src/newstr.c

   1 /*
   2  * Copyright 1993, 1995 Christopher Seiwald.
   3  *
   4  * This file is part of Jam - see jam.c for Copyright information.
   5  */
   6 /*
   7  * newstr.c - string manipulation routines
   8  *
   9  * To minimize string copying, string creation, copying, and freeing
  10  * is done through newstr.
  11  *
  12  * External functions:
  13  *
  14  *    newstr() - return a malloc'ed copy of a string
  15  *    copystr() - return a copy of a string previously returned by newstr()
  16  *    freestr() - free a string returned by newstr() or copystr()
  17  *    donestr() - free string tables
  18  *
  19  * Once a string is passed to newstr(), the returned string is readonly.
  20  *
  21  * This implementation builds a hash table of all strings, so that multiple
  22  * calls of newstr() on the same string allocate memory for the string once.
  23  * Strings are never actually freed.
  24  *
  25  * 11/04/02 (seiwald) - const-ing for string literals
  26  */
  27 #include "jam.h"
  28 #include "newstr.h"
  29 #include "hash.h"
  30
  31 typedef const char *STRING;
  32
  33 static struct hash *strhash = 0;
  34 static int strtotal = 0;
  35
  36
  37 /*
  38  * newstr() - return a malloc'ed copy of a string
  39  */
  40 const char *newstr (const char *string) {
  41   STRING str, *s = &str;
  42   //
  43   if (!strhash) strhash = hashinit(sizeof(STRING), "strings");
  44   *s = string;
  45   if (hashenter(strhash, (HASHDATA **)&s)) {
  46     int l = strlen(string);
  47     char *m = (char *)malloc(l+1);
  48     if (DEBUG_MEM) printf("newstr: allocating %d bytes\n", l+1);
  49     strtotal += l+1;
  50     memcpy(m, string, l+1);
  51     *s = m;
  52   }
  53   return *s;
  54 }
  55
  56
  57 /*
  58  * copystr() - return a copy of a string previously returned by newstr()
  59  */
  60 const char *copystr (const char *s) {
  61   return s;
  62 }
  63
  64
  65 /*
  66  * freestr() - free a string returned by newstr() or copystr()
  67  */
  68 void freestr (const char *s) {
  69 }
  70
  71
  72 /*
  73  * donestr() - free string tables
  74  */
  75 void donestr (void) {
  76   hashdone(strhash);
  77   if (DEBUG_MEM) printf("%dK in strings\n", strtotal/1024);
  78 }