Implement @@toStringTag well-known symbol related features (#2739)

JerryScript-DCO-1.0-Signed-off-by: Robert Fancsik frobert@inf.u-szeged.hu

jerry-core/ecma/builtin-objects/ecma-builtin-arraybuffer-prototype.inc.h

@@ -33,6 +33,13 @@ ACCESSOR_READ_ONLY (LIT_MAGIC_STRING_BYTE_LENGTH_UL,
                     ecma_builtin_arraybuffer_prototype_bytelength_getter,
                     ECMA_PROPERTY_FIXED)
 
+#ifndef CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN
+/* ECMA-262 v6, 24.1.4.4 */
+STRING_VALUE (LIT_GLOBAL_SYMBOL_TO_STRING_TAG,
+              LIT_MAGIC_STRING_ARRAY_BUFFER_UL,
+              ECMA_PROPERTY_FLAG_CONFIGURABLE)
+#endif /* !CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN */
+
 /* Routine properties:
  *  (property name, C routine name, arguments number or NON_FIXED, value of the routine's length property) */
 ROUTINE (LIT_MAGIC_STRING_SLICE, ecma_builtin_arraybuffer_prototype_object_slice, 2, 2)

jerry-core/ecma/builtin-objects/ecma-builtin-helpers.c

@@ -21,7 +21,9 @@
 #include "ecma-conversion.h"
 #include "ecma-function-object.h"
 #include "ecma-exceptions.h"
+#include "ecma-gc.h"
 #include "ecma-helpers.h"
+#include "jmem.h"
 #include "ecma-objects.h"
 #include "ecma-try-catch-macro.h"
 #include "lit-magic-strings.h"
@@ -33,6 +35,69 @@
  * @{
  */
 
+#ifndef CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN
+/**
+ * Helper function for Object.prototype.toString routine when
+ * the @@toStringTag property is present
+ *
+ * See also:
+ *          ECMA-262 v6, 19.1.3.6
+ *
+ * @return ecma value
+ *         Returned value must be freed with ecma_free_value.
+ */
+static ecma_value_t
+ecma_builtin_helper_object_to_string_tag_helper (ecma_value_t tag_value) /**< string tag */
+{
+  JERRY_ASSERT (ecma_is_value_string (tag_value));
+
+  ecma_string_t *tag_str_p = ecma_get_string_from_value (tag_value);
+  ecma_string_t *ret_string_p;
+
+  /* Building string "[object #@@toStringTag#]"
+     The string size will be size("[object ") + size(#@@toStringTag#) + size ("]"). */
+  const lit_utf8_size_t buffer_size = 9 + ecma_string_get_size (tag_str_p);
+  JMEM_DEFINE_LOCAL_ARRAY (str_buffer, buffer_size, lit_utf8_byte_t);
+
+  lit_utf8_byte_t *buffer_ptr = str_buffer;
+
+  const lit_magic_string_id_t magic_string_ids[] =
+  {
+    LIT_MAGIC_STRING_LEFT_SQUARE_CHAR,
+    LIT_MAGIC_STRING_OBJECT,
+    LIT_MAGIC_STRING_SPACE_CHAR,
+  };
+
+  /* Copy to buffer the "[object " string */
+  for (uint32_t i = 0; i < sizeof (magic_string_ids) / sizeof (lit_magic_string_id_t); ++i)
+  {
+    buffer_ptr = lit_copy_magic_string_to_buffer (magic_string_ids[i], buffer_ptr,
+                                                  (lit_utf8_size_t) ((str_buffer + buffer_size) - buffer_ptr));
+
+    JERRY_ASSERT (buffer_ptr <= str_buffer + buffer_size);
+  }
+
+  /* Copy to buffer the #@@toStringTag# string */
+  buffer_ptr += ecma_string_copy_to_utf8_buffer (tag_str_p, buffer_ptr,
+                                                 (lit_utf8_size_t) ((str_buffer + buffer_size) - buffer_ptr));
+
+  JERRY_ASSERT (buffer_ptr <= str_buffer + buffer_size);
+
+  /* Copy to buffer the "]" string */
+  buffer_ptr = lit_copy_magic_string_to_buffer (LIT_MAGIC_STRING_RIGHT_SQUARE_CHAR, buffer_ptr,
+                                                (lit_utf8_size_t) ((str_buffer + buffer_size) - buffer_ptr));
+
+  JERRY_ASSERT (buffer_ptr <= str_buffer + buffer_size);
+
+  ret_string_p = ecma_new_ecma_string_from_utf8 (str_buffer, (lit_utf8_size_t) (buffer_ptr - str_buffer));
+
+  JMEM_FINALIZE_LOCAL_ARRAY (str_buffer);
+  ecma_deref_ecma_string (tag_str_p);
+
+  return ecma_make_string_value (ret_string_p);
+} /* ecma_builtin_helper_object_to_string_tag_helper */
+#endif /* !CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN */
+
 /**
  * Common implementation of the Object.prototype.toString routine
  *
@@ -75,7 +140,25 @@ ecma_builtin_helper_object_to_string (const ecma_value_t this_arg) /**< this arg
 
