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|
/******************************************************************************
** $Id: symbols.c,v 2.20 1997/12/06 22:56:00 gerd Exp gerd $
**=============================================================================
**
** This file is part of BibTool.
** It is distributed under the GNU General Public License.
** See the file COPYING for details.
**
** (c) 1996-1997 Gerd Neugebauer
**
** Net: gerd@informatik.uni-koblenz.de
**
**-----------------------------------------------------------------------------
** Description:
** This module contains functions which deal with symbols and
** general memory management.
** This module implements a single symbol table.
**
** This module required initialization before all functions can
** be used. Especially the symbol table does not exist before
** initialization.
**
******************************************************************************/
#include <bibtool/general.h>
#include <bibtool/symbols.h>
#include <bibtool/error.h>
#include "config.h"
/*-----------------------------------------------------------------------------
** Typedef*: StringTab
** Purpose: This is the pointer type representing an entry in the symbol
** table. It contains a string and some integers.
**
**___________________________________________________ */
typedef struct STAB /* */
{ char *st_name; /* The string representation of the symbol */
int st_count; /* */
int st_flags; /* Bits of certain flags. */
int st_used; /* Counter for determining the number of uses*/
struct STAB *st_next; /* Pointer to the next item. */
} *StringTab;
/*-----------------------------------------------------------------------------
** Macro*: NextSymbol()
** Type: StringTab
** Purpose: The next |StringTab| of the argument. This macro
** can also be used as lvalue.
** Arguments:
** ST Current |StringTab|
** Returns: The next |StringTab| or |NULL|.
**___________________________________________________ */
#define NextSymbol(ST) ((ST)->st_next)
/*-----------------------------------------------------------------------------
** Macro*: SymbolCount()
** Type: int
** Purpose: The count slot of a |StringTab|. This macro
** can also be used as lvalue.
** Arguments:
** ST Current |StringTab|
** Returns: The count slot of |ST|.
**___________________________________________________ */
#define SymbolCount(ST) ((ST)->st_count)
/*-----------------------------------------------------------------------------
** Macro*: SymbolUsed()
** Type: int
** Purpose: The used slot of a |StringTab|. This macro
** can also be used as lvalue.
** Arguments:
** ST Current |StringTab|
** Returns: The used slot of |ST|.
**___________________________________________________ */
#define SymbolUsed(ST) ((ST)->st_used)
/*-----------------------------------------------------------------------------
** Macro*: SymbolName()
** Type: char *
** Purpose: The name slot of a |StringTab|, i.e.\ the string
** representation. This macro can also be used as lvalue.
** Arguments:
** ST Current |StringTab|
** Returns: The name slot of |ST|.
**___________________________________________________ */
#define SymbolName(ST) ((ST)->st_name)
/*-----------------------------------------------------------------------------
** Macro*: SymbolFlags()
** Type: int
** Purpose: The flags slot of a |StringTab|. This macro
** can also be used as lvalue.
** Arguments:
** ST Current |StringTab|
** Returns: The flags slot of |ST|.
**___________________________________________________ */
#define SymbolFlags(ST) ((ST)->st_flags)
/*****************************************************************************/
/* Internal Programs */
/*===========================================================================*/
#ifdef __STDC__
#define _ARG(A) A
#else
#define _ARG(A) ()
#endif
static StringTab new_string_tab _ARG((char *name,int count,int flags));/* symbols.c*/
char * new_string _ARG((char * s)); /* symbols.c */
char * sym_add _ARG((char *s,int count)); /* symbols.c */
char * sym_extract _ARG((char *ap,char *ep,int count));/* symbols.c */
int sym_flag _ARG((char * s)); /* symbols.c */
static int hashindex _ARG((char *s)); /* symbols.c */
void init_symbols _ARG((void)); /* symbols.c */
void sym_dump _ARG((void)); /* symbols.c */
void sym_gc _ARG((void)); /* symbols.c */
void sym_set_flag _ARG((char *s,int flags)); /* symbols.c */
void sym_unlink _ARG((char *s)); /* symbols.c */
/*****************************************************************************/
/* External Programs */
/*===========================================================================*/
#ifdef HASH_TABLE_SIZE
#define HASHMAX HASH_TABLE_SIZE
#else
#define HASHMAX 307
#endif
char * sym_empty = NULL;
char * sym_crossref = NULL;
