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- /* obstack.h - object stack macros
- Copyright (C) 1988-2019 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
- The GNU C Library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 2.1 of the License, or (at your option) any later version.
- The GNU C Library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
- You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library; if not, see
- <http://www.gnu.org/licenses/>. */
- /* 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
- #ifndef _OBSTACK_INTERFACE_VERSION
- # define _OBSTACK_INTERFACE_VERSION 2
- #endif
- #include <stddef.h> /* For size_t and ptrdiff_t. */
- #include <string.h> /* For __GNU_LIBRARY__, and memcpy. */
- #if _OBSTACK_INTERFACE_VERSION == 1
- /* For binary compatibility with obstack version 1, which used "int"
- and "long" for these two types. */
- # define _OBSTACK_SIZE_T unsigned int
- # define _CHUNK_SIZE_T unsigned long
- # define _OBSTACK_CAST(type, expr) ((type) (expr))
- #else
- /* Version 2 with sane types, especially for 64-bit hosts. */
- # define _OBSTACK_SIZE_T size_t
- # define _CHUNK_SIZE_T size_t
- # define _OBSTACK_CAST(type, expr) (expr)
- #endif
- /* If B is the base of an object addressed by P, return the result of
- aligning P to the next multiple of A + 1. B and P must be of type
- char *. A + 1 must be a power of 2. */
- #define __BPTR_ALIGN(B, P, A) ((B) + (((P) - (B) + (A)) & ~(A)))
- /* Similar to __BPTR_ALIGN (B, P, A), except optimize the common case
- where pointers can be converted to integers, aligned as integers,
- and converted back again. If ptrdiff_t is narrower than a
- pointer (e.g., the AS/400), play it safe and compute the alignment
- relative to B. Otherwise, use the faster strategy of computing the
- alignment relative to 0. */
- #define __PTR_ALIGN(B, P, A) \
- __BPTR_ALIGN (sizeof (ptrdiff_t) < sizeof (void *) ? (B) : (char *) 0, \
- P, A)
- #ifndef __attribute_pure__
- # if defined __GNUC_MINOR__ && __GNUC__ * 1000 + __GNUC_MINOR__ >= 2096
- # define __attribute_pure__ __attribute__ ((__pure__))
- # else
- # define __attribute_pure__
- # endif
- #endif
- #ifdef __cplusplus
- extern "C" {
- #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 */
- {
- _CHUNK_SIZE_T 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 */
- union
- {
- _OBSTACK_SIZE_T i;
- void *p;
- } temp; /* Temporary for some macros. */
- _OBSTACK_SIZE_T alignment_mask; /* Mask of alignment for each object. */
- /* These prototypes vary based on 'use_extra_arg'. */
- union
- {
- void *(*plain) (size_t);
- void *(*extra) (void *, size_t);
- } chunkfun;
- union
- {
- void (*plain) (void *);
- void (*extra) (void *, void *);
- } freefun;
- 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 *, _OBSTACK_SIZE_T);
- extern void _obstack_free (struct obstack *, void *);
- extern int _obstack_begin (struct obstack *,
- _OBSTACK_SIZE_T, _OBSTACK_SIZE_T,
- void *(*) (size_t), void (*) (void *));
- extern int _obstack_begin_1 (struct obstack *,
- _OBSTACK_SIZE_T, _OBSTACK_SIZE_T,
- void *(*) (void *, size_t),
- void (*) (void *, void *), void *);
- extern _OBSTACK_SIZE_T _obstack_memory_used (struct obstack *)
- __attribute_pure__;
- /* Error handler called when 'obstack_chunk_alloc' failed to allocate
- more memory. This can be set to a user defined function which
- should either abort gracefully or use longjump - but shouldn't
- return. The default action is to print a message and abort. */
- extern void (*obstack_alloc_failed_handler) (void);
- /* Exit value used when 'print_and_abort' is used. */
- extern int obstack_exit_failure;
- /* Pointer to beginning of object being allocated or to be allocated next.
