5e6, 0x5bc, 0},            /* 0xfb46	tsadi+dagesh */
    {0x5e7, 0x5bc, 0},            /* 0xfb47	qof+dagesh */
    {0x5e8, 0x5bc, 0},            /* 0xfb48	resh+dagesh */
    {0x5e9, 0x5bc, 0},            /* 0xfb49	shin+dagesh */
    {0x5ea, 0x5bc, 0},            /* 0xfb4a	tav+dagesh */
    {0x5d5, 0x5b9, 0},            /* 0xfb4b	vav+holam */
    {0x5d1, 0x5bf, 0},            /* 0xfb4c	bet+rafe */
    {0x5db, 0x5bf, 0},            /* 0xfb4d	kaf+rafe */
    {0x5e4, 0x5bf, 0},            /* 0xfb4e	pe+rafe */
    {0x5d0, 0x5dc, 0}             /* 0xfb4f	alef-lamed */
  };
  
  static void mb_decompose(c, c1, c2, c3)
  int c, *c1, *c2, *c3;
  {
    decomp_T d;
  
    if (c >= 0xfb20 && c <= 0xfb4f) {
      d = decomp_table[c - 0xfb20];
      *c1 = d.a;
      *c2 = d.b;
      *c3 = d.c;
    } else   {
      *c1 = c;
      *c2 = *c3 = 0;
    }
  }
  
  /*
   * Compare two strings, ignore case if ireg_ic set.
   * Return 0 if strings match, non-zero otherwise.
   * Correct the length "*n" when composing characters are ignored.
   */
  static int cstrncmp(s1, s2, n)
  char_u      *s1, *s2;
  int         *n;
  {
    int result;
  
    if (!ireg_ic)
      result = STRNCMP(s1, s2, *n);
    else
      result = MB_STRNICMP(s1, s2, *n);
  
    /* if it failed and it's utf8 and we want to combineignore: */
    if (result != 0 && enc_utf8 && ireg_icombine) {
      char_u  *str1, *str2;
      int c1, c2, c11, c12;
      int junk;
  
      /* we have to handle the strcmp ourselves, since it is necessary to
       * deal with the composing characters by ignoring them: */
      str1 = s1;
      str2 = s2;
      c1 = c2 = 0;
      while ((int)(str1 - s1) < *n) {
        c1 = mb_ptr2char_adv(&str1);
        c2 = mb_ptr2char_adv(&str2);
  
        /* decompose the character if necessary, into 'base' characters
         * because I don't care about Arabic, I will hard-code the Hebrew
         * which I *do* care about!  So sue me... */
        if (c1 != c2 && (!ireg_ic || utf_fold(c1) != utf_fold(c2))) {
          /* decomposition necessary? */
          mb_decompose(c1, &c11, &junk, &junk);
          mb_decompose(c2, &c12, &junk, &junk);
          c1 = c11;
          c2 = c12;
          if (c11 != c12 && (!ireg_ic || utf_fold(c11) != utf_fold(c12)))
            break;
        }
      }
      result = c2 - c1;
      if (result == 0)
        *n = (int)(str2 - s2);
    }
  
    return result;
  }
  
  /*
   * cstrchr: This function is used a lot for simple searches, keep it fast!
   */
  static char_u * cstrchr(s, c)
  char_u      *s;
  int c;
  {
    char_u      *p;
    int cc;
  
    if (!ireg_ic
        || (!enc_utf8 && mb_char2len(c) > 1)
        )
      return vim_strchr(s, c);
  
    /* tolower() and toupper() can be slow, comparing twice should be a lot
     * faster (esp. when using MS Visual C++!).
     * For UTF-8 need to use folded case. */
    if (enc_utf8 && c > 0x80)
      cc = utf_fold(c);
    else if (MB_ISUPPER(c))
      cc = MB_TOLOWER(c);
    else if (MB_ISLOWER(c))
      cc = MB_TOUPPER(c);
    else
      return vim_strchr(s, c);
  
    if (has_mbyte) {
      for (p = s; *p != NUL; p += (*mb_ptr2len)(p)) {
        if (enc_utf8 && c > 0x80) {
          if (utf_fold(utf_ptr2char(p)) == cc)
            return p;
        } else if (*p == c || *p == cc)
          return p;
      }
    } else
      /* Faster version for when there are no multi-byte characters. */
      for (p = s; *p != NUL; ++p)
        if (*p == c || *p == cc)
          return p;
  
    return NULL;
  }
  
  /***************************************************************
  *		      regsub stuff			       *
  ***************************************************************/
  