/*****************************************************************************/
/*** Misc string allocation routine ***/
/*****************************************************************************/
/*-----------------------------------------------------------------------------
** Function: new_string()
** Purpose: Allocate a space for a string and copy the argument
** there. Note this is just a new copy of the memory not
** a symbol!
**
** If no more memory is available then an error is raised
** and the program is terminated.
** Arguments:
** s String to duplicate
** Returns: Pointer to newly allocated memory containing a
** duplicate of the argument string.
**___________________________________________________ */
char * new_string(s) /* */
register char * s; /* */
{ register char * t; /* */
if ( (t=malloc((size_t)strlen(s)+1)) == NULL ) /* */
{ OUT_OF_MEMORY("string"); } /* */
(void)strcpy(t,s); /* */
return(t); /* */
} /*------------------------*/
/*****************************************************************************/
/*** Symbol Table Section ***/
/*****************************************************************************/
/*-----------------------------------------------------------------------------
** Function: new_string_tab()
** Purpose: Allocate a new |StringTab| structure and fill it with initial
** values.
**
** If no more memory is available then an error is raised
** and the program is terminated.
** Arguments:
** name String value of the |StringTab| node.
** count Initial use count of the |StringTab| node.
** flags Flags of the new |StringTab| node.
** Returns: Pointer to a new inbstance of a |StringTab|.
**___________________________________________________ */
static StringTab new_string_tab(name,count,flags) /* */
char *name; /* */
int count; /* */
int flags; /* */
{ register StringTab new; /* */
/* */
if ( (new=(StringTab)malloc(sizeof(struct STAB))) == 0L )/* */
{ OUT_OF_MEMORY("StringTab"); } /* */
SymbolName(new) = name; /* */
SymbolCount(new) = count; /* */
SymbolFlags(new) = flags; /* */
SymbolUsed(new) = 0; /* */
NextSymbol(new) = (StringTab)0; /* */
return(new); /* */
} /*------------------------*/
/*-----------------------------------------------------------------------------
** Function: hashindex()
** Purpose: Compute the sum of ASCII values modulo HASHMAX
** to be used as an hashindex.
** Arguments:
** s string to be analyzed.
** Returns: hashindex
**___________________________________________________ */
static int hashindex(s) /* */
char *s; /* */
{ int index=0; /* */
while ( *s ) index = (index+*(s++)) % HASHMAX; /* */
return ( index < 0 ? -index : index ); /* */
} /*------------------------*/
static StringTab sym_tab[HASHMAX];
/*-----------------------------------------------------------------------------
** Function: init_symbols()
** Purpose: Initialize the symbols module.
** The symbol table is cleared. This is not secure when
** the symbols have already been initialized because it
** would lead to a memory leak and a violation of the
** symbol comparison assumtion. Thus this case is caught
** and nothing is done when the initialization seems to
** be requested for the second time.
**
** If no more memory is available then an error is raised
** and the program is terminated.
**
** Note that this function is for internal purposes
** only. The normal user should call |init_bibtool()|
** instead.
** Arguments: none
** Returns: nothing
**___________________________________________________ */
void init_symbols() /* */
{ register int i; /* */
/* */
if ( sym_empty != NULL ) return; /* */
for ( i=0; i<HASHMAX; i++ ) sym_tab[i] = NULL; /* */
sym_empty = sym_add("",-1); /* */
sym_crossref = sym_add("crossref",-1); /* */
} /*------------------------*/
static StringTab last_stp = NULL;
