Disguise accessor properties as data properties

docs/02.API-REFERENCE.md

@@ -461,6 +461,22 @@ The naming scheme is similar to the JavaScript `Object.defineProperty` method.
 Fields should be used in pairs. That is if the `is_value_defined` is set to `true`
 the `value` field should contain the value for the property.
 
+The `is_data_accessor` value is a non-standard extension. When an accessor property is
+defined, and the `is_data_accessor` is set to true, the `Object.getOwnPropertyDescriptor`
+and `Object.getOwnPropertyDescriptors` ECMAScript functions returns the property as a
+data property. The `writable` flag in the returned property descriptor is set to true,
+if the property has a `setter` accessor. These types of properties can only be defined
+using the JerryScript API. The property is not converted to data property when it is
+retrieved using the JerryScript API. Property re-definition has the following rules:
+
+* When `is_configurable` is set, the property can be re-defined as a real data property
+later.
+
+* When `is_configurable` is not set, the `setter` accessor function is called, and the
+`value` provided in the data property descriptor is passed as an argument. If `setter`
+is not available, the `value` is compared to the value returned by the `getter` accessor
+function.
+
 **Prototype**
 
 ```c
@@ -493,6 +509,9 @@ typedef struct
   /** [[Configurable]] */
   bool is_configurable;
 
+  /** Is data accessor property */
+  bool is_data_accessor;
+
   /** [[Value]] */
   jerry_value_t value;
 

jerry-core/api/jerry.c

@@ -3065,6 +3065,7 @@ jerry_init_property_descriptor_fields (jerry_property_descriptor_t *prop_desc_p)
   prop_desc_p->is_enumerable = false;
   prop_desc_p->is_configurable_defined = false;
   prop_desc_p->is_configurable = false;
+  prop_desc_p->is_data_accessor = false;
   prop_desc_p->is_get_defined = false;
   prop_desc_p->getter = ECMA_VALUE_UNDEFINED;
   prop_desc_p->is_set_defined = false;
@@ -3084,31 +3085,33 @@ jerry_property_descriptor_from_ecma (const ecma_property_descriptor_t *prop_desc
   jerry_property_descriptor_t prop_desc;
   jerry_init_property_descriptor_fields (&prop_desc);
 
-  if (prop_desc_p->flags & (ECMA_PROP_IS_ENUMERABLE_DEFINED))
+  if (prop_desc_p->flags & ECMA_PROP_IS_ENUMERABLE_DEFINED)
   {
     prop_desc.is_enumerable_defined = true;
-    prop_desc.is_enumerable = prop_desc_p->flags & (ECMA_PROP_IS_ENUMERABLE);
+    prop_desc.is_enumerable = (prop_desc_p->flags & ECMA_PROP_IS_ENUMERABLE) != 0;
   }
 
-  if (prop_desc_p->flags & (ECMA_PROP_IS_CONFIGURABLE_DEFINED))
+  if (prop_desc_p->flags & ECMA_PROP_IS_CONFIGURABLE_DEFINED)
   {
     prop_desc.is_configurable_defined = true;
-    prop_desc.is_configurable = prop_desc_p->flags & (ECMA_PROP_IS_CONFIGURABLE);
+    prop_desc.is_configurable = (prop_desc_p->flags & ECMA_PROP_IS_CONFIGURABLE) != 0;
   }
 
-  prop_desc.is_value_defined = prop_desc_p->flags & (ECMA_PROP_IS_VALUE_DEFINED);
+  prop_desc.is_value_defined = (prop_desc_p->flags & ECMA_PROP_IS_VALUE_DEFINED) != 0;
 
   if (prop_desc.is_value_defined)
