/* obstack.h - object stack macros   Copyright (C) 1988 Free Software Foundation, Inc.This program is free software; you can redistribute it and/or modify itunder the terms of the GNU General Public License as published by theFree Software Foundation; either version 1, or (at your option) anylater version.This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See theGNU General Public License for more details.You should have received a copy of the GNU General Public Licensealong with this program; if not, write to the Free SoftwareFoundation, 675 Mass Ave, Cambridge, MA 02139, USA.In other words, you are welcome to use, share and improve this program.You are forbidden to forbid anyone else to use, share and improvewhat you give them.   Help stamp out software-hoarding!  *//* Summary:All the apparent functions defined here are macros. The ideais that you would use these pre-tested macros to solve avery specific set of problems, and they would run fast.Caution: no side-effects in arguments please!! They may beevaluated MANY times!!These macros operate a stack of objects.  Each object starts lifesmall, and may grow to maturity.  (Consider building a word syllableby syllable.)  An object can move while it is growing.  Once it hasbeen "finished" it never changes address again.  So the "top of thestack" is typically an immature growing object, while the rest of thestack is of mature, fixed size and fixed address objects.These routines grab large chunks of memory, using a function yousupply, called `obstack_chunk_alloc'.  On occasion, they free chunks,by calling `obstack_chunk_free'.  You must define them and declarethem 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 structureas the first argument.One motivation for this package is the problem of growing char stringsin symbol tables.  Unless you are "fascist pig with a read-only mind"[Gosper's immortal quote from HAKMEM item 154, out of context] youwould not like to put any arbitrary upper limit on the length of yoursymbols.In practice this often means you will build many short symbols and afew long symbols.  At the time you are reading a symbol you don't knowhow long it is.  One traditional method is to read a symbol into abuffer, realloc()ating the buffer every time you try to read a symbolthat is longer than the buffer.  This is beaut, but you still willwant to copy the symbol from the buffer to a more permanentsymbol-table entry say about half the time.With obstacks, you can work differently.  Use one obstack for all symbolnames.  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 fromlow addresses.  When you want to build a symbol in the chunk you justadd chars above the current "high water mark" in the chunk.  When youhave 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 aslong as an average object.In case that isn't clear, when we have enough chars to make upthe object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)so we just point to it where it lies.  No moving of chars isneeded and this is the second win: potentially long strings neednever be explicitly shuffled. Once an object is formed, it does notchange its address during its lifetime.When the chars burst over a chunk boundary, we allocate a largerchunk, and then copy the partly formed object from the end of the oldchunk to the beginning of the new larger chunk.  We then carry onaccreting 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 agrowing object.  This allows the use of register variables, whichbreak 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' a 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)#endifstruct _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 */  int	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.  */};#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, obstack_chunk_alloc, obstack_chunk_free)