     type_string = ecma_object_get_class_name (obj_p);
 
-    ecma_free_value (obj_this);
+#ifndef CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN
+    ecma_value_t tag_value = ecma_op_object_get_by_symbol_id (obj_p, LIT_MAGIC_STRING_TO_STRING_TAG);
+
+    if (ECMA_IS_VALUE_ERROR (tag_value))
+    {
+      ecma_deref_object (obj_p);
+      return tag_value;
+    }
+
+    if (ecma_is_value_string (tag_value))
+    {
+      ecma_deref_object (obj_p);
+      return ecma_builtin_helper_object_to_string_tag_helper (tag_value);
+    }
+
+    ecma_free_value (tag_value);
+#endif /* !CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN */
+
+    ecma_deref_object (obj_p);
   }
 
   ecma_string_t *ret_string_p;

jerry-core/ecma/builtin-objects/ecma-builtin-json.inc.h

@@ -21,6 +21,13 @@
 
 #ifndef CONFIG_DISABLE_JSON_BUILTIN
 
+#ifndef CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN
+/* ECMA-262 v6, 24.3.3 */
+STRING_VALUE (LIT_GLOBAL_SYMBOL_TO_STRING_TAG,
+              LIT_MAGIC_STRING_JSON_U,
+              ECMA_PROPERTY_FLAG_CONFIGURABLE)
+#endif /* !CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN */
+
 /* Routine properties:
  *  (property name, C routine name, arguments number or NON_FIXED, value of the routine's length property) */
 ROUTINE (LIT_MAGIC_STRING_PARSE, ecma_builtin_json_parse, 2, 2)

jerry-core/ecma/builtin-objects/ecma-builtin-map-prototype.inc.h

@@ -29,6 +29,13 @@ OBJECT_VALUE (LIT_MAGIC_STRING_CONSTRUCTOR,
               ECMA_BUILTIN_ID_MAP,
               ECMA_PROPERTY_CONFIGURABLE_WRITABLE)
 
+#ifndef CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN
+/* ECMA-262 v6, 23.1.3.13 */
+STRING_VALUE (LIT_GLOBAL_SYMBOL_TO_STRING_TAG,
+              LIT_MAGIC_STRING_MAP_UL,
+              ECMA_PROPERTY_FLAG_CONFIGURABLE)
+#endif /* !CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN */
+
 /* Routine properties:
  *  (property name, C routine name, arguments number or NON_FIXED, value of the routine's length property) */
 ROUTINE (LIT_MAGIC_STRING_CLEAR, ecma_builtin_map_prototype_object_clear, 0, 0)

jerry-core/ecma/builtin-objects/ecma-builtin-math.inc.h

@@ -64,6 +64,13 @@ NUMBER_VALUE (LIT_MAGIC_STRING_SQRT2_U,
               ECMA_BUILTIN_NUMBER_SQRT2,
               ECMA_PROPERTY_FIXED)
 