  /* This stuff below really confuses cc on an SGI -- webb */
  
  /*
   * We should define ftpr as a pointer to a function returning a pointer to
   * a function returning a pointer to a function ...
   * This is impossible, so we declare a pointer to a function returning a
   * pointer to a function returning void. This should work for all compilers.
   */
  typedef void (*(*fptr_T)__ARGS((int *, int)))();
  
  static fptr_T do_upper __ARGS((int *, int));
  static fptr_T do_Upper __ARGS((int *, int));
  static fptr_T do_lower __ARGS((int *, int));
  static fptr_T do_Lower __ARGS((int *, int));
  
  static int vim_regsub_both __ARGS((char_u *source, char_u *dest, int copy,
                                     int magic,
                                     int backslash));
  
  static fptr_T do_upper(d, c)
  int         *d;
  int c;
  {
    *d = MB_TOUPPER(c);
  
    return (fptr_T)NULL;
  }
  
  static fptr_T do_Upper(d, c)
  int         *d;
  int c;
  {
    *d = MB_TOUPPER(c);
  
    return (fptr_T)do_Upper;
  }
  
  static fptr_T do_lower(d, c)
  int         *d;
  int c;
  {
    *d = MB_TOLOWER(c);
  
    return (fptr_T)NULL;
  }
  
  static fptr_T do_Lower(d, c)
  int         *d;
  int c;
  {
    *d = MB_TOLOWER(c);
  
    return (fptr_T)do_Lower;
  }
  
  /*
   * regtilde(): Replace tildes in the pattern by the old pattern.
   *
   * Short explanation of the tilde: It stands for the previous replacement
   * pattern.  If that previous pattern also contains a ~ we should go back a
   * step further...  But we insert the previous pattern into the current one
   * and remember that.
   * This still does not handle the case where "magic" changes.  So require the
   * user to keep his hands off of "magic".
   *
   * The tildes are parsed once before the first call to vim_regsub().
   */
  char_u * regtilde(source, magic)
  char_u      *source;
  int magic;
  {
    char_u      *newsub = source;
    char_u      *tmpsub;
    char_u      *p;
    int len;
    int prevlen;
  
    for (p = newsub; *p; ++p) {
      if ((*p == '~' && magic) || (*p == '\\' && *(p + 1) == '~' && !magic)) {
        if (reg_prev_sub != NULL) {
          /* length = len(newsub) - 1 + len(prev_sub) + 1 */
          prevlen = (int)STRLEN(reg_prev_sub);
          tmpsub = alloc((unsigned)(STRLEN(newsub) + prevlen));
          if (tmpsub != NULL) {
            /* copy prefix */
            len = (int)(p - newsub);              /* not including ~ */
            mch_memmove(tmpsub, newsub, (size_t)len);
            /* interpret tilde */
            mch_memmove(tmpsub + len, reg_prev_sub, (size_t)prevlen);
            /* copy postfix */
            if (!magic)
              ++p;                                /* back off \ */
            STRCPY(tmpsub + len + prevlen, p + 1);
  
            if (newsub != source)                 /* already allocated newsub */
              vim_free(newsub);
            newsub = tmpsub;
            p = newsub + len + prevlen;
          }
        } else if (magic)
          STRMOVE(p, p + 1);              /* remove '~' */
        else
          STRMOVE(p, p + 2);              /* remove '\~' */
        --p;
      } else   {
        if (*p == '\\' && p[1])                   /* skip escaped characters */
          ++p;
        if (has_mbyte)
          p += (*mb_ptr2len)(p) - 1;
      }
    }
  
    vim_free(reg_prev_sub);
    if (newsub != source)         /* newsub was allocated, just keep it */
      reg_prev_sub = newsub;
    else                          /* no ~ found, need to save newsub  */
      reg_prev_sub = vim_strsave(newsub);
    return newsub;
  }
  
  static int can_f_submatch = FALSE;      /* TRUE when submatch() can be used */
  
  /* These pointers are used instead of reg_match and reg_mmatch for
   * reg_submatch().  Needed for when the substitution string is an expression
   * that contains a call to substitute() and submatch(). */
  static regmatch_T       *submatch_match;
  static regmmatch_T      *submatch_mmatch;
  static linenr_T submatch_firstlnum;
  static linenr_T submatch_maxline;
  static int submatch_line_lbr;
  
