485 lines
18 KiB
C
485 lines
18 KiB
C
/* obstack.h - object stack macros
|
||
Copyright (C) 1988, 1992 Free Software Foundation, Inc.
|
||
|
||
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, 675 Mass Ave, Cambridge, MA 02139, 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 __OBSTACKS__
|
||
#define __OBSTACKS__
|
||
|
||
/* 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. In ANSI C it is ptrdiff_t
|
||
but in traditional C it is usually long. If we are in ANSI C and
|
||
don't already have ptrdiff_t get it. */
|
||
|
||
#if defined (__STDC__) && ! defined (offsetof)
|
||
#if defined (__GNUC__) && defined (IN_GCC)
|
||
/* On Next machine, the system's stddef.h screws up if included
|
||
after we have defined just ptrdiff_t, so include all of gstddef.h.
|
||
Otherwise, define just ptrdiff_t, which is all we need. */
|
||
#ifndef __NeXT__
|
||
#define __need_ptrdiff_t
|
||
#endif
|
||
|
||
/* While building GCC, the stddef.h that goes with GCC has this name. */
|
||
#include "gstddef.h"
|
||
#else
|
||
#include <stddef.h>
|
||
#endif
|
||
#endif
|
||
|
||
#ifdef __STDC__
|
||
#define PTR_INT_TYPE ptrdiff_t
|
||
#else
|
||
#define PTR_INT_TYPE long
|
||
#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. */
|
||
struct _obstack_chunk *(*chunkfun) (); /* User's fcn to allocate a chunk. */
|
||
void (*freefun) (); /* User's function to free a chunk. */
|
||
char *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. */
|
||
};
|
||
|
||
/* Declare the external functions we use; they are in obstack.c. */
|
||
|
||
#ifdef __STDC__
|
||
extern void _obstack_newchunk (struct obstack *, int);
|
||
extern void _obstack_free (struct obstack *, void *);
|
||
extern void _obstack_begin (struct obstack *, int, int,
|
||
void *(*) (), void (*) ());
|
||
extern void _obstack_begin_1 (struct obstack *, int, int,
|
||
void *(*) (), void (*) (), void *);
|
||
#else
|
||
extern void _obstack_newchunk ();
|
||
extern void _obstack_free ();
|
||
extern void _obstack_begin ();
|
||
extern void _obstack_begin_1 ();
|
||
#endif
|
||
|
||
#ifdef __STDC__
|
||
|
||
/* 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_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);
|
||
|
||
#endif /* __STDC__ */
|
||
|
||
/* Non-ANSI C cannot really support alternative functions for these macros,
|
||
so we do not declare them. */
|
||
|
||
/* 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)
|
||
|
||
#define obstack_init(h) \
|
||
_obstack_begin ((h), 0, 0, \
|
||
(void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)
|
||
|
||
#define obstack_begin(h, size) \
|
||
_obstack_begin ((h), (size), 0, \
|
||
(void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)
|
||
|
||
#define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
|
||
_obstack_begin ((h), (size), (alignment), \
|
||
(void *(*) ()) (chunkfun), (void (*) ()) (freefun))
|
||
|
||
#define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
|
||
_obstack_begin_1 ((h), (size), (alignment), \
|
||
(void *(*) ()) (chunkfun), (void (*) ()) (freefun), (arg))
|
||
|
||
#define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = achar)
|
||
|
||
#define obstack_blank_fast(h,n) ((h)->next_free += (n))
|
||
|
||
#if defined (__GNUC__) && defined (__STDC__)
|
||
#if __GNUC__ < 2 || defined(NeXT)
|
||
#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); })
|
||
|
||
/* 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_grow(OBSTACK,where,length) \
|
||
__extension__ \
|
||
({ struct obstack *__o = (OBSTACK); \
|
||
int __len = (length); \
|
||
((__o->next_free + __len > __o->chunk_limit) \
|
||
? (_obstack_newchunk (__o, __len), 0) : 0); \
|
||
bcopy (where, __o->next_free, __len); \
|
||
__o->next_free += __len; \
|
||
(void) 0; })
|
||
|
||
#define obstack_grow0(OBSTACK,where,length) \
|
||
__extension__ \
|
||
({ struct obstack *__o = (OBSTACK); \
|
||
int __len = (length); \
|
||
((__o->next_free + __len + 1 > __o->chunk_limit) \
|
