Add iterator close support for array destructuring (#3337)

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

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

@@ -26,6 +26,7 @@
 #include "ecma-objects.h"
 #include "ecma-objects-general.h"
 #include "ecma-function-object.h"
+#include "jcontext.h"
 
 /** \addtogroup ecma ECMA
  * @{
@@ -393,6 +394,97 @@ ecma_op_iterator_step (ecma_value_t iterator) /**< iterator value */
   return result;
 } /* ecma_op_iterator_step */
 
+/**
+ * IteratorClose operation
+ *
+ * See also: ECMA-262 v6, 7.4.6
+ *
+ * @return ECMA_VALUE_EMPTY - if "return" is succesfully invoked,
+ *                            and the operation is called with normal completion
+ *         ECMA_VALUE_ERROR - otherwise
+ */
+ecma_value_t
+ecma_op_iterator_close (ecma_value_t iterator) /**< iterator value */
+{
+  /* 1. */
+  JERRY_ASSERT (ecma_is_value_object (iterator));
+
+  /* 2. */
+  ecma_value_t completion = ECMA_VALUE_EMPTY;
+
+  if (JERRY_CONTEXT (status_flags) & ECMA_STATUS_EXCEPTION)
+  {
+    completion = JERRY_CONTEXT (error_value);
+    JERRY_CONTEXT (status_flags) &= (uint32_t) ~ECMA_STATUS_EXCEPTION;
+  }
+
+  /* 3. */
+  ecma_value_t return_method = ecma_op_get_method_by_magic_id (iterator, LIT_MAGIC_STRING_RETURN);
+
+  /* 4. */
+  if (ECMA_IS_VALUE_ERROR (return_method))
+  {
+    ecma_free_value (completion);
+    return return_method;
+  }
+
+  /* 5. */
+  if (ecma_is_value_undefined (return_method))
+  {
+    if (ecma_is_value_empty (completion))
+    {
+      return ECMA_VALUE_UNDEFINED;
+    }
+
+    JERRY_CONTEXT (status_flags) |= ECMA_STATUS_EXCEPTION;
+    return ECMA_VALUE_ERROR;
+  }
+
+  /* 6. */
+  ecma_object_t *return_obj_p = ecma_get_object_from_value (return_method);
+  ecma_value_t inner_result = ecma_op_function_call (return_obj_p, iterator, NULL, 0);
+  ecma_deref_object (return_obj_p);
+
+  /* 7. */
+  if (!ecma_is_value_empty (completion))
+  {
+    if (ECMA_IS_VALUE_ERROR (inner_result))
+    {
+      ecma_free_value (JERRY_CONTEXT (error_value));
+      JERRY_CONTEXT (error_value) = completion;
+    }
+
+    ecma_free_value (inner_result);
+    JERRY_CONTEXT (status_flags) |= ECMA_STATUS_EXCEPTION;
+    return ECMA_VALUE_ERROR;
+  }
+
+  /* 8. */
+  if (ECMA_IS_VALUE_ERROR (inner_result))
+  {
+    ecma_free_value (completion);
+    return inner_result;
+  }
+
+  /* 9. */
+  bool is_object = ecma_is_value_object (inner_result);
+  ecma_free_value (inner_result);
+
+  if (!is_object)
+  {
+    ecma_free_value (completion);
+    return ecma_raise_type_error (ECMA_ERR_MSG ("method 'return' is not callable."));
+  }
+
+  /* 10. */
+  if (ecma_is_value_empty (completion))
+  {
+    return ECMA_VALUE_UNDEFINED;
+  }
+
+  JERRY_CONTEXT (status_flags) |= ECMA_STATUS_EXCEPTION;
+  return ECMA_VALUE_ERROR;
+} /* ecma_op_iterator_close */
 #endif /* ENABLED (JERRY_ES2015_BUILTIN_ITERATOR) */
 /**
  * @}

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

@@ -52,6 +52,9 @@ ecma_op_iterator_value (ecma_value_t iter_result);
 ecma_value_t
 ecma_op_iterator_step (ecma_value_t iterator);
 
+ecma_value_t
+ecma_op_iterator_close (ecma_value_t iterator);
+
 #endif /* ENABLED (JERRY_ES2015_BUILTIN_ITERATOR) */
 