  /*
   * vim_regsub() - perform substitutions after a vim_regexec() or
   * vim_regexec_multi() match.
   *
   * If "copy" is TRUE really copy into "dest".
   * If "copy" is FALSE nothing is copied, this is just to find out the length
   * of the result.
   *
   * If "backslash" is TRUE, a backslash will be removed later, need to double
   * them to keep them, and insert a backslash before a CR to avoid it being
   * replaced with a line break later.
   *
   * Note: The matched text must not change between the call of
   * vim_regexec()/vim_regexec_multi() and vim_regsub()!  It would make the back
   * references invalid!
   *
   * Returns the size of the replacement, including terminating NUL.
   */
  int vim_regsub(rmp, source, dest, copy, magic, backslash)
  regmatch_T  *rmp;
  char_u      *source;
  char_u      *dest;
  int copy;
  int magic;
  int backslash;
  {
    reg_match = rmp;
    reg_mmatch = NULL;
    reg_maxline = 0;
    reg_buf = curbuf;
    return vim_regsub_both(source, dest, copy, magic, backslash);
  }
  
  int vim_regsub_multi(rmp, lnum, source, dest, copy, magic, backslash)
  regmmatch_T *rmp;
  linenr_T lnum;
  char_u      *source;
  char_u      *dest;
  int copy;
  int magic;
  int backslash;
  {
    reg_match = NULL;
    reg_mmatch = rmp;
    reg_buf = curbuf;             /* always works on the current buffer! */
    reg_firstlnum = lnum;
    reg_maxline = curbuf->b_ml.ml_line_count - lnum;
    return vim_regsub_both(source, dest, copy, magic, backslash);
  }
  
  static int vim_regsub_both(source, dest, copy, magic, backslash)
  char_u      *source;
  char_u      *dest;
  int copy;
  int magic;
  int backslash;
  {
    char_u      *src;
    char_u      *dst;
    char_u      *s;
    int c;
    int cc;
    int no = -1;
    fptr_T func_all = (fptr_T)NULL;
    fptr_T func_one = (fptr_T)NULL;
    linenr_T clnum = 0;           /* init for GCC */
    int len = 0;                  /* init for GCC */
    static char_u *eval_result = NULL;
  
    /* Be paranoid... */
    if (source == NULL || dest == NULL) {
      EMSG(_(e_null));
      return 0;
    }
    if (prog_magic_wrong())
      return 0;
    src = source;
    dst = dest;
  
    /*
     * When the substitute part starts with "\=" evaluate it as an expression.
     */
    if (source[0] == '\\' && source[1] == '='
        && !can_f_submatch            /* can't do this recursively */
        ) {
      /* To make sure that the length doesn't change between checking the
       * length and copying the string, and to speed up things, the
       * resulting string is saved from the call with "copy" == FALSE to the
       * call with "copy" == TRUE. */
      if (copy) {
        if (eval_result != NULL) {
          STRCPY(dest, eval_result);
          dst += STRLEN(eval_result);
          vim_free(eval_result);
          eval_result = NULL;
        }
      } else   {
        win_T       *save_reg_win;
        int save_ireg_ic;
  
        vim_free(eval_result);
  
