Quelle ecs.c Sprache: C

/* ecs - equivalence class routines */

/*  Copyright (c) 1990 The Regents of the University of California. */
/*  All rights reserved. */

/*  This code is derived from software contributed to Berkeley by */
/*  Vern Paxson. */

/*  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 file is part of flex */

/*  Redistribution and use in source and binary forms, with or without */
/*  modification, are permitted provided that the following conditions */
/*  are met: */

/*  1. Redistributions of source code must retain the above copyright */
/*     notice, this list of conditions and the following disclaimer. */
/*  2. Redistributions in binary form must reproduce the above copyright */
/*     notice, this list of conditions and the following disclaimer in the */
/*     documentation and/or other materials provided with the distribution. */

/*  Neither the name of the University nor the names of its contributors */
/*  may be used to endorse or promote products derived from this software */
/*  without specific prior written permission. */

/*  THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR */
/*  IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED */
/*  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR */
/*  PURPOSE. */

#include "flexdef.h"

/* ccl2ecl - convert character classes to set of equivalence classes */

void    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
*
* 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, NUL_mapping;
*    void mkeccl( Char ccls[], int lenccl, int fwd[llsiz], int bck[llsiz],
* int llsiz, int NUL_mapping );
*
* 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.
*
* NUL_mapping is the value which NUL (0) should be mapped to.
*/

void    mkeccl (ccls, lenccl, fwd, bck, llsiz, NUL_mapping)
     Char    ccls[];
     int     lenccl, fwd[], bck[], llsiz, NUL_mapping;
{
int     cclp, oldec, newec;
int     cclm, i, j;
static unsigned char cclflags[CSIZE]; /* initialized to all '\0' */

/* 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];

  if (NUL_mapping && cclm == 0)
   cclm = NUL_mapping;

  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; ++j) {
    int ccl_char;

    if (NUL_mapping && ccls[j] == 0)
     ccl_char = NUL_mapping;
    else
     ccl_char = ccls[j];

    if (ccl_char > i)
     break;

    if (ccl_char == i && !cclflags[j]) {
     /* 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;
     /* Set flag so we don't reprocess. */
     cclflags[j] = 1;

     /* 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; cclp < lenccl && cclflags[cclp]; ++cclp) {
   /* Reset "doesn't need processing" flag. */
   cclflags[cclp] = 0;
  }
}
}

/* mkechar - create equivalence class for single character */

void    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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