+#ifndef CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN
+/* ECMA-262 v6, 20.2.1.9 */
+STRING_VALUE (LIT_GLOBAL_SYMBOL_TO_STRING_TAG,
+              LIT_MAGIC_STRING_MATH_UL,
+              ECMA_PROPERTY_FLAG_CONFIGURABLE)
+#endif /* !CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN */
+
 /* Routine properties:
  *  (property name, C routine name, arguments number or NON_FIXED, value of the routine's length property) */
 ROUTINE (LIT_MAGIC_STRING_ABS, ECMA_MATH_OBJECT_ABS, 1, 1)

jerry-core/ecma/builtin-objects/ecma-builtin-promise-prototype.inc.h

@@ -28,6 +28,13 @@ NUMBER_VALUE (LIT_MAGIC_STRING_LENGTH,
               1,
               ECMA_PROPERTY_FLAG_WRITABLE)
 
+#ifndef CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN
+/* ECMA-262 v6, 25.4.5.4 */
+STRING_VALUE (LIT_GLOBAL_SYMBOL_TO_STRING_TAG,
+              LIT_MAGIC_STRING_PROMISE_UL,
+              ECMA_PROPERTY_FLAG_CONFIGURABLE)
+#endif /* !CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN */
+
 ROUTINE (LIT_MAGIC_STRING_THEN, ecma_builtin_promise_prototype_then, 2, 2)
 ROUTINE (LIT_MAGIC_STRING_CATCH, ecma_builtin_promise_prototype_catch, 1, 1)
 

jerry-core/ecma/builtin-objects/typedarray/ecma-builtin-typedarray-prototype.c

@@ -140,6 +140,28 @@ ecma_builtin_typedarray_prototype_length_getter (ecma_value_t this_arg) /**< thi
   return ecma_raise_type_error (ECMA_ERR_MSG ("Argument 'this' is not a TypedArray."));
 } /* ecma_builtin_typedarray_prototype_length_getter */
 
+#ifndef CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN
+/**
+ * The %TypedArray%.prototype[Symbol.toStringTag] accessor
+ *
+ * See also:
+ *          ES2015, 22.2.3.31
+ *
+ * @return ecma value
+ *         Returned value must be freed with ecma_free_value.
+ */
+static ecma_value_t
+ecma_builtin_typedarray_prototype_to_string_tag_getter (ecma_value_t this_arg) /**< this argument */
+{
+  if (!ecma_is_typedarray (this_arg))
+  {
+    return ECMA_VALUE_UNDEFINED;
+  }
+
+  return ecma_make_magic_string_value (ecma_object_get_class_name (ecma_get_object_from_value (this_arg)));
+} /* ecma_builtin_typedarray_prototype_to_string_tag_getter */
+#endif /* !CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN */
+
 /**
  * Type of routine.
  */

jerry-core/ecma/builtin-objects/typedarray/ecma-builtin-typedarray-prototype.inc.h

@@ -45,6 +45,13 @@ ACCESSOR_READ_ONLY (LIT_MAGIC_STRING_LENGTH,
                     ecma_builtin_typedarray_prototype_length_getter,
                     ECMA_PROPERTY_FIXED)
 
+#ifndef CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN
+/* ECMA-262 v6, 23.1.3.13 */
+ACCESSOR_READ_ONLY (LIT_GLOBAL_SYMBOL_TO_STRING_TAG,
+                    ecma_builtin_typedarray_prototype_to_string_tag_getter,
+                    ECMA_PROPERTY_FLAG_CONFIGURABLE)
+#endif /* !CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN */
+
 /* Routine properties:
  *  (property name, C routine name, arguments number or NON_FIXED, value of the routine's length property) */
 ROUTINE (LIT_MAGIC_STRING_TO_STRING_UL, ecma_builtin_typedarray_prototype_object_to_string, 0, 0)

jerry-core/ecma/operations/ecma-objects.c

@@ -734,6 +734,30 @@ ecma_op_object_get_by_magic_id (ecma_object_t *object_p, /**< the object */
   return ecma_op_object_get (object_p, ecma_get_magic_string (property_id));
 } /* ecma_op_object_get_by_magic_id */
 
