Implement the string iterators (#2873)

JerryScript-DCO-1.0-Signed-off-by: Robert Fancsik frobert@inf.u-szeged.hu
2019-05-30 12:34:19 -04:00
parent 442e482afa
commit 076f515d61
15 changed files with 372 additions and 17 deletions
@@ -329,15 +329,17 @@ ecma_gc_mark (ecma_object_t *object_p) /**< object to mark from */
 #if ENABLED (JERRY_ES2015_BUILTIN_ITERATOR)
          case ECMA_PSEUDO_ARRAY_ITERATOR:
          {
-            ecma_object_t *iterated_obj_p = ECMA_GET_POINTER (ecma_object_t,
-                                                              ext_object_p->u.pseudo_array.u2.iterated_value_cp);
-
-            if (iterated_obj_p != NULL)
+            ecma_value_t iterated_value = ext_object_p->u.pseudo_array.u2.iterated_value;
+            if (!ecma_is_value_empty (iterated_value))
            {
-              ecma_gc_set_object_visited (iterated_obj_p);
+              ecma_gc_set_object_visited (ecma_get_object_from_value (iterated_value));
            }
            break;
          }
+          case ECMA_PSEUDO_STRING_ITERATOR:
+          {
+            break;
+          }
 #endif /* ENABLED (JERRY_ES2015_BUILTIN_ITERATOR) */
          default:
          {
@@ -755,6 +757,17 @@ ecma_gc_free_object (ecma_object_t *object_p) /**< object to free */
          ecma_dealloc_extended_object (object_p, sizeof (ecma_extended_object_t));
          return;
        }
+        case ECMA_PSEUDO_STRING_ITERATOR:
+        {
+          ecma_value_t iterated_value = ext_object_p->u.pseudo_array.u2.iterated_value;
+
+          if (!ecma_is_value_empty (iterated_value))
+          {
+            ecma_deref_ecma_string (ecma_get_string_from_value (iterated_value));
+          }
+          ecma_dealloc_extended_object (object_p, sizeof (ecma_extended_object_t));
+          return;
+        }
 #endif /* ENABLED (JERRY_ES2015_BUILTIN_ITERATOR) */
        default:
        {
@@ -628,8 +628,9 @@ typedef enum
  ECMA_PSEUDO_ARRAY_TYPEDARRAY = 1, /**< TypedArray which does NOT need extra space to store length and offset */
  ECMA_PSEUDO_ARRAY_TYPEDARRAY_WITH_INFO = 2, /**< TypedArray which NEEDS extra space to store length and offset */
  ECMA_PSEUDO_ARRAY_ITERATOR = 3, /**< Array iterator object (ECMAScript v6, 22.1.5.1) */
+  ECMA_PSEUDO_STRING_ITERATOR = 4, /**< Array iterator object (ECMAScript v6, 22.1.5.1) */

-  ECMA_PSEUDO_ARRAY__MAX = ECMA_PSEUDO_ARRAY_ITERATOR /**< maximum value */
+  ECMA_PSEUDO_ARRAY__MAX = ECMA_PSEUDO_STRING_ITERATOR /**< maximum value */
 } ecma_pseudo_array_type_t;

 /**
@@ -836,7 +837,7 @@ typedef struct
      {
        ecma_value_t lex_env_cp; /**< for arguments: lexical environment */
        ecma_value_t arraybuffer; /**< for typedarray: internal arraybuffer */
-        ecma_value_t iterated_value_cp; /**< for %Iterator%: [[IteratedObject]] property */
+        ecma_value_t iterated_value; /**< for %Iterator%: [[IteratedObject]] property */
      } u2;
    } pseudo_array;

@@ -476,6 +476,24 @@ ecma_new_ecma_string_from_code_unit (ecma_char_t code_unit) /**< code unit */
  return ecma_new_ecma_string_from_utf8 (lit_utf8_bytes, bytes_size);
 } /* ecma_new_ecma_string_from_code_unit */