        /* The expression may contain substitute(), which calls us
         * recursively.  Make sure submatch() gets the text from the first
         * level.  Don't need to save "reg_buf", because
         * vim_regexec_multi() can't be called recursively. */
        submatch_match = reg_match;
        submatch_mmatch = reg_mmatch;
        submatch_firstlnum = reg_firstlnum;
        submatch_maxline = reg_maxline;
        submatch_line_lbr = reg_line_lbr;
        save_reg_win = reg_win;
        save_ireg_ic = ireg_ic;
        can_f_submatch = TRUE;
  
        eval_result = eval_to_string(source + 2, NULL, TRUE);
        if (eval_result != NULL) {
          int had_backslash = FALSE;
  
          for (s = eval_result; *s != NUL; mb_ptr_adv(s)) {
            /* Change NL to CR, so that it becomes a line break,
             * unless called from vim_regexec_nl().
             * Skip over a backslashed character. */
            if (*s == NL && !submatch_line_lbr)
              *s = CAR;
            else if (*s == '\\' && s[1] != NUL) {
              ++s;
              /* Change NL to CR here too, so that this works:
               * :s/abc\\\ndef/\="aaa\\\nbbb"/  on text:
               *   abc\
               *   def
               * Not when called from vim_regexec_nl().
               */
              if (*s == NL && !submatch_line_lbr)
                *s = CAR;
              had_backslash = TRUE;
            }
          }
          if (had_backslash && backslash) {
            /* Backslashes will be consumed, need to double them. */
            s = vim_strsave_escaped(eval_result, (char_u *)"\\");
            if (s != NULL) {
              vim_free(eval_result);
              eval_result = s;
            }
          }
  
          dst += STRLEN(eval_result);
        }
  
        reg_match = submatch_match;
        reg_mmatch = submatch_mmatch;
        reg_firstlnum = submatch_firstlnum;
        reg_maxline = submatch_maxline;
        reg_line_lbr = submatch_line_lbr;
        reg_win = save_reg_win;
        ireg_ic = save_ireg_ic;
        can_f_submatch = FALSE;
      }
    } else
      while ((c = *src++) != NUL) {
        if (c == '&' && magic)
          no = 0;
        else if (c == '\\' && *src != NUL) {
          if (*src == '&' && !magic) {
            ++src;
            no = 0;
          } else if ('0' <= *src && *src <= '9')   {
            no = *src++ - '0';
          } else if (vim_strchr((char_u *)"uUlLeE", *src))   {
            switch (*src++) {
            case 'u':   func_one = (fptr_T)do_upper;
              continue;
            case 'U':   func_all = (fptr_T)do_Upper;
              continue;
            case 'l':   func_one = (fptr_T)do_lower;
              continue;
            case 'L':   func_all = (fptr_T)do_Lower;
              continue;
            case 'e':
            case 'E':   func_one = func_all = (fptr_T)NULL;
              continue;
            }
          }
        }
        if (no < 0) {           /* Ordinary character. */
          if (c == K_SPECIAL && src[0] != NUL && src[1] != NUL) {
            /* Copy a special key as-is. */
            if (copy) {
              *dst++ = c;
              *dst++ = *src++;
              *dst++ = *src++;
            } else   {
              dst += 3;
              src += 2;
            }
            continue;
          }
  
          if (c == '\\' && *src != NUL) {
            /* Check for abbreviations -- webb */
            switch (*src) {
            case 'r':   c = CAR;        ++src;  break;
            case 'n':   c = NL;         ++src;  break;
            case 't':   c = TAB;        ++src;  break;
            /* Oh no!  \e already has meaning in subst pat :-( */
            /* case 'e':   c = ESC;	++src;	break; */
            case 'b':   c = Ctrl_H;     ++src;  break;
  
            /* If "backslash" is TRUE the backslash will be removed
             * later.  Used to insert a literal CR. */
            default:    if (backslash) {
                if (copy)
                  *dst = '\\';
                ++dst;
            }
              c = *src++;
            }
          } else if (has_mbyte)
            c = mb_ptr2char(src - 1);
  
          /* Write to buffer, if copy is set. */
          if (func_one != (fptr_T)NULL)
            /* Turbo C complains without the typecast */
            func_one = (fptr_T)(func_one(&cc, c));
          else if (func_all != (fptr_T)NULL)
            /* Turbo C complains without the typecast */
            func_all = (fptr_T)(func_all(&cc, c));
          else     /* just copy */
            cc = c;
  
          if (has_mbyte) {
            int totlen = mb_ptr2len(src - 1);
  
            if (copy)
              mb_char2bytes(cc, dst);
            dst += mb_char2len(cc) - 1;
            if (enc_utf8) {
              int clen = utf_ptr2len(src - 1);
  
