text: /*
   * Utility functions for handling cvecs
   * This file is #included by regcomp.c.
   *
   * Copyright (c) 1998, 1999 Henry Spencer.  All rights reserved.
   *
   * Development of this software was funded, in part, by Cray Research Inc.,
   * UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
   * Corporation, none of whom are responsible for the results.  The author
   * thanks all of them.
   *
   * Redistribution and use in source and binary forms -- with or without
   * modification -- are permitted for any purpose, provided that
   * redistributions in source form retain this entire copyright notice and
   * indicate the origin and nature of any modifications.
   *
   * I'd appreciate being given credit for this package in the documentation
   * of software which uses it, but that is not a requirement.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
   * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
   * HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
   * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
   * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
   * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * src/backend/regex/regc_cvec.c
   *
   */
  
  /*
   * Notes:
   * Only (selected) functions in _this_ file should treat the chr arrays
   * of a cvec as non-constant.
   */
  
  /*
   * newcvec - allocate a new cvec
   */
  static struct cvec *
  newcvec(int nchrs,				/* to hold this many chrs... */
  		int nranges)			/* ... and this many ranges */
  {
  	size_t		nc = (size_t) nchrs + (size_t) nranges * 2;
  	size_t		n = sizeof(struct cvec) + nc * sizeof(chr);
  	struct cvec *cv = (struct cvec *) MALLOC(n);
  
  	if (cv == NULL)
  		return NULL;
  	cv->chrspace = nchrs;
  	cv->chrs = (chr *) (((char *) cv) + sizeof(struct cvec));
  	cv->ranges = cv->chrs + nchrs;
  	cv->rangespace = nranges;
  	return clearcvec(cv);
  }
  
  /*
   * clearcvec - clear a possibly-new cvec
   * Returns pointer as convenience.
   */
  static struct cvec *
  clearcvec(struct cvec *cv)
  {
  	assert(cv != NULL);
  	cv->nchrs = 0;
  	cv->nranges = 0;
  	cv->cclasscode = -1;
  	return cv;
  }
  
  /*
   * addchr - add a chr to a cvec
   */
  static void
  addchr(struct cvec *cv,			/* character vector */
  	   chr c)					/* character to add */
  {
  	assert(cv->nchrs < cv->chrspace);
  	cv->chrs[cv->nchrs++] = c;
  }
  
  /*
   * addrange - add a range to a cvec
   */
  static void
  addrange(struct cvec *cv,		/* character vector */
  		 chr from,				/* first character of range */
  		 chr to)				/* last character of range */
  {
  	assert(cv->nranges < cv->rangespace);
  	cv->ranges[cv->nranges * 2] = from;
  	cv->ranges[cv->nranges * 2 + 1] = to;
  	cv->nranges++;
  }
  
  /*
   * getcvec - get a transient cvec, initialized to empty
   *
   * The returned cvec is valid only until the next call of getcvec, which
   * typically will recycle the space.  Callers should *not* free the cvec
   * explicitly; it will be cleaned up when the struct vars is destroyed.
   *
   * This is typically used while interpreting bracket expressions.  In that
   * usage the cvec is only needed momentarily until we build arcs from it,
   * so transientness is a convenient behavior.
   */
  static struct cvec *
  getcvec(struct vars *v,			/* context */
  		int nchrs,				/* to hold this many chrs... */
  		int nranges)			/* ... and this many ranges */
  {
  	/* recycle existing transient cvec if large enough */
  	if (v->cv != NULL && nchrs <= v->cv->chrspace &&
  		nranges <= v->cv->rangespace)
  		return clearcvec(v->cv);
  
  	/* nope, make a new one */
  	if (v->cv != NULL)
  		freecvec(v->cv);
  	v->cv = newcvec(nchrs, nranges);
  	if (v->cv == NULL)
  		ERR(REG_ESPACE);
  
  	return v->cv;
  }
  
  /*
   * freecvec - free a cvec
   */
  static void
  freecvec(struct cvec *cv)
  {
  	FREE(cv);
  }
  