text: /*
   * Copyright 1998-2008 The OpenLDAP Foundation.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted only as authorized by the OpenLDAP
   * Public License.
   *
   * A copy of this license is available in file LICENSE in the
   * top-level directory of the distribution or, alternatively, at
   * <http://www.OpenLDAP.org/license.html>.
   */
  /* Copyright 1997, 1998, 1999 Computing Research Labs,
   * New Mexico State University
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   * and/or sell copies of the Software, and to permit persons to whom the
   * Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
   * THE COMPUTING RESEARCH LAB OR NEW MEXICO STATE UNIVERSITY BE LIABLE FOR ANY
   * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT
   * OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
   * THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  /*
   * This work is part of OpenLDAP Software <http://www.openldap.org/>.
   * $OpenLDAP: pkg/ldap/libraries/liblunicode/ure/ure.c,v 1.19 2008/01/07 23:20:05 kurt Exp $
   * $Id: ure.c,v 1.2 1999/09/21 15:47:43 mleisher Exp $"
   */
  
  #include <k5-int.h>
  
  #include <stdlib.h>
  #include <string.h>
  #ifndef _WIN32
  #include <unistd.h>
  #endif
  
  #include "ure.h"
  
  /*
   * Flags used internally in the DFA.
   */
  #define _URE_DFA_CASEFOLD  0x01
  #define _URE_DFA_BLANKLINE 0x02
  
  static unsigned long cclass_flags[] = {
      0,
      _URE_NONSPACING,
      _URE_COMBINING,
      _URE_NUMDIGIT,
      _URE_NUMOTHER,
      _URE_SPACESEP,
      _URE_LINESEP,
      _URE_PARASEP,
      _URE_CNTRL,
      _URE_PUA,
      _URE_UPPER,
      _URE_LOWER,
      _URE_TITLE,
      _URE_MODIFIER,
      _URE_OTHERLETTER,
      _URE_DASHPUNCT,
      _URE_OPENPUNCT,
      _URE_CLOSEPUNCT,
      _URE_OTHERPUNCT,
      _URE_MATHSYM,
      _URE_CURRENCYSYM,
      _URE_OTHERSYM,
      _URE_LTR,
      _URE_RTL,
      _URE_EURONUM,
      _URE_EURONUMSEP,
      _URE_EURONUMTERM,
      _URE_ARABNUM,
      _URE_COMMONSEP,
      _URE_BLOCKSEP,
      _URE_SEGMENTSEP,
      _URE_WHITESPACE,
      _URE_OTHERNEUT,
  };
  
  /*
   * Symbol types for the DFA.
   */
  #define _URE_ANY_CHAR   1
  #define _URE_CHAR       2
  #define _URE_CCLASS     3
  #define _URE_NCCLASS    4
  #define _URE_BOL_ANCHOR 5
  #define _URE_EOL_ANCHOR 6
  
  /*
   * Op codes for converting the NFA to a DFA.
   */
  #define _URE_SYMBOL     10
  #define _URE_PAREN      11
  #define _URE_QUEST      12
  #define _URE_STAR       13
  #define _URE_PLUS       14
  #define _URE_ONE        15
  #define _URE_AND        16
  #define _URE_OR         17
  
  #define _URE_NOOP       0xffff
  
  #define _URE_REGSTART 0x8000
  #define _URE_REGEND   0x4000
  
  /*
   * Structure used to handle a compacted range of characters.
   */
  typedef struct {
      ucs4_t min_code;
      ucs4_t max_code;
  } _ure_range_t;
  
  typedef struct {
      _ure_range_t *ranges;
      ucs2_t ranges_used;
      ucs2_t ranges_size;
  } _ure_ccl_t;
  
  typedef union {
      ucs4_t chr;
      _ure_ccl_t ccl;
  } _ure_sym_t;
  
  /*
   * This is a general element structure used for expressions and stack
   * elements.
   */
  typedef struct {
      ucs2_t reg;
      ucs2_t onstack;
      ucs2_t type;
      ucs2_t lhs;
      ucs2_t rhs;
  } _ure_elt_t;
  
  /*
   * This is a structure used to track a list or a stack of states.
   */
  typedef struct {
      ucs2_t *slist;
      ucs2_t slist_size;
      ucs2_t slist_used;
  } _ure_stlist_t;
  
  /*
   * Structure to track the list of unique states for a symbol
   * during reduction.
   */
  typedef struct {
      ucs2_t id;
      ucs2_t type;
      unsigned long mods;
      unsigned long props;
      _ure_sym_t sym;
      _ure_stlist_t states;
  } _ure_symtab_t;
  
  /*
   * Structure to hold a single state.
   */
  typedef struct {
      ucs2_t id;
      ucs2_t accepting;
      ucs2_t pad;
      _ure_stlist_t st;
      _ure_elt_t *trans;
      ucs2_t trans_size;
      ucs2_t trans_used;
  } _ure_state_t;
  
  /*
   * Structure used for keeping lists of states.
   */
  typedef struct {
      _ure_state_t *states;
      ucs2_t states_size;
      ucs2_t states_used;
  } _ure_statetable_t;
  
  /*
   * Structure to track pairs of DFA states when equivalent states are
   * merged.
   */
  typedef struct {
      ucs2_t l;
      ucs2_t r;
  } _ure_equiv_t;
  
  /*
   * Structure used for constructing the NFA and reducing to a minimal DFA.
   */
  typedef struct _ure_buffer_t {
      int reducing;
      int error;
      unsigned long flags;
  
      _ure_stlist_t stack;
  
      /*
       * Table of unique symbols encountered.
       */
      _ure_symtab_t *symtab;
      ucs2_t symtab_size;
      ucs2_t symtab_used;
  
      /*
       * Tracks the unique expressions generated for the NFA and when the NFA is
       * reduced.
       */
      _ure_elt_t *expr;
      ucs2_t expr_used;
      ucs2_t expr_size;
  
      /*
       * The reduced table of unique groups of NFA states.
       */
      _ure_statetable_t states;
  
      /*
       * Tracks states when equivalent states are merged.
       */
      _ure_equiv_t *equiv;
      ucs2_t equiv_used;
      ucs2_t equiv_size;
  } _ure_buffer_t;
  
  typedef struct {
      ucs2_t symbol;
      ucs2_t next_state;
  } _ure_trans_t;
  
  typedef struct {
      ucs2_t accepting;
      ucs2_t ntrans;
      _ure_trans_t *trans;
  } _ure_dstate_t;
  
  typedef struct _ure_dfa_t {
      unsigned long flags;
  
      _ure_symtab_t *syms;
      ucs2_t nsyms;
  
      _ure_dstate_t *states;
      ucs2_t nstates;
  
      _ure_trans_t *trans;
      ucs2_t ntrans;
  } _ure_dfa_t;
  
  /*************************************************************************
   *
   * Functions.
   *
   *************************************************************************/
  
  static void
  _ure_memmove(char *dest, char *src, unsigned long bytes)
  {
      long i, j;
  
      i = (long) bytes;
      j = i & 7;
      i = (i + 7) >> 3;
  
      /*
       * Do a memmove using Ye Olde Duff's Device for efficiency.
       */
      if (src < dest) {
          src += bytes;
          dest += bytes;
  
          switch (j) {
            case 0: do {
                *--dest = *--src;
              case 7: *--dest = *--src;
              case 6: *--dest = *--src;
              case 5: *--dest = *--src;
              case 4: *--dest = *--src;
              case 3: *--dest = *--src;
              case 2: *--dest = *--src;
              case 1: *--dest = *--src;
            } while (--i > 0);
          }
      } else if (src > dest) {
          switch (j) {
            case 0: do {
                *dest++ = *src++;
              case 7: *dest++ = *src++;
              case 6: *dest++ = *src++;
              case 5: *dest++ = *src++;
              case 4: *dest++ = *src++;
              case 3: *dest++ = *src++;
              case 2: *dest++ = *src++;
              case 1: *dest++ = *src++;
            } while (--i > 0);
          }
      }
  }
  
  static void
  _ure_push(ucs2_t v, _ure_buffer_t *b)
  {
      _ure_stlist_t *s;
  
      if (b == 0)
        return;
  
