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510 строки
19 KiB
C++
510 строки
19 KiB
C++
/* obstack.h - object stack macros
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Copyright (C) 1988-1994,1996-1999,2003,2004,2005,2009
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Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* Summary:
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All the apparent functions defined here are macros. The idea
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is that you would use these pre-tested macros to solve a
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very specific set of problems, and they would run fast.
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Caution: no side-effects in arguments please!! They may be
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evaluated MANY times!!
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These macros operate a stack of objects. Each object starts life
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small, and may grow to maturity. (Consider building a word syllable
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by syllable.) An object can move while it is growing. Once it has
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been "finished" it never changes address again. So the "top of the
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stack" is typically an immature growing object, while the rest of the
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stack is of mature, fixed size and fixed address objects.
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These routines grab large chunks of memory, using a function you
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supply, called `obstack_chunk_alloc'. On occasion, they free chunks,
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by calling `obstack_chunk_free'. You must define them and declare
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them before using any obstack macros.
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Each independent stack is represented by a `struct obstack'.
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Each of the obstack macros expects a pointer to such a structure
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as the first argument.
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One motivation for this package is the problem of growing char strings
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in symbol tables. Unless you are "fascist pig with a read-only mind"
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--Gosper's immortal quote from HAKMEM item 154, out of context--you
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would not like to put any arbitrary upper limit on the length of your
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symbols.
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In practice this often means you will build many short symbols and a
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few long symbols. At the time you are reading a symbol you don't know
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how long it is. One traditional method is to read a symbol into a
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buffer, realloc()ating the buffer every time you try to read a symbol
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that is longer than the buffer. This is beaut, but you still will
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want to copy the symbol from the buffer to a more permanent
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symbol-table entry say about half the time.
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With obstacks, you can work differently. Use one obstack for all symbol
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names. As you read a symbol, grow the name in the obstack gradually.
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When the name is complete, finalize it. Then, if the symbol exists already,
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free the newly read name.
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The way we do this is to take a large chunk, allocating memory from
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low addresses. When you want to build a symbol in the chunk you just
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add chars above the current "high water mark" in the chunk. When you
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have finished adding chars, because you got to the end of the symbol,
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you know how long the chars are, and you can create a new object.
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Mostly the chars will not burst over the highest address of the chunk,
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because you would typically expect a chunk to be (say) 100 times as
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long as an average object.
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In case that isn't clear, when we have enough chars to make up
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the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
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so we just point to it where it lies. No moving of chars is
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needed and this is the second win: potentially long strings need
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never be explicitly shuffled. Once an object is formed, it does not
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change its address during its lifetime.
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When the chars burst over a chunk boundary, we allocate a larger
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chunk, and then copy the partly formed object from the end of the old
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chunk to the beginning of the new larger chunk. We then carry on
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accreting characters to the end of the object as we normally would.
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A special macro is provided to add a single char at a time to a
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growing object. This allows the use of register variables, which
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break the ordinary 'growth' macro.
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Summary:
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We allocate large chunks.
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We carve out one object at a time from the current chunk.
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Once carved, an object never moves.
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We are free to append data of any size to the currently
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growing object.
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Exactly one object is growing in an obstack at any one time.
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You can run one obstack per control block.
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You may have as many control blocks as you dare.
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Because of the way we do it, you can `unwind' an obstack
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back to a previous state. (You may remove objects much
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as you would with a stack.)
