text: /* obstack.h - object stack macros
     Copyright (C) 1988-1994,1996-1999,2003,2004 Free Software Foundation, Inc.
     This file is part of the GNU C Library.  Its master source is NOT part of
     the C library, however.  The master source lives in /gd/gnu/lib.
  
     The GNU C Library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
     License as published by the Free Software Foundation; either
     version 2.1 of the License, or (at your option) any later version.
  
     The GNU C Library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public
     License along with the GNU C Library; if not, write to the Free
     Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
     02111-1307 USA.  */
  
  /* Summary:
  
  All the apparent functions defined here are macros. The idea
  is that you would use these pre-tested macros to solve a
  very specific set of problems, and they would run fast.
  Caution: no side-effects in arguments please!! They may be
  evaluated MANY times!!
  
  These macros operate a stack of objects.  Each object starts life
  small, and may grow to maturity.  (Consider building a word syllable
  by syllable.)  An object can move while it is growing.  Once it has
  been "finished" it never changes address again.  So the "top of the
  stack" is typically an immature growing object, while the rest of the
  stack is of mature, fixed size and fixed address objects.
  
  These routines grab large chunks of memory, using a function you
  supply, called `obstack_chunk_alloc'.  On occasion, they free chunks,
  by calling `obstack_chunk_free'.  You must define them and declare
  them before using any obstack macros.
  
  Each independent stack is represented by a `struct obstack'.
  Each of the obstack macros expects a pointer to such a structure
  as the first argument.
  
  One motivation for this package is the problem of growing char strings
  in symbol tables.  Unless you are "fascist pig with a read-only mind"
  --Gosper's immortal quote from HAKMEM item 154, out of context--you
  would not like to put any arbitrary upper limit on the length of your
  symbols.
  
  In practice this often means you will build many short symbols and a
  few long symbols.  At the time you are reading a symbol you don't know
  how long it is.  One traditional method is to read a symbol into a
  buffer, realloc()ating the buffer every time you try to read a symbol
  that is longer than the buffer.  This is beaut, but you still will
  want to copy the symbol from the buffer to a more permanent
  symbol-table entry say about half the time.
  
  With obstacks, you can work differently.  Use one obstack for all symbol
  names.  As you read a symbol, grow the name in the obstack gradually.
  When the name is complete, finalize it.  Then, if the symbol exists already,
  free the newly read name.
  
  The way we do this is to take a large chunk, allocating memory from
  low addresses.  When you want to build a symbol in the chunk you just
  add chars above the current "high water mark" in the chunk.  When you
  have finished adding chars, because you got to the end of the symbol,
  you know how long the chars are, and you can create a new object.
  Mostly the chars will not burst over the highest address of the chunk,
  because you would typically expect a chunk to be (say) 100 times as
  long as an average object.
  
  In case that isn't clear, when we have enough chars to make up
  the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
  so we just point to it where it lies.  No moving of chars is
  needed and this is the second win: potentially long strings need
  never be explicitly shuffled. Once an object is formed, it does not
  change its address during its lifetime.
  
  When the chars burst over a chunk boundary, we allocate a larger
  chunk, and then copy the partly formed object from the end of the old
  chunk to the beginning of the new larger chunk.  We then carry on
  accreting characters to the end of the object as we normally would.
  
  A special macro is provided to add a single char at a time to a
  growing object.  This allows the use of register variables, which
  break the ordinary 'growth' macro.
  