      /*
       * If the `reducing' parameter is non-zero, check to see if the value
       * passed is already on the stack.
       */
      if (b->reducing != 0 && b->expr[v].onstack != 0)
        return;
  
      s = &b->stack;
      if (s->slist_used == s->slist_size) {
          if (s->slist_size == 0)
            s->slist = (ucs2_t *) malloc(sizeof(ucs2_t) << 3);
          else
            s->slist = (ucs2_t *) realloc((char *) s->slist,
                                          sizeof(ucs2_t) * (s->slist_size + 8));
          s->slist_size += 8;
      }
      s->slist[s->slist_used++] = v;
  
      /*
       * If the `reducing' parameter is non-zero, flag the element as being on
       * the stack.
       */
      if (b->reducing != 0)
        b->expr[v].onstack = 1;
  }
  
  static ucs2_t
  _ure_peek(_ure_buffer_t *b)
  {
      if (b == 0 || b->stack.slist_used == 0)
        return _URE_NOOP;
  
      return b->stack.slist[b->stack.slist_used - 1];
  }
  
  static ucs2_t
  _ure_pop(_ure_buffer_t *b)
  {
      ucs2_t v;
  
      if (b == 0 || b->stack.slist_used == 0)
        return _URE_NOOP;
  
      v = b->stack.slist[--b->stack.slist_used];
      if (b->reducing)
        b->expr[v].onstack = 0;
  
      return v;
  }
  
  /*************************************************************************
   *
   * Start symbol parse functions.
   *
   *************************************************************************/
  
  /*
   * Parse a comma-separated list of integers that represent character
   * properties.  Combine them into a mask that is returned in the `mask'
   * variable, and return the number of characters consumed.
   */
  static unsigned long
  _ure_prop_list(ucs2_t *pp, unsigned long limit, unsigned long *mask,
                 _ure_buffer_t *b)
  {
      unsigned long n, m;
      ucs2_t *sp, *ep;
  
      sp = pp;
      ep = sp + limit;
  
      for (m = n = 0; b->error == _URE_OK && sp < ep; sp++) {
          if (*sp == ',') {
              /*
               * Encountered a comma, so select the next character property flag
               * and reset the number.
               */
              m |= cclass_flags[n];
              n = 0;
          } else if (*sp >= '0' && *sp <= '9')
            /*
             * Encountered a digit, so start or continue building the cardinal
             * that represents the character property flag.
             */
            n = (n * 10) + (*sp - '0');
          else
            /*
             * Encountered something that is not part of the property list.
             * Indicate that we are done.
             */
            break;
  
          /*
           * If a property number greater than 32 occurs, then there is a
           * problem.  Most likely a missing comma separator.
           */
          if (n > 32)
            b->error = _URE_INVALID_PROPERTY;
      }
  
      if (n != 0)
        m |= cclass_flags[n];
  
      /*
       * Set the mask that represents the group of character properties.
       */
      *mask = m;
  
      /*
       * Return the number of characters consumed.
       */
      return sp - pp;
  }
  
  /*
   * Collect a hex number with 1 to 4 digits and return the number
   * of characters used.
   */
  static unsigned long
  _ure_hex(ucs2_t *np, unsigned long limit, ucs4_t *n)
  {
      ucs2_t i;
      ucs2_t *sp, *ep;
      ucs4_t nn;
  
      sp = np;
      ep = sp + limit;
  
      for (nn = 0, i = 0; i < 4 && sp < ep; i++, sp++) {
          if (*sp >= '0' && *sp <= '9')
            nn = (nn << 4) + (*sp - '0');
          else if (*sp >= 'A' && *sp <= 'F')
            nn = (nn << 4) + ((*sp - 'A') + 10);
          else if (*sp >= 'a' && *sp <= 'f')
            nn = (nn << 4) + ((*sp - 'a') + 10);
          else
            /*
             * Encountered something that is not a hex digit.
             */
            break;
      }
  
      /*
       * Assign the character code collected and return the number of
       * characters used.
       */
      *n = nn;
  
      return sp - np;
  }
  
  /*
   * Insert a range into a character class, removing duplicates and ordering
   * them in increasing range-start order.
   */
  static void
  _ure_add_range(_ure_ccl_t *ccl, _ure_range_t *r, _ure_buffer_t *b)
  {
      ucs2_t i;
      ucs4_t tmp;
      _ure_range_t *rp;
  
      /*
       * If the `casefold' flag is set, then make sure both endpoints of the
       * range are converted to lower case.
       */
      if (b->flags & _URE_DFA_CASEFOLD) {
          r->min_code = _ure_tolower(r->min_code);
          r->max_code = _ure_tolower(r->max_code);
      }
  
      /*
       * Swap the range endpoints if they are not in increasing order.
       */
      if (r->min_code > r->max_code) {
          tmp = r->min_code;
          r->min_code = r->max_code;
          r->max_code = tmp;
      }
  
      for (i = 0, rp = ccl->ranges;
           i < ccl->ranges_used && r->min_code < rp->min_code; i++, rp++) ;
  
      /*
       * Check for a duplicate.
       */
      if (i < ccl->ranges_used &&
          r->min_code == rp->min_code && r->max_code == rp->max_code)
        return;
  
      if (ccl->ranges_used == ccl->ranges_size) {
          if (ccl->ranges_size == 0)
            ccl->ranges = (_ure_range_t *) malloc(sizeof(_ure_range_t) << 3);
          else
            ccl->ranges = (_ure_range_t *)
                realloc((char *) ccl->ranges,
                        sizeof(_ure_range_t) * (ccl->ranges_size + 8));
          ccl->ranges_size += 8;
      }
  
      rp = ccl->ranges + ccl->ranges_used;
  
      if (i < ccl->ranges_used)
        _ure_memmove((char *) (rp + 1), (char *) rp,
                     sizeof(_ure_range_t) * (ccl->ranges_used - i));
  
      ccl->ranges_used++;
      rp->min_code = r->min_code;
      rp->max_code = r->max_code;
  }
  
  #define _URE_ALPHA_MASK  (_URE_UPPER|_URE_LOWER|_URE_OTHERLETTER|\
  _URE_MODIFIER|_URE_TITLE|_URE_NONSPACING|_URE_COMBINING)
  #define _URE_ALNUM_MASK  (_URE_ALPHA_MASK|_URE_NUMDIGIT)
  #define _URE_PUNCT_MASK  (_URE_DASHPUNCT|_URE_OPENPUNCT|_URE_CLOSEPUNCT|\
  _URE_OTHERPUNCT)
  #define _URE_GRAPH_MASK (_URE_NUMDIGIT|_URE_NUMOTHER|_URE_ALPHA_MASK|\
  _URE_MATHSYM|_URE_CURRENCYSYM|_URE_OTHERSYM)
  #define _URE_PRINT_MASK (_URE_GRAPH_MASK|_URE_SPACESEP)
  #define _URE_SPACE_MASK  (_URE_SPACESEP|_URE_LINESEP|_URE_PARASEP)
  
  typedef void (*_ure_cclsetup_t)(
      _ure_symtab_t *sym,
      unsigned long mask,
      _ure_buffer_t *b
  );
  
  typedef struct {
      ucs2_t key;
      unsigned int len : 8;
      unsigned int next : 8;
      _ure_cclsetup_t func;
      unsigned long mask;
  } _ure_trie_t;
  
  static void
  _ure_ccl_setup(_ure_symtab_t *sym, unsigned long mask, _ure_buffer_t *b)
  {
      sym->props |= mask;
  }
  
  static void
  _ure_space_setup(_ure_symtab_t *sym, unsigned long mask, _ure_buffer_t *b)
  {
      _ure_range_t range;
  
      sym->props |= mask;
  
      /*
       * Add the additional characters needed for handling isspace().
       */
      range.min_code = range.max_code = '\t';
      _ure_add_range(&sym->sym.ccl, &range, b);
      range.min_code = range.max_code = '\r';
      _ure_add_range(&sym->sym.ccl, &range, b);
      range.min_code = range.max_code = '\n';
      _ure_add_range(&sym->sym.ccl, &range, b);
      range.min_code = range.max_code = '\f';
      _ure_add_range(&sym->sym.ccl, &range, b);
      range.min_code = range.max_code = 0xfeff;
      _ure_add_range(&sym->sym.ccl, &range, b);
  }
  
  static void
  _ure_xdigit_setup(_ure_symtab_t *sym, unsigned long mask, _ure_buffer_t *b)
  {
      _ure_range_t range;
  