   {
     prop_desc.value = prop_desc_p->value;
   }
 
-  if (prop_desc_p->flags & (ECMA_PROP_IS_WRITABLE_DEFINED))
+  if (prop_desc_p->flags & ECMA_PROP_IS_WRITABLE_DEFINED)
   {
     prop_desc.is_writable_defined = true;
-    prop_desc.is_writable = prop_desc_p->flags & (ECMA_PROP_IS_WRITABLE);
+    prop_desc.is_writable = (prop_desc_p->flags & ECMA_PROP_IS_WRITABLE) != 0;
   }
 
+  prop_desc.is_data_accessor = (prop_desc_p->flags & ECMA_PROP_IS_DATA_ACCESSOR) != 0;
+
   if (prop_desc_p->flags & (ECMA_PROP_IS_GET_DEFINED))
   {
     ecma_value_t getter = ecma_make_object_value (prop_desc_p->get_p);
@@ -3176,6 +3179,11 @@ jerry_property_descriptor_to_ecma (const jerry_property_descriptor_t *prop_desc_
                                                                                    : ECMA_PROP_NO_OPTS));
   }
 
+  if (prop_desc_p->is_data_accessor)
+  {
+    flags |= ECMA_PROP_IS_DATA_ACCESSOR;
+  }
+
   /* Copy accessor property info. */
   if (prop_desc_p->is_get_defined)
   {
@@ -3311,6 +3319,8 @@ jerry_get_own_property_descriptor (const jerry_value_t  obj_val, /**< object val
   prop_desc_p->is_writable_defined = (prop_desc.flags & ECMA_PROP_IS_WRITABLE_DEFINED) != 0;
   prop_desc_p->is_writable = prop_desc_p->is_writable_defined ? (prop_desc.flags & ECMA_PROP_IS_WRITABLE) != 0 : false;
 
+  prop_desc_p->is_data_accessor = (prop_desc.flags & ECMA_PROP_IS_DATA_ACCESSOR) != 0;
+
   prop_desc_p->is_value_defined = (prop_desc.flags & ECMA_PROP_IS_VALUE_DEFINED) != 0;
   prop_desc_p->is_get_defined = (prop_desc.flags & ECMA_PROP_IS_GET_DEFINED) != 0;
   prop_desc_p->is_set_defined = (prop_desc.flags & ECMA_PROP_IS_SET_DEFINED) != 0;

jerry-core/ecma/base/ecma-globals.h

@@ -398,6 +398,7 @@ typedef enum
   ECMA_PROPERTY_FLAG_CONFIGURABLE = 1u << 2, /**< property is configurable */
   ECMA_PROPERTY_FLAG_ENUMERABLE = 1u << 3, /**< property is enumerable */
   ECMA_PROPERTY_FLAG_WRITABLE = 1u << 4, /**< property is writable */
+  ECMA_PROPERTY_FLAG_DATA_ACCESSOR = 1u << 4, /**< property is data accessor */
   ECMA_PROPERTY_FLAG_DATA = 1u << 5, /**< property contains data */
 } ecma_property_flags_t;
 
@@ -1155,6 +1156,7 @@ typedef enum
   ECMA_PROP_IS_CONFIGURABLE_DEFINED = (1 << 7), /** Is [[Configurable]] defined? */
   ECMA_PROP_IS_ENUMERABLE_DEFINED = (1 << 8), /** Is [[Enumerable]] defined? */
   ECMA_PROP_IS_WRITABLE_DEFINED = (1 << 9), /** Is [[Writable]] defined? */
+  ECMA_PROP_IS_DATA_ACCESSOR = (1 << 10), /** Is data accessor */
 } ecma_property_descriptor_status_flags_t;
 
 /**
@@ -1169,7 +1171,6 @@ typedef enum
  */
 typedef struct
 {
-
   /** any combination of ecma_property_descriptor_status_flags_t bits */
   uint16_t flags;
 

jerry-core/ecma/base/ecma-helpers.c

@@ -548,7 +548,7 @@ ecma_create_named_accessor_property (ecma_object_t *object_p, /**< object */
   JERRY_ASSERT (ecma_is_lexical_environment (object_p)
                 || !ecma_op_object_is_fast_array (object_p));
   JERRY_ASSERT (ecma_find_named_property (object_p, name_p) == NULL);