  Summary:
  	We allocate large chunks.
  	We carve out one object at a time from the current chunk.
  	Once carved, an object never moves.
  	We are free to append data of any size to the currently
  	  growing object.
  	Exactly one object is growing in an obstack at any one time.
  	You can run one obstack per control block.
  	You may have as many control blocks as you dare.
  	Because of the way we do it, you can `unwind' an obstack
  	  back to a previous state. (You may remove objects much
  	  as you would with a stack.)
  */
  
  
  /* Don't do the contents of this file more than once.  */
  
  #ifndef _OBSTACK_H
  #define _OBSTACK_H 1
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /* We use subtraction of (char *) 0 instead of casting to int
     because on word-addressable machines a simple cast to int
     may ignore the byte-within-word field of the pointer.  */
  
  #ifndef __PTR_TO_INT
  # define __PTR_TO_INT(P) ((P) - (char *) 0)
  #endif
  
  #ifndef __INT_TO_PTR
  # define __INT_TO_PTR(P) ((P) + (char *) 0)
  #endif
  
  /* We need the type of the resulting object.  If __PTRDIFF_TYPE__ is
     defined, as with GNU C, use that; that way we don't pollute the
     namespace with <stddef.h>'s symbols.  Otherwise, include <stddef.h>
     and use ptrdiff_t.  */
  
  #ifdef __PTRDIFF_TYPE__
  # define PTR_INT_TYPE __PTRDIFF_TYPE__
  #else
  # include <stddef.h>
  # define PTR_INT_TYPE ptrdiff_t
  #endif
  
  #include <string.h>
  
  struct _obstack_chunk		/* Lives at front of each chunk. */
  {
    char  *limit;			/* 1 past end of this chunk */
    struct _obstack_chunk *prev;	/* address of prior chunk or NULL */
    char	contents[4];		/* objects begin here */
  };
  
  struct obstack		/* control current object in current chunk */
  {
    long	chunk_size;		/* preferred size to allocate chunks in */
    struct _obstack_chunk *chunk;	/* address of current struct obstack_chunk */
    char	*object_base;		/* address of object we are building */
    char	*next_free;		/* where to add next char to current object */
    char	*chunk_limit;		/* address of char after current chunk */
    PTR_INT_TYPE temp;		/* Temporary for some macros.  */
    int   alignment_mask;		/* Mask of alignment for each object. */
    /* These prototypes vary based on `use_extra_arg', and we use
       casts to the prototypeless function type in all assignments,
       but having prototypes here quiets -Wstrict-prototypes.  */
    struct _obstack_chunk *(*chunkfun) (void *, long);
    void (*freefun) (void *, struct _obstack_chunk *);
    void *extra_arg;		/* first arg for chunk alloc/dealloc funcs */
    unsigned use_extra_arg:1;	/* chunk alloc/dealloc funcs take extra arg */
    unsigned maybe_empty_object:1;/* There is a possibility that the current
  				   chunk contains a zero-length object.  This
  				   prevents freeing the chunk if we allocate
  				   a bigger chunk to replace it. */
    unsigned alloc_failed:1;	/* No longer used, as we now call the failed
  				   handler on error, but retained for binary
  				   compatibility.  */
  };
  
  /* Declare the external functions we use; they are in obstack.c.  */
  
  extern void _obstack_newchunk (struct obstack *, int);
  extern int _obstack_begin (struct obstack *, int, int,
  			    void *(*) (long), void (*) (void *));
  extern int _obstack_begin_1 (struct obstack *, int, int,
  			     void *(*) (void *, long),
  			     void (*) (void *, void *), void *);
  extern int _obstack_memory_used (struct obstack *);
  
  void obstack_free (struct obstack *obstack, void *block);
  
  
  /* Error handler called when `obstack_chunk_alloc' failed to allocate
     more memory.  This can be set to a user defined function which
     should either abort gracefully or use longjump - but shouldn't
     return.  The default action is to print a message and abort.  */
  extern void (*obstack_alloc_failed_handler) (void);
  
  /* Exit value used when `print_and_abort' is used.  */
  extern int obstack_exit_failure;
  
  /* Pointer to beginning of object being allocated or to be allocated next.
     Note that this might not be the final address of the object
     because a new chunk might be needed to hold the final size.  */
  
  #define obstack_base(h) ((void *) (h)->object_base)
  