      /*
       * Add the additional characters needed for handling isxdigit().
       */
      range.min_code = '0';
      range.max_code = '9';
      _ure_add_range(&sym->sym.ccl, &range, b);
      range.min_code = 'A';
      range.max_code = 'F';
      _ure_add_range(&sym->sym.ccl, &range, b);
      range.min_code = 'a';
      range.max_code = 'f';
      _ure_add_range(&sym->sym.ccl, &range, b);
  }
  
  static const _ure_trie_t cclass_trie[] = {
      {0x003a, 1, 1, 0, 0},
      {0x0061, 9, 10, 0, 0},
      {0x0063, 8, 19, 0, 0},
      {0x0064, 7, 24, 0, 0},
      {0x0067, 6, 29, 0, 0},
      {0x006c, 5, 34, 0, 0},
      {0x0070, 4, 39, 0, 0},
      {0x0073, 3, 49, 0, 0},
      {0x0075, 2, 54, 0, 0},
      {0x0078, 1, 59, 0, 0},
      {0x006c, 1, 11, 0, 0},
      {0x006e, 2, 13, 0, 0},
      {0x0070, 1, 16, 0, 0},
      {0x0075, 1, 14, 0, 0},
      {0x006d, 1, 15, 0, 0},
      {0x003a, 1, 16, _ure_ccl_setup, _URE_ALNUM_MASK},
      {0x0068, 1, 17, 0, 0},
      {0x0061, 1, 18, 0, 0},
      {0x003a, 1, 19, _ure_ccl_setup, _URE_ALPHA_MASK},
      {0x006e, 1, 20, 0, 0},
      {0x0074, 1, 21, 0, 0},
      {0x0072, 1, 22, 0, 0},
      {0x006c, 1, 23, 0, 0},
      {0x003a, 1, 24, _ure_ccl_setup, _URE_CNTRL},
      {0x0069, 1, 25, 0, 0},
      {0x0067, 1, 26, 0, 0},
      {0x0069, 1, 27, 0, 0},
      {0x0074, 1, 28, 0, 0},
      {0x003a, 1, 29, _ure_ccl_setup, _URE_NUMDIGIT},
      {0x0072, 1, 30, 0, 0},
      {0x0061, 1, 31, 0, 0},
      {0x0070, 1, 32, 0, 0},
      {0x0068, 1, 33, 0, 0},
      {0x003a, 1, 34, _ure_ccl_setup, _URE_GRAPH_MASK},
      {0x006f, 1, 35, 0, 0},
      {0x0077, 1, 36, 0, 0},
      {0x0065, 1, 37, 0, 0},
      {0x0072, 1, 38, 0, 0},
      {0x003a, 1, 39, _ure_ccl_setup, _URE_LOWER},
      {0x0072, 2, 41, 0, 0},
      {0x0075, 1, 45, 0, 0},
      {0x0069, 1, 42, 0, 0},
      {0x006e, 1, 43, 0, 0},
      {0x0074, 1, 44, 0, 0},
      {0x003a, 1, 45, _ure_ccl_setup, _URE_PRINT_MASK},
      {0x006e, 1, 46, 0, 0},
      {0x0063, 1, 47, 0, 0},
      {0x0074, 1, 48, 0, 0},
      {0x003a, 1, 49, _ure_ccl_setup, _URE_PUNCT_MASK},
      {0x0070, 1, 50, 0, 0},
      {0x0061, 1, 51, 0, 0},
      {0x0063, 1, 52, 0, 0},
      {0x0065, 1, 53, 0, 0},
      {0x003a, 1, 54, _ure_space_setup, _URE_SPACE_MASK},
      {0x0070, 1, 55, 0, 0},
      {0x0070, 1, 56, 0, 0},
      {0x0065, 1, 57, 0, 0},
      {0x0072, 1, 58, 0, 0},
      {0x003a, 1, 59, _ure_ccl_setup, _URE_UPPER},
      {0x0064, 1, 60, 0, 0},
      {0x0069, 1, 61, 0, 0},
      {0x0067, 1, 62, 0, 0},
      {0x0069, 1, 63, 0, 0},
      {0x0074, 1, 64, 0, 0},
      {0x003a, 1, 65, _ure_xdigit_setup, 0},
  };
  
  /*
   * Probe for one of the POSIX colon delimited character classes in the static
   * trie.
   */
  static unsigned long
  _ure_posix_ccl(ucs2_t *cp, unsigned long limit, _ure_symtab_t *sym,
                 _ure_buffer_t *b)
  {
      int i;
      unsigned long n;
      const _ure_trie_t *tp;
      ucs2_t *sp, *ep;
  
      /*
       * If the number of characters left is less than 7, then this cannot be
       * interpreted as one of the colon delimited classes.
       */
      if (limit < 7)
        return 0;
  
      sp = cp;
      ep = sp + limit;
      tp = cclass_trie;
      for (i = 0; sp < ep && i < 8; i++, sp++) {
          n = tp->len;
  
          for (; n > 0 && tp->key != *sp; tp++, n--) ;
  
          if (n == 0)
            return 0;
  
          if (*sp == ':' && (i == 6 || i == 7)) {
              sp++;
              break;
          }
          if (sp + 1 < ep)
            tp = cclass_trie + tp->next;
      }
      if (tp->func == 0)
        return 0;
  
      (*tp->func)(sym, tp->mask, b);
  
      return sp - cp;
  }
  
  /*
   * Construct a list of ranges and return the number of characters consumed.
   */
  static unsigned long
  _ure_cclass(ucs2_t *cp, unsigned long limit, _ure_symtab_t *symp,
              _ure_buffer_t *b)
  {
      int range_end;
      unsigned long n;
      ucs2_t *sp, *ep;
      ucs4_t c, last;
      _ure_ccl_t *cclp;
      _ure_range_t range;
  
      sp = cp;
      ep = sp + limit;
  
      if (*sp == '^') {
        symp->type = _URE_NCCLASS;
        sp++;
      } else
        symp->type = _URE_CCLASS;
  
      for (last = 0, range_end = 0;
           b->error == _URE_OK && sp < ep && *sp != ']'; ) {
          c = *sp++;
          if (c == '\\') {
              if (sp == ep) {
                  /*
                   * The EOS was encountered when expecting the reverse solidus
                   * to be followed by the character it is escaping.  Set an
                   * error code and return the number of characters consumed up
                   * to this point.
                   */
                  b->error = _URE_UNEXPECTED_EOS;
                  return sp - cp;
              }
  
              c = *sp++;
              switch (c) {
                case 'a':
                  c = 0x07;
                  break;
                case 'b':
                  c = 0x08;
                  break;
                case 'f':
                  c = 0x0c;
                  break;
                case 'n':
                  c = 0x0a;
                  break;
                case 'r':
                  c = 0x0d;
                  break;
                case 't':
                  c = 0x09;
                  break;
                case 'v':
                  c = 0x0b;
                  break;
                case 'p':
                case 'P':
                  sp += _ure_prop_list(sp, ep - sp, &symp->props, b);
                  /*
                   * Invert the bit mask of the properties if this is a negated
                   * character class or if 'P' is used to specify a list of
                   * character properties that should *not* match in a
                   * character class.
                   */
                  if (c == 'P')
                    symp->props = ~symp->props;
                  continue;
                  break;
                case 'x':
                case 'X':
                case 'u':
                case 'U':
                  if (sp < ep &&
                      ((*sp >= '0' && *sp <= '9') ||
                       (*sp >= 'A' && *sp <= 'F') ||
                       (*sp >= 'a' && *sp <= 'f')))
                    sp += _ure_hex(sp, ep - sp, &c);
              }
          } else if (c == ':') {
              /*
               * Probe for a POSIX colon delimited character class.
               */
              sp--;
              if ((n = _ure_posix_ccl(sp, ep - sp, symp, b)) == 0)
                sp++;
              else {
                  sp += n;
                  continue;
              }
          }
  
          cclp = &symp->sym.ccl;
  
          /*
           * Check to see if the current character is a low surrogate that needs
           * to be combined with a preceding high surrogate.
           */
          if (last != 0) {
              if (c >= 0xdc00 && c <= 0xdfff)
                /*
                 * Construct the UTF16 character code.
                 */
                c = 0x10000 + (((last & 0x03ff) << 10) | (c & 0x03ff));
              else {
                  /*
                   * Add the isolated high surrogate to the range.
                   */
                  if (range_end == 1)
                    range.max_code = last & 0xffff;
                  else
                    range.min_code = range.max_code = last & 0xffff;
  
                  _ure_add_range(cclp, &range, b);
                  range_end = 0;
              }
          }
  