-  JERRY_ASSERT ((prop_attributes & ~ECMA_PROPERTY_CONFIGURABLE_ENUMERABLE) == 0);
+  JERRY_ASSERT ((prop_attributes & ~(ECMA_PROPERTY_CONFIGURABLE_ENUMERABLE | ECMA_PROPERTY_FLAG_DATA_ACCESSOR)) == 0);
 
   uint8_t type_and_flags = prop_attributes;
 

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

@@ -725,6 +725,17 @@ ecma_builtin_object_object_get_own_property_descriptor (ecma_object_t *obj_p, /*
 
   if (ecma_is_value_true (status))
   {
+    if (JERRY_UNLIKELY (prop_desc.flags & ECMA_PROP_IS_DATA_ACCESSOR))
+    {
+      status = ecma_op_to_data_property (obj_p, &prop_desc);
+
+      if (ECMA_IS_VALUE_ERROR (status))
+      {
+        ecma_free_property_descriptor (&prop_desc);
+        return status;
+      }
+    }
+
     /* 4. */
     ecma_object_t *desc_obj_p = ecma_op_from_property_descriptor (&prop_desc);
 
@@ -786,6 +797,20 @@ ecma_builtin_object_object_get_own_property_descriptors (ecma_object_t *obj_p) /
 
     if (ecma_is_value_true (status))
     {
+      if (JERRY_UNLIKELY (prop_desc.flags & ECMA_PROP_IS_DATA_ACCESSOR))
+      {
+        status = ecma_op_to_data_property (obj_p, &prop_desc);
+
+        if (ECMA_IS_VALUE_ERROR (status))
+        {
+          ecma_free_property_descriptor (&prop_desc);
+          ecma_deref_object (descriptors_p);
+          ecma_collection_free (prop_names_p);
+
+          return status;
+        }
+      }
+
       /* 4.b */
       ecma_object_t *desc_obj_p = ecma_op_from_property_descriptor (&prop_desc);
       /* 4.c */

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

@@ -907,6 +907,50 @@ ecma_op_to_property_descriptor (ecma_value_t obj_value, /**< object value */
   return ret_value;
 } /* ecma_op_to_property_descriptor */
 
+/**
+ * Convert accessor to data property.
+ *
+ * @return ECMA_VALUE_EMPTY - if the opertation is successful
+ *         error - otherwise
+ */
+ecma_value_t
+ecma_op_to_data_property (ecma_object_t *object_p, /**< base object */
+                          ecma_property_descriptor_t *prop_desc_p) /**< [in/out] property descriptor */
+{
+  JERRY_ASSERT (prop_desc_p->flags & ECMA_PROP_IS_DATA_ACCESSOR);
+
+  ecma_value_t result = ECMA_VALUE_UNDEFINED;
+  uint16_t flags = prop_desc_p->flags;
+
+  if ((flags & ECMA_PROP_IS_GET_DEFINED) && prop_desc_p->get_p != NULL)
+  {
+    result = ecma_op_function_call (prop_desc_p->get_p, ecma_make_object_value (object_p), NULL, 0);
+
+    if (ECMA_IS_VALUE_ERROR (result))
+    {
+      return result;
+    }
+
+    ecma_deref_object (prop_desc_p->get_p);
+    prop_desc_p->get_p = NULL;
+  }
+
+  if ((flags & ECMA_PROP_IS_SET_DEFINED) && prop_desc_p->set_p != NULL)
+  {
+    ecma_deref_object (prop_desc_p->set_p);
+    prop_desc_p->set_p = NULL;
+
+    flags |= ECMA_PROP_IS_WRITABLE;
+  }
+
+  flags |= ECMA_PROP_IS_WRITABLE_DEFINED | ECMA_PROP_IS_VALUE_DEFINED;
+  flags &= (uint16_t) ~(ECMA_PROP_IS_GET_DEFINED | ECMA_PROP_IS_SET_DEFINED | ECMA_PROP_IS_DATA_ACCESSOR);
+
+  prop_desc_p->value = result;
+  prop_desc_p->flags = flags;
+  return ECMA_VALUE_EMPTY;
+} /* ecma_op_to_data_property */
+
 /**
  * IsInteger operation.
