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