+#ifndef CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN
+/**
+ * [[Get]] operation of ecma object where the property is a well-known symbol
+ *
+ * @return ecma value
+ *         Returned value must be freed with ecma_free_value
+ */
+ecma_value_t
+ecma_op_object_get_by_symbol_id (ecma_object_t *object_p, /**< the object */
+                                 lit_magic_string_id_t property_id) /**< property symbol id */
+{
+  ecma_value_t symbol_value = ecma_op_object_get_by_magic_id (ecma_builtin_get (ECMA_BUILTIN_ID_SYMBOL),
+                                                              property_id);
+  JERRY_ASSERT (ecma_is_value_symbol (symbol_value));
+
+  ecma_string_t *symbol_p = ecma_get_symbol_from_value (symbol_value);
+  ecma_value_t ret_value = ecma_op_object_get (object_p, symbol_p);
+
+  ecma_deref_ecma_string (symbol_p);
+
+  return ret_value;
+} /* ecma_op_object_get_by_symbol_id */
+#endif /* !CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN */
+
 /**
  * [[Put]] ecma general object's operation
  *

jerry-core/ecma/operations/ecma-objects.h

@@ -35,6 +35,9 @@ ecma_value_t ecma_op_object_find (ecma_object_t *object_p, ecma_string_t *proper
 ecma_value_t ecma_op_object_get_own_data_prop (ecma_object_t *object_p, ecma_string_t *property_name_p);
 ecma_value_t ecma_op_object_get (ecma_object_t *object_p, ecma_string_t *property_name_p);
 ecma_value_t ecma_op_object_get_by_magic_id (ecma_object_t *object_p, lit_magic_string_id_t property_id);
+#ifndef CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN
+ecma_value_t ecma_op_object_get_by_symbol_id (ecma_object_t *object_p, lit_magic_string_id_t property_id);
+#endif /* CONFIG_DISABLE_ES2015_SYMBOL_BUILTIN */
 ecma_value_t ecma_op_object_put (ecma_object_t *object_p, ecma_string_t *property_name_p, ecma_value_t value,
                                  bool is_throw);
 ecma_value_t ecma_op_object_delete (ecma_object_t *obj_p, ecma_string_t *property_name_p, bool is_throw);