          /*
           * Clear the last character code.
           */
          last = 0;
  
          /*
           * This slightly awkward code handles the different cases needed to
           * construct a range.
           */
          if (c >= 0xd800 && c <= 0xdbff) {
              /*
               * If the high surrogate is followed by a range indicator, simply
               * add it as the range start.  Otherwise, save it in case the next
               * character is a low surrogate.
               */
              if (*sp == '-') {
                  sp++;
                  range.min_code = c;
                  range_end = 1;
              } else
                last = c;
          } else if (range_end == 1) {
              range.max_code = c;
              _ure_add_range(cclp, &range, b);
              range_end = 0;
          } else {
              range.min_code = range.max_code = c;
              if (*sp == '-') {
                  sp++;
                  range_end = 1;
              } else
                _ure_add_range(cclp, &range, b);
          }
      }
  
      if (sp < ep && *sp == ']')
        sp++;
      else
        /*
         * The parse was not terminated by the character class close symbol
         * (']'), so set an error code.
         */
        b->error = _URE_CCLASS_OPEN;
  
      return sp - cp;
  }
  
  /*
   * Probe for a low surrogate hex code.
   */
  static unsigned long
  _ure_probe_ls(ucs2_t *ls, unsigned long limit, ucs4_t *c)
  {
      ucs4_t i, code;
      ucs2_t *sp, *ep;
  
      for (i = code = 0, sp = ls, ep = sp + limit; i < 4 && sp < ep; sp++) {
          if (*sp >= '0' && *sp <= '9')
            code = (code << 4) + (*sp - '0');
          else if (*sp >= 'A' && *sp <= 'F')
            code = (code << 4) + ((*sp - 'A') + 10);
          else if (*sp >= 'a' && *sp <= 'f')
            code = (code << 4) + ((*sp - 'a') + 10);
          else
            break;
      }
  
      *c = code;
      return (0xdc00 <= code && code <= 0xdfff) ? sp - ls : 0;
  }
  
  static unsigned long
  _ure_compile_symbol(ucs2_t *sym, unsigned long limit, _ure_symtab_t *symp,
                      _ure_buffer_t *b)
  {
      ucs4_t c;
      ucs2_t *sp, *ep;
  
      sp = sym;
      ep = sym + limit;
  
      if ((c = *sp++) == '\\') {
  
          if (sp == ep) {
              /*
               * The EOS was encountered when expecting the reverse solidus to
               * be followed by the character it is escaping.  Set an error code
               * and return the number of characters consumed up to this point.
               */
              b->error = _URE_UNEXPECTED_EOS;
              return sp - sym;
          }
  
          c = *sp++;
          switch (c) {
            case 'p':
            case 'P':
              symp->type = (c == 'p') ? _URE_CCLASS : _URE_NCCLASS;
              sp += _ure_prop_list(sp, ep - sp, &symp->props, b);
              break;
            case 'a':
              symp->type = _URE_CHAR;
              symp->sym.chr = 0x07;
              break;
            case 'b':
              symp->type = _URE_CHAR;
              symp->sym.chr = 0x08;
              break;
            case 'f':
              symp->type = _URE_CHAR;
              symp->sym.chr = 0x0c;
              break;
            case 'n':
              symp->type = _URE_CHAR;
              symp->sym.chr = 0x0a;
              break;
            case 'r':
              symp->type = _URE_CHAR;
              symp->sym.chr = 0x0d;
              break;
            case 't':
              symp->type = _URE_CHAR;
              symp->sym.chr = 0x09;
              break;
            case 'v':
              symp->type = _URE_CHAR;
              symp->sym.chr = 0x0b;
              break;
            case 'x':
            case 'X':
            case 'u':
            case 'U':
              /*
               * Collect between 1 and 4 digits representing a UCS2 code.  Fall
               * through to the next case.
               */
              if (sp < ep &&
                  ((*sp >= '0' && *sp <= '9') ||
                   (*sp >= 'A' && *sp <= 'F') ||
                   (*sp >= 'a' && *sp <= 'f')))
                sp += _ure_hex(sp, ep - sp, &c);
              /* FALLTHROUGH */
            default:
              /*
               * Simply add an escaped character here.
               */
              symp->type = _URE_CHAR;
              symp->sym.chr = c;
          }
      } else if (c == '^' || c == '$')
        /*
         * Handle the BOL and EOL anchors.  This actually consists simply of
         * setting a flag that indicates that the user supplied anchor match
         * function should be called.  This needs to be done instead of simply
         * matching line/paragraph separators because beginning-of-text and
         * end-of-text tests are needed as well.
         */
        symp->type = (c == '^') ? _URE_BOL_ANCHOR : _URE_EOL_ANCHOR;
      else if (c == '[')
        /*
         * Construct a character class.
         */
        sp += _ure_cclass(sp, ep - sp, symp, b);
      else if (c == '.')
        symp->type = _URE_ANY_CHAR;
      else {
          symp->type = _URE_CHAR;
          symp->sym.chr = c;
      }
  
      /*
       * If the symbol type happens to be a character and is a high surrogate,
       * then probe forward to see if it is followed by a low surrogate that
       * needs to be added.
       */
      if (sp < ep && symp->type == _URE_CHAR &&
          0xd800 <= symp->sym.chr && symp->sym.chr <= 0xdbff) {
  
          if (0xdc00 <= *sp && *sp <= 0xdfff) {
              symp->sym.chr = 0x10000 + (((symp->sym.chr & 0x03ff) << 10) |
                                         (*sp & 0x03ff));
              sp++;
          } else if (*sp == '\\' && (*(sp + 1) == 'x' || *(sp + 1) == 'X' ||
                                   *(sp + 1) == 'u' || *(sp + 1) == 'U')) {
              sp += _ure_probe_ls(sp + 2, ep - (sp + 2), &c);
              if (0xdc00 <= c && c <= 0xdfff) {
                  /*
                   * Take into account the \[xu] in front of the hex code.
                   */
                  sp += 2;
                  symp->sym.chr = 0x10000 + (((symp->sym.chr & 0x03ff) << 10) |
                                             (c & 0x03ff));
              }
          }
      }
  
      /*
       * Last, make sure any _URE_CHAR type symbols are changed to lower case if
       * the `casefold' flag is set.
       */
      if ((b->flags & _URE_DFA_CASEFOLD) && symp->type == _URE_CHAR)
        symp->sym.chr = _ure_tolower(symp->sym.chr);
  
      /*
       * If the symbol constructed is anything other than one of the anchors,
       * make sure the _URE_DFA_BLANKLINE flag is removed.
       */
      if (symp->type != _URE_BOL_ANCHOR && symp->type != _URE_EOL_ANCHOR)
        b->flags &= ~_URE_DFA_BLANKLINE;
  
      /*
       * Return the number of characters consumed.
       */
      return sp - sym;
  }
  
  static int
  _ure_sym_neq(_ure_symtab_t *a, _ure_symtab_t *b)
  {
      if (a->type != b->type || a->mods != b->mods || a->props != b->props)
        return 1;
  
      if (a->type == _URE_CCLASS || a->type == _URE_NCCLASS) {
          if (a->sym.ccl.ranges_used != b->sym.ccl.ranges_used)
            return 1;
          if (a->sym.ccl.ranges_used > 0 &&
              memcmp((char *) a->sym.ccl.ranges, (char *) b->sym.ccl.ranges,
                     sizeof(_ure_range_t) * a->sym.ccl.ranges_used) != 0)
            return 1;
      } else if (a->type == _URE_CHAR && a->sym.chr != b->sym.chr)
        return 1;
      return 0;
  }
  
  /*
   * Construct a symbol, but only keep unique symbols.
   */
  static ucs2_t
  _ure_make_symbol(ucs2_t *sym, unsigned long limit, unsigned long *consumed,
                   _ure_buffer_t *b)
  {
      ucs2_t i;
      _ure_symtab_t *sp, symbol;
  
      /*
       * Build the next symbol so we can test to see if it is already in the
       * symbol table.
       */
      (void) memset((char *) &symbol, '\0', sizeof(_ure_symtab_t));
      *consumed = _ure_compile_symbol(sym, limit, &symbol, b);
  