+#if ENABLED (JERRY_ES2015_BUILTIN_ITERATOR)
+/**
+ * Allocate new ecma-string and fill it with cesu-8 character which represents specified code units
+ *
+ * @return pointer to ecma-string descriptor
+ */
+ecma_string_t *
+ecma_new_ecma_string_from_code_units (ecma_char_t first_code_unit, /**< code unit */
+                                      ecma_char_t second_code_unit) /**< code unit */
+{
+  lit_utf8_byte_t lit_utf8_bytes[2 * LIT_UTF8_MAX_BYTES_IN_CODE_UNIT];
+  lit_utf8_size_t bytes_size = lit_code_unit_to_utf8 (first_code_unit, lit_utf8_bytes);
+  bytes_size += lit_code_unit_to_utf8 (second_code_unit, lit_utf8_bytes + bytes_size);
+
+  return ecma_new_ecma_string_from_utf8 (lit_utf8_bytes, bytes_size);
+} /* ecma_new_ecma_string_from_code_units */
+#endif /* ENABLED (JERRY_ES2015_BUILTIN_ITERATOR) */
+
 /**
 * Allocate new ecma-string and fill it with ecma-number
 *
@@ -230,6 +230,9 @@ ecma_string_t *ecma_new_ecma_string_from_utf8 (const lit_utf8_byte_t *string_p,
 ecma_string_t *ecma_new_ecma_string_from_utf8_converted_to_cesu8 (const lit_utf8_byte_t *string_p,
                                                                  lit_utf8_size_t string_size);
 ecma_string_t *ecma_new_ecma_string_from_code_unit (ecma_char_t code_unit);
+#if ENABLED (JERRY_ES2015_BUILTIN_ITERATOR)
+ecma_string_t *ecma_new_ecma_string_from_code_units (ecma_char_t first_code_unit, ecma_char_t second_code_unit);
+#endif /* ENABLED (JERRY_ES2015_BUILTIN_ITERATOR) */
 ecma_string_t *ecma_new_ecma_string_from_uint32 (uint32_t uint32_number);
 ecma_string_t *ecma_get_ecma_string_from_uint32 (uint32_t uint32_number);
 ecma_string_t *ecma_new_ecma_string_from_number (ecma_number_t num);
@@ -66,21 +66,22 @@ ecma_builtin_array_iterator_prototype_object_next (ecma_value_t this_val) /**< t
  ecma_extended_object_t *ext_obj_p = (ecma_extended_object_t *) obj_p;

  /* 3. */
-  if (ext_obj_p->u.pseudo_array.type != ECMA_PSEUDO_ARRAY_ITERATOR)
+  if (ecma_get_object_type (obj_p) != ECMA_OBJECT_TYPE_PSEUDO_ARRAY
+      || ext_obj_p->u.pseudo_array.type != ECMA_PSEUDO_ARRAY_ITERATOR)
  {
    return ecma_raise_type_error (ECMA_ERR_MSG ("Argument 'this' is not an iterator."));
  }

-  ecma_object_t *array_object_p = ECMA_GET_POINTER (ecma_object_t,
-                                                    ext_obj_p->u.pseudo_array.u2.iterated_value_cp);
-
+  ecma_value_t iterated_value = ext_obj_p->u.pseudo_array.u2.iterated_value;

  /* 4 - 5 */
-  if (array_object_p == NULL)
+  if (ecma_is_value_empty (iterated_value))
  {
    return ecma_create_iter_result_object (ECMA_VALUE_UNDEFINED, ECMA_VALUE_TRUE);
  }

+  ecma_object_t *array_object_p = ecma_get_object_from_value (iterated_value);
+
  uint32_t length;

  /* 8 - 9. */
@@ -147,7 +148,7 @@ ecma_builtin_array_iterator_prototype_object_next (ecma_value_t this_val) /**< t

  if (index >= length)
  {
-    ECMA_SET_POINTER (ext_obj_p->u.pseudo_array.u2.iterated_value_cp, NULL);
+    ext_obj_p->u.pseudo_array.u2.iterated_value = ECMA_VALUE_EMPTY;
    return ecma_create_iter_result_object (ECMA_VALUE_UNDEFINED, ECMA_VALUE_TRUE);
  }