              /* If the character length is shorter than "totlen", there
               * are composing characters; copy them as-is. */
              if (clen < totlen) {
                if (copy)
                  mch_memmove(dst + 1, src - 1 + clen,
                      (size_t)(totlen - clen));
                dst += totlen - clen;
              }
            }
            src += totlen - 1;
          } else if (copy)
            *dst = cc;
          dst++;
        } else   {
          if (REG_MULTI) {
            clnum = reg_mmatch->startpos[no].lnum;
            if (clnum < 0 || reg_mmatch->endpos[no].lnum < 0)
              s = NULL;
            else {
              s = reg_getline(clnum) + reg_mmatch->startpos[no].col;
              if (reg_mmatch->endpos[no].lnum == clnum)
                len = reg_mmatch->endpos[no].col
                      - reg_mmatch->startpos[no].col;
              else
                len = (int)STRLEN(s);
            }
          } else   {
            s = reg_match->startp[no];
            if (reg_match->endp[no] == NULL)
              s = NULL;
            else
              len = (int)(reg_match->endp[no] - s);
          }
          if (s != NULL) {
            for (;; ) {
              if (len == 0) {
                if (REG_MULTI) {
                  if (reg_mmatch->endpos[no].lnum == clnum)
                    break;
                  if (copy)
                    *dst = CAR;
                  ++dst;
                  s = reg_getline(++clnum);
                  if (reg_mmatch->endpos[no].lnum == clnum)
                    len = reg_mmatch->endpos[no].col;
                  else
                    len = (int)STRLEN(s);
                } else
                  break;
              } else if (*s == NUL)   {   /* we hit NUL. */
                if (copy)
                  EMSG(_(e_re_damg));
                goto exit;
              } else   {
                if (backslash && (*s == CAR || *s == '\\')) {
                  /*
                   * Insert a backslash in front of a CR, otherwise
                   * it will be replaced by a line break.
                   * Number of backslashes will be halved later,
                   * double them here.
                   */
                  if (copy) {
                    dst[0] = '\\';
                    dst[1] = *s;
                  }
                  dst += 2;
                } else   {
                  if (has_mbyte)
                    c = mb_ptr2char(s);
                  else
                    c = *s;
  
                  if (func_one != (fptr_T)NULL)
                    /* Turbo C complains without the typecast */
                    func_one = (fptr_T)(func_one(&cc, c));
                  else if (func_all != (fptr_T)NULL)
                    /* Turbo C complains without the typecast */
                    func_all = (fptr_T)(func_all(&cc, c));
                  else             /* just copy */
                    cc = c;
  
                  if (has_mbyte) {
                    int l;
  
                    /* Copy composing characters separately, one
                     * at a time. */
                    if (enc_utf8)
                      l = utf_ptr2len(s) - 1;
                    else
                      l = mb_ptr2len(s) - 1;
  
                    s += l;
                    len -= l;
                    if (copy)
                      mb_char2bytes(cc, dst);
                    dst += mb_char2len(cc) - 1;
                  } else if (copy)
                    *dst = cc;
                  dst++;
                }
  
                ++s;
                --len;
              }
            }
          }
          no = -1;
        }
      }
    if (copy)
      *dst = NUL;
  
  exit:
    return (int)((dst - dest) + 1);
  }
  
  static char_u *reg_getline_submatch __ARGS((linenr_T lnum));
  
  /*
   * Call reg_getline() with the line numbers from the submatch.  If a
   * substitute() was used the reg_maxline and other values have been
   * overwritten.
   */
  static char_u * reg_getline_submatch(lnum)
  linenr_T lnum;
  {
    char_u *s;
    linenr_T save_first = reg_firstlnum;
    linenr_T save_max = reg_maxline;
  
    reg_firstlnum = submatch_firstlnum;
    reg_maxline = submatch_maxline;
  
    s = reg_getline(lnum);
  
    reg_firstlnum = save_first;
    reg_maxline = save_max;
    return s;
  }
  
  /*
   * Used for the submatch() function: get the string from the n'th submatch in
   * allocated memory.
   * Returns NULL when not in a ":s" command and for a non-existing submatch.
   */
  char_u * reg_submatch(no)
  int no;
  {
    char_u      *retval = NULL;
    char_u      *s;
    int len;
    int round;
    linenr_T lnum;
  
