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obstack.h
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/* obstack.h - object stack macros
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Copyright (C) 1988-1994,1996-1999,2003,2004,2005
3
Free Software Foundation, Inc.
4
This file is part of the GNU C Library.
5
6
The GNU C Library is free software; you can redistribute it and/or
7
modify it under the terms of the GNU Lesser General Public
8
License as published by the Free Software Foundation; either
9
version 2.1 of the License, or (at your option) any later version.
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11
The GNU C Library is distributed in the hope that it will be useful,
12
but WITHOUT ANY WARRANTY; without even the implied warranty of
13
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14
Lesser General Public License for more details.
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16
You should have received a copy of the GNU Lesser General Public
17
License along with the GNU C Library; if not, write to the Free
18
Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, USA. */
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/* Summary:
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All the apparent functions defined here are macros. The idea
24
is that you would use these pre-tested macros to solve a
25
very specific set of problems, and they would run fast.
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Caution: no side-effects in arguments please!! They may be
27
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
32
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
37
supply, called `obstack_chunk_alloc'. On occasion, they free chunks,
38
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
43
as the first argument.
44
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One motivation for this package is the problem of growing char strings
46
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
114
defined, as with GNU C, use that; that way we don't pollute the
115
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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/* Similiar 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
134
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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142
#include <string.h>
143
144
struct
_obstack_chunk
/* Lives at front of each chunk. */
145
{
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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
159
{
160
PTR_INT_TYPE tempint;
161
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', and we use
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casts to the prototypeless function type in all assignments,
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but having prototypes here quiets -Wstrict-prototypes. */
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struct
_obstack_chunk *(*chunkfun) (
void
*, long);
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void (*freefun) (
void
*,
struct
_obstack_chunk *);
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void
*extra_arg;
/* first arg for chunk alloc/dealloc funcs */
170
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
174
a bigger chunk to replace it. */
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unsigned
alloc_failed:1;
/* No longer used, as we now call the failed
176
handler on error, but retained for binary
177
compatibility. */
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};
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/* Declare the external functions we use; they are in obstack.c. */
181
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extern
void
_obstack_newchunk (
struct
obstack *,
int
);
183
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 *obstack,
void
*block);
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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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/* Exit value used when `print_and_abort' is used. */
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extern
int
obstack_exit_failure;
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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)
207
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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. */
213
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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))
235
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#define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
237
_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 = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun))
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#define obstack_freefun(h, newfreefun) \
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((h) -> freefun = (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__
254
/* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
255
does not implement __extension__. But that compiler doesn't define
256
__GNUC_MINOR__. */
257
# if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
258
# define __extension__
259
# endif
260
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/* For GNU C, if not -traditional,
262
we can define these macros to compute all args only once
263
without using a global variable.
264
Also, we can avoid using the `temp' slot, to make faster code. */
265
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# define obstack_object_size(OBSTACK) \
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__extension__ \
268
({ struct obstack const *__o = (OBSTACK); \
