Implement Symbol.prototype.description (#3995)

The algorithm is based on ECMA-262 v11, 19.4.3.2

Also added a custom dispatcher for the Symbol prototype

JerryScript-DCO-1.0-Signed-off-by: Adam Szilagyi aszilagy@inf.u-szeged.hu

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

@@ -30,6 +30,23 @@
 #define ECMA_BUILTINS_INTERNAL
 #include "ecma-builtins-internal.h"
 
+/**
+ * This object has a custom dispatch function.
+ */
+#define BUILTIN_CUSTOM_DISPATCH
+
+/**
+ * List of built-in routine identifiers.
+ */
+enum
+{
+  ECMA_SYMBOL_PROTOTYPE_ROUTINE_START = ECMA_BUILTIN_ID__COUNT - 1,
+  ECMA_SYMBOL_PROTOTYPE_VALUE_OF, /**< ECMA-262 v11, 19.4.3.4 */
+  ECMA_SYMBOL_PROTOTYPE_TO_PRIMITIVE, /**< ECMA-262 v11, 19.4.3.5 */
+  ECMA_SYMBOL_PROTOTYPE_TO_STRING, /**< ECMA-262 v11, 19.4.3.3 */
+  ECMA_SYMBOL_PROTOTYPE_DESCRIPTION, /**< ECMA-262 v11, 19.4.3.2 */
+};
+
 #define BUILTIN_INC_HEADER_NAME "ecma-builtin-symbol-prototype.inc.h"
 #define BUILTIN_UNDERSCORED_ID symbol_prototype
 #include "ecma-builtin-internal-routines-template.inc.h"
@@ -45,49 +62,45 @@
  */
 
 /**
- * The Symbol.prototype object's 'toString' routine
- *
- * See also:
- *          ECMA-262 v6, 19.4.3.2
+ * Dispatcher of the Symbol built-in's routines
  *
  * @return ecma value
  *         Returned value must be freed with ecma_free_value.
  */
-static ecma_value_t
-ecma_builtin_symbol_prototype_object_to_string (ecma_value_t this_arg) /**< this argument */
+ecma_value_t
+ecma_builtin_symbol_prototype_dispatch_routine (uint16_t builtin_routine_id, /**< built-in wide routine
+                                                                     *   identifier */
+                                                ecma_value_t this_arg, /**< 'this' argument value */
+                                                const ecma_value_t arguments_list[], /**< list of arguments
+                                                                             *   passed to routine */
+                                                ecma_length_t arguments_number) /**< length of arguments' list */
 {
-  return ecma_symbol_to_string_helper (this_arg, true);
-} /* ecma_builtin_symbol_prototype_object_to_string */
+  JERRY_UNUSED_2 (arguments_list, arguments_number);
 
-/**
- * The Symbol.prototype object's 'valueOf' routine
- *
- * See also:
- *          ECMA-262 v6, 19.4.3.3
- *
- * @return ecma value
- *         Returned value must be freed with ecma_free_value.
- */
-static ecma_value_t
-ecma_builtin_symbol_prototype_object_value_of (ecma_value_t this_arg) /**< this argument */
-{
-  return ecma_symbol_to_string_helper (this_arg, false);
-} /* ecma_builtin_symbol_prototype_object_value_of */
+  ecma_value_t sym = ecma_symbol_this_value (this_arg);
 
-/**
- * The Symbol.prototype object's '@@toPrimitive' routine
- *
- * See also:
- *          ECMA-262 v6, 19.4.3.3
- *
- * @return ecma value
- *         Returned value must be freed with ecma_free_value.
- */
-static ecma_value_t
-ecma_builtin_symbol_prototype_object_to_primitive (ecma_value_t this_arg) /**< this argument */
-{
-  return ecma_builtin_symbol_prototype_object_value_of (this_arg);
-} /* ecma_builtin_symbol_prototype_object_to_primitive */
+  if (ECMA_IS_VALUE_ERROR (sym))
+  {
+    return sym;
+  }
+
+  if (builtin_routine_id < ECMA_SYMBOL_PROTOTYPE_TO_STRING)
+  {
+    return ecma_copy_value (sym);
+  }
+
+  if (builtin_routine_id == ECMA_SYMBOL_PROTOTYPE_TO_STRING)
+  {
+    return ecma_get_symbol_descriptive_string (sym);
+  }
+
+  JERRY_ASSERT (builtin_routine_id == ECMA_SYMBOL_PROTOTYPE_DESCRIPTION);
+  ecma_string_t *symbol_p = ecma_get_symbol_from_value (sym);
+  ecma_string_t *desc_p = ecma_get_symbol_description (symbol_p);
+  ecma_ref_ecma_string (desc_p);
+
+  return ecma_make_string_value (desc_p);
+} /* ecma_builtin_symbol_prototype_dispatch_routine */
 