- Note that this might not be the final address of the object
- because a new chunk might be needed to hold the final size. */
- #define obstack_base(h) ((void *) (h)->object_base)
- /* Size for allocating ordinary chunks. */
- #define obstack_chunk_size(h) ((h)->chunk_size)
- /* Pointer to next byte not yet allocated in current chunk. */
- #define obstack_next_free(h) ((void *) (h)->next_free)
- /* Mask specifying low bits that should be clear in address of an object. */
- #define obstack_alignment_mask(h) ((h)->alignment_mask)
- /* To prevent prototype warnings provide complete argument list. */
- #define obstack_init(h) \
- _obstack_begin ((h), 0, 0, \
- _OBSTACK_CAST (void *(*) (size_t), obstack_chunk_alloc), \
- _OBSTACK_CAST (void (*) (void *), obstack_chunk_free))
- #define obstack_begin(h, size) \
- _obstack_begin ((h), (size), 0, \
- _OBSTACK_CAST (void *(*) (size_t), obstack_chunk_alloc), \
- _OBSTACK_CAST (void (*) (void *), obstack_chunk_free))
- #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
- _obstack_begin ((h), (size), (alignment), \
- _OBSTACK_CAST (void *(*) (size_t), chunkfun), \
- _OBSTACK_CAST (void (*) (void *), freefun))
- #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
- _obstack_begin_1 ((h), (size), (alignment), \
- _OBSTACK_CAST (void *(*) (void *, size_t), chunkfun), \
- _OBSTACK_CAST (void (*) (void *, void *), freefun), arg)
- #define obstack_chunkfun(h, newchunkfun) \
- ((void) ((h)->chunkfun.extra = (void *(*) (void *, size_t)) (newchunkfun)))
- #define obstack_freefun(h, newfreefun) \
- ((void) ((h)->freefun.extra = (void *(*) (void *, void *)) (newfreefun)))
- #define obstack_1grow_fast(h, achar) ((void) (*((h)->next_free)++ = (achar)))
- #define obstack_blank_fast(h, n) ((void) ((h)->next_free += (n)))
- #define obstack_memory_used(h) _obstack_memory_used (h)
- #if defined __GNUC__
- # if !defined __GNUC_MINOR__ || __GNUC__ * 1000 + __GNUC_MINOR__ < 2008
- # define __extension__
- # endif
- /* For GNU C, if not -traditional,
- we can define these macros to compute all args only once
- without using a global variable.
- Also, we can avoid using the 'temp' slot, to make faster code. */
- # define obstack_object_size(OBSTACK) \
- __extension__ \
- ({ struct obstack const *__o = (OBSTACK); \
- (_OBSTACK_SIZE_T) (__o->next_free - __o->object_base); })
- /* The local variable is named __o1 to avoid a shadowed variable
- warning when invoked from other obstack macros. */
- # define obstack_room(OBSTACK) \
- __extension__ \
- ({ struct obstack const *__o1 = (OBSTACK); \
- (_OBSTACK_SIZE_T) (__o1->chunk_limit - __o1->next_free); })
- # define obstack_make_room(OBSTACK, length) \
- __extension__ \
- ({ struct obstack *__o = (OBSTACK); \
- _OBSTACK_SIZE_T __len = (length); \
- if (obstack_room (__o) < __len) \
- _obstack_newchunk (__o, __len); \
- (void) 0; })
- # define obstack_empty_p(OBSTACK) \
- __extension__ \
- ({ struct obstack const *__o = (OBSTACK); \
- (__o->chunk->prev == 0 \
- && __o->next_free == __PTR_ALIGN ((char *) __o->chunk, \
- __o->chunk->contents, \
- __o->alignment_mask)); })
- # define obstack_grow(OBSTACK, where, length) \
- __extension__ \
- ({ struct obstack *__o = (OBSTACK); \
- _OBSTACK_SIZE_T __len = (length); \
- if (obstack_room (__o) < __len) \
- _obstack_newchunk (__o, __len); \
- memcpy (__o->next_free, where, __len); \
- __o->next_free += __len; \
- (void) 0; })
- # define obstack_grow0(OBSTACK, where, length) \
- __extension__ \
- ({ struct obstack *__o = (OBSTACK); \
- _OBSTACK_SIZE_T __len = (length); \
- if (obstack_room (__o) < __len + 1) \
- _obstack_newchunk (__o, __len + 1); \
- memcpy (__o->next_free, where, __len); \
- __o->next_free += __len; \
- *(__o->next_free)++ = 0; \
- (void) 0; })
- # define obstack_1grow(OBSTACK, datum) \
- __extension__ \
- ({ struct obstack *__o = (OBSTACK); \
- if (obstack_room (__o) < 1) \
- _obstack_newchunk (__o, 1); \
- obstack_1grow_fast (__o, datum); })
- /* 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 (obstack_room (__o) < sizeof (void *)) \
- _obstack_newchunk (__o, sizeof (void *)); \
- obstack_ptr_grow_fast (__o, datum); })
- # define obstack_int_grow(OBSTACK, datum) \
