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/* ecs - equivalence class routines */
/*
* Copyright (c) 1987, the University of California
*
* The United States Government has rights in this work pursuant to
* contract no. DE-AC03-76SF00098 between the United States Department of
* Energy and the University of California.
*
* This program may be redistributed. Enhancements and derivative works
* may be created provided the new works, if made available to the general
* public, are made available for use by anyone.
*/
#include "flexdef.h"
#ifndef lint
static char rcsid[] =
"@(#) $Header: /cvsroot/flex/flex/ecs.c,v 1.4 1988/05/08 19:53:13 vern Exp $ (LBL)";
#endif
/* ccl2ecl - convert character classes to set of equivalence classes
*
* synopsis
* ccl2ecl();
*/
ccl2ecl()
{
int i, ich, newlen, cclp, ccls, cclmec;
for ( i = 1; i <= lastccl; ++i )
{
/* we loop through each character class, and for each character
* in the class, add the character's equivalence class to the
* new "character" class we are creating. Thus when we are all
* done, character classes will really consist of collections
* of equivalence classes
*/
newlen = 0;
cclp = cclmap[i];
for ( ccls = 0; ccls < ccllen[i]; ++ccls )
{
ich = ccltbl[cclp + ccls];
cclmec = ecgroup[ich];
if ( cclmec > 0 )
{
ccltbl[cclp + newlen] = cclmec;
++newlen;
}
}
ccllen[i] = newlen;
}
}
/* cre8ecs - associate equivalence class numbers with class members
*
* synopsis
* int cre8ecs();
* number of classes = cre8ecs( fwd, bck, num );
*
* fwd is the forward linked-list of equivalence class members. bck
* is the backward linked-list, and num is the number of class members.
* Returned is the number of classes.
*/
int cre8ecs( fwd, bck, num )
int fwd[], bck[], num;
{
int i, j, numcl;
numcl = 0;
/* create equivalence class numbers. From now on, abs( bck(x) )
* is the equivalence class number for object x. If bck(x)
* is positive, then x is the representative of its equivalence
* class.
*/
for ( i = 1; i <= num; ++i )
if ( bck[i] == NIL )
{
bck[i] = ++numcl;
for ( j = fwd[i]; j != NIL; j = fwd[j] )
bck[j] = -numcl;
}
return ( numcl );
}
/* mkeccl - update equivalence classes based on character class xtions
*
* synopsis
* char ccls[];
* int lenccl, fwd[llsiz], bck[llsiz], llsiz;
* mkeccl( ccls, lenccl, fwd, bck, llsiz );
*
* where ccls contains the elements of the character class, lenccl is the
* number of elements in the ccl, fwd is the forward link-list of equivalent
* characters, bck is the backward link-list, and llsiz size of the link-list
*/
mkeccl( ccls, lenccl, fwd, bck, llsiz )
char ccls[];
int lenccl, fwd[], bck[], llsiz;
{
int cclp, oldec, newec;
int cclm, i, j;
#define PROCFLG 0x80
/* note that it doesn't matter whether or not the character class is
* negated. The same results will be obtained in either case.
*/
cclp = 0;
while ( cclp < lenccl )
{
cclm = ccls[cclp];
oldec = bck[cclm];
newec = cclm;
j = cclp + 1;
for ( i = fwd[cclm]; i != NIL && i <= llsiz; i = fwd[i] )
{ /* look for the symbol in the character class */
for ( ; j < lenccl && (ccls[j] <= i || (ccls[j] & PROCFLG)); ++j )
if ( ccls[j] == i )
{
/* we found an old companion of cclm in the ccl.
* link it into the new equivalence class and flag it as
* having been processed
*/
bck[i] = newec;
fwd[newec] = i;
newec = i;
ccls[j] |= PROCFLG; /* set flag so we don't reprocess */
/* get next equivalence class member */
/* continue 2 */
goto next_pt;
}
/* symbol isn't in character class. Put it in the old equivalence
* class
*/
bck[i] = oldec;
if ( oldec != NIL )
fwd[oldec] = i;
oldec = i;
next_pt:
;
}
if ( bck[cclm] != NIL || oldec != bck[cclm] )
{
bck[cclm] = NIL;
fwd[oldec] = NIL;
}
fwd[newec] = NIL;
/* find next ccl member to process */
for ( ++cclp; (ccls[cclp] & PROCFLG) && cclp < lenccl; ++cclp )
{
/* reset "doesn't need processing" flag */
ccls[cclp] &= ~PROCFLG;
}
}
}
/* mkechar - create equivalence class for single character
*
* synopsis
* int tch, fwd[], bck[];
* mkechar( tch, fwd, bck );
*/
mkechar( tch, fwd, bck )
int tch, fwd[], bck[];
{
/* if until now the character has been a proper subset of
* an equivalence class, break it away to create a new ec
*/
if ( fwd[tch] != NIL )
bck[fwd[tch]] = bck[tch];
if ( bck[tch] != NIL )
fwd[bck[tch]] = fwd[tch];
fwd[tch] = NIL;
bck[tch] = NIL;
}
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