    if (!can_f_submatch || no < 0)
      return NULL;
  
    if (submatch_match == NULL) {
      /*
       * First round: compute the length and allocate memory.
       * Second round: copy the text.
       */
      for (round = 1; round <= 2; ++round) {
        lnum = submatch_mmatch->startpos[no].lnum;
        if (lnum < 0 || submatch_mmatch->endpos[no].lnum < 0)
          return NULL;
  
        s = reg_getline_submatch(lnum) + submatch_mmatch->startpos[no].col;
        if (s == NULL)        /* anti-crash check, cannot happen? */
          break;
        if (submatch_mmatch->endpos[no].lnum == lnum) {
          /* Within one line: take form start to end col. */
          len = submatch_mmatch->endpos[no].col
                - submatch_mmatch->startpos[no].col;
          if (round == 2)
            vim_strncpy(retval, s, len);
          ++len;
        } else   {
          /* Multiple lines: take start line from start col, middle
           * lines completely and end line up to end col. */
          len = (int)STRLEN(s);
          if (round == 2) {
            STRCPY(retval, s);
            retval[len] = '\n';
          }
          ++len;
          ++lnum;
          while (lnum < submatch_mmatch->endpos[no].lnum) {
            s = reg_getline_submatch(lnum++);
            if (round == 2)
              STRCPY(retval + len, s);
            len += (int)STRLEN(s);
            if (round == 2)
              retval[len] = '\n';
            ++len;
          }
          if (round == 2)
            STRNCPY(retval + len, reg_getline_submatch(lnum),
                submatch_mmatch->endpos[no].col);
          len += submatch_mmatch->endpos[no].col;
          if (round == 2)
            retval[len] = NUL;
          ++len;
        }
  
        if (retval == NULL) {
          retval = lalloc((long_u)len, TRUE);
          if (retval == NULL)
            return NULL;
        }
      }
    } else   {
      s = submatch_match->startp[no];
      if (s == NULL || submatch_match->endp[no] == NULL)
        retval = NULL;
      else
        retval = vim_strnsave(s, (int)(submatch_match->endp[no] - s));
    }
  
    return retval;
  }
  
  static regengine_T bt_regengine =
  {
    bt_regcomp,
    bt_regfree,
    bt_regexec,
  #if defined(FEAT_MODIFY_FNAME) || defined(FEAT_EVAL) \
    || defined(FIND_REPLACE_DIALOG) || defined(PROTO)
    bt_regexec_nl,
  #endif
    bt_regexec_multi
  #ifdef REGEXP_DEBUG
    ,(char_u *)""
  #endif
  };
  
  
  #include "regexp_nfa.c"
  
  static regengine_T nfa_regengine =
  {
    nfa_regcomp,
    nfa_regfree,
    nfa_regexec,
  #if defined(FEAT_MODIFY_FNAME) || defined(FEAT_EVAL) \
    || defined(FIND_REPLACE_DIALOG) || defined(PROTO)
    nfa_regexec_nl,
  #endif
    nfa_regexec_multi
  #ifdef REGEXP_DEBUG
    ,(char_u *)""
  #endif
  };
  
  /* Which regexp engine to use? Needed for vim_regcomp().
   * Must match with 'regexpengine'. */
  static int regexp_engine = 0;
  #define     AUTOMATIC_ENGINE    0
  #define     BACKTRACKING_ENGINE 1
  #define     NFA_ENGINE          2
  #ifdef REGEXP_DEBUG
  static char_u regname[][30] = {
    "AUTOMATIC Regexp Engine",
    "BACKTRACKING Regexp Engine",
    "NFA Regexp Engine"
  };
  #endif
  
  /*
   * Compile a regular expression into internal code.
   * Returns the program in allocated memory.
   * Use vim_regfree() to free the memory.
   * Returns NULL for an error.
   */
  regprog_T * vim_regcomp(expr_arg, re_flags)
  char_u      *expr_arg;
  int re_flags;
  {
    regprog_T   *prog = NULL;
    char_u      *expr = expr_arg;
  
    regexp_engine = p_re;
  
