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  * $PostgreSQL$
  32  *
  33  */
  34
  35 /*
  36  * Notes:
  37  * Only (selected) functions in _this_ file should treat chr* as non-constant.
  38  */
  39
  40 /*
  41  * newcvec - allocate a new cvec
  42  */
  43 static struct cvec *
  44 newcvec(int nchrs,                              /* to hold this many chrs... */
  45                 int nranges)                    /* ... and this many ranges */
  46 {
  47         size_t          nc = (size_t) nchrs + (size_t) nranges * 2;
  48         size_t          n = sizeof(struct cvec) + nc * sizeof(chr);
  49         struct cvec *cv = (struct cvec *) MALLOC(n);
  50
  51         if (cv == NULL)
  52                 return NULL;
  53         cv->chrspace = nchrs;
  54         cv->chrs = (chr *) (((char *) cv) + sizeof(struct cvec));
  55         cv->ranges = cv->chrs + nchrs;
  56         cv->rangespace = nranges;
  57         return clearcvec(cv);
  58 }
  59
  60 /*
  61  * clearcvec - clear a possibly-new cvec
  62  * Returns pointer as convenience.
  63  */
  64 static struct cvec *
  65 clearcvec(struct cvec * cv)
  66 {
  67         assert(cv != NULL);
  68         cv->nchrs = 0;
  69         cv->nranges = 0;
  70         return cv;
  71 }
  72
  73 /*
  74  * addchr - add a chr to a cvec
  75  */
  76 static void
  77 addchr(struct cvec * cv,                /* character vector */
  78            chr c)                                       /* character to add */
  79 {
  80         cv->chrs[cv->nchrs++] = (chr) c;
  81 }
  82
  83 /*
  84  * addrange - add a range to a cvec
  85  */
  86 static void
  87 addrange(struct cvec * cv,              /* character vector */
  88                  chr from,                              /* first character of range */
  89                  chr to)                                /* last character of range */
  90 {
  91         assert(cv->nranges < cv->rangespace);
  92         cv->ranges[cv->nranges * 2] = (chr) from;
  93         cv->ranges[cv->nranges * 2 + 1] = (chr) to;
  94         cv->nranges++;
  95 }
  96
  97 /*
  98  * getcvec - get a cvec, remembering it as v->cv
  99  */
 100 static struct cvec *
 101 getcvec(struct vars * v,                /* context */
 102                 int nchrs,                              /* to hold this many chrs... */
 103                 int nranges)                    /* ... and this many ranges */
 104 {
 105         if (v->cv != NULL && nchrs <= v->cv->chrspace &&
 106                 nranges <= v->cv->rangespace)
 107                 return clearcvec(v->cv);
 108
 109         if (v->cv != NULL)
 110                 freecvec(v->cv);
 111         v->cv = newcvec(nchrs, nranges);
 112         if (v->cv == NULL)
 113                 ERR(REG_ESPACE);
 114
 115         return v->cv;
 116 }
 117
 118 /*
 119  * freecvec - free a cvec
 120  */
 121 static void
 122 freecvec(struct cvec * cv)
 123 {
 124         FREE(cv);
 125 }