src/newstr.c

   1 /*
   2  * Copyright 1993, 1995 Christopher Seiwald.
   3  * This file is part of Jam - see jam.c for Copyright information.
   4  *
   5  * This program is free software: you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation, version 3 of the License ONLY.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17 /*
  18  * newstr.c - string manipulation routines
  19  *
  20  * To minimize string copying, string creation, copying, and freeing
  21  * is done through newstr.
  22  *
  23  * External functions:
  24  *
  25  *    newstr() - return a malloc'ed copy of a string
  26  *    copystr() - return a copy of a string previously returned by newstr()
  27  *    freestr() - free a string returned by newstr() or copystr()
  28  *    donestr() - free string tables
  29  *
  30  * Once a string is passed to newstr(), the returned string is readonly.
  31  *
  32  * This implementation builds a hash table of all strings, so that multiple
  33  * calls of newstr() on the same string allocate memory for the string once.
  34  * Strings are never actually freed.
  35  */
  36 #include "jam.h"
  37 #include "newstr.h"
  38 #include "hash.h"
  39
  40
  41 typedef const char *STRING;
  42
  43 static struct hash *strhash = 0;
  44 static int strtotal = 0;
  45
  46
  47 /*
  48  * newstr() - return a malloc'ed copy of a string
  49  */
  50 const char *newstr (const char *string) {
  51   STRING str, *s = &str;
  52   if (!strhash) strhash = hashinit(sizeof(STRING), "strings");
  53   *s = string;
  54   if (hashenter(strhash, (HASHDATA **)&s)) {
  55     int l = strlen(string);
  56     char *m = (char *)malloc(l+1);
  57     if (DEBUG_MEM) printf("newstr: allocating %d bytes\n", l+1);
  58     strtotal += l+1;
  59     memcpy(m, string, l+1);
  60     *s = m;
  61   }
  62   return *s;
  63 }
  64
  65
  66 /*
  67  * copystr() - return a copy of a string previously returned by newstr()
  68  */
  69 JAMFA_CONST const char *copystr (const char *s) {
  70   return s;
  71 }
  72
  73
  74 /*
  75  * freestr() - free a string returned by newstr() or copystr()
  76  */
  77 void freestr (const char *s) {
  78 }
  79
  80
  81 /*
  82  * donestr() - free string tables
  83  */
  84 void donestr (void) {
  85   hashdone(strhash);
  86   if (DEBUG_MEM) printf("%dK in strings\n", strtotal/1024);
  87 }