  /* Size for allocating ordinary chunks.  */
  
  #define obstack_chunk_size(h) ((h)->chunk_size)
  
  /* Pointer to next byte not yet allocated in current chunk.  */
  
  #define obstack_next_free(h)	((h)->next_free)
  
  /* Mask specifying low bits that should be clear in address of an object.  */
  
  #define obstack_alignment_mask(h) ((h)->alignment_mask)
  
  /* To prevent prototype warnings provide complete argument list.  */
  #define obstack_init(h)						\
    _obstack_begin ((h), 0, 0,					\
  		  (void *(*) (long)) obstack_chunk_alloc,	\
  		  (void (*) (void *)) obstack_chunk_free)
  
  #define obstack_begin(h, size)					\
    _obstack_begin ((h), (size), 0,				\
  		  (void *(*) (long)) obstack_chunk_alloc,	\
  		  (void (*) (void *)) obstack_chunk_free)
  
  #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun)  \
    _obstack_begin ((h), (size), (alignment),				   \
  		  (void *(*) (long)) (chunkfun),			   \
  		  (void (*) (void *)) (freefun))
  
  #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
    _obstack_begin_1 ((h), (size), (alignment),				\
  		    (void *(*) (void *, long)) (chunkfun),		\
  		    (void (*) (void *, void *)) (freefun), (arg))
  
  #define obstack_chunkfun(h, newchunkfun) \
    ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun))
  
  #define obstack_freefun(h, newfreefun) \
    ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun))
  
  #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar))
  
  #define obstack_blank_fast(h,n) ((h)->next_free += (n))
  
  #define obstack_memory_used(h) _obstack_memory_used (h)
  
  #if defined __GNUC__ && defined __STDC__ && __STDC__
  /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
     does not implement __extension__.  But that compiler doesn't define
     __GNUC_MINOR__.  */
  # if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
  #  define __extension__
  # endif
  
  /* For GNU C, if not -traditional,
     we can define these macros to compute all args only once
     without using a global variable.
     Also, we can avoid using the `temp' slot, to make faster code.  */
  
  # define obstack_object_size(OBSTACK)					\
    __extension__								\
    ({ struct obstack const *__o = (OBSTACK);				\
       (unsigned) (__o->next_free - __o->object_base); })
  
  # define obstack_room(OBSTACK)						\
    __extension__								\
    ({ struct obstack const *__o = (OBSTACK);				\
       (unsigned) (__o->chunk_limit - __o->next_free); })
  
  # define obstack_make_room(OBSTACK,length)				\
  __extension__								\
  ({ struct obstack *__o = (OBSTACK);					\
     int __len = (length);						\
     if (__o->chunk_limit - __o->next_free < __len)			\
       _obstack_newchunk (__o, __len);					\
     (void) 0; })
  
  # define obstack_empty_p(OBSTACK)					\
    __extension__								\
    ({ struct obstack const *__o = (OBSTACK);				\
       (__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); })
  
  # define obstack_grow(OBSTACK,where,length)				\
  __extension__								\
  ({ struct obstack *__o = (OBSTACK);					\
     int __len = (length);						\
     if (__o->next_free + __len > __o->chunk_limit)			\
       _obstack_newchunk (__o, __len);					\
     memcpy (__o->next_free, where, __len);				\
     __o->next_free += __len;						\
     (void) 0; })
  
  # define obstack_grow0(OBSTACK,where,length)				\
  __extension__								\
  ({ struct obstack *__o = (OBSTACK);					\
     int __len = (length);						\
     if (__o->next_free + __len + 1 > __o->chunk_limit)			\
       _obstack_newchunk (__o, __len + 1);				\
     memcpy (__o->next_free, where, __len);				\
     __o->next_free += __len;						\
     *(__o->next_free)++ = 0;						\
     (void) 0; })
  