||
? (_obstack_newchunk (__o, __len + 1), 0) : 0), \
|
||
bcopy (where, __o->next_free, __len), \
|
||
__o->next_free += __len, \
|
||
*(__o->next_free)++ = 0; \
|
||
(void) 0; })
|
||
|
||
#define obstack_1grow(OBSTACK,datum) \
|
||
__extension__ \
|
||
({ struct obstack *__o = (OBSTACK); \
|
||
((__o->next_free + 1 > __o->chunk_limit) \
|
||
? (_obstack_newchunk (__o, 1), 0) : 0), \
|
||
*(__o->next_free)++ = (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); \
|
||
((__o->next_free + sizeof (void *) > __o->chunk_limit) \
|
||
? (_obstack_newchunk (__o, sizeof (void *)), 0) : 0), \
|
||
*((void **)__o->next_free)++ = ((void *)datum); \
|
||
(void) 0; })
|
||
|
||
#define obstack_int_grow(OBSTACK,datum) \
|
||
__extension__ \
|
||
({ struct obstack *__o = (OBSTACK); \
|
||
((__o->next_free + sizeof (int) > __o->chunk_limit) \
|
||
? (_obstack_newchunk (__o, sizeof (int)), 0) : 0), \
|
||
*((int *)__o->next_free)++ = ((int)datum); \
|
||
(void) 0; })
|
||
|
||
#define obstack_ptr_grow_fast(h,aptr) (*((void **)(h)->next_free)++ = (void *)aptr)
|
||
#define obstack_int_grow_fast(h,aint) (*((int *)(h)->next_free)++ = (int)aint)
|
||
|
||
#define obstack_blank(OBSTACK,length) \
|
||
__extension__ \
|
||
({ struct obstack *__o = (OBSTACK); \
|
||
int __len = (length); \
|
||
((__o->chunk_limit - __o->next_free < __len) \
|
||
? (_obstack_newchunk (__o, __len), 0) : 0); \
|
||
__o->next_free += __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 \
|
||
= __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
|
||
& ~ (__o1->alignment_mask)); \
|
||
((__o1->next_free - (char *)__o1->chunk \
|
||
> __o1->chunk_limit - (char *)__o1->chunk) \
|
||
? (__o1->next_free = __o1->chunk_limit) : 0); \
|
||
__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 = __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_grow(h,where,length) \
|
||
( (h)->temp = (length), \
|
||
(((h)->next_free + (h)->temp > (h)->chunk_limit) \
|
||
? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
|
||
bcopy (where, (h)->next_free, (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), \
|
||
bcopy (where, (h)->next_free, (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), \
|
||
*((h)->next_free)++ = (datum))
|
||
|
||
#define obstack_ptr_grow(h,datum) \
|
||
( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
|
||
? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
|
||
*((char **)(((h)->next_free+=sizeof(char *))-sizeof(char *))) = ((char *)datum))
|
||
|
||
#define obstack_int_grow(h,datum) \
|
||
( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
|
||
? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
|
||
*((int *)(((h)->next_free+=sizeof(int))-sizeof(int))) = ((int)datum))
|
||
|
||
#define obstack_ptr_grow_fast(h,aptr) (*((char **)(h)->next_free)++ = (char *)aptr)
|
||
#define obstack_int_grow_fast(h,aint) (*((int *)(h)->next_free)++ = (int)aint)
|
||
|
||
#define obstack_blank(h,length) \
|
||
( (h)->temp = (length), \
|
||
(((h)->chunk_limit - (h)->next_free < (h)->temp) \
|
||
? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
|
||
(h)->next_free += (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, \
|
||
__INT_TO_PTR ((h)->temp))
|
||
|
||
#ifdef __STDC__
|
||
#define obstack_free(h,obj) \
|
||
( (h)->temp = (char *)(obj) - (char *) (h)->chunk, \
|
||
(((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
|
||
? (int) ((h)->next_free = (h)->object_base \
|
||
= (h)->temp + (char *) (h)->chunk) \
|
||
: (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
|
||
#else
|
||
#define obstack_free(h,obj) \
|
||
( (h)->temp = (char *)(obj) - (char *) (h)->chunk, \
|
||
(((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
|
||
? (int) ((h)->next_free = (h)->object_base \
|
||
= (h)->temp + (char *) (h)->chunk) \
|
||
: (_obstack_free ((h), (h)->temp + (char *) (h)->chunk), 0)))
|
||
#endif
|
||
|
||
#endif /* not __GNUC__ or not __STDC__ */
|
||
|
||
#endif /* not __OBSTACKS__ */
|