/*-----------------------------------------------------------------------------
** Function: sym_flag()
** Purpose: Get the flags of the symbol given as argument.
** Arguments:
** s Symbol
** Returns: The flags of the recently touched |StringTab|.
**___________________________________________________ */
int sym_flag(s) /* */
char * s; /* */
{ /* */
if ( last_stp == NULL || SymbolName(last_stp) != s )/* */
{ s = sym_add(s,0); } /* */
return SymbolFlags(last_stp); /* */
} /*------------------------*/
/*-----------------------------------------------------------------------------
** Function: sym_set_flag()
** Purpose: Add the flags to the symbol corresponding to the
** argument |s| by oring them together with the given
** value.
** Arguments:
** s Symbol to augment.
** flags New flags to add.
** Returns: nothing
**___________________________________________________ */
void sym_set_flag(s,flags) /* */
register char *s; /* */
register int flags; /* */
{ /* */
if ( last_stp == NULL || SymbolName(last_stp) != s )/* */
{ s = sym_add(s,0); } /* */
SymbolFlags(last_stp) |= flags; /* */
} /*------------------------*/
/*-----------------------------------------------------------------------------
** Function: sym_add()
** Purpose: Add a symbol to the global symbol table. If the string
** already has a symbol assigned to it then this symbol
** is returned. If the symbol is not static then the use
** count is incremented by |count|.
**
** If the symbol does not exist already then a new symbol
** is added to the symbol table and the use count is
** initialized to |count|. A negative value for |count|
** indicates that a static symbol is requested. A static
** symbol will never bee deleted from the symbol
** table. Static can be used at places where one does not
** care about the memory occupied.
**
** If no more memory is available then an error is raised
** and the program is terminated.
**
** See also the macro |symbol()| in |symbols.h| for a
** convenient alternative to this function.
** Arguments:
** s String which should be translated into a symbol.
** count The use count which should be added t the symbol
** Returns: The new symbol.
**___________________________________________________ */
char * sym_add(s,count) /* */
register char *s; /* */
register int count; /* */
{ register StringTab *stp; /* */
/* */
if ( s == NULL ) return(NULL); /* ignore dummies. */
/* */
for ( stp = &sym_tab[hashindex(s)]; /* */
*stp != NULL; /* */
stp = &NextSymbol(*stp) ) /* */
{ /* */
if ( strcmp(s,SymbolName(*stp)) == 0 ) /* */
{ if ( count>0 ) SymbolCount(*stp) += count; /* */
last_stp = *stp; /* */
if ( s != SymbolName(*stp) ) /* */
{ SymbolUsed(*stp)++; } /* */
return SymbolName(*stp); /* */
} /* */
} /* */
if ( count<0 ) /* */
{ count = 0; /* */
SymbolFlags(*stp) != SYMBOL_STATIC; /* */
} /* */
else /* */
{ s = new_string(s); } /* */
*stp = new_string_tab(s,count,0); /* */
last_stp = *stp; /* */
SymbolUsed(*stp)++; /* */
return SymbolName(*stp); /* */
} /*------------------------*/
/*-----------------------------------------------------------------------------
** Function: sym_unlink()
** Purpose: Free a symbol since it is no longer used.
** This does not mean that the memory is also freed. The
** symbol can be static or used at other places. The real
** free operation requires that the garbage collector
** |sym_gc()| to be called.
**
** If the argument is |NULL| or an arbitrary string (no
** symbol) then this case is also dealt with.
** Arguments:
** s Symbol to be released.
** Returns: nothing
**___________________________________________________ */
void sym_unlink(s) /* */
register char *s; /* */
{ register StringTab st; /* */
/* */
if ( s == NULL ) return; /* ignore dummies. */
/* */
for ( st = sym_tab[hashindex(s)]; /* */
st != NULL; /* */
st = NextSymbol(st) ) /* */
{ if ( s == SymbolName(st) ) /* */
{ SymbolUsed(st)--; /* reduce reference count */
return; /* */
} /* */
} /* */
#ifdef DEBUG
ErrPrintF("*** Attempt to free an undefined symbol: %s\n",s);/* */
#endif
} /*------------------------*/
/*-----------------------------------------------------------------------------
** Function*: sym_gc()
** Purpose: This is the garbade collector. It analyzes the symbol
** table and releases all |SymbolTab| nodes not needed
** any more.
**
** Right now it is purely experimental. Better let your
** hands off.
**
** Arguments: none
** Returns: nothing
**___________________________________________________ */
void sym_gc() /* */
{ /* */
register StringTab st, st2; /* */
register int i; /* */
/* */
for ( i=0;i<HASHMAX;i++ ) /* */
{ /* */
while (sym_tab[i] && SymbolUsed(sym_tab[i])<=0)
{ st = sym_tab[i];
sym_tab[i] = NextSymbol(st);
if ( SymbolFlags(st) & SYMBOL_STATIC == 0 )
{ free(SymbolName(st)); }
free(st);
}
st = sym_tab[i];
if ( st )
{
while ( (st2=NextSymbol(st)) != NULL &&
SymbolUsed(st) <= 0 )
{ NextSymbol(st) = NextSymbol(st2);
if ( SymbolFlags(st2) & SYMBOL_STATIC == 0 )
{ free(SymbolName(st2)); }
free(st2);
} /* */
} /* */
} /* */
} /*------------------------*/
#ifdef New
/*-----------------------------------------------------------------------------
** Function*: sym_extract()
** Purpose: Extract a symbol from a string.
** Arguments:
** ap
** ep
** count
** Returns:
**___________________________________________________ */
char * sym_extract(ap,ep,count) /* */
register char *ap; /* pointer to first char */
register char *ep; /* pointer after last char*/
register int count; /* */
{ char c; /* */
/* */
c = *ep; /* */
*ep = '\0'; /* */
ap = sym_add(ap,count<0?0:count); /* */
*ep = c; /* */
return ap; /* */
} /*------------------------*/
#endif
#ifdef SYMBOL_DUMP
/*-----------------------------------------------------------------------------
** Function: sym_dump()
** Purpose: Dump the symbol table to the error stream---see module
** |error.c|.
** The symbols are printed according to their hash value
** and the sequence they are occurring in the buckets. A
** summary of the memory used is also printed.
** Arguments: none
** Returns: nothing
**___________________________________________________ */
void sym_dump() /* */
{ register int i,l; /* */
register StringTab st; /* */
register long len = 0l; /* */
register long cnt = 0l; /* */
register long used = 0l; /* */
/* */
for ( i=0;i<HASHMAX;i++ ) /* */
{ for ( st = sym_tab[i]; st; st=NextSymbol(st) ) /* */
{ ErrPrintF2("--- BibTool symbol %4d %s\n", /* */
(int)SymbolCount(st), /* */
SymbolName(st)); /* */
l = strlen(SymbolName(st))+1; /* */
len += l; /* */
used += l*SymbolCount(st); /* */
++cnt; /* */
} /* */
} /* */
ErrPrintF2("--- BibTool symbol table: %ld bytes for %ld symbols\n",/* */
len, cnt); /* */
ErrPrintF("--- BibTool symbol table emulates %ld bytes\n",/* */
used); /* */
} /*------------------------*/
#endif
|
