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Diffstat (limited to 'lib/obstack.h')
| -rw-r--r-- | lib/obstack.h | 551 |
1 files changed, 551 insertions, 0 deletions
diff --git a/lib/obstack.h b/lib/obstack.h new file mode 100644 index 0000000..cb080c3 --- /dev/null +++ b/lib/obstack.h @@ -0,0 +1,551 @@ +/* obstack.h - object stack macros + Copyright (C) 1988-2023 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + This file 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 3 of the + License, or (at your option) any later version. + + This file 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 this program. If not, see <https://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 + +/* This file uses _Noreturn, _GL_ATTRIBUTE_PURE. */ +#if !_GL_CONFIG_H_INCLUDED + #error "Please include config.h first." +#endif + +#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 __STDC_VERSION__ < 199901L || defined __HP_cc +# define __FLEXIBLE_ARRAY_MEMBER 1 +#else +# define __FLEXIBLE_ARRAY_MEMBER +#endif + +#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__ +# define __attribute_pure__ _GL_ATTRIBUTE_PURE +#endif + +/* Not the same as _Noreturn, since it also works with function pointers. */ +#ifndef __attribute_noreturn__ +# if 2 < __GNUC__ + (8 <= __GNUC_MINOR__) || defined __clang__ || 0x5110 <= __SUNPRO_C +# define __attribute_noreturn__ __attribute__ ((__noreturn__)) +# else +# define __attribute_noreturn__ +# 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[__FLEXIBLE_ARRAY_MEMBER]; /* 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 __attribute_noreturn__ 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__ || defined __clang__ +# if !(defined __GNUC_MINOR__ && __GNUC__ * 1000 + __GNUC_MINOR__ >= 2008 \ + || defined __clang__) +# 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 */ |