 /**

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

@@ -968,19 +968,21 @@ ecma_op_object_get_by_symbol_id (ecma_object_t *object_p, /**< the object */
 } /* ecma_op_object_get_by_symbol_id */
 
 /**
- * GetMethod operation the property is a well-known symbol
+ * GetMethod operation
  *
  * See also: ECMA-262 v6, 7.3.9
  *
  * Note:
  *      Returned value must be freed with ecma_free_value.
  *
- * @return iterator fucntion object - if success
+ * @return iterator function object - if success
  *         raised error - otherwise
  */
-ecma_value_t
+static ecma_value_t
-ecma_op_get_method_by_symbol_id (ecma_value_t value, /**< ecma value */
+ecma_op_get_method_by_id (ecma_value_t value, /**< ecma value */
-                                 lit_magic_string_id_t property_id) /**< property symbol id */
+                          lit_magic_string_id_t id, /**< property magic id */
+                          bool is_symbol_id) /**< true - if id represents a symbol id
+                                              *   false - otherwise */
 {
   /* 2. */
   ecma_value_t obj_value = ecma_op_to_object (value);
@@ -991,7 +993,16 @@ ecma_op_get_method_by_symbol_id (ecma_value_t value, /**< ecma value */
   }
 
   ecma_object_t *obj_p = ecma_get_object_from_value (obj_value);
-  ecma_value_t func = ecma_op_object_get_by_symbol_id (obj_p, property_id);
+  ecma_value_t func;
+
+  if (is_symbol_id)
+  {
+    func = ecma_op_object_get_by_symbol_id (obj_p, id);
+  }
+  else
+  {
+    func = ecma_op_object_get_by_magic_id (obj_p, id);
+  }
   ecma_deref_object (obj_p);
 
   /* 3. */
@@ -1015,7 +1026,43 @@ ecma_op_get_method_by_symbol_id (ecma_value_t value, /**< ecma value */
 
   /* 6. */
   return func;
+} /* ecma_op_get_method_by_id */
+
+/**
+ * GetMethod operation when the property is a well-known symbol
+ *
+ * See also: ECMA-262 v6, 7.3.9
+ *
+ * Note:
+ *      Returned value must be freed with ecma_free_value.
+ *
+ * @return iterator function object - if success
+ *         raised error - otherwise
+ */
+ecma_value_t
+ecma_op_get_method_by_symbol_id (ecma_value_t value, /**< ecma value */
+                                 lit_magic_string_id_t symbol_id) /**< property symbol id */
+{
+  return ecma_op_get_method_by_id (value, symbol_id, true);
 } /* ecma_op_get_method_by_symbol_id */
+
+/**
+ * GetMethod operation when the property is a magic string
+ *
+ * See also: ECMA-262 v6, 7.3.9
+ *
+ * Note:
+ *      Returned value must be freed with ecma_free_value.
+ *
+ * @return iterator function object - if success
+ *         raised error - otherwise
+ */
+ecma_value_t
+ecma_op_get_method_by_magic_id (ecma_value_t value, /**< ecma value */
+                                lit_magic_string_id_t magic_id) /**< property magic id */
+{
+  return ecma_op_get_method_by_id (value, magic_id, false);
+} /* ecma_op_get_method_by_magic_id */
 #endif /* ENABLED (JERRY_ES2015) */
 
 /**

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

@@ -43,7 +43,8 @@ ecma_value_t ecma_op_object_get_by_uint32_index (ecma_object_t *object_p, uint32
 ecma_value_t ecma_op_object_get_by_magic_id (ecma_object_t *object_p, lit_magic_string_id_t property_id);
 #if ENABLED (JERRY_ES2015)
 ecma_value_t ecma_op_object_get_by_symbol_id (ecma_object_t *object_p, lit_magic_string_id_t property_id);
-ecma_value_t ecma_op_get_method_by_symbol_id (ecma_value_t value, lit_magic_string_id_t property_id);
+ecma_value_t ecma_op_get_method_by_symbol_id (ecma_value_t value, lit_magic_string_id_t symbol_id);
+ecma_value_t ecma_op_get_method_by_magic_id (ecma_value_t value, lit_magic_string_id_t magic_id);
 #endif /* ENABLED (JERRY_ES2015) */
 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);

jerry-core/include/jerryscript-snapshot.h

@@ -30,7 +30,7 @@ extern "C"
 /**
  * Jerry snapshot format version.
  */
-#define JERRY_SNAPSHOT_VERSION (30u)
+#define JERRY_SNAPSHOT_VERSION (31u)
 
 /**
  * Flags for jerry_generate_snapshot and jerry_generate_function_snapshot.