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*/
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/* Don't do the contents of this file more than once. */
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#ifndef _OBSTACK_H
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#define _OBSTACK_H 1
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* We need the type of a pointer subtraction. If __PTRDIFF_TYPE__ is
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defined, as with GNU C, use that; that way we don't pollute the
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namespace with <stddef.h>'s symbols. Otherwise, include <stddef.h>
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and use ptrdiff_t. */
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#ifdef __PTRDIFF_TYPE__
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# define PTR_INT_TYPE __PTRDIFF_TYPE__
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#else
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# include <stddef.h>
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# define PTR_INT_TYPE ptrdiff_t
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#endif
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/* If B is the base of an object addressed by P, return the result of
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aligning P to the next multiple of A + 1. B and P must be of type
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char *. A + 1 must be a power of 2. */
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#define __BPTR_ALIGN(B, P, A) ((B) + (((P) - (B) + (A)) & ~(A)))
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/* Similar to _BPTR_ALIGN (B, P, A), except optimize the common case
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where pointers can be converted to integers, aligned as integers,
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and converted back again. If PTR_INT_TYPE is narrower than a
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pointer (e.g., the AS/400), play it safe and compute the alignment
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relative to B. Otherwise, use the faster strategy of computing the
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alignment relative to 0. */
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#define __PTR_ALIGN(B, P, A) \
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__BPTR_ALIGN (sizeof (PTR_INT_TYPE) < sizeof (void *) ? (B) : (char *) 0, \
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P, A)
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#include <string.h>
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struct _obstack_chunk /* Lives at front of each chunk. */
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{
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char *limit; /* 1 past end of this chunk */
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struct _obstack_chunk *prev; /* address of prior chunk or NULL */
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char contents[4]; /* objects begin here */
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};
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struct obstack /* control current object in current chunk */
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{
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long chunk_size; /* preferred size to allocate chunks in */
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struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */
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char *object_base; /* address of object we are building */
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char *next_free; /* where to add next char to current object */
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char *chunk_limit; /* address of char after current chunk */
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union
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{
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PTR_INT_TYPE tempint;
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void *tempptr;
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} temp; /* Temporary for some macros. */
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int alignment_mask; /* Mask of alignment for each object. */
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/* These prototypes vary based on `use_extra_arg'. */
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union {
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void *(*plain) (long);
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struct _obstack_chunk *(*extra) (void *, long);
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} chunkfun;
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union {
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void (*plain) (void *);
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void (*extra) (void *, struct _obstack_chunk *);
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} freefun;
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void *extra_arg; /* first arg for chunk alloc/dealloc funcs */
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unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */
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unsigned maybe_empty_object:1;/* There is a possibility that the current
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chunk contains a zero-length object. This
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prevents freeing the chunk if we allocate
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a bigger chunk to replace it. */
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unsigned alloc_failed:1; /* No longer used, as we now call the failed
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handler on error, but retained for binary
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compatibility. */
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};
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/* Declare the external functions we use; they are in obstack.c. */
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extern void _obstack_newchunk (struct obstack *, int);
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extern int _obstack_begin (struct obstack *, int, int,
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void *(*) (long), void (*) (void *));
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extern int _obstack_begin_1 (struct obstack *, int, int,
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void *(*) (void *, long),
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void (*) (void *, void *), void *);
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extern int _obstack_memory_used (struct obstack *);
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void obstack_free (struct obstack *, void *);
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/* Error handler called when `obstack_chunk_alloc' failed to allocate
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more memory. This can be set to a user defined function which
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should either abort gracefully or use longjump - but shouldn't
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return. The default action is to print a message and abort. */
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extern void (*obstack_alloc_failed_handler) (void);
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/* Pointer to beginning of object being allocated or to be allocated next.
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Note that this might not be the final address of the object
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because a new chunk might be needed to hold the final size. */
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#define obstack_base(h) ((void *) (h)->object_base)
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/* Size for allocating ordinary chunks. */
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#define obstack_chunk_size(h) ((h)->chunk_size)
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/* Pointer to next byte not yet allocated in current chunk. */
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#define obstack_next_free(h) ((h)->next_free)
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/* Mask specifying low bits that should be clear in address of an object. */
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#define obstack_alignment_mask(h) ((h)->alignment_mask)
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/* To prevent prototype warnings provide complete argument list. */
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#define obstack_init(h) \
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_obstack_begin ((h), 0, 0, \
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(void *(*) (long)) obstack_chunk_alloc, \
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(void (*) (void *)) obstack_chunk_free)
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#define obstack_begin(h, size) \
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_obstack_begin ((h), (size), 0, \
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(void *(*) (long)) obstack_chunk_alloc, \
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(void (*) (void *)) obstack_chunk_free)
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#define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
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_obstack_begin ((h), (size), (alignment), \
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(void *(*) (long)) (chunkfun), \
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(void (*) (void *)) (freefun))
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#define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
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_obstack_begin_1 ((h), (size), (alignment), \
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(void *(*) (void *, long)) (chunkfun), \
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(void (*) (void *, void *)) (freefun), (arg))
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#define obstack_chunkfun(h, newchunkfun) \
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((h)->chunkfun.extra = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun))
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#define obstack_freefun(h, newfreefun) \
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((h)->freefun.extra = (void (*)(void *, struct _obstack_chunk *)) (newfreefun))
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#define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar))
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#define obstack_blank_fast(h,n) ((h)->next_free += (n))
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#define obstack_memory_used(h) _obstack_memory_used (h)
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#if defined __GNUC__ && defined __STDC__ && __STDC__
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/* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
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does not implement __extension__. But that compiler doesn't define
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__GNUC_MINOR__. */
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# if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
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# define __extension__
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# endif
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/* For GNU C, if not -traditional,
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we can define these macros to compute all args only once
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without using a global variable.
