[Feature] Allow to reserve elements in libucl

contrib/libucl/lua_ucl.c

@@ -355,7 +355,8 @@ ucl_object_lua_fromtable (lua_State *L, int idx, ucl_string_flags_t flags)
 			lua_pop (L, 1);
 		}
 	}
-	else if (is_array) {
+
+	if (is_array) {
 #if LUA_VERSION_NUM >= 502
 		max = lua_rawlen (L, idx);
 #else

contrib/libucl/ucl.h

@@ -462,6 +462,13 @@ UCL_EXTERN ucl_object_t* ucl_object_pop_key (ucl_object_t *top, const char *key)
 UCL_EXTERN bool ucl_object_insert_key_merged (ucl_object_t *top, ucl_object_t *elt,
 		const char *key, size_t keylen, bool copy_key);
 
+/**
+ * Reserve space in ucl array or object for `elt` elements
+ * @param obj object to reserve
+ * @param reserved size to reserve in an object
+ */
+UCL_EXTERN void ucl_object_reserve (ucl_object_t *obj, size_t reserved);
+
 /**
  * Append an element to the end of array object
  * @param top destination object (must NOT be NULL)

contrib/libucl/ucl_hash.c

@@ -395,3 +395,25 @@ ucl_hash_delete (ucl_hash_t* hashlin, const ucl_object_t *obj)
 		}
 	}
 }
+
+void ucl_hash_reserve (ucl_hash_t *hashlin, size_t sz)
+{
+	if (hashlin == NULL) {
+		return;
+	}
+
+	if (sz > hashlin->ar.m) {
+		kv_resize (const ucl_object_t *, hashlin->ar, sz);
+
+		if (hashlin->caseless) {
+			khash_t(ucl_hash_caseless_node) *h = (khash_t(
+					ucl_hash_caseless_node) *)
+					hashlin->hash;
+			kh_resize (ucl_hash_caseless_node, h, sz);
+		} else {
+			khash_t(ucl_hash_node) *h = (khash_t(ucl_hash_node) *)
+					hashlin->hash;
+			kh_resize (ucl_hash_node, h, sz);
+		}
+	}
+}

contrib/libucl/ucl_hash.h

@@ -90,4 +90,10 @@ const void* ucl_hash_iterate (ucl_hash_t *hashlin, ucl_hash_iter_t *iter);
  */
 bool ucl_hash_iter_has_next (ucl_hash_t *hashlin, ucl_hash_iter_t iter);
 
+/**
+ * Reserves space in hash
+ * @param hashlin
+ */
+void ucl_hash_reserve (ucl_hash_t *hashlin, size_t sz);
+
 #endif

contrib/libucl/ucl_util.c

@@ -2755,6 +2755,21 @@ ucl_object_new_full (ucl_type_t type, unsigned priority)
 	return new;
 }
 
+void ucl_object_reserve (ucl_object_t *obj, size_t reserved)
+{
+	if (obj->type == UCL_ARRAY) {
+		UCL_ARRAY_GET (vec, obj);
+
+		if (vec->m < reserved) {
+			/* Preallocate some space for arrays */
+			kv_resize (ucl_object_t *, *vec, reserved);
+		}
+	}
+	else if (obj->type == UCL_OBJECT) {
+		ucl_hash_reserve (obj->value.ov, reserved);
+	}
+}
+
 ucl_object_t*
 ucl_object_new_userdata (ucl_userdata_dtor dtor,
 		ucl_userdata_emitter emitter,