0,0 → 1,545 |
/* obstack.h - object stack macros |
Copyright 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1996, 1997, 1998, |
1999, 2000, 2001, 2002, 2003, 2004, 2005, 2008 |
Free Software Foundation, Inc. |
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NOTE: The canonical source of this file is maintained with the GNU C Library. |
Bugs can be reported to bug-glibc@gnu.org. |
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This program is free software; you can redistribute it and/or modify it |
under the terms of the GNU General Public License as published by the |
Free Software Foundation; either version 2, or (at your option) any |
later version. |
|
This program 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 General Public License for more details. |
|
You should have received a copy of the GNU General Public License |
along with this program; if not, write to the Free Software |
Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, |
USA. */ |
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/* 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. |
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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. |
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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. |
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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. |
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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. |
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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. |
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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. |
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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. |
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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. |
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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.) |
*/ |
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/* Don't do the contents of this file more than once. */ |
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#ifndef _OBSTACK_H |
#define _OBSTACK_H 1 |
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#ifdef __cplusplus |
extern "C" { |
#endif |
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/* 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. */ |
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#ifndef __PTR_TO_INT |
# define __PTR_TO_INT(P) ((P) - (char *) 0) |
#endif |
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#ifndef __INT_TO_PTR |
# define __INT_TO_PTR(P) ((P) + (char *) 0) |
#endif |
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/* 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, if <stddef.h> is |
available, include it and use ptrdiff_t. In traditional C, long is |
the best that we can do. */ |
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#ifdef __PTRDIFF_TYPE__ |
# define PTR_INT_TYPE __PTRDIFF_TYPE__ |
#else |
# ifdef HAVE_STDDEF_H |
# include <stddef.h> |
# define PTR_INT_TYPE ptrdiff_t |
# else |
# define PTR_INT_TYPE long |
# endif |
#endif |
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#if defined _LIBC || defined HAVE_STRING_H |
# include <string.h> |
# define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N)) |
#else |
# ifdef memcpy |
# define _obstack_memcpy(To, From, N) memcpy ((To), (char *)(From), (N)) |
# else |
# define _obstack_memcpy(To, From, N) bcopy ((char *)(From), (To), (N)) |
# endif |
#endif |
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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 */ |
}; |
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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. */ |
}; |
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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); |
extern void _obstack_free (struct obstack *, void *); |
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 *); |
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/* Do the function-declarations after the structs |
but before defining the macros. */ |
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void obstack_init (struct obstack *obstack); |
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void * obstack_alloc (struct obstack *obstack, int size); |
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void * obstack_copy (struct obstack *obstack, void *address, int size); |
void * obstack_copy0 (struct obstack *obstack, void *address, int size); |
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void obstack_free (struct obstack *obstack, void *block); |
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void obstack_blank (struct obstack *obstack, int size); |
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void obstack_grow (struct obstack *obstack, void *data, int size); |
void obstack_grow0 (struct obstack *obstack, void *data, int size); |
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void obstack_1grow (struct obstack *obstack, int data_char); |
void obstack_ptr_grow (struct obstack *obstack, void *data); |
void obstack_int_grow (struct obstack *obstack, int data); |
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void * obstack_finish (struct obstack *obstack); |
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int obstack_object_size (struct obstack *obstack); |
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int obstack_room (struct obstack *obstack); |
void obstack_make_room (struct obstack *obstack, int size); |
void obstack_1grow_fast (struct obstack *obstack, int data_char); |
void obstack_ptr_grow_fast (struct obstack *obstack, void *data); |
void obstack_int_grow_fast (struct obstack *obstack, int data); |
void obstack_blank_fast (struct obstack *obstack, int size); |
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void * obstack_base (struct obstack *obstack); |
void * obstack_next_free (struct obstack *obstack); |
int obstack_alignment_mask (struct obstack *obstack); |
int obstack_chunk_size (struct obstack *obstack); |
int obstack_memory_used (struct obstack *obstack); |
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/* Error handler called when `obstack_chunk_alloc' failed to allocate |
more memory. This can be set to a user defined function. The |
default action is to print a message and abort. */ |
extern void (*obstack_alloc_failed_handler) (void); |
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/* Exit value used when `print_and_abort' is used. */ |
extern int obstack_exit_failure; |
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/* 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. */ |
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#define obstack_base(h) ((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 in |
standard C version. */ |
# define obstack_init(h) \ |
_obstack_begin ((h), 0, 0, \ |
(void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free) |
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# define obstack_begin(h, size) \ |
_obstack_begin ((h), (size), 0, \ |
(void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free) |
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# define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \ |
_obstack_begin ((h), (size), (alignment), \ |