tests/jerry/es2015/object-prototype-tostring.js

@@ -0,0 +1,102 @@
+// Copyright JS Foundation and other contributors, http://js.foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/* Symbol prototype @@toStringTag */
+assert (Symbol.prototype[Symbol.toStringTag] === "Symbol");
+assert (Object.prototype.toString.call (Symbol ()) === "[object Symbol]");
+
+assert (delete Symbol.prototype[Symbol.toStringTag]);
+assert (Symbol.prototype[Symbol.toStringTag] === undefined);
+Symbol.prototype[Symbol.toStringTag] = "myStringTag1";
+assert (Object.prototype.toString.call (Symbol ()) === "[object myStringTag1]");
+Symbol.prototype[Symbol.toStringTag] = {};
+assert (Object.prototype.toString.call (Symbol ()) === "[object Symbol]");
+
+/* Math @@toStringTag */
+assert (Math[Symbol.toStringTag] === "Math");
+assert (Object.prototype.toString.call (Math) === "[object Math]");
+
+assert (delete Math[Symbol.toStringTag]);
+assert (Math[Symbol.toStringTag] === undefined);
+Math[Symbol.toStringTag] = "myStringTag2";
+assert (Object.prototype.toString.call (Math) === "[object myStringTag2]");
+Math[Symbol.toStringTag] = {};
+assert (Object.prototype.toString.call (Math) === "[object Math]");
+
+/* ArrayBuffer.prototype @@toStringTag */
+assert (ArrayBuffer.prototype[Symbol.toStringTag] === "ArrayBuffer");
+assert (Object.prototype.toString.call (new ArrayBuffer ()) === "[object ArrayBuffer]");
+
+assert (delete ArrayBuffer.prototype[Symbol.toStringTag]);
+assert (ArrayBuffer.prototype[Symbol.toStringTag] === undefined);
+ArrayBuffer.prototype[Symbol.toStringTag] = "myStringTag3";
+assert (Object.prototype.toString.call (new ArrayBuffer ()) === "[object myStringTag3]");
+ArrayBuffer.prototype[Symbol.toStringTag] = {};
+assert (ArrayBuffer.prototype.toString.call (new ArrayBuffer ()) === "[object ArrayBuffer]");
+
+/* Promise.prototype @@toStringTag */
+assert (Promise.prototype[Symbol.toStringTag] === "Promise");
+assert (Object.prototype.toString.call (new Promise (function () {})) === "[object Promise]");
+
+assert (delete Promise.prototype[Symbol.toStringTag]);
+assert (Promise.prototype[Symbol.toStringTag] === undefined);
+Promise.prototype[Symbol.toStringTag] = "myStringTag4";
+assert (Object.prototype.toString.call (new Promise (function () {})) === "[object myStringTag4]");
+Promise.prototype[Symbol.toStringTag] = {};
+assert (Promise.prototype.toString.call (new Promise (function () {})) === "[object Promise]");
+
+/* Map.prototype @@toStringTag */
+assert (Map.prototype[Symbol.toStringTag] === "Map");
+assert (Object.prototype.toString.call (new Map ()) === "[object Map]");
+assert (Object.prototype.toString.call (Map) === "[object Function]");
+
+assert (delete Map.prototype[Symbol.toStringTag]);
+assert (Map.prototype[Symbol.toStringTag] === undefined);
+Map.prototype[Symbol.toStringTag] = "myStringTag5";
+assert (Map.prototype.toString.call (new Map ()) === "[object myStringTag5]");
+assert (Object.prototype.toString.call (Map) === "[object Function]");
+Map.prototype[Symbol.toStringTag] = {};
+assert (Map.prototype.toString.call (new Map) === "[object Map]");
+
+/* JSON @@toStringTag */
+assert (JSON[Symbol.toStringTag] === "JSON");
+assert (Object.prototype.toString.call (JSON) === "[object JSON]");
+
+assert (delete JSON[Symbol.toStringTag]);
+assert (JSON[Symbol.toStringTag] === undefined);
+JSON[Symbol.toStringTag] = "myStringTag6";
+assert (Map.prototype.toString.call (JSON) === "[object myStringTag6]");
+JSON[Symbol.toStringTag] = {};
+assert (Object.prototype.toString.call (JSON) === "[object JSON]");
+
+var typedArrayTypes = ["Int8Array",
+                       "Uint8Array",
+                       "Uint8ClampedArray",
+                       "Int16Array",
+                       "Uint16Array",
+                       "Int32Array",
+                       "Uint32Array",
+                       "Float32Array",
+                       "Float64Array"];
+
+for (var i = 0; i < typedArrayTypes.length; i++) {
+  var typedArray = this[typedArrayTypes[i]];
+  assert (typedArray.prototype[Symbol.toStringTag] === undefined);
+  assert (Object.prototype.toString.call (typedArray) === "[object Function]");
+  assert (Object.prototype.toString.call (typedArray.prototype) === "[object Object]");
+
+  var newArray = new typedArray ();
+  assert (newArray[Symbol.toStringTag] === typedArrayTypes[i]);
+  assert (Object.prototype.toString.call (newArray) === "[object " + typedArrayTypes[i] + "]");
+}