      /*
       * Check to see if the symbol exists.
       */
      for (i = 0, sp = b->symtab;
           i < b->symtab_used && _ure_sym_neq(&symbol, sp); i++, sp++) ;
  
      if (i < b->symtab_used) {
          /*
           * Free up any ranges used for the symbol.
           */
          if ((symbol.type == _URE_CCLASS || symbol.type == _URE_NCCLASS) &&
              symbol.sym.ccl.ranges_size > 0)
            free((char *) symbol.sym.ccl.ranges);
  
          return b->symtab[i].id;
      }
  
      /*
       * Need to add the new symbol.
       */
      if (b->symtab_used == b->symtab_size) {
          if (b->symtab_size == 0)
            b->symtab = (_ure_symtab_t *) malloc(sizeof(_ure_symtab_t) << 3);
          else
            b->symtab = (_ure_symtab_t *)
                realloc((char *) b->symtab,
                        sizeof(_ure_symtab_t) * (b->symtab_size + 8));
          sp = b->symtab + b->symtab_size;
          (void) memset((char *) sp, '\0', sizeof(_ure_symtab_t) << 3);
          b->symtab_size += 8;
      }
  
      symbol.id = b->symtab_used++;
      (void) memcpy((char *) &b->symtab[symbol.id], (char *) &symbol,
                    sizeof(_ure_symtab_t));
  
      return symbol.id;
  }
  
  /*************************************************************************
   *
   * End symbol parse functions.
   *
   *************************************************************************/
  
  static ucs2_t
  _ure_make_expr(ucs2_t type, ucs2_t lhs, ucs2_t rhs, _ure_buffer_t *b)
  {
      ucs2_t i;
  
      if (b == 0)
        return _URE_NOOP;
  
      /*
       * Determine if the expression already exists or not.
       */
      for (i = 0; i < b->expr_used; i++) {
          if (b->expr[i].type == type && b->expr[i].lhs == lhs &&
              b->expr[i].rhs == rhs)
            break;
      }
      if (i < b->expr_used)
        return i;
  
      /*
       * Need to add a new expression.
       */
      if (b->expr_used == b->expr_size) {
          if (b->expr_size == 0)
            b->expr = (_ure_elt_t *) malloc(sizeof(_ure_elt_t) << 3);
          else
            b->expr = (_ure_elt_t *)
                realloc((char *) b->expr,
                        sizeof(_ure_elt_t) * (b->expr_size + 8));
          b->expr_size += 8;
      }
  
      b->expr[b->expr_used].onstack = 0;
      b->expr[b->expr_used].type = type;
      b->expr[b->expr_used].lhs = lhs;
      b->expr[b->expr_used].rhs = rhs;
  
      return b->expr_used++;
  }
  
  static unsigned char spmap[] = {
      0x00, 0x00, 0x00, 0x00, 0x00, 0x0f, 0x00, 0x80, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  };
  
  #define _ure_isspecial(cc) ((cc) > 0x20 && (cc) < 0x7f && \
                              (spmap[(cc) >> 3] & (1 << ((cc) & 7))))
  
  /*
   * Convert the regular expression into an NFA in a form that will be easy to
   * reduce to a DFA.  The starting state for the reduction will be returned.
   */
  static ucs2_t
  _ure_re2nfa(ucs2_t *re, unsigned long relen, _ure_buffer_t *b)
  {
      ucs2_t c, state, top, sym, *sp, *ep;
      unsigned long used;
  
      state = _URE_NOOP;
  
      sp = re;
      ep = sp + relen;
      while (b->error == _URE_OK && sp < ep) {
          c = *sp++;
          switch (c) {
            case '(':
              _ure_push(_URE_PAREN, b);
              break;
            case ')':
              /*
               * Check for the case of too many close parentheses.
               */
              if (_ure_peek(b) == _URE_NOOP) {
                  b->error = _URE_UNBALANCED_GROUP;
                  break;
              }
  
              while ((top = _ure_peek(b)) == _URE_AND || top == _URE_OR)
                /*
                 * Make an expression with the AND or OR operator and its right
                 * hand side.
                 */
                state = _ure_make_expr(_ure_pop(b), _ure_pop(b), state, b);
  
              /*
               * Remove the _URE_PAREN off the stack.
               */
              (void) _ure_pop(b);
              break;
            case '*':
              state = _ure_make_expr(_URE_STAR, state, _URE_NOOP, b);
              break;
            case '+':
              state = _ure_make_expr(_URE_PLUS, state, _URE_NOOP, b);
              break;
            case '?':
              state = _ure_make_expr(_URE_QUEST, state, _URE_NOOP, b);
              break;
            case '|':
              while ((top = _ure_peek(b)) == _URE_AND || top == _URE_OR)
                /*
                 * Make an expression with the AND or OR operator and its right
                 * hand side.
                 */
                state = _ure_make_expr(_ure_pop(b), _ure_pop(b), state, b);
  
              _ure_push(state, b);
              _ure_push(_URE_OR, b);
              break;
            default:
              sp--;
              sym = _ure_make_symbol(sp, ep - sp, &used, b);
              sp += used;
              state = _ure_make_expr(_URE_SYMBOL, sym, _URE_NOOP, b);
              break;
          }
  
          if (c != '(' && c != '|' && sp < ep &&
              (!_ure_isspecial(*sp) || *sp == '(')) {
              _ure_push(state, b);
              _ure_push(_URE_AND, b);
          }
      }
      while ((top = _ure_peek(b)) == _URE_AND || top == _URE_OR)
        /*
         * Make an expression with the AND or OR operator and its right
         * hand side.
         */
        state = _ure_make_expr(_ure_pop(b), _ure_pop(b), state, b);
  
      if (b->stack.slist_used > 0)
        b->error = _URE_UNBALANCED_GROUP;
  
      return (b->error == _URE_OK) ? state : _URE_NOOP;
  }
  
  static void
  _ure_add_symstate(ucs2_t sym, ucs2_t state, _ure_buffer_t *b)
  {
      ucs2_t i, *stp;
      _ure_symtab_t *sp;
  
      /*
       * Locate the symbol in the symbol table so the state can be added.
       * If the symbol doesn't exist, then a real problem exists.
       */
      for (i = 0, sp = b->symtab; i < b->symtab_used && sym != sp->id;
           i++, sp++) ;
  
      /*
       * Now find out if the state exists in the symbol's state list.
       */
      for (i = 0, stp = sp->states.slist;
           i < sp->states.slist_used && state > *stp; i++, stp++) ;
  
      if (i == sp->states.slist_used || state < *stp) {
          /*
           * Need to add the state in order.
           */
          if (sp->states.slist_used == sp->states.slist_size) {
              if (sp->states.slist_size == 0)
                sp->states.slist = (ucs2_t *) malloc(sizeof(ucs2_t) << 3);
              else
                sp->states.slist = (ucs2_t *)
                    realloc((char *) sp->states.slist,
                            sizeof(ucs2_t) * (sp->states.slist_size + 8));
              sp->states.slist_size += 8;
          }
          if (i < sp->states.slist_used)
            (void) _ure_memmove((char *) (sp->states.slist + i + 1),
                                (char *) (sp->states.slist + i),
                                sizeof(ucs2_t) * (sp->states.slist_used - i));
          sp->states.slist[i] = state;
          sp->states.slist_used++;
      }
  }
  
  static ucs2_t
  _ure_add_state(ucs2_t nstates, ucs2_t *states, _ure_buffer_t *b)
  {
      ucs2_t i;
      _ure_state_t *sp;
  
      for (i = 0, sp = b->states.states; i < b->states.states_used; i++, sp++) {
          if (sp->st.slist_used == nstates &&
              memcmp((char *) states, (char *) sp->st.slist,
                     sizeof(ucs2_t) * nstates) == 0)
            break;
      }
  
      if (i == b->states.states_used) {
          /*
           * Need to add a new DFA state (set of NFA states).
           */
          if (b->states.states_used == b->states.states_size) {
              if (b->states.states_size == 0)
                b->states.states = (_ure_state_t *)
                    malloc(sizeof(_ure_state_t) << 3);
              else
                b->states.states = (_ure_state_t *)
                    realloc((char *) b->states.states,
                            sizeof(_ure_state_t) * (b->states.states_size + 8));
              sp = b->states.states + b->states.states_size;
              (void) memset((char *) sp, '\0', sizeof(_ure_state_t) << 3);
              b->states.states_size += 8;
          }
  
          sp = b->states.states + b->states.states_used++;
          sp->id = i;
  
          if (sp->st.slist_used + nstates > sp->st.slist_size) {
              if (sp->st.slist_size == 0)
                sp->st.slist = (ucs2_t *)
                    malloc(sizeof(ucs2_t) * (sp->st.slist_used + nstates));
              else
                sp->st.slist = (ucs2_t *)
                    realloc((char *) sp->st.slist,
                            sizeof(ucs2_t) * (sp->st.slist_used + nstates));
              sp->st.slist_size = sp->st.slist_used + nstates;
          }
          sp->st.slist_used = nstates;
          (void) memcpy((char *) sp->st.slist, (char *) states,
                        sizeof(ucs2_t) * nstates);
      }
  