  # define obstack_1grow(OBSTACK,datum)					\
  __extension__								\
  ({ struct obstack *__o = (OBSTACK);					\
     if (__o->next_free + 1 > __o->chunk_limit)				\
       _obstack_newchunk (__o, 1);					\
     obstack_1grow_fast (__o, datum);					\
     (void) 0; })
  
  /* These assume that the obstack alignment is good enough for pointers
     or ints, and that the data added so far to the current object
     shares that much alignment.  */
  
  # define obstack_ptr_grow(OBSTACK,datum)				\
  __extension__								\
  ({ struct obstack *__o = (OBSTACK);					\
     if (__o->next_free + sizeof (void *) > __o->chunk_limit)		\
       _obstack_newchunk (__o, sizeof (void *));				\
     obstack_ptr_grow_fast (__o, datum); })				\
  
  # define obstack_int_grow(OBSTACK,datum)				\
  __extension__								\
  ({ struct obstack *__o = (OBSTACK);					\
     if (__o->next_free + sizeof (int) > __o->chunk_limit)		\
       _obstack_newchunk (__o, sizeof (int));				\
     obstack_int_grow_fast (__o, datum); })
  
  # define obstack_ptr_grow_fast(OBSTACK,aptr)				\
  __extension__								\
  ({ struct obstack *__o1 = (OBSTACK);					\
     *(const void **) __o1->next_free = (aptr);				\
     __o1->next_free += sizeof (const void *);				\
     (void) 0; })
  
  # define obstack_int_grow_fast(OBSTACK,aint)				\
  __extension__								\
  ({ struct obstack *__o1 = (OBSTACK);					\
     *(int *) __o1->next_free = (aint);					\
     __o1->next_free += sizeof (int);					\
     (void) 0; })
  
  # define obstack_blank(OBSTACK,length)					\
  __extension__								\
  ({ struct obstack *__o = (OBSTACK);					\
     int __len = (length);						\
     if (__o->chunk_limit - __o->next_free < __len)			\
       _obstack_newchunk (__o, __len);					\
     obstack_blank_fast (__o, __len);					\
     (void) 0; })
  
  # define obstack_alloc(OBSTACK,length)					\
  __extension__								\
  ({ struct obstack *__h = (OBSTACK);					\
     obstack_blank (__h, (length));					\
     obstack_finish (__h); })
  
  # define obstack_copy(OBSTACK,where,length)				\
  __extension__								\
  ({ struct obstack *__h = (OBSTACK);					\
     obstack_grow (__h, (where), (length));				\
     obstack_finish (__h); })
  
  # define obstack_copy0(OBSTACK,where,length)				\
  __extension__								\
  ({ struct obstack *__h = (OBSTACK);					\
     obstack_grow0 (__h, (where), (length));				\
     obstack_finish (__h); })
  
  /* The local variable is named __o1 to avoid a name conflict
     when obstack_blank is called.  */
  # define obstack_finish(OBSTACK)					\
  __extension__								\
  ({ struct obstack *__o1 = (OBSTACK);					\
     void *__value = (void *) __o1->object_base;				\
     if (__o1->next_free == __value)					\
       __o1->maybe_empty_object = 1;					\
     __o1->next_free							\
       = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
  		     & ~ (__o1->alignment_mask));			\
     if (__o1->next_free - (char *)__o1->chunk				\
         > __o1->chunk_limit - (char *)__o1->chunk)			\
       __o1->next_free = __o1->chunk_limit;				\
     __o1->object_base = __o1->next_free;					\
     __value; })
  
  # define obstack_free(OBSTACK, OBJ)					\
  __extension__								\
  ({ struct obstack *__o = (OBSTACK);					\
     void *__obj = (OBJ);							\
     if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit)  \
       __o->next_free = __o->object_base = (char *)__obj;			\
     else (obstack_free) (__o, __obj); })
  