  *

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

@@ -72,6 +72,7 @@ ecma_collection_t *ecma_op_create_list_from_array_like (ecma_value_t arr, bool p
 
 ecma_object_t *ecma_op_from_property_descriptor (const ecma_property_descriptor_t *src_prop_desc_p);
 ecma_value_t ecma_op_to_property_descriptor (ecma_value_t obj_value, ecma_property_descriptor_t *out_prop_desc_p);
+ecma_value_t ecma_op_to_data_property (ecma_object_t *object_p, ecma_property_descriptor_t *prop_desc_p);
 
 /**
  * @}

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

@@ -411,6 +411,11 @@ ecma_op_general_object_define_own_property (ecma_object_t *object_p, /**< the ob
     else
     {
       /* b. */
+      if (property_desc_p->flags & ECMA_PROP_IS_DATA_ACCESSOR)
+      {
+        prop_attributes |= ECMA_PROPERTY_FLAG_DATA_ACCESSOR;
+      }
+
       ecma_create_named_accessor_property (object_p,
                                            property_name_p,
                                            property_desc_p->get_p,
@@ -503,15 +508,9 @@ ecma_op_general_object_define_own_property (ecma_object_t *object_p, /**< the ob
       }
     }
   }
-  else
+  else if (is_current_configurable)
   {
     /* 9. */
-    if (!is_current_configurable)
-    {
-      /* a. */
-      return ecma_reject (property_desc_p->flags & ECMA_PROP_IS_THROW);
-    }
-
     ecma_property_value_t *value_p = ext_property_ref.property_ref.value_p;
 
     if (property_desc_type == ECMA_OP_OBJECT_DEFINE_ACCESSOR)
@@ -548,6 +547,81 @@ ecma_op_general_object_define_own_property (ecma_object_t *object_p, /**< the ob
     prop_flags ^= ECMA_PROPERTY_FLAG_DATA;
     *(ext_property_ref.property_p) = prop_flags;
   }
+  else
+  {
+    /* Property is non-configurable. */
+    if ((current_prop & ECMA_PROPERTY_FLAG_DATA)
+        || !(current_prop & ECMA_PROPERTY_FLAG_DATA_ACCESSOR))
+    {
+      /* a. */
+      return ecma_reject (property_desc_p->flags & ECMA_PROP_IS_THROW);
+    }
+
+    /* Non-standard extension. */
+    ecma_getter_setter_pointers_t *getter_setter_pair_p;
+    getter_setter_pair_p = ecma_get_named_accessor_property (ext_property_ref.property_ref.value_p);
+
+    if (getter_setter_pair_p->setter_cp == JMEM_CP_NULL)
+    {
+      const uint16_t mask = ECMA_PROP_IS_WRITABLE_DEFINED | ECMA_PROP_IS_WRITABLE;
+
+      if ((property_desc_p->flags & mask) == mask)
+      {
+        return ecma_reject (property_desc_p->flags & ECMA_PROP_IS_THROW);
+      }
+
+      if (!(property_desc_p->flags & ECMA_PROP_IS_VALUE_DEFINED))
+      {
+        return ECMA_VALUE_TRUE;
+      }
+
+      ecma_value_t result = ECMA_VALUE_UNDEFINED;
+
+      if (getter_setter_pair_p->getter_cp != JMEM_CP_NULL)
+      {
+        ecma_object_t *getter_p = ECMA_GET_NON_NULL_POINTER (ecma_object_t, getter_setter_pair_p->getter_cp);
+        result = ecma_op_function_call (getter_p, ecma_make_object_value (object_p), NULL, 0);
+