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

@@ -322,6 +322,9 @@ LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_REJECT, "reject")
 #if ENABLED (JERRY_BUILTIN_STRING) && ENABLED (JERRY_ES2015_BUILTIN)
 LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_REPEAT, "repeat")
 #endif
+#if ENABLED (JERRY_ES2015_BUILTIN_ITERATOR)
+LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_RETURN, "return")
+#endif
 #if ENABLED (JERRY_BUILTIN_REGEXP) && ENABLED (JERRY_BUILTIN_STRING) \
 || ENABLED (JERRY_ES2015)
 LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_SEARCH, "search")

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

@@ -144,6 +144,7 @@ LIT_MAGIC_STRING_RANDOM = "random"
 LIT_MAGIC_STRING_REDUCE = "reduce"
 LIT_MAGIC_STRING_REJECT = "reject"
 LIT_MAGIC_STRING_REPEAT = "repeat"
+LIT_MAGIC_STRING_RETURN = "return"
 LIT_MAGIC_STRING_SEARCH = "search"
 LIT_MAGIC_STRING_SOURCE = "source"
 LIT_MAGIC_STRING_SPLICE = "splice"

jerry-core/parser/js/byte-code.h

@@ -644,6 +644,8 @@
               VM_OC_ITERATOR_STEP) \
   CBC_OPCODE (CBC_EXT_ITERATOR_STEP_PROP, CBC_NO_FLAG, 1, \
               VM_OC_ITERATOR_STEP) \
+  CBC_OPCODE (CBC_EXT_ITERATOR_CLOSE, CBC_NO_FLAG, -1, \
+              VM_OC_ITERATOR_CLOSE | VM_OC_GET_STACK) \
   CBC_OPCODE (CBC_EXT_REST_INITIALIZER, CBC_NO_FLAG, 1, \
               VM_OC_REST_INITIALIZER) \
   CBC_OPCODE (CBC_EXT_REST_INITIALIZER_PROP, CBC_NO_FLAG, 1, \

jerry-core/parser/js/js-parser-expr.c

@@ -2491,8 +2491,8 @@ parser_parse_array_initializer (parser_context_t *context_p, /**< context */
     }
   }
 
-  /* pop the iterator */
+  /* close the iterator */
-  parser_emit_cbc (context_p, CBC_POP);
+  parser_emit_cbc_ext (context_p, CBC_EXT_ITERATOR_CLOSE);
 
   parser_pattern_finalize (context_p, flags, &end_pos);
 } /* parser_parse_array_initializer */

jerry-core/vm/vm.c

@@ -1965,6 +1965,17 @@ vm_loop (vm_frame_ctx_t *frame_ctx_p) /**< frame context */
           *stack_top_p++ = value;
           continue;
         }
+        case VM_OC_ITERATOR_CLOSE:
+        {
+          result = ecma_op_iterator_close (left_value);
+
+          if (ECMA_IS_VALUE_ERROR (result))
+          {
+            goto error;
+          }
+
+          goto free_left_value;
+        }
         case VM_OC_DEFAULT_INITIALIZER:
         {
           JERRY_ASSERT (stack_top_p > frame_ctx_p->registers_p + register_end);
@@ -3883,6 +3894,8 @@ error:
         JERRY_DEBUGGER_CLEAR_FLAGS (JERRY_DEBUGGER_VM_EXCEPTION_THROWN);
 #endif /* ENABLED (JERRY_DEBUGGER) */
 
