src/backend/regex/regc_cvec.c

   1 /*
   2  * Utility functions for handling cvecs
   3  * This file is #included by regcomp.c.
   4  *
   5  * Copyright (c) 1998, 1999 Henry Spencer.  All rights reserved.
   6  *
   7  * Development of this software was funded, in part, by Cray Research Inc.,
   8  * UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
   9  * Corporation, none of whom are responsible for the results.  The author
  10  * thanks all of them.
  11  *
  12  * Redistribution and use in source and binary forms -- with or without
  13  * modification -- are permitted for any purpose, provided that
  14  * redistributions in source form retain this entire copyright notice and
  15  * indicate the origin and nature of any modifications.
  16  *
  17  * I'd appreciate being given credit for this package in the documentation
  18  * of software which uses it, but that is not a requirement.
  19  *
  20  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
  21  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
  22  * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
  23  * HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  24  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  25  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  26  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  27  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  28  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  29  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  30  *
  31  * src/backend/regex/regc_cvec.c
  32  *
  33  */
  34
  35 /*
  36  * Notes:
  37  * Only (selected) functions in _this_ file should treat the chr arrays
  38  * of a cvec as non-constant.
  39  */
  40
  41 /*
  42  * newcvec - allocate a new cvec
  43  */
  44 static struct cvec *
  45 newcvec(int nchrs,                              /* to hold this many chrs... */
  46                 int nranges)                    /* ... and this many ranges */
  47 {
  48         size_t          nc = (size_t) nchrs + (size_t) nranges * 2;
  49         size_t          n = sizeof(struct cvec) + nc * sizeof(chr);
  50         struct cvec *cv = (struct cvec *) MALLOC(n);
  51
  52         if (cv == NULL)
  53                 return NULL;
  54         cv->chrspace = nchrs;
  55         cv->chrs = (chr *) (((char *) cv) + sizeof(struct cvec));
  56         cv->ranges = cv->chrs + nchrs;
  57         cv->rangespace = nranges;
  58         return clearcvec(cv);
  59 }
  60
  61 /*
  62  * clearcvec - clear a possibly-new cvec
  63  * Returns pointer as convenience.
  64  */
  65 static struct cvec *
  66 clearcvec(struct cvec *cv)
  67 {
  68         assert(cv != NULL);
  69         cv->nchrs = 0;
  70         cv->nranges = 0;
  71         cv->cclasscode = -1;
  72         return cv;
  73 }
  74
  75 /*
  76  * addchr - add a chr to a cvec
  77  */
  78 static void
  79 addchr(struct cvec *cv,                 /* character vector */
  80            chr c)                                       /* character to add */
  81 {
  82         assert(cv->nchrs < cv->chrspace);
  83         cv->chrs[cv->nchrs++] = c;
  84 }
  85
  86 /*
  87  * addrange - add a range to a cvec
  88  */
  89 static void
  90 addrange(struct cvec *cv,               /* character vector */
  91                  chr from,                              /* first character of range */
  92                  chr to)                                /* last character of range */
  93 {
  94         assert(cv->nranges < cv->rangespace);
  95         cv->ranges[cv->nranges * 2] = from;
  96         cv->ranges[cv->nranges * 2 + 1] = to;
  97         cv->nranges++;
  98 }
  99
 100 /*
 101  * getcvec - get a transient cvec, initialized to empty
 102  *
 103  * The returned cvec is valid only until the next call of getcvec, which
 104  * typically will recycle the space.  Callers should *not* free the cvec
 105  * explicitly; it will be cleaned up when the struct vars is destroyed.
 106  *
 107  * This is typically used while interpreting bracket expressions.  In that
 108  * usage the cvec is only needed momentarily until we build arcs from it,
 109  * so transientness is a convenient behavior.
 110  */
 111 static struct cvec *
 112 getcvec(struct vars *v,                 /* context */
 113                 int nchrs,                              /* to hold this many chrs... */
 114                 int nranges)                    /* ... and this many ranges */
 115 {
 116         /* recycle existing transient cvec if large enough */
 117         if (v->cv != NULL && nchrs <= v->cv->chrspace &&
 118                 nranges <= v->cv->rangespace)
 119                 return clearcvec(v->cv);
 120
 121         /* nope, make a new one */
 122         if (v->cv != NULL)
 123                 freecvec(v->cv);
 124         v->cv = newcvec(nchrs, nranges);
 125         if (v->cv == NULL)
 126                 ERR(REG_ESPACE);
 127
 128         return v->cv;
 129 }
 130
 131 /*
 132  * freecvec - free a cvec
 133  */
 134 static void
 135 freecvec(struct cvec *cv)
 136 {
 137         FREE(cv);
 138 }