+        if (ECMA_IS_VALUE_ERROR (result))
+        {
+          return result;
+        }
+      }
+
+      bool same_value = ecma_op_same_value (property_desc_p->value, result);
+      ecma_free_value (result);
+
+      if (!same_value)
+      {
+        return ecma_reject (property_desc_p->flags & ECMA_PROP_IS_THROW);
+      }
+      return ECMA_VALUE_TRUE;
+    }
+
+    if (property_desc_p->flags & ECMA_PROP_IS_VALUE_DEFINED)
+    {
+      ecma_object_t *setter_p = ECMA_GET_NON_NULL_POINTER (ecma_object_t, getter_setter_pair_p->setter_cp);
+
+      ecma_value_t result;
+      result = ecma_op_function_call (setter_p, ecma_make_object_value (object_p), &property_desc_p->value, 1);
+
+      if (ECMA_IS_VALUE_ERROR (result))
+      {
+        return result;
+      }
+
+      ecma_free_value (result);
+    }
+
+    /* Because the property is non-configurable, it cannot be modified. */
+    if ((property_desc_p->flags & ECMA_PROP_IS_WRITABLE_DEFINED)
+        && !(property_desc_p->flags & ECMA_PROP_IS_WRITABLE))
+    {
+      getter_setter_pair_p->setter_cp = JMEM_CP_NULL;
+    }
+
+    return ECMA_VALUE_TRUE;
+  }
 
   /* 12. */
   if (property_desc_type == ECMA_OP_OBJECT_DEFINE_DATA)
@@ -583,6 +657,15 @@ ecma_op_general_object_define_own_property (ecma_object_t *object_p, /**< the ob
                                                ext_property_ref.property_ref.value_p,
                                                property_desc_p->set_p);
     }
+
+    if (property_desc_p->flags & ECMA_PROP_IS_DATA_ACCESSOR)
+    {
+      *ext_property_ref.property_p |= ECMA_PROPERTY_FLAG_DATA_ACCESSOR;
+    }
+    else
+    {
+      *ext_property_ref.property_p &= (uint8_t) ~ECMA_PROPERTY_FLAG_DATA_ACCESSOR;
+    }
   }
 
   if (property_desc_p->flags & ECMA_PROP_IS_ENUMERABLE_DEFINED)

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

@@ -65,8 +65,8 @@
  * See also:
  *          ECMA-262 v5, 8.6.2; ECMA-262 v5, Table 8
  *
- * @return pointer to a property - if it exists,
- *         NULL (i.e. ecma-undefined) - otherwise.
+ * @return property descriptor - if it exists,
+ *         ECMA_PROPERTY_TYPE_NOT_FOUND / ECMA_PROPERTY_TYPE_NOT_FOUND_AND_STOP - otherwise.
  */
 ecma_property_t
 ecma_op_object_get_own_property (ecma_object_t *object_p, /**< the object */
@@ -1935,6 +1935,11 @@ ecma_op_object_get_own_property_descriptor (ecma_object_t *object_p, /**< the ob
       prop_desc_p->set_p = ECMA_GET_NON_NULL_POINTER (ecma_object_t, get_set_pair_p->setter_cp);
       ecma_ref_object (prop_desc_p->set_p);
     }
+
+    if (property & ECMA_PROPERTY_FLAG_DATA_ACCESSOR)
+    {
+      prop_desc_p->flags |= ECMA_PROP_IS_DATA_ACCESSOR;
+    }
   }
 
   return ECMA_VALUE_TRUE;

jerry-core/include/jerryscript-core.h

@@ -194,6 +194,9 @@ typedef struct
   /** [[Configurable]] */
   bool is_configurable;
 
+  /** Is data accessor property */
+  bool is_data_accessor;
+
   /** [[Value]] */
   jerry_value_t value;