- __extension__ \
- ({ struct obstack *__o = (OBSTACK); \
- if (obstack_room (__o) < sizeof (int)) \
- _obstack_newchunk (__o, sizeof (int)); \
- obstack_int_grow_fast (__o, datum); })
- # define obstack_ptr_grow_fast(OBSTACK, aptr) \
- __extension__ \
- ({ struct obstack *__o1 = (OBSTACK); \
- void *__p1 = __o1->next_free; \
- *(const void **) __p1 = (aptr); \
- __o1->next_free += sizeof (const void *); \
- (void) 0; })
- # define obstack_int_grow_fast(OBSTACK, aint) \
- __extension__ \
- ({ struct obstack *__o1 = (OBSTACK); \
- void *__p1 = __o1->next_free; \
- *(int *) __p1 = (aint); \
- __o1->next_free += sizeof (int); \
- (void) 0; })
- # define obstack_blank(OBSTACK, length) \
- __extension__ \
- ({ struct obstack *__o = (OBSTACK); \
- _OBSTACK_SIZE_T __len = (length); \
- if (obstack_room (__o) < __len) \
- _obstack_newchunk (__o, __len); \
- obstack_blank_fast (__o, __len); })
- # 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 shadowed variable
- warning when invoked from other obstack macros, typically obstack_free. */
- # define obstack_finish(OBSTACK) \
- __extension__ \
- ({ struct obstack *__o1 = (OBSTACK); \
- void *__value = (void *) __o1->object_base; \
- if (__o1->next_free == __value) \
- __o1->maybe_empty_object = 1; \
- __o1->next_free \
- = __PTR_ALIGN (__o1->object_base, __o1->next_free, \
- __o1->alignment_mask); \
- if ((size_t) (__o1->next_free - (char *) __o1->chunk) \
- > (size_t) (__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__ */
- # define obstack_object_size(h) \
- ((_OBSTACK_SIZE_T) ((h)->next_free - (h)->object_base))
- # define obstack_room(h) \
- ((_OBSTACK_SIZE_T) ((h)->chunk_limit - (h)->next_free))
- # define obstack_empty_p(h) \
- ((h)->chunk->prev == 0 \
- && (h)->next_free == __PTR_ALIGN ((char *) (h)->chunk, \
- (h)->chunk->contents, \
- (h)->alignment_mask))
- /* 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.i = (length), \
- ((obstack_room (h) < (h)->temp.i) \
- ? (_obstack_newchunk (h, (h)->temp.i), 0) : 0), \
- (void) 0)
- # define obstack_grow(h, where, length) \
- ((h)->temp.i = (length), \
- ((obstack_room (h) < (h)->temp.i) \
- ? (_obstack_newchunk ((h), (h)->temp.i), 0) : 0), \
- memcpy ((h)->next_free, where, (h)->temp.i), \
- (h)->next_free += (h)->temp.i, \
- (void) 0)
- # define obstack_grow0(h, where, length) \
- ((h)->temp.i = (length), \
- ((obstack_room (h) < (h)->temp.i + 1) \
- ? (_obstack_newchunk ((h), (h)->temp.i + 1), 0) : 0), \
- memcpy ((h)->next_free, where, (h)->temp.i), \
- (h)->next_free += (h)->temp.i, \
- *((h)->next_free)++ = 0, \
- (void) 0)
- # define obstack_1grow(h, datum) \
- (((obstack_room (h) < 1) \
- ? (_obstack_newchunk ((h), 1), 0) : 0), \
- obstack_1grow_fast (h, datum))
- # define obstack_ptr_grow(h, datum) \
- (((obstack_room (h) < sizeof (char *)) \
- ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
- obstack_ptr_grow_fast (h, datum))
- # define obstack_int_grow(h, datum) \
- (((obstack_room (h) < sizeof (int)) \
- ? (_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), \
- (void) 0)
- # define obstack_int_grow_fast(h, aint) \
- (((int *) ((h)->next_free += sizeof (int)))[-1] = (aint), \
- (void) 0)
- # define obstack_blank(h, length) \
- ((h)->temp.i = (length), \
- ((obstack_room (h) < (h)->temp.i) \
- ? (_obstack_newchunk ((h), (h)->temp.i), 0) : 0), \
- obstack_blank_fast (h, (h)->temp.i))
- # 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.p = (h)->object_base, \
- (h)->next_free \
- = __PTR_ALIGN ((h)->object_base, (h)->next_free, \
- (h)->alignment_mask), \
- (((size_t) ((h)->next_free - (char *) (h)->chunk) \
- > (size_t) ((h)->chunk_limit - (char *) (h)->chunk)) \
- ? ((h)->next_free = (h)->chunk_limit) : 0), \
- (h)->object_base = (h)->next_free, \
- (h)->temp.p)
- # define obstack_free(h, obj) \
- ((h)->temp.p = (void *) (obj), \
- (((h)->temp.p > (void *) (h)->chunk \
- && (h)->temp.p < (void *) (h)->chunk_limit) \
- ? (void) ((h)->next_free = (h)->object_base = (char *) (h)->temp.p) \
- : _obstack_free ((h), (h)->temp.p)))
- #endif /* not __GNUC__ */
- #ifdef __cplusplus
- } /* C++ */
- #endif
- #endif /* _OBSTACK_H */
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