stb_ds: Allow STBDS_REALLOC and STBDS_FREE defines to customize memory management.

stb_ds.h

@@ -41,6 +41,15 @@ COMPILE-TIME OPTIONS
      hash table insertion about 20% slower on 4- and 8-byte keys, 5% slower on
      64-byte keys, and 10% slower on 256-byte keys on my test computer.
 
+  #define STBDS_REALLOC better_realloc
+  #define STBDS_FREE better_free
+
+     These defines need to be set globally.
+
+     By default stb_ds uses stdlib realloc() and free() for memory management. You can
+     substitute your own functions (with the same signatures) instead by defining these
+     symbols. You must either define both, or neither.
+
 LICENSE
 
   Placed in the public domain and also MIT licensed.
@@ -321,7 +330,6 @@ CREDITS
 #ifndef INCLUDE_STB_DS_H
 #define INCLUDE_STB_DS_H
 
-#include <stdlib.h>
 #include <stddef.h>
 #include <string.h>
 
@@ -374,6 +382,16 @@ CREDITS
 #define stralloc    stbds_stralloc
 #define strreset    stbds_strreset
 #endif      
+
+#if defined(STBDS_REALLOC) && !defined(STBDS_FREE) || !defined(STBDS_REALLOC) && defined(STBDS_FREE)
+#error "You must define both STBDS_REALLOC and STBDS_FREE, or neither."
+#endif
+#if !defined(STBDS_REALLOC) && !defined(STBDS_FREE)
+#include <stdlib.h>
+#define STBDS_REALLOC realloc
+#define STBDS_FREE free
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -449,7 +467,7 @@ extern void * stbds_shmode_func(size_t elemsize, int mode);
 #define stbds_arrpop(a)       (stbds_header(a)->length--, (a)[stbds_header(a)->length])
 #define stbds_arraddn(a,n)    (stbds_arrmaybegrow(a,n), stbds_header(a)->length += (n))
 #define stbds_arrlast(a)      ((a)[stbds_header(a)->length-1])
-#define stbds_arrfree(a)      ((void) ((a) ? free(stbds_header(a)) : (void)0), (a)=NULL)
+#define stbds_arrfree(a)      ((void) ((a) ? STBDS_FREE(stbds_header(a)) : (void)0), (a)=NULL)
 #define stbds_arrdel(a,i)     stbds_arrdeln(a,i,1)
 #define stbds_arrdeln(a,i,n)  (memmove(&(a)[i], &(a)[(i)+(n)], sizeof *(a) * (stbds_header(a)->length-(n)-(i))), stbds_header(a)->length -= (n))
 #define stbds_arrdelswap(a,i) ((a)[i] = stbds_arrlast(a), stbds_header(a)->length -= 1)
@@ -645,7 +663,7 @@ void *stbds_arrgrowf(void *a, size_t elemsize, size_t addlen, size_t min_cap)
   else if (min_cap < 4)
     min_cap = 4;
 
-  b = realloc((a) ? stbds_header(a) : 0, elemsize * min_cap + sizeof(stbds_array_header));
+  b = STBDS_REALLOC((a) ? stbds_header(a) : 0, elemsize * min_cap + sizeof(stbds_array_header));
   b = (char *) b + sizeof(stbds_array_header);
   if (a == NULL) {
     stbds_header(b)->length = 0;
@@ -737,7 +755,7 @@ static size_t stbds_log2(size_t slot_count)
 static stbds_hash_index *stbds_make_hash_index(size_t slot_count, stbds_hash_index *ot)
 {
   stbds_hash_index *t;
-  t = (stbds_hash_index *) realloc(0,(slot_count >> STBDS_BUCKET_SHIFT) * sizeof(stbds_hash_bucket) + sizeof(stbds_hash_index) + STBDS_CACHE_LINE_SIZE-1);
+  t = (stbds_hash_index *) STBDS_REALLOC(0,(slot_count >> STBDS_BUCKET_SHIFT) * sizeof(stbds_hash_bucket) + sizeof(stbds_hash_index) + STBDS_CACHE_LINE_SIZE-1);
   t->storage = (stbds_hash_bucket *) STBDS_ALIGN_FWD((size_t) (t+1), STBDS_CACHE_LINE_SIZE);
   t->slot_count = slot_count;
   t->slot_count_log2 = stbds_log2(slot_count);
@@ -1053,7 +1071,6 @@ static int stbds_is_key_equal(void *a, size_t elemsize, void *key, size_t keysiz
 
 #define STBDS_HASH_TO_ARR(x,elemsize) ((char*) (x) - (elemsize))
 #define STBDS_ARR_TO_HASH(x,elemsize) ((char*) (x) + (elemsize))
-#define STBDS_FREE(x)  free(x)
 
 #define stbds_hash_table(a)  ((stbds_hash_index *) stbds_header(a)->hash_table)
  
@@ -1374,7 +1391,7 @@ static char *stbds_strdup(char *str)
   // to keep replaceable allocator simple, we don't want to use strdup.
   // rolling our own also avoids problem of strdup vs _strdup
   size_t len = strlen(str)+1;
-  char *p = (char*) realloc(0, len);
+  char *p = (char*) STBDS_REALLOC(0, len);
   memmove(p, str, len);
   return p;
 }
@@ -1407,7 +1424,7 @@ char *stbds_stralloc(stbds_string_arena *a, char *str)
       // note that we still advance string_block so block size will continue
       // increasing, so e.g. if somebody only calls this with 1000-long strings,
       // eventually the arena will start doubling and handling those as well
-      stbds_string_block *sb = (stbds_string_block *) realloc(0, sizeof(*sb)-8 + len);
+      stbds_string_block *sb = (stbds_string_block *) STBDS_REALLOC(0, sizeof(*sb)-8 + len);
       memmove(sb->storage, str, len);
       if (a->storage) {
         // insert it after the first element, so that we don't waste the space there
@@ -1420,7 +1437,7 @@ char *stbds_stralloc(stbds_string_arena *a, char *str)
       }
       return sb->storage;
     } else {
-      stbds_string_block *sb = (stbds_string_block *) realloc(0, sizeof(*sb)-8 + blocksize);
+      stbds_string_block *sb = (stbds_string_block *) STBDS_REALLOC(0, sizeof(*sb)-8 + blocksize);
       sb->next = a->storage;
       a->storage = sb;
       a->remaining = blocksize;
@@ -1440,7 +1457,7 @@ void stbds_strreset(stbds_string_arena *a)
   x = a->storage;
   while (x) {
     y = x->next;
-    free(x);
+    STBDS_FREE(x);
     x = y;
   }
   memset(a, 0, sizeof(*a));