(void *(*) (long)) (chunkfun), (void (*) (void *)) (freefun)) |
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# 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)) |
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# define obstack_chunkfun(h, newchunkfun) \ |
((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun)) |
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# define obstack_freefun(h, newfreefun) \ |
((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__ |
/* 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 |
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/* 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. */ |
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# define obstack_object_size(OBSTACK) \ |
__extension__ \ |
({ struct obstack *__o = (OBSTACK); \ |
(unsigned) (__o->next_free - __o->object_base); }) |
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# define obstack_room(OBSTACK) \ |
__extension__ \ |
({ struct obstack *__o = (OBSTACK); \ |
(unsigned) (__o->chunk_limit - __o->next_free); }) |
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# 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; }) |
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# define obstack_empty_p(OBSTACK) \ |
__extension__ \ |
({ struct obstack *__o = (OBSTACK); \ |
(__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); }) |
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# 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); \ |
_obstack_memcpy (__o->next_free, (where), __len); \ |
__o->next_free += __len; \ |
(void) 0; }) |
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# 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); \ |
_obstack_memcpy (__o->next_free, (where), __len); \ |
__o->next_free += __len; \ |
*(__o->next_free)++ = 0; \ |
(void) 0; }) |
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# 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; }) |
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/* 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. */ |
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# 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); }) |
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# 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); }) |
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# 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; }) |
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# define obstack_int_grow_fast(OBSTACK,aint) \ |
__extension__ \ |
({ struct obstack *__o1 = (OBSTACK); \ |
*(int *) __o1->next_free = (aint); \ |
__o1->next_free += sizeof (int); \ |
(void) 0; }) |
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# 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; }) |
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# define obstack_alloc(OBSTACK,length) \ |
__extension__ \ |
({ struct obstack *__h = (OBSTACK); \ |
obstack_blank (__h, (length)); \ |
obstack_finish (__h); }) |
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# define obstack_copy(OBSTACK,where,length) \ |
__extension__ \ |
({ struct obstack *__h = (OBSTACK); \ |
obstack_grow (__h, (where), (length)); \ |
obstack_finish (__h); }) |
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# define obstack_copy0(OBSTACK,where,length) \ |
__extension__ \ |
({ struct obstack *__h = (OBSTACK); \ |
obstack_grow0 (__h, (where), (length)); \ |
obstack_finish (__h); }) |
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/* 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; \ |
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; }) |
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# define obstack_free(OBSTACK, OBJ) \ |
__extension__ \ |
({ struct obstack *__o = (OBSTACK); \ |
void *__obj = (void *) (OBJ); \ |
if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \ |
__o->next_free = __o->object_base = (char *) __obj; \ |
else (obstack_free) (__o, __obj); }) |
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#else /* not __GNUC__ or not __STDC__ */ |
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# define obstack_object_size(h) \ |
(unsigned) ((h)->next_free - (h)->object_base) |
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# define obstack_room(h) \ |
(unsigned) ((h)->chunk_limit - (h)->next_free) |
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# define obstack_empty_p(h) \ |
((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0) |
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/* 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. */ |
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# define obstack_make_room(h,length) \ |
( (h)->temp = (length), \ |
(((h)->next_free + (h)->temp > (h)->chunk_limit) \ |
? (_obstack_newchunk ((h), (h)->temp), 0) : 0)) |
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# define obstack_grow(h,where,length) \ |
( (h)->temp = (length), \ |
(((h)->next_free + (h)->temp > (h)->chunk_limit) \ |
? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \ |
_obstack_memcpy ((h)->next_free, (where), (h)->temp), \ |
(h)->next_free += (h)->temp) |
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# 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), \ |
_obstack_memcpy ((h)->next_free, (where), (h)->temp), \ |
(h)->next_free += (h)->temp, \ |
*((h)->next_free)++ = 0) |
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# define obstack_1grow(h,datum) \ |
( (((h)->next_free + 1 > (h)->chunk_limit) \ |
? (_obstack_newchunk ((h), 1), 0) : 0), \ |
obstack_1grow_fast (h, datum)) |
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# 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)) |
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# 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)) |
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# define obstack_ptr_grow_fast(h,aptr) \ |
(((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr)) |
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# define obstack_int_grow_fast(h,aint) \ |
(((int *) ((h)->next_free += sizeof (int)))[-1] = (aptr)) |
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# 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)) |
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# define obstack_alloc(h,length) \ |
(obstack_blank ((h), (length)), obstack_finish ((h))) |
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# define obstack_copy(h,where,length) \ |
(obstack_grow ((h), (where), (length)), obstack_finish ((h))) |
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# define obstack_copy0(h,where,length) \ |
(obstack_grow0 ((h), (where), (length)), obstack_finish ((h))) |
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# 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)) |
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# define obstack_free(h,obj) \ |
( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \ |
(((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\ |
? (((h)->next_free = (h)->object_base \ |
= (h)->temp + (char *) (h)->chunk), 0) \ |
: ((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0))) |
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#endif /* not __GNUC__ or not __STDC__ */ |
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#ifdef __cplusplus |
} /* C++ */ |
#endif |
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#endif /* obstack.h */ |