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Also, we can avoid using the `temp' slot, to make faster code. */
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# define obstack_object_size(OBSTACK) \
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__extension__ \
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({ struct obstack const *__o = (OBSTACK); \
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(unsigned) (__o->next_free - __o->object_base); })
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# define obstack_room(OBSTACK) \
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__extension__ \
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({ struct obstack const *__o = (OBSTACK); \
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(unsigned) (__o->chunk_limit - __o->next_free); })
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# define obstack_make_room(OBSTACK,length) \
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__extension__ \
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({ struct obstack *__o = (OBSTACK); \
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int __len = (length); \
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if (__o->chunk_limit - __o->next_free < __len) \
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_obstack_newchunk (__o, __len); \
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(void) 0; })
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# define obstack_empty_p(OBSTACK) \
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__extension__ \
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({ struct obstack const *__o = (OBSTACK); \
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(__o->chunk->prev == 0 \
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&& __o->next_free == __PTR_ALIGN ((char *) __o->chunk, \
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__o->chunk->contents, \
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__o->alignment_mask)); })
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# define obstack_grow(OBSTACK,where,length) \
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__extension__ \
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({ struct obstack *__o = (OBSTACK); \
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int __len = (length); \
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if (__o->next_free + __len > __o->chunk_limit) \
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_obstack_newchunk (__o, __len); \
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memcpy (__o->next_free, where, __len); \
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__o->next_free += __len; \
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(void) 0; })
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# define obstack_grow0(OBSTACK,where,length) \
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__extension__ \
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({ struct obstack *__o = (OBSTACK); \
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int __len = (length); \
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if (__o->next_free + __len + 1 > __o->chunk_limit) \
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_obstack_newchunk (__o, __len + 1); \
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memcpy (__o->next_free, where, __len); \
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__o->next_free += __len; \
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*(__o->next_free)++ = 0; \
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(void) 0; })
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# define obstack_1grow(OBSTACK,datum) \
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__extension__ \
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({ struct obstack *__o = (OBSTACK); \
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if (__o->next_free + 1 > __o->chunk_limit) \
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_obstack_newchunk (__o, 1); \
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obstack_1grow_fast (__o, datum); \
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(void) 0; })
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/* These assume that the obstack alignment is good enough for pointers
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or ints, and that the data added so far to the current object
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shares that much alignment. */
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# define obstack_ptr_grow(OBSTACK,datum) \
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__extension__ \
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({ struct obstack *__o = (OBSTACK); \
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if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
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_obstack_newchunk (__o, sizeof (void *)); \
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obstack_ptr_grow_fast (__o, datum); }) \
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# define obstack_int_grow(OBSTACK,datum) \
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__extension__ \
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({ struct obstack *__o = (OBSTACK); \
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if (__o->next_free + sizeof (int) > __o->chunk_limit) \
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_obstack_newchunk (__o, sizeof (int)); \
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obstack_int_grow_fast (__o, datum); })
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# define obstack_ptr_grow_fast(OBSTACK,aptr) \
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__extension__ \
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({ struct obstack *__o1 = (OBSTACK); \
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*(const void **) __o1->next_free = (aptr); \
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__o1->next_free += sizeof (const void *); \
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(void) 0; })
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# define obstack_int_grow_fast(OBSTACK,aint) \
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__extension__ \
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({ struct obstack *__o1 = (OBSTACK); \
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*(int *) __o1->next_free = (aint); \
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__o1->next_free += sizeof (int); \
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(void) 0; })
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# define obstack_blank(OBSTACK,length) \
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__extension__ \
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({ struct obstack *__o = (OBSTACK); \
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int __len = (length); \
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if (__o->chunk_limit - __o->next_free < __len) \
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_obstack_newchunk (__o, __len); \
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obstack_blank_fast (__o, __len); \
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(void) 0; })
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# define obstack_alloc(OBSTACK,length) \
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__extension__ \