@@ -0,0 +1,152 @@
+/* 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.
+ */
+
+#include "ecma-builtin-helpers.h"
+#include "ecma-builtins.h"
+#include "ecma-iterator-object.h"
+
+#if ENABLED (JERRY_ES2015_BUILTIN_ITERATOR)
+
+#if !ENABLED (JERRY_ES2015_BUILTIN_SYMBOL)
+#error "Iterator builtin requires ES2015 symbol builtin"
+#endif /* !ENABLED (JERRY_ES2015_BUILTIN_SYMBOL) */
+
+#define ECMA_BUILTINS_INTERNAL
+#include "ecma-builtins-internal.h"
+
+#define BUILTIN_INC_HEADER_NAME "ecma-builtin-string-iterator-prototype.inc.h"
+#define BUILTIN_UNDERSCORED_ID string_iterator_prototype
+#include "ecma-builtin-internal-routines-template.inc.h"
+
+/** \addtogroup ecma ECMA
+ * @{
+ *
+ * \addtogroup ecmabuiltins
+ * @{
+ *
+ * \addtogroup %stringiteratorprototype% ECMA %ArrayIteratorPrototype% object built-in
+ * @{
+ */
+
+/**
+ * The %StringIteratorPrototype% object's 'next' routine
+ *
+ * See also:
+ *          ECMA-262 v6, 22.1.5.2.1
+ *
+ * Note:
+ *     Returned value must be freed with ecma_free_value.
+ *
+ * @return iterator result object, if success
+ *         error - otherwise
+ */
+static ecma_value_t
+ecma_builtin_string_iterator_prototype_object_next (ecma_value_t this_val) /**< this argument */
+{
+    /* 1 - 2. */
+  if (!ecma_is_value_object (this_val))
+  {
+    return ecma_raise_type_error (ECMA_ERR_MSG ("Argument 'this' is not an object."));
+  }
+
+  ecma_object_t *obj_p = ecma_get_object_from_value (this_val);
+  ecma_extended_object_t *ext_obj_p = (ecma_extended_object_t *) obj_p;
+
+  /* 3. */
+  if (ecma_get_object_type (obj_p) != ECMA_OBJECT_TYPE_PSEUDO_ARRAY
+      || ext_obj_p->u.pseudo_array.type != ECMA_PSEUDO_STRING_ITERATOR)
+  {
+    return ecma_raise_type_error (ECMA_ERR_MSG ("Argument 'this' is not an iterator."));
+  }
+
+  ecma_value_t iterated_value = ext_obj_p->u.pseudo_array.u2.iterated_value;
+
+  /* 4 - 5 */
+  if (ecma_is_value_empty (iterated_value))
+  {
+    return ecma_create_iter_result_object (ECMA_VALUE_UNDEFINED, ECMA_VALUE_TRUE);
+  }
+
+  JERRY_ASSERT (ecma_is_value_string (iterated_value));
+
+
+  ecma_string_t *string_p = ecma_get_string_from_value (iterated_value);
+
+  /* 6. */
+  ecma_length_t position = ext_obj_p->u.pseudo_array.u1.iterator_index;
+
+  if (JERRY_UNLIKELY (position == ECMA_ITERATOR_INDEX_LIMIT))
+  {
+    return ecma_raise_range_error (ECMA_ERR_MSG ("String iteration cannot be continued."));
+  }
+
+  /* 7. */
+  ecma_length_t len = ecma_string_get_length (string_p);
+
+  /* 8. */
+  if (position >= len)
+  {
+    ecma_deref_ecma_string (string_p);
+    ext_obj_p->u.pseudo_array.u2.iterated_value = ECMA_VALUE_EMPTY;
+    return ecma_create_iter_result_object (ECMA_VALUE_UNDEFINED, ECMA_VALUE_TRUE);
+  }
+
+  /* 9. */
+  ecma_char_t first = ecma_string_get_char_at_pos (string_p, position);
+
+  ecma_string_t *result_str_p;
+  ecma_length_t result_size = 1;
+
+  /* 10. */
+  if (first < LIT_UTF16_HIGH_SURROGATE_MIN || first > LIT_UTF16_HIGH_SURROGATE_MAX || (position + 1 == len))
+  {
+    result_str_p = ecma_new_ecma_string_from_code_unit (first);
+  }
+  /* 11. */
+  else
+  {
+    /* 11.a */
+    ecma_char_t second = ecma_string_get_char_at_pos (string_p, (ecma_length_t) (position + 1));
+
+    /* 11.b */
+    if (second < LIT_UTF16_LOW_SURROGATE_MIN || second > LIT_UTF16_LOW_SURROGATE_MAX)
+    {
+      result_str_p = ecma_new_ecma_string_from_code_unit (first);
+    }
+    /* 11.c */
+    else
+    {
+      result_str_p = ecma_new_ecma_string_from_code_units (first, second);
+      result_size = 2;
+    }
+  }
+
+  /* 13. */
+  ext_obj_p->u.pseudo_array.u1.iterator_index = (uint16_t) (position + result_size);
+
+  /* 14. */
+  ecma_value_t result = ecma_create_iter_result_object (ecma_make_string_value (result_str_p), ECMA_VALUE_FALSE);
+  ecma_deref_ecma_string (result_str_p);
+
+  return result;
+} /* ecma_builtin_string_iterator_prototype_object_next */
+
+/**
+ * @}
+ * @}
+ * @}
+ */
+
+#endif /* ENABLED (JERRY_ES2015_BUILTIN_ITERATOR) */
@@ -0,0 +1,34 @@
+/* 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.
+ */
+
+/*
+ * %StringIteratorPrototype% built-in description
+ */
+
+#include "ecma-builtin-helpers-macro-defines.inc.h"
+
+#if ENABLED (JERRY_ES2015_BUILTIN_ITERATOR)
+
+STRING_VALUE (LIT_GLOBAL_SYMBOL_TO_STRING_TAG,
+              LIT_MAGIC_STRING_STRING_ITERATOR_UL,
+              ECMA_PROPERTY_FLAG_CONFIGURABLE)
+
+/* Routine properties:
+ *  (property name, C routine name, arguments number or NON_FIXED, value of the routine's length property) */
+ROUTINE (LIT_MAGIC_STRING_NEXT, ecma_builtin_string_iterator_prototype_object_next, 0, 0)
+
+#endif /* ENABLED (JERRY_ES2015_BUILTIN_ITERATOR) */
+
+#include "ecma-builtin-helpers-macro-undefs.inc.h"
@@ -23,6 +23,7 @@
 #include "ecma-gc.h"
 #include "ecma-globals.h"
 #include "ecma-helpers.h"
+#include "ecma-iterator-object.h"
 #include "ecma-objects.h"
 #include "ecma-string-object.h"
 #include "ecma-try-catch-macro.h"
@@ -2164,6 +2165,40 @@ ecma_builtin_string_prototype_object_substr (ecma_value_t this_arg, /**< this ar