 /**
  * @}

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

@@ -28,10 +28,10 @@ OBJECT_VALUE (LIT_MAGIC_STRING_CONSTRUCTOR,
               ECMA_BUILTIN_ID_SYMBOL,
               ECMA_PROPERTY_CONFIGURABLE_WRITABLE)
 
-ROUTINE (LIT_MAGIC_STRING_TO_STRING_UL, ecma_builtin_symbol_prototype_object_to_string, 0, 0)
-ROUTINE (LIT_MAGIC_STRING_VALUE_OF_UL, ecma_builtin_symbol_prototype_object_value_of, 0, 0)
+ROUTINE (LIT_MAGIC_STRING_TO_STRING_UL, ECMA_SYMBOL_PROTOTYPE_TO_STRING, 0, 0)
+ROUTINE (LIT_MAGIC_STRING_VALUE_OF_UL, ECMA_SYMBOL_PROTOTYPE_VALUE_OF, 0, 0)
 ROUTINE_CONFIGURABLE_ONLY (LIT_GLOBAL_SYMBOL_TO_PRIMITIVE,
-                           ecma_builtin_symbol_prototype_object_to_primitive,
+                           ECMA_SYMBOL_PROTOTYPE_TO_PRIMITIVE,
                            0,
                            1)
 
@@ -40,6 +40,10 @@ STRING_VALUE (LIT_GLOBAL_SYMBOL_TO_STRING_TAG,
               LIT_MAGIC_STRING_SYMBOL_UL,
               ECMA_PROPERTY_FLAG_CONFIGURABLE)
 
+/* ECMA-262, v11, 19.4.3.2 */
+ACCESSOR_READ_ONLY (LIT_MAGIC_STRING_DESCRIPTION,
+                    ECMA_SYMBOL_PROTOTYPE_DESCRIPTION,
+                    ECMA_PROPERTY_FLAG_CONFIGURABLE)
 #endif /* ENABLED (JERRY_ESNEXT) */
 
 #include "ecma-builtin-helpers-macro-undefs.inc.h"

jerry-core/ecma/operations/ecma-symbol-object.c

@@ -137,42 +137,42 @@ ecma_get_symbol_descriptive_string (ecma_value_t symbol_value) /**< symbol to st
 } /* ecma_get_symbol_descriptive_string */
 
 /**
- * Helper for Symbol.prototype.{toString, valueOf} routines
+ * thisSymbolValue abstract operation
  *
- * See also: 19.4.3.2, 19.4.3.3
+ * See also:
+ *          ECMA-262 v11, 19.4.3
  *
  * @return ecma value
  *         Returned value must be freed with ecma_free_value.
  */
 ecma_value_t
-ecma_symbol_to_string_helper (ecma_value_t this_arg, /**< this argument value */
-                              bool is_to_string) /**< true - perform the 'toString' routine steps
-                                                  *   false - perform the 'valueOf' routine steps */
+ecma_symbol_this_value (ecma_value_t this_arg) /**< this argument value */
 {
+  /* 1. */
   if (ecma_is_value_symbol (this_arg))
   {
-    return is_to_string ? ecma_get_symbol_descriptive_string (this_arg) : ecma_copy_value (this_arg);
+    return this_arg;
   }
 
+  /* 2. */
   if (ecma_is_value_object (this_arg))
   {
     ecma_object_t *object_p = ecma_get_object_from_value (this_arg);
 
     if (ecma_get_object_type (object_p) == ECMA_OBJECT_TYPE_CLASS)
     {
-      ecma_extended_object_t *ext_object_p = (ecma_extended_object_t *) object_p;
+      ecma_extended_object_t *ext_obj_p = (ecma_extended_object_t *) object_p;
 