+        JERRY_CONTEXT (status_flags) &= (uint32_t) ~ECMA_STATUS_EXCEPTION;
+
         byte_code_p = frame_ctx_p->byte_code_p;
 
         if (VM_GET_CONTEXT_TYPE (stack_top_p[-1]) == VM_CONTEXT_FINALLY_THROW)

jerry-core/vm/vm.h

@@ -250,6 +250,7 @@ typedef enum
   VM_OC_PUSH_SPREAD_ELEMENT,     /**< push spread element */
   VM_OC_GET_ITERATOR,            /**< GetIterator abstract operation */
   VM_OC_ITERATOR_STEP,           /**< IteratorStep abstract operation */
+  VM_OC_ITERATOR_CLOSE,          /**< IteratorClose abstract operation */
   VM_OC_DEFAULT_INITIALIZER,     /**< default initializer inside a pattern */
   VM_OC_REST_INITIALIZER,        /**< create rest object inside an array pattern */
   VM_OC_INITIALIZER_PUSH_PROP,   /**< push property for object initializer */
@@ -299,6 +300,7 @@ typedef enum
   VM_OC_PUSH_SPREAD_ELEMENT = VM_OC_NONE,     /**< push spread element */
   VM_OC_GET_ITERATOR = VM_OC_NONE,            /**< GetIterator abstract operation */
   VM_OC_ITERATOR_STEP = VM_OC_NONE,           /**< IteratorStep abstract operation */
+  VM_OC_ITERATOR_CLOSE = VM_OC_NONE,          /**< IteratorClose abstract operation */
   VM_OC_DEFAULT_INITIALIZER = VM_OC_NONE,     /**< default initializer inside a pattern */
   VM_OC_REST_INITIALIZER = VM_OC_NONE,        /**< create rest object inside an array pattern */
   VM_OC_INITIALIZER_PUSH_PROP = VM_OC_NONE,   /**< push property for object initializer */

tests/jerry/es2015/array-pattern.js

@@ -247,3 +247,60 @@ mustThrow ("var [a] = { [Symbol.iterator] () { return { next () { return { get d
   [((a))] = [7];
   assert (a === 7);
 }) ();
+
+// Test iterator closing
+function __createIterableObject (arr, methods) {
+  methods = methods || {};
+  if (typeof Symbol !== 'function' || !Symbol.iterator) {
+    return {};
+  }
+  arr.length++;
+  var iterator = {
+    next: function() {
+      return { value: arr.shift(), done: arr.length <= 0 };
+    },
+    'return': methods['return'],
+    'throw': methods['throw']
+  };
+  var iterable = {};
+  iterable[Symbol.iterator] = function () { return iterator; };
+  return iterable;
+};
+
+(function () {
+  var closed = false;
+  var iter = __createIterableObject([1, 2, 3], {
+    'return': function() { closed = true; return {}; }
+  });
+  var [a, b] = iter;
+  assert (closed === true);
+  assert (a === 1);
+  assert (b === 2);
+}) ();
+
+mustThrow ("var iter = __createIterableObject([], "
+           + "{ get 'return'() { throw new TypeError() }});"
+           + "var [a] = iter");
+
+mustThrow ("var iter = __createIterableObject([], "
+           + "{ 'return': 5 });"
+           + "var [a] = iter");
+
+mustThrow ("var iter = __createIterableObject([], "
+           + "{ 'return': function() { return 5; }});"
+           + "var [a] = iter");
+
+mustThrow ("try { throw 5 } catch (e) {"
+           + "var iter = __createIterableObject([], "
+           + "{ get 'return'() { throw new TypeError() }});"
+           + "var [a] = iter }");
+
+mustThrow ("try { throw 5 } catch (e) {"
+           + "var iter = __createIterableObject([], "
+           + "{ 'return': 5 });"
+           + "var [a] = iter }");
+
+mustThrow ("try { throw 5 } catch (e) {"
+           + "var iter = __createIterableObject([], "
+           + "{ 'return': function() { return 5; }});"
+           + "var [a] = iter }");

tests/unit-core/test-snapshot.c

@@ -223,7 +223,7 @@ main (void)
     /* Check the snapshot data. Unused bytes should be filled with zeroes */
     const uint8_t expected_data[] =
     {
-      0x4A, 0x52, 0x52, 0x59, 0x1E, 0x00, 0x00, 0x00,
+      0x4A, 0x52, 0x52, 0x59, 0x1F, 0x00, 0x00, 0x00,
       0x00, 0x00, 0x00, 0x00, 0x48, 0x00, 0x00, 0x00,
       0x01, 0x00, 0x00, 0x00, 0x18, 0x00, 0x00, 0x00,
       0x03, 0x00, 0x01, 0x00, 0x41, 0x00, 0x01, 0x00,