| /* obstack.h - object stack macros |
| Copyright (C) 1988-2016 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 |
| |
| /* We need the type of a pointer subtraction. 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, include <stddef.h> |
| and use ptrdiff_t. */ |
| |
| #ifdef __PTRDIFF_TYPE__ |
| # define PTR_INT_TYPE __PTRDIFF_TYPE__ |
| #else |
| # include <stddef.h> |
| # define PTR_INT_TYPE ptrdiff_t |
| #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 PTR_INT_TYPE 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 (PTR_INT_TYPE) < sizeof (void *) ? (B) : (char *) 0, \ |
| P, A) |
| |
| #include <string.h> |
| |
| #ifndef __attribute_pure__ |
| # define __attribute_pure__ _GL_ATTRIBUTE_PURE |
| #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 */ |
| { |
| 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 */ |
| union |
| { |
| PTR_INT_TYPE tempint; |
| void *tempptr; |
| } 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 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 *) __attribute_pure__; |
| |
| /* The default name of the function for freeing a chunk is 'obstack_free', |
| but gnulib users can override this by defining '__obstack_free'. */ |
| #ifndef __obstack_free |
| # define __obstack_free obstack_free |
| #endif |
| extern void __obstack_free (struct obstack *, void *); |
| |
| |
| /* 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) ((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, \ |
| (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__ |
| # if ! (2 < __GNUC__ + (8 <= __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 const *__o = (OBSTACK); \ |
| (unsigned) (__o->next_free - __o->object_base); }) |
| |
| # define obstack_room(OBSTACK) \ |
| __extension__ \ |
| ({ struct obstack const *__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 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); \ |
| int __len = (length); \ |
| if (__o->next_free + __len > __o->chunk_limit) \ |
| _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); \ |
| int __len = (length); \ |
| if (__o->next_free + __len + 1 > __o->chunk_limit) \ |
| _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 (__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); \ |
| 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); \ |
| 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 = (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 (__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 = (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) \ |
| (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 == __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.tempint = (length), \ |
| (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \ |
| ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0)) |
| |
| # define obstack_grow(h, where, length) \ |
| ((h)->temp.tempint = (length), \ |
| (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \ |
| ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \ |
| memcpy ((h)->next_free, where, (h)->temp.tempint), \ |
| (h)->next_free += (h)->temp.tempint) |
| |
| # define obstack_grow0(h, where, length) \ |
| ((h)->temp.tempint = (length), \ |
| (((h)->next_free + (h)->temp.tempint + 1 > (h)->chunk_limit) \ |
| ? (_obstack_newchunk ((h), (h)->temp.tempint + 1), 0) : 0), \ |
| memcpy ((h)->next_free, where, (h)->temp.tempint), \ |
| (h)->next_free += (h)->temp.tempint, \ |
| *((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] = (aint)) |
| |
| # define obstack_blank(h, length) \ |
| ((h)->temp.tempint = (length), \ |
| (((h)->chunk_limit - (h)->next_free < (h)->temp.tempint) \ |
| ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \ |
| obstack_blank_fast (h, (h)->temp.tempint)) |
| |
| # 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.tempptr = (h)->object_base, \ |
| (h)->next_free \ |
| = __PTR_ALIGN ((h)->object_base, (h)->next_free, \ |
| (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, \ |
| (h)->temp.tempptr) |
| |
| # define obstack_free(h, obj) \ |
| ((h)->temp.tempint = (char *) (obj) - (char *) (h)->chunk, \ |
| ((((h)->temp.tempint > 0 \ |
| && (h)->temp.tempint < (h)->chunk_limit - (char *) (h)->chunk)) \ |
| ? (void) ((h)->next_free = (h)->object_base \ |
| = (h)->temp.tempint + (char *) (h)->chunk) \ |
| : (__obstack_free) (h, (h)->temp.tempint + (char *) (h)->chunk))) |
| |
| #endif /* not __GNUC__ */ |
| |
| #ifdef __cplusplus |
| } /* C++ */ |
| #endif |
| |
| #endif /* obstack.h */ |