      /*
       * Return the ID of the DFA state representing a group of NFA states.
       */
      return i;
  }
  
  static void
  _ure_reduce(ucs2_t start, _ure_buffer_t *b)
  {
      ucs2_t i, j, state, eval, syms, rhs;
      ucs2_t s1, s2, ns1, ns2;
      _ure_state_t *sp;
      _ure_symtab_t *smp;
  
      b->reducing = 1;
  
      /*
       * Add the starting state for the reduction.
       */
      _ure_add_state(1, &start, b);
  
      /*
       * Process each set of NFA states that get created.
       */
      for (i = 0; i < b->states.states_used; i++) {
          sp = b->states.states + i;
  
          /*
           * Push the current states on the stack.
           */
          for (j = 0; j < sp->st.slist_used; j++)
            _ure_push(sp->st.slist[j], b);
  
          /*
           * Reduce the NFA states.
           */
          for (j = sp->accepting = syms = 0; j < b->stack.slist_used; j++) {
              state = b->stack.slist[j];
              eval = 1;
  
              /*
               * This inner loop is the iterative equivalent of recursively
               * reducing subexpressions generated as a result of a reduction.
               */
              while (eval) {
                  switch (b->expr[state].type) {
                    case _URE_SYMBOL:
                      ns1 = _ure_make_expr(_URE_ONE, _URE_NOOP, _URE_NOOP, b);
                      _ure_add_symstate(b->expr[state].lhs, ns1, b);
                      syms++;
                      eval = 0;
                      break;
                    case _URE_ONE:
                      sp->accepting = 1;
                      eval = 0;
                      break;
                    case _URE_QUEST:
                      s1 = b->expr[state].lhs;
                      ns1 = _ure_make_expr(_URE_ONE, _URE_NOOP, _URE_NOOP, b);
                      state = _ure_make_expr(_URE_OR, ns1, s1, b);
                      break;
                    case _URE_PLUS:
                      s1 = b->expr[state].lhs;
                      ns1 = _ure_make_expr(_URE_STAR, s1, _URE_NOOP, b);
                      state = _ure_make_expr(_URE_AND, s1, ns1, b);
                      break;
                    case _URE_STAR:
                      s1 = b->expr[state].lhs;
                      ns1 = _ure_make_expr(_URE_ONE, _URE_NOOP, _URE_NOOP, b);
                      ns2 = _ure_make_expr(_URE_PLUS, s1, _URE_NOOP, b);
                      state = _ure_make_expr(_URE_OR, ns1, ns2, b);
                      break;
                    case _URE_OR:
                      s1 = b->expr[state].lhs;
                      s2 = b->expr[state].rhs;
                      _ure_push(s1, b);
                      _ure_push(s2, b);
                      eval = 0;
                      break;
                    case _URE_AND:
                      s1 = b->expr[state].lhs;
                      s2 = b->expr[state].rhs;
                      switch (b->expr[s1].type) {
                        case _URE_SYMBOL:
                          _ure_add_symstate(b->expr[s1].lhs, s2, b);
                          syms++;
                          eval = 0;
                          break;
                        case _URE_ONE:
                          state = s2;
                          break;
                        case _URE_QUEST:
                          ns1 = b->expr[s1].lhs;
                          ns2 = _ure_make_expr(_URE_AND, ns1, s2, b);
                          state = _ure_make_expr(_URE_OR, s2, ns2, b);
                          break;
                        case _URE_PLUS:
                          ns1 = b->expr[s1].lhs;
                          ns2 = _ure_make_expr(_URE_OR, s2, state, b);
                          state = _ure_make_expr(_URE_AND, ns1, ns2, b);
                          break;
                        case _URE_STAR:
                          ns1 = b->expr[s1].lhs;
                          ns2 = _ure_make_expr(_URE_AND, ns1, state, b);
                          state = _ure_make_expr(_URE_OR, s2, ns2, b);
                          break;
                        case _URE_OR:
                          ns1 = b->expr[s1].lhs;
                          ns2 = b->expr[s1].rhs;
                          ns1 = _ure_make_expr(_URE_AND, ns1, s2, b);
                          ns2 = _ure_make_expr(_URE_AND, ns2, s2, b);
                          state = _ure_make_expr(_URE_OR, ns1, ns2, b);
                          break;
                        case _URE_AND:
                          ns1 = b->expr[s1].lhs;
                          ns2 = b->expr[s1].rhs;
                          ns2 = _ure_make_expr(_URE_AND, ns2, s2, b);
                          state = _ure_make_expr(_URE_AND, ns1, ns2, b);
                          break;
                      }
                  }
              }
          }
  
          /*
           * Clear the state stack.
           */
          while (_ure_pop(b) != _URE_NOOP) ;
  
          /*
           * Reset the state pointer because the reduction may have moved it
           * during a reallocation.
           */
          sp = b->states.states + i;
  
          /*
           * Generate the DFA states for the symbols collected during the
           * current reduction.
           */
          if (sp->trans_used + syms > sp->trans_size) {
              if (sp->trans_size == 0)
                sp->trans = (_ure_elt_t *)
                    malloc(sizeof(_ure_elt_t) * (sp->trans_used + syms));
              else
                sp->trans = (_ure_elt_t *)
                    realloc((char *) sp->trans,
                            sizeof(_ure_elt_t) * (sp->trans_used + syms));
              sp->trans_size = sp->trans_used + syms;
          }
  
          /*
           * Go through the symbol table and generate the DFA state transitions
           * for each symbol that has collected NFA states.
           */
          for (j = syms = 0, smp = b->symtab; j < b->symtab_used; j++, smp++) {
              sp = b->states.states + i;
  
              if (smp->states.slist_used > 0) {
                  sp->trans[syms].lhs = smp->id;
                  rhs = _ure_add_state(smp->states.slist_used,
                                       smp->states.slist, b);
                  /*
                   * Reset the state pointer in case the reallocation moves it
                   * in memory.
                   */
                  sp = b->states.states + i;
                  sp->trans[syms].rhs = rhs;
  
                  smp->states.slist_used = 0;
                  syms++;
              }
          }
  
          /*
           * Set the number of transitions actually used.
           */
          sp->trans_used = syms;
      }
      b->reducing = 0;
  }
  
  static void
  _ure_add_equiv(ucs2_t l, ucs2_t r, _ure_buffer_t *b)
  {
      ucs2_t tmp;
  
      l = b->states.states[l].id;
      r = b->states.states[r].id;
  
      if (l == r)
        return;
  
      if (l > r) {
          tmp = l;
          l = r;
          r = tmp;
      }
  
      /*
       * Check to see if the equivalence pair already exists.
       */
      for (tmp = 0; tmp < b->equiv_used &&
               (b->equiv[tmp].l != l || b->equiv[tmp].r != r);
           tmp++) ;
  
      if (tmp < b->equiv_used)
        return;
  
      if (b->equiv_used == b->equiv_size) {
          if (b->equiv_size == 0)
            b->equiv = (_ure_equiv_t *) malloc(sizeof(_ure_equiv_t) << 3);
          else
            b->equiv = (_ure_equiv_t *) realloc((char *) b->equiv,
                                                sizeof(_ure_equiv_t) *
                                                (b->equiv_size + 8));
          b->equiv_size += 8;
      }
      b->equiv[b->equiv_used].l = l;
      b->equiv[b->equiv_used].r = r;
      b->equiv_used++;
  }
  