-      if (ext_object_p->u.class_prop.class_id == LIT_MAGIC_STRING_SYMBOL_UL)
+      if (ext_obj_p->u.class_prop.class_id == LIT_MAGIC_STRING_SYMBOL_UL)
       {
-        return (is_to_string ? ecma_get_symbol_descriptive_string (ext_object_p->u.class_prop.u.value)
-                             : ecma_copy_value (ext_object_p->u.class_prop.u.value));
+        return ext_obj_p->u.class_prop.u.value;
       }
     }
   }
 
-  return ecma_raise_type_error (ECMA_ERR_MSG ("Argument 'this' is must be a Symbol."));
-} /* ecma_symbol_to_string_helper */
-
+  /* 3. */
+  return ecma_raise_type_error (ECMA_ERR_MSG ("Argument 'this' must be a Symbol."));
+} /* ecma_symbol_this_value */
 #endif /* ENABLED (JERRY_ESNEXT) */
 
 /**

jerry-core/ecma/operations/ecma-symbol-object.h

@@ -39,7 +39,7 @@ ecma_string_t *
 ecma_get_symbol_description (ecma_string_t *symbol_p);
 
 ecma_value_t
-ecma_symbol_to_string_helper (ecma_value_t this_arg, bool is_to_string);
+ecma_symbol_this_value (ecma_value_t this_arg);
 
 ecma_value_t
 ecma_get_symbol_descriptive_string (ecma_value_t symbol_value);

jerry-core/lit/lit-magic-strings.inc.h

@@ -721,6 +721,9 @@ LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_UINT32_ARRAY_UL, "Uint32Array")
 LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_CODE_POINT_AT, "codePointAt")
 #endif
 LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_CONSTRUCTOR, "constructor")
+#if ENABLED (JERRY_ESNEXT)
+LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_DESCRIPTION, "description")
+#endif
 #if ENABLED (JERRY_BUILTIN_DATE)
 LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_GET_FULL_YEAR_UL, "getFullYear")
 LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_GET_UTC_HOURS_UL, "getUTCHours")

jerry-core/lit/lit-magic-strings.ini

@@ -285,6 +285,7 @@ LIT_MAGIC_STRING_SET_UTC_DATE_UL = "setUTCDate"
 LIT_MAGIC_STRING_STARTS_WITH = "startsWith"
 LIT_MAGIC_STRING_RESOURCE_ANON = "<anonymous>"
 LIT_MAGIC_STRING_ARRAY_BUFFER_UL = "ArrayBuffer"
+LIT_MAGIC_STRING_DESCRIPTION = "description"
 LIT_MAGIC_STRING_SYNTAX_ERROR_UL = "SyntaxError"
 LIT_MAGIC_STRING_UINT16_ARRAY_UL = "Uint16Array"
 LIT_MAGIC_STRING_UINT32_ARRAY_UL = "Uint32Array"

tests/jerry/es.next/symbol-prototype-description.js

@@ -0,0 +1,75 @@
+/* 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.
+ */
+
+assert(Symbol('desc').description === "desc");
+assert(Symbol.iterator.description === "Symbol.iterator");
+assert(Symbol.for('foo').description === "foo");
+assert(`${Symbol('foo').description}bar` === "foobar");
+
+var desc = Object.getOwnPropertyDescriptor(Symbol.prototype, 'description');
+
+assert(desc.set === undefined);
+assert(typeof desc.get === "function");
+assert(desc.writable === undefined);
+assert(desc.enumerable === false);
+assert(desc.configurable === true);
+
+var sym = Symbol('foo')
+assert(desc.get.call(Object(sym)) === "foo")
+
+var obj_sym = Object(Symbol('foo'));
+assert(obj_sym.description === "foo");
+
+try {
+  desc.get.call(null);
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+try {
+  desc.get.call(123);
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+try {
+  desc.get.call('test');
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+try {
+  desc.get.call(undefined);
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+try {
+  desc.get.call({});
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+try {
+  desc.get.call(new Proxy({}, {}));
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}