    /* Check for prefix "\%#=", that sets the regexp engine */
    if (STRNCMP(expr, "\\%#=", 4) == 0) {
      int newengine = expr[4] - '0';
  
      if (newengine == AUTOMATIC_ENGINE
          || newengine == BACKTRACKING_ENGINE
          || newengine == NFA_ENGINE) {
        regexp_engine = expr[4] - '0';
        expr += 5;
  #ifdef REGEXP_DEBUG
        EMSG3("New regexp mode selected (%d): %s", regexp_engine,
            regname[newengine]);
  #endif
      } else   {
        EMSG(_(
                "E864: \\%#= can only be followed by 0, 1, or 2. The automatic engine will be used "));
        regexp_engine = AUTOMATIC_ENGINE;
      }
    }
  #ifdef REGEXP_DEBUG
    bt_regengine.expr = expr;
    nfa_regengine.expr = expr;
  #endif
  
    /*
     * First try the NFA engine, unless backtracking was requested.
     */
    if (regexp_engine != BACKTRACKING_ENGINE)
      prog = nfa_regengine.regcomp(expr, re_flags);
    else
      prog = bt_regengine.regcomp(expr, re_flags);
  
    if (prog == NULL) {       /* error compiling regexp with initial engine */
  #ifdef BT_REGEXP_DEBUG_LOG
      if (regexp_engine != BACKTRACKING_ENGINE) {     /* debugging log for NFA */
        FILE *f;
        f = fopen(BT_REGEXP_DEBUG_LOG_NAME, "a");
        if (f) {
          fprintf(f, "Syntax error in \"%s\"\n", expr);
          fclose(f);
        } else
          EMSG2("(NFA) Could not open \"%s\" to write !!!",
              BT_REGEXP_DEBUG_LOG_NAME);
      }
  #endif
      /*
       * If the NFA engine failed, the backtracking engine won't work either.
       *
         if (regexp_engine == AUTOMATIC_ENGINE)
          prog = bt_regengine.regcomp(expr, re_flags);
       */
    }
  
    return prog;
  }
  
  /*
   * Free a compiled regexp program, returned by vim_regcomp().
   */
  void vim_regfree(prog)
  regprog_T   *prog;
  {
    if (prog != NULL)
      prog->engine->regfree(prog);
  }
  
  /*
   * Match a regexp against a string.
   * "rmp->regprog" is a compiled regexp as returned by vim_regcomp().
   * Uses curbuf for line count and 'iskeyword'.
   *
   * Return TRUE if there is a match, FALSE if not.
   */
  int vim_regexec(rmp, line, col)
  regmatch_T *rmp;
  char_u      *line;      /* string to match against */
  colnr_T col;            /* column to start looking for match */
  {
    return rmp->regprog->engine->regexec(rmp, line, col);
  }
  
  #if defined(FEAT_MODIFY_FNAME) || defined(FEAT_EVAL) \
    || defined(FIND_REPLACE_DIALOG) || defined(PROTO)
  /*
   * Like vim_regexec(), but consider a "\n" in "line" to be a line break.
   */
  int vim_regexec_nl(rmp, line, col)
  regmatch_T *rmp;
  char_u *line;
  colnr_T col;
  {
    return rmp->regprog->engine->regexec_nl(rmp, line, col);
  }
  #endif
  
  /*
   * Match a regexp against multiple lines.
   * "rmp->regprog" is a compiled regexp as returned by vim_regcomp().
   * Uses curbuf for line count and 'iskeyword'.
   *
   * Return zero if there is no match.  Return number of lines contained in the
   * match otherwise.
   */
  long vim_regexec_multi(rmp, win, buf, lnum, col, tm)
  regmmatch_T *rmp;
  win_T       *win;               /* window in which to search or NULL */
  buf_T       *buf;               /* buffer in which to search */
  linenr_T lnum;                  /* nr of line to start looking for match */
  colnr_T col;                    /* column to start looking for match */
  proftime_T  *tm;                /* timeout limit or NULL */
  {
    return rmp->regprog->engine->regexec_multi(rmp, win, buf, lnum, col, tm);
  }
  