  /*
   * Merge the DFA states that are equivalent.
   */
  static void
  _ure_merge_equiv(_ure_buffer_t *b)
  {
      ucs2_t i, j, k, eq, done;
      _ure_state_t *sp1, *sp2, *ls, *rs;
  
      for (i = 0; i < b->states.states_used; i++) {
          sp1 = b->states.states + i;
          if (sp1->id != i)
            continue;
          for (j = 0; j < i; j++) {
              sp2 = b->states.states + j;
              if (sp2->id != j)
                continue;
              b->equiv_used = 0;
              _ure_add_equiv(i, j, b);
              for (eq = 0, done = 0; eq < b->equiv_used; eq++) {
                  ls = b->states.states + b->equiv[eq].l;
                  rs = b->states.states + b->equiv[eq].r;
                  if (ls->accepting != rs->accepting ||
                      ls->trans_used != rs->trans_used) {
                      done = 1;
                      break;
                  }
                  for (k = 0; k < ls->trans_used &&
                           ls->trans[k].lhs == rs->trans[k].lhs; k++) ;
                  if (k < ls->trans_used) {
                      done = 1;
                      break;
                  }
  
                  for (k = 0; k < ls->trans_used; k++)
                    _ure_add_equiv(ls->trans[k].rhs, rs->trans[k].rhs, b);
              }
              if (done == 0)
                break;
          }
          for (eq = 0; j < i && eq < b->equiv_used; eq++)
            b->states.states[b->equiv[eq].r].id =
                b->states.states[b->equiv[eq].l].id;
      }
  
      /*
       * Renumber the states appropriately.
       */
      for (i = eq = 0, sp1 = b->states.states; i < b->states.states_used;
           sp1++, i++)
        sp1->id = (sp1->id == i) ? eq++ : b->states.states[sp1->id].id;
  }
  
  /*************************************************************************
   *
   * API.
   *
   *************************************************************************/
  
  ure_buffer_t
  ure_buffer_create(void)
  {
      ure_buffer_t b;
  
      b = (ure_buffer_t) calloc(1, sizeof(_ure_buffer_t));
  
      return b;
  }
  
  void
  ure_buffer_free(ure_buffer_t buf)
  {
      unsigned long i;
  
      if (buf == 0)
        return;
  
      if (buf->stack.slist_size > 0)
        free((char *) buf->stack.slist);
  
      if (buf->expr_size > 0)
        free((char *) buf->expr);
  
      for (i = 0; i < buf->symtab_size; i++) {
          if (buf->symtab[i].states.slist_size > 0)
            free((char *) buf->symtab[i].states.slist);
      }
  
      if (buf->symtab_size > 0)
        free((char *) buf->symtab);
  
      for (i = 0; i < buf->states.states_size; i++) {
          if (buf->states.states[i].trans_size > 0)
            free((char *) buf->states.states[i].trans);
          if (buf->states.states[i].st.slist_size > 0)
            free((char *) buf->states.states[i].st.slist);
      }
  
      if (buf->states.states_size > 0)
        free((char *) buf->states.states);
  
      if (buf->equiv_size > 0)
        free((char *) buf->equiv);
  
      free((char *) buf);
  }
  
  ure_dfa_t
  ure_compile(ucs2_t *re, unsigned long relen, int casefold, ure_buffer_t buf)
  {
      ucs2_t i, j, state;
      _ure_state_t *sp;
      _ure_dstate_t *dsp;
      _ure_trans_t *tp;
      ure_dfa_t dfa;
  
      if (re == 0 || *re == 0 || relen == 0 || buf == 0)
        return 0;
  
      /*
       * Reset the various fields of the compilation buffer.  Default the flags
       * to indicate the presense of the "^$" pattern.  If any other pattern
       * occurs, then this flag will be removed.  This is done to catch this
       * special pattern and handle it specially when matching.
       */
      buf->flags = _URE_DFA_BLANKLINE | ((casefold) ? _URE_DFA_CASEFOLD : 0);
      buf->reducing = 0;
      buf->stack.slist_used = 0;
      buf->expr_used = 0;
  
      for (i = 0; i < buf->symtab_used; i++)
        buf->symtab[i].states.slist_used = 0;
      buf->symtab_used = 0;
  
      for (i = 0; i < buf->states.states_used; i++) {
          buf->states.states[i].st.slist_used = 0;
          buf->states.states[i].trans_used = 0;
      }
      buf->states.states_used = 0;
  
      /*
       * Construct the NFA.  If this stage returns a 0, then an error occured or
       * an empty expression was passed.
       */
      if ((state = _ure_re2nfa(re, relen, buf)) == _URE_NOOP)
        return 0;
  
      /*
       * Do the expression reduction to get the initial DFA.
       */
      _ure_reduce(state, buf);
  
      /*
       * Merge all the equivalent DFA states.
       */
      _ure_merge_equiv(buf);
  
      /*
       * Construct the minimal DFA.
       */
      dfa = (ure_dfa_t) malloc(sizeof(_ure_dfa_t));
      (void) memset((char *) dfa, '\0', sizeof(_ure_dfa_t));
  
      dfa->flags = buf->flags & (_URE_DFA_CASEFOLD|_URE_DFA_BLANKLINE);
  
      /*
       * Free up the NFA state groups and transfer the symbols from the buffer
       * to the DFA.
       */
      for (i = 0; i < buf->symtab_size; i++) {
          if (buf->symtab[i].states.slist_size > 0)
            free((char *) buf->symtab[i].states.slist);
      }
      dfa->syms = buf->symtab;
      dfa->nsyms = buf->symtab_used;
  
      buf->symtab_used = buf->symtab_size = 0;
  
      /*
       * Collect the total number of states and transitions needed for the DFA.
       */
      for (i = state = 0, sp = buf->states.states; i < buf->states.states_used;
           i++, sp++) {
          if (sp->id == state) {
              dfa->nstates++;
              dfa->ntrans += sp->trans_used;
              state++;
          }
      }
  
      /*
       * Allocate enough space for the states and transitions.
       */
      dfa->states = (_ure_dstate_t *) malloc(sizeof(_ure_dstate_t) *
                                             dfa->nstates);
      dfa->trans = (_ure_trans_t *) malloc(sizeof(_ure_trans_t) * dfa->ntrans);
  
      /*
       * Actually transfer the DFA states from the buffer.
       */
      dsp = dfa->states;
      tp = dfa->trans;
      for (i = state = 0, sp = buf->states.states; i < buf->states.states_used;
           i++, sp++) {
          if (sp->id == state) {
              dsp->trans = tp;
              dsp->ntrans = sp->trans_used;
              dsp->accepting = sp->accepting;
  
              /*
               * Add the transitions for the state.
               */
              for (j = 0; j < dsp->ntrans; j++, tp++) {
                  tp->symbol = sp->trans[j].lhs;
                  tp->next_state = buf->states.states[sp->trans[j].rhs].id;
              }
  
              dsp++;
              state++;
          }
      }
  
      return dfa;
  }
  
  void
  ure_dfa_free(ure_dfa_t dfa)
  {
      ucs2_t i;
  
      if (dfa == 0)
        return;
  
      for (i = 0; i < dfa->nsyms; i++) {
          if ((dfa->syms[i].type == _URE_CCLASS ||
               dfa->syms[i].type == _URE_NCCLASS) &&
              dfa->syms[i].sym.ccl.ranges_size > 0)
            free((char *) dfa->syms[i].sym.ccl.ranges);
      }
      if (dfa->nsyms > 0)
        free((char *) dfa->syms);
  
      if (dfa->nstates > 0)
        free((char *) dfa->states);
      if (dfa->ntrans > 0)
        free((char *) dfa->trans);
      free((char *) dfa);
  }
  
  void
  ure_write_dfa(ure_dfa_t dfa, FILE *out)
  {
      ucs2_t i, j, k, h, l;
      _ure_dstate_t *sp;
      _ure_symtab_t *sym;
      _ure_range_t *rp;
  
      if (dfa == 0 || out == 0)
        return;
  
