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, either version 3 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18 /*
  19  * newstr.c - string manipulation routines
  20  *
  21  * To minimize string copying, string creation, copying, and freeing
  22  * is done through newstr.
  23  *
  24  * External functions:
  25  *
  26  *    newstr() - return a malloc'ed copy of a string
  27  *    copystr() - return a copy of a string previously returned by newstr()
  28  *    freestr() - free a string returned by newstr() or copystr()
  29  *    donestr() - free string tables
  30  *
  31  * Once a string is passed to newstr(), the returned string is readonly.
  32  *
  33  * This implementation builds a hash table of all strings, so that multiple
  34  * calls of newstr() on the same string allocate memory for the string once.
  35  * Strings are never actually freed.
  36  */
  37 #include "jam.h"
  38 #include "newstr.h"
  39 #include "hash.h"
  40
  41
  42 typedef const char *STRING;
  43
  44 static struct hash *strhash = 0;
  45 static int strtotal = 0;
  46
  47
  48 /*
  49  * newstr() - return a malloc'ed copy of a string
  50  */
  51 const char *newstr (const char *string) {
  52   STRING str, *s = &str;
  53   if (!strhash) strhash = hashinit(sizeof(STRING), "strings");
  54   *s = string;
  55   if (hashenter(strhash, (HASHDATA **)&s)) {
  56     int l = strlen(string);
  57     char *m = (char *)malloc(l+1);
  58     if (DEBUG_MEM) printf("newstr: allocating %d bytes\n", l+1);
  59     strtotal += l+1;
  60     memcpy(m, string, l+1);
  61     *s = m;
  62   }
  63   return *s;
  64 }
  65
  66
  67 /*
  68  * copystr() - return a copy of a string previously returned by newstr()
  69  */
  70 JAMFA_CONST const char *copystr (const char *s) {
  71   return s;
  72 }
  73
  74
  75 /*
  76  * freestr() - free a string returned by newstr() or copystr()
  77  */
  78 JAMFA_CONST void freestr (const char *s) {
  79 }
  80
  81
  82 /*
  83  * donestr() - free string tables
  84  */
  85 void donestr (void) {
  86   hashdone(strhash);
  87   if (DEBUG_MEM) printf("%dK in strings\n", strtotal/1024);
  88 }