269
(unsigned) (__o->next_free - __o->object_base); })
270
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# define obstack_room(OBSTACK) \
272
__extension__ \
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({ struct obstack const *__o = (OBSTACK); \
274
(unsigned) (__o->chunk_limit - __o->next_free); })
275
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# define obstack_make_room(OBSTACK,length) \
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__extension__ \
278
({ struct obstack *__o = (OBSTACK); \
279
int __len = (length); \
280
if (__o->chunk_limit - __o->next_free < __len) \
281
_obstack_newchunk (__o, __len); \
282
(void) 0; })
283
284
# define obstack_empty_p(OBSTACK) \
285
__extension__ \
286
({ struct obstack const *__o = (OBSTACK); \
287
(__o->chunk->prev == 0 \
288
&& __o->next_free == __PTR_ALIGN ((char *) __o->chunk, \
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__o->chunk->contents, \
290
__o->alignment_mask)); })
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# define obstack_grow(OBSTACK,where,length) \
293
__extension__ \
294
({ struct obstack *__o = (OBSTACK); \
295
int __len = (length); \
296
if (__o->next_free + __len > __o->chunk_limit) \
297
_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; })
301
302
# define obstack_grow0(OBSTACK,where,length) \
303
__extension__ \
304
({ struct obstack *__o = (OBSTACK); \
305
int __len = (length); \
306
if (__o->next_free + __len + 1 > __o->chunk_limit) \
307
_obstack_newchunk (__o, __len + 1); \
308
memcpy (__o->next_free, where, __len); \
309
__o->next_free += __len; \
310
*(__o->next_free)++ = 0; \
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(void) 0; })
312
313
# define obstack_1grow(OBSTACK,datum) \
314
__extension__ \
315
({ struct obstack *__o = (OBSTACK); \
316
if (__o->next_free + 1 > __o->chunk_limit) \
317
_obstack_newchunk (__o, 1); \
318
obstack_1grow_fast (__o, datum); \
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(void) 0; })
320
321
/* These assume that the obstack alignment is good enough for pointers
322
or ints, and that the data added so far to the current object
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shares that much alignment. */
324
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# define obstack_ptr_grow(OBSTACK,datum) \
326
__extension__ \
327
({ struct obstack *__o = (OBSTACK); \
328
if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
329
_obstack_newchunk (__o, sizeof (void *)); \
330
obstack_ptr_grow_fast (__o, datum); }) \
331
332
# define obstack_int_grow(OBSTACK,datum) \
333
__extension__ \
334
({ struct obstack *__o = (OBSTACK); \
335
if (__o->next_free + sizeof (int) > __o->chunk_limit) \
336
_obstack_newchunk (__o, sizeof (int)); \
337
obstack_int_grow_fast (__o, datum); })
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# define obstack_ptr_grow_fast(OBSTACK,aptr) \
340
__extension__ \
341
({ struct obstack *__o1 = (OBSTACK); \
342
*(const void **) __o1->next_free = (aptr); \
343
__o1->next_free += sizeof (const void *); \
344
(void) 0; })
345
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# define obstack_int_grow_fast(OBSTACK,aint) \
347
__extension__ \
348
({ struct obstack *__o1 = (OBSTACK); \
349
*(int *) __o1->next_free = (aint); \
350
__o1->next_free += sizeof (int); \
351
(void) 0; })
352
353
# define obstack_blank(OBSTACK,length) \
354
__extension__ \
355
({ struct obstack *__o = (OBSTACK); \
356
int __len = (length); \
357
if (__o->chunk_limit - __o->next_free < __len) \
358
_obstack_newchunk (__o, __len); \
359
obstack_blank_fast (__o, __len); \
360
(void) 0; })
361
362
# define obstack_alloc(OBSTACK,length) \
363
__extension__ \
364
({ struct obstack *__h = (OBSTACK); \
365
obstack_blank (__h, (length)); \
366
obstack_finish (__h); })
367
368
# define obstack_copy(OBSTACK,where,length) \
369
__extension__ \
370
({ struct obstack *__h = (OBSTACK); \
371
obstack_grow (__h, (where), (length)); \
372
obstack_finish (__h); })
373
374
# define obstack_copy0(OBSTACK,where,length) \
375
__extension__ \
376
({ struct obstack *__h = (OBSTACK); \
377
obstack_grow0 (__h, (where), (length)); \
378
obstack_finish (__h); })
379
380
/* The local variable is named __o1 to avoid a name conflict
381
when obstack_blank is called. */
382
# define obstack_finish(OBSTACK) \
383
__extension__ \
384
({ struct obstack *__o1 = (OBSTACK); \
385
void *__value = (void *) __o1->object_base; \
386
if (__o1->next_free == __value) \
387
__o1->maybe_empty_object = 1; \
388
__o1->next_free \
389
= __PTR_ALIGN (__o1->object_base, __o1->next_free, \
390
__o1->alignment_mask); \
391
if (__o1->next_free - (char *)__o1->chunk \
392
> __o1->chunk_limit - (char *)__o1->chunk) \
393
__o1->next_free = __o1->chunk_limit; \
394
__o1->object_base = __o1->next_free; \
395
__value; })
396
397
# define obstack_free(OBSTACK, OBJ) \
398
__extension__ \
399
({ struct obstack *__o = (OBSTACK); \
400
void *__obj = (OBJ); \
401
if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
402
__o->next_free = __o->object_base = (char *)__obj; \
403
else (obstack_free) (__o, __obj); })
404
405
#else
/* not __GNUC__ or not __STDC__ */
406
407
# define obstack_object_size(h) \
408
(unsigned) ((h)->next_free - (h)->object_base)
409
410
# define obstack_room(h) \
411
(unsigned) ((h)->chunk_limit - (h)->next_free)
412
413
# define obstack_empty_p(h) \
414
((h)->chunk->prev == 0 \
415
&& (h)->next_free == __PTR_ALIGN ((char *) (h)->chunk, \
416
(h)->chunk->contents, \
417
(h)->alignment_mask))
418
419
/* Note that the call to _obstack_newchunk is enclosed in (..., 0)
420
so that we can avoid having void expressions
421
in the arms of the conditional expression.