      /*
       * Write all the different character classes.
       */
      for (i = 0, sym = dfa->syms; i < dfa->nsyms; i++, sym++) {
          if (sym->type == _URE_CCLASS || sym->type == _URE_NCCLASS) {
              fprintf(out, "C%hd = ", sym->id);
              if (sym->sym.ccl.ranges_used > 0) {
                  putc('[', out);
                  if (sym->type == _URE_NCCLASS)
                    putc('^', out);
              }
              if (sym->props != 0) {
                  if (sym->type == _URE_NCCLASS)
                    fprintf(out, "\\P");
                  else
                    fprintf(out, "\\p");
                  for (k = h = 0; k < 32; k++) {
                      if (sym->props & (1 << k)) {
                          if (h != 0)
                            putc(',', out);
                          fprintf(out, "%d", k + 1);
                          h = 1;
                      }
                  }
              }
              /*
               * Dump the ranges.
               */
              for (k = 0, rp = sym->sym.ccl.ranges;
                   k < sym->sym.ccl.ranges_used; k++, rp++) {
                  /*
                   * Check for UTF16 characters.
                   */
                  if (0x10000 <= rp->min_code &&
                      rp->min_code <= 0x10ffff) {
                      h = (ucs2_t) (((rp->min_code - 0x10000) >> 10) + 0xd800);
                      l = (ucs2_t) (((rp->min_code - 0x10000) & 1023) + 0xdc00);
                      fprintf(out, "\\x%04hX\\x%04hX", h, l);
                  } else
                      fprintf(out, "\\x%04lX",
                              (unsigned long)(rp->min_code & 0xffff));
                  if (rp->max_code != rp->min_code) {
                      putc('-', out);
                      if (rp->max_code >= 0x10000 &&
                          rp->max_code <= 0x10ffff) {
                          h = (ucs2_t) (((rp->max_code - 0x10000) >> 10) + 0xd800);
                          l = (ucs2_t) (((rp->max_code - 0x10000) & 1023) + 0xdc00);
                          fprintf(out, "\\x%04hX\\x%04hX", h, l);
                      } else
                          fprintf(out, "\\x%04lX",
                                  (unsigned long)(rp->max_code & 0xffff));
                  }
              }
              if (sym->sym.ccl.ranges_used > 0)
                putc(']', out);
              putc('\n', out);
          }
      }
  
      for (i = 0, sp = dfa->states; i < dfa->nstates; i++, sp++) {
          fprintf(out, "S%hd = ", i);
          if (sp->accepting) {
              fprintf(out, "1 ");
              if (sp->ntrans)
                fprintf(out, "| ");
          }
          for (j = 0; j < sp->ntrans; j++) {
              if (j > 0)
                fprintf(out, "| ");
  
              sym = dfa->syms + sp->trans[j].symbol;
              switch (sym->type) {
                case _URE_CHAR:
                  if (0x10000 <= sym->sym.chr && sym->sym.chr <= 0x10ffff) {
                      /*
                       * Take care of UTF16 characters.
                       */
                      h = (ucs2_t) (((sym->sym.chr - 0x10000) >> 10) + 0xd800);
                      l = (ucs2_t) (((sym->sym.chr - 0x10000) & 1023) + 0xdc00);
                      fprintf(out, "\\x%04hX\\x%04hX ", h, l);
                  } else
                      fprintf(out, "\\x%04lX ",
                              (unsigned long)(sym->sym.chr & 0xffff));
                  break;
                case _URE_ANY_CHAR:
                  fprintf(out, "<any> ");
                  break;
                case _URE_BOL_ANCHOR:
                  fprintf(out, "<bol-anchor> ");
                  break;
                case _URE_EOL_ANCHOR:
                  fprintf(out, "<eol-anchor> ");
                  break;
                case _URE_CCLASS:
                case _URE_NCCLASS:
                  fprintf(out, "[C%hd] ", sym->id);
                  break;
              }
              fprintf(out, "S%hd", sp->trans[j].next_state);
              if (j + 1 < sp->ntrans)
                putc(' ', out);
          }
          putc('\n', out);
      }
  }
  
  #define _ure_issep(cc) ((cc) == '\n' || (cc) == '\r' || (cc) == 0x2028 ||\
                          (cc) == 0x2029)
  
  int
  ure_exec(ure_dfa_t dfa, int flags, ucs2_t *text, unsigned long textlen,
           unsigned long *match_start, unsigned long *match_end)
  {
      int i, j, matched, found;
      unsigned long ms, me;
      ucs4_t c;
      ucs2_t *sp, *ep, *lp;
      _ure_dstate_t *stp;
      _ure_symtab_t *sym;
      _ure_range_t *rp;
  
      if (dfa == 0 || text == 0)
        return 0;
  
      /*
       * Handle the special case of an empty string matching the "^$" pattern.
       */
      if (textlen == 0 && (dfa->flags & _URE_DFA_BLANKLINE)) {
          *match_start = *match_end = 0;
          return 1;
      }
  
      sp = text;
      ep = sp + textlen;
  
      ms = me = ~0;
  
      stp = dfa->states;
  
      for (found = 0; found == 0 && sp < ep; ) {
          lp = sp;
          c = *sp++;
  
          /*
           * Check to see if this is a high surrogate that should be
           * combined with a following low surrogate.
           */
          if (sp < ep && 0xd800 <= c && c <= 0xdbff &&
              0xdc00 <= *sp && *sp <= 0xdfff)
            c = 0x10000 + (((c & 0x03ff) << 10) | (*sp++ & 0x03ff));
  
          /*
           * Determine if the character is non-spacing and should be skipped.
           */
          if (_ure_matches_properties(_URE_NONSPACING, c) &&
              (flags & URE_IGNORE_NONSPACING)) {
              sp++;
              continue;
          }
  
          if (dfa->flags & _URE_DFA_CASEFOLD)
            c = _ure_tolower(c);
  
          /*
           * See if one of the transitions matches.
           */
          for (i = 0, matched = 0; matched == 0 && i < stp->ntrans; i++) {
              sym = dfa->syms + stp->trans[i].symbol;
              switch (sym->type) {
                case _URE_ANY_CHAR:
                  if ((flags & URE_DOT_MATCHES_SEPARATORS) ||
                      !_ure_issep(c))
                    matched = 1;
                  break;
                case _URE_CHAR:
                  if (c == sym->sym.chr)
                    matched = 1;
                  break;
                case _URE_BOL_ANCHOR:
                  if (lp == text) {
                      sp = lp;
                      matched = 1;
                  } else if (_ure_issep(c)) {
                      if (c == '\r' && sp < ep && *sp == '\n')
                        sp++;
                      lp = sp;
                      matched = 1;
                  }
                  break;
                case _URE_EOL_ANCHOR:
                  if (_ure_issep(c)) {
                      /*
                       * Put the pointer back before the separator so the match
                       * end position will be correct.  This case will also
                       * cause the `sp' pointer to be advanced over the current
                       * separator once the match end point has been recorded.
                       */
                      sp = lp;
                      matched = 1;
                  }
                  break;
                case _URE_CCLASS:
                case _URE_NCCLASS:
                  if (sym->props != 0)
                    matched = _ure_matches_properties(sym->props, c);
                  for (j = 0, rp = sym->sym.ccl.ranges;
                       j < sym->sym.ccl.ranges_used; j++, rp++) {
                      if (rp->min_code <= c && c <= rp->max_code)
                        matched = 1;
                  }
                  if (sym->type == _URE_NCCLASS)
                    matched = !matched;
                  break;
              }
  
              if (matched) {
                  if (ms == ~0UL)
                    ms = lp - text;
                  else
                    me = sp - text;
                  stp = dfa->states + stp->trans[i].next_state;
  
                  /*
                   * If the match was an EOL anchor, adjust the pointer past the
                   * separator that caused the match.  The correct match
                   * position has been recorded already.
                   */
                  if (sym->type == _URE_EOL_ANCHOR) {
                      /*
                       * Skip the character that caused the match.
                       */
                      sp++;
  
                      /*
                       * Handle the infamous CRLF situation.
                       */
                      if (sp < ep && c == '\r' && *sp == '\n')
                        sp++;
                  }
              }
          }
  
          if (matched == 0) {
              if (stp->accepting == 0) {
                  /*
                   * If the last state was not accepting, then reset
                   * and start over.
                   */
                  stp = dfa->states;
                  ms = me = ~0;
              } else
                /*
                 * The last state was accepting, so terminate the matching
                 * loop to avoid more work.
                 */
                found = 1;
          } else if (sp == ep) {
              if (!stp->accepting) {
                  /*
                   * This ugly hack is to make sure the end-of-line anchors
                   * match when the source text hits the end.  This is only done
                   * if the last subexpression matches.
                   */
                  for (i = 0; found == 0 && i < stp->ntrans; i++) {
                      sym = dfa->syms + stp->trans[i].symbol;
                      if (sym->type ==_URE_EOL_ANCHOR) {
                          stp = dfa->states + stp->trans[i].next_state;
                          if (stp->accepting) {
                              me = sp - text;
                              found = 1;
                          } else
                            break;
                      }
                  }
              } else {
                  /*
                   * Make sure any conditions that match all the way to the end
                   * of the string match.
                   */
                  found = 1;
                  me = sp - text;
              }
          }
      }
  
      if (found == 0)
        ms = me = ~0;
  
      *match_start = ms;
      *match_end = me;
  
      return (ms != ~0UL) ? 1 : 0;
  }
  