zipmap iteration code

zipmap.c

@@ -304,6 +304,37 @@ unsigned char *zipmapDel(unsigned char *zm, unsigned char *key, unsigned int kle
     return zm;
 }
 
+/* This function is used to iterate through all the zipmap elements.
+ * In the first call the first argument is the pointer to the zipmap + 1.
+ * In the next calls what zipmapNext returns is used as first argument.
+ * Example:
+ *
+ * unsigned char *i = my_zipmap+1;
+ * while((i = zipmapNext(i,&key,&klen,&value,&vlen)) != NULL) {
+ *     printf("%d bytes key at $p\n", klen, key);
+ *     printf("%d bytes value at $p\n", vlen, value);
+ * }
+ */
+unsigned char *zipmapNext(unsigned char *zm, unsigned char **key,
+            unsigned int *klen, unsigned char **value, unsigned int *vlen) {
+    while(zm[0] == ZIPMAP_EMPTY)
+        zm += zipmapDecodeLength(zm+1);
+    if (zm[0] == ZIPMAP_END) return NULL;
+    if (key) {
+        *key = zm;
+        *klen = zipmapDecodeLength(zm);
+        *key += (*klen < ZIPMAP_BIGLEN) ? 1 : sizeof(unsigned int);
+    }
+    zm += zipmapRawKeyLength(zm);
+    if (value) {
+        *value = zm+1;
+        *vlen = zipmapDecodeLength(zm);
+        *value += (*vlen < ZIPMAP_BIGLEN) ? 1 : sizeof(unsigned int);
+    }
+    zm += zipmapRawValueLength(zm);
+    return zm;
+}
+
 void zipmapRepr(unsigned char *p) {
     unsigned int l;
 
@@ -355,5 +386,15 @@ int main(void) {
     zipmapRepr(zm);
     zm = zipmapDel(zm,(unsigned char*) "new",3,NULL);
     zipmapRepr(zm);
+    printf("Iterate trought elements:\n");
+    {
+        unsigned char *i = zm+1;
+        unsigned char *key, *value;
+        unsigned int klen, vlen;
+
+        while((i = zipmapNext(i,&key,&klen,&value,&vlen)) != NULL) {
+            printf("%d:%.*s => %d:%.*s\n", klen, klen, key, vlen, vlen, value);
+        }
+    }
     return 0;
 }