422
Casting the third operand to void was tried before,
423
but some compilers won't accept it. */
424
425
# define obstack_make_room(h,length) \
426
( (h)->temp.tempint = (length), \
427
(((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \
428
? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0))
429
430
# define obstack_grow(h,where,length) \
431
( (h)->temp.tempint = (length), \
432
(((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \
433
? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \
434
memcpy ((h)->next_free, where, (h)->temp.tempint), \
435
(h)->next_free += (h)->temp.tempint)
436
437
# define obstack_grow0(h,where,length) \
438
( (h)->temp.tempint = (length), \
439
(((h)->next_free + (h)->temp.tempint + 1 > (h)->chunk_limit) \
440
? (_obstack_newchunk ((h), (h)->temp.tempint + 1), 0) : 0), \
441
memcpy ((h)->next_free, where, (h)->temp.tempint), \
442
(h)->next_free += (h)->temp.tempint, \
443
*((h)->next_free)++ = 0)
444
445
# define obstack_1grow(h,datum) \
446
( (((h)->next_free + 1 > (h)->chunk_limit) \
447
? (_obstack_newchunk ((h), 1), 0) : 0), \
448
obstack_1grow_fast (h, datum))
449
450
# define obstack_ptr_grow(h,datum) \
451
( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
452
? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
453
obstack_ptr_grow_fast (h, datum))
454
455
# define obstack_int_grow(h,datum) \
456
( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
457
? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
458
obstack_int_grow_fast (h, datum))
459
460
# define obstack_ptr_grow_fast(h,aptr) \
461
(((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr))
462
463
# define obstack_int_grow_fast(h,aint) \
464
(((int *) ((h)->next_free += sizeof (int)))[-1] = (aint))
465
466
# define obstack_blank(h,length) \
467
( (h)->temp.tempint = (length), \
468
(((h)->chunk_limit - (h)->next_free < (h)->temp.tempint) \
469
? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \
470
obstack_blank_fast (h, (h)->temp.tempint))
471
472
# define obstack_alloc(h,length) \
473
(obstack_blank ((h), (length)), obstack_finish ((h)))
474
475
# define obstack_copy(h,where,length) \
476
(obstack_grow ((h), (where), (length)), obstack_finish ((h)))
477
478
# define obstack_copy0(h,where,length) \
479
(obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
480
481
# define obstack_finish(h) \
482
( ((h)->next_free == (h)->object_base \
483
? (((h)->maybe_empty_object = 1), 0) \
484
: 0), \
485
(h)->temp.tempptr = (h)->object_base, \
486
(h)->next_free \
487
= __PTR_ALIGN ((h)->object_base, (h)->next_free, \
488
(h)->alignment_mask), \
489
(((h)->next_free - (char *) (h)->chunk \
490
> (h)->chunk_limit - (char *) (h)->chunk) \
491
? ((h)->next_free = (h)->chunk_limit) : 0), \
492
(h)->object_base = (h)->next_free, \
493
(h)->temp.tempptr)
494
495
# define obstack_free(h,obj) \
496
( (h)->temp.tempint = (char *) (obj) - (char *) (h)->chunk, \
497
((((h)->temp.tempint > 0 \
498
&& (h)->temp.tempint < (h)->chunk_limit - (char *) (h)->chunk)) \
499
? (int) ((h)->next_free = (h)->object_base \
500
= (h)->temp.tempint + (char *) (h)->chunk) \
501
: (((obstack_free) ((h), (h)->temp.tempint + (char *) (h)->chunk), 0), 0)))
502
503
#endif
/* not __GNUC__ or not __STDC__ */
504
505
#ifdef __cplusplus
506
}
/* C++ */
507
#endif
508
509
#endif
/* obstack.h */
include
boilerplate
obstack.h
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