  #else /* not __GNUC__ or not __STDC__ */
  
  # define obstack_object_size(h) \
   (unsigned) ((h)->next_free - (h)->object_base)
  
  # define obstack_room(h)		\
   (unsigned) ((h)->chunk_limit - (h)->next_free)
  
  # define obstack_empty_p(h) \
   ((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0)
  
  /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
     so that we can avoid having void expressions
     in the arms of the conditional expression.
     Casting the third operand to void was tried before,
     but some compilers won't accept it.  */
  
  # define obstack_make_room(h,length)					\
  ( (h)->temp = (length),							\
    (((h)->next_free + (h)->temp > (h)->chunk_limit)			\
     ? (_obstack_newchunk ((h), (h)->temp), 0) : 0))
  
  # define obstack_grow(h,where,length)					\
  ( (h)->temp = (length),							\
    (((h)->next_free + (h)->temp > (h)->chunk_limit)			\
     ? (_obstack_newchunk ((h), (h)->temp), 0) : 0),			\
    memcpy ((h)->next_free, where, (h)->temp),				\
    (h)->next_free += (h)->temp)
  
  # define obstack_grow0(h,where,length)					\
  ( (h)->temp = (length),							\
    (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit)			\
     ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0),			\
    memcpy ((h)->next_free, where, (h)->temp),				\
    (h)->next_free += (h)->temp,						\
    *((h)->next_free)++ = 0)
  
  # define obstack_1grow(h,datum)						\
  ( (((h)->next_free + 1 > (h)->chunk_limit)				\
     ? (_obstack_newchunk ((h), 1), 0) : 0),				\
    obstack_1grow_fast (h, datum))
  
  # define obstack_ptr_grow(h,datum)					\
  ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit)		\
     ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0),		\
    obstack_ptr_grow_fast (h, datum))
  
  # define obstack_int_grow(h,datum)					\
  ( (((h)->next_free + sizeof (int) > (h)->chunk_limit)			\
     ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0),			\
    obstack_int_grow_fast (h, datum))
  
  # define obstack_ptr_grow_fast(h,aptr)					\
    (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr))
  
  # define obstack_int_grow_fast(h,aint)					\
    (((int *) ((h)->next_free += sizeof (int)))[-1] = (aptr))
  
  # define obstack_blank(h,length)					\
  ( (h)->temp = (length),							\
    (((h)->chunk_limit - (h)->next_free < (h)->temp)			\
     ? (_obstack_newchunk ((h), (h)->temp), 0) : 0),			\
    obstack_blank_fast (h, (h)->temp))
  
  # define obstack_alloc(h,length)					\
   (obstack_blank ((h), (length)), obstack_finish ((h)))
  
  # define obstack_copy(h,where,length)					\
   (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
  
  # define obstack_copy0(h,where,length)					\
   (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
  
  # define obstack_finish(h)						\
  ( ((h)->next_free == (h)->object_base					\
     ? (((h)->maybe_empty_object = 1), 0)					\
     : 0),								\
    (h)->temp = __PTR_TO_INT ((h)->object_base),				\
    (h)->next_free							\
      = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask)	\
  		    & ~ ((h)->alignment_mask)),				\
    (((h)->next_free - (char *) (h)->chunk				\
      > (h)->chunk_limit - (char *) (h)->chunk)				\
     ? ((h)->next_free = (h)->chunk_limit) : 0),				\
    (h)->object_base = (h)->next_free,					\
    (void *) __INT_TO_PTR ((h)->temp))
  
  # define obstack_free(h,obj)						\
  ( (h)->temp = (char *) (obj) - (char *) (h)->chunk,			\
    (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
     ? (int) ((h)->next_free = (h)->object_base				\
  	    = (h)->temp + (char *) (h)->chunk)				\
     : (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
  
  #endif /* not __GNUC__ or not __STDC__ */
  
  #ifdef __cplusplus
  }	/* C++ */
  #endif
  
  #endif /* obstack.h */
  