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({ struct obstack *__h = (OBSTACK); \
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obstack_blank (__h, (length)); \
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obstack_finish (__h); })
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# define obstack_copy(OBSTACK,where,length) \
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__extension__ \
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({ struct obstack *__h = (OBSTACK); \
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obstack_grow (__h, (where), (length)); \
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obstack_finish (__h); })
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# define obstack_copy0(OBSTACK,where,length) \
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__extension__ \
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({ struct obstack *__h = (OBSTACK); \
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obstack_grow0 (__h, (where), (length)); \
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obstack_finish (__h); })
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/* The local variable is named __o1 to avoid a name conflict
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when obstack_blank is called. */
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# define obstack_finish(OBSTACK) \
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__extension__ \
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({ struct obstack *__o1 = (OBSTACK); \
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void *__value = (void *) __o1->object_base; \
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if (__o1->next_free == __value) \
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__o1->maybe_empty_object = 1; \
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__o1->next_free \
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= __PTR_ALIGN (__o1->object_base, __o1->next_free, \
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__o1->alignment_mask); \
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if (__o1->next_free - (char *)__o1->chunk \
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> __o1->chunk_limit - (char *)__o1->chunk) \
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__o1->next_free = __o1->chunk_limit; \
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__o1->object_base = __o1->next_free; \
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__value; })
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# define obstack_free(OBSTACK, OBJ) \
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__extension__ \
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({ struct obstack *__o = (OBSTACK); \
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void *__obj = (OBJ); \
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if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
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__o->next_free = __o->object_base = (char *)__obj; \
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else (obstack_free) (__o, __obj); })
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#else /* not __GNUC__ or not __STDC__ */
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# define obstack_object_size(h) \
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(unsigned) ((h)->next_free - (h)->object_base)
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# define obstack_room(h) \
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(unsigned) ((h)->chunk_limit - (h)->next_free)
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# define obstack_empty_p(h) \
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((h)->chunk->prev == 0 \
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&& (h)->next_free == __PTR_ALIGN ((char *) (h)->chunk, \
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(h)->chunk->contents, \
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(h)->alignment_mask))
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/* Note that the call to _obstack_newchunk is enclosed in (..., 0)
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so that we can avoid having void expressions
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in the arms of the conditional expression.
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Casting the third operand to void was tried before,
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but some compilers won't accept it. */
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# define obstack_make_room(h,length) \
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( (h)->temp.tempint = (length), \
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(((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \
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? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0))
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# define obstack_grow(h,where,length) \
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( (h)->temp.tempint = (length), \
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(((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \
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? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \
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memcpy ((h)->next_free, where, (h)->temp.tempint), \
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(h)->next_free += (h)->temp.tempint)
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# define obstack_grow0(h,where,length) \
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( (h)->temp.tempint = (length), \
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(((h)->next_free + (h)->temp.tempint + 1 > (h)->chunk_limit) \
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? (_obstack_newchunk ((h), (h)->temp.tempint + 1), 0) : 0), \
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memcpy ((h)->next_free, where, (h)->temp.tempint), \
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(h)->next_free += (h)->temp.tempint, \
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*((h)->next_free)++ = 0)
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# define obstack_1grow(h,datum) \
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( (((h)->next_free + 1 > (h)->chunk_limit) \
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? (_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] = (aint))
|
||
|
||
# define obstack_blank(h,length) \
|
||
( (h)->temp.tempint = (length), \
|
||
(((h)->chunk_limit - (h)->next_free < (h)->temp.tempint) \
|
||
? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \
|
||
obstack_blank_fast (h, (h)->temp.tempint))
|
||
|
||
# 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.tempptr = (h)->object_base, \
|
||
(h)->next_free \
|
||
= __PTR_ALIGN ((h)->object_base, (h)->next_free, \
|
||
(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, \
|
||
(h)->temp.tempptr)
|
||
|
||
# define obstack_free(h,obj) \
|
||
( (h)->temp.tempint = (char *) (obj) - (char *) (h)->chunk, \
|
||
((((h)->temp.tempint > 0 \
|
||
&& (h)->temp.tempint < (h)->chunk_limit - (char *) (h)->chunk)) \
|
||
? (ptrdiff_t) ((h)->next_free = (h)->object_base \
|
||
= (h)->temp.tempint + (char *) (h)->chunk) \
|
||
: (((obstack_free) ((h), (h)->temp.tempint + (char *) (h)->chunk), 0), 0)))
|
||
|
||
#endif /* not __GNUC__ or not __STDC__ */
|
||
|
||
#ifdef __cplusplus
|
||
} /* C++ */
|
||
#endif
|
||
|
||
#endif /* obstack.h */
|