 #endif /* ENABLED (JERRY_BUILTIN_ANNEXB) */

+#if ENABLED (JERRY_ES2015_BUILTIN_ITERATOR)
+/**
+ * The String.prototype object's @@iterator routine
+ *
+ * See also:
+ *          ECMA-262 v6, 21.1.3.27
+ *
+ * @return ecma value
+ *         Returned value must be freed with ecma_free_value.
+ */
+static ecma_value_t
+ecma_builtin_string_prototype_object_iterator (ecma_value_t this_arg) /**< this argument */
+{
+  ecma_value_t coercible = ecma_op_check_object_coercible (this_arg);
+
+  if (ECMA_IS_VALUE_ERROR (coercible))
+  {
+    return coercible;
+  }
+
+  ecma_value_t to_string = ecma_op_to_string (this_arg);
+
+  if (ECMA_IS_VALUE_ERROR (to_string))
+  {
+    return to_string;
+  }
+
+  return ecma_op_create_iterator_object (to_string,
+                                         ecma_builtin_get (ECMA_BUILTIN_ID_STRING_ITERATOR_PROTOTYPE),
+                                         ECMA_PSEUDO_STRING_ITERATOR,
+                                         0);
+} /* ecma_builtin_string_prototype_object_iterator */
+#endif /* ENABLED (JERRY_ES2015_BUILTIN_ITERATOR) */
+
 /**
 * @}
 * @}
@@ -67,6 +67,10 @@ ROUTINE (LIT_MAGIC_STRING_TRIM, ecma_builtin_string_prototype_object_trim, 0, 0)
 ROUTINE (LIT_MAGIC_STRING_SUBSTR, ecma_builtin_string_prototype_object_substr, 2, 2)
 #endif /* ENABLED (JERRY_BUILTIN_ANNEXB) */

+#if ENABLED (JERRY_ES2015_BUILTIN_ITERATOR)
+ROUTINE (LIT_GLOBAL_SYMBOL_ITERATOR, ecma_builtin_string_prototype_object_iterator, 0, 0)
+#endif /* ENABLED (JERRY_ES2015_BUILTIN_ITERATOR) */
+
 #endif /* ENABLED (JERRY_BUILTIN_STRING) */

 #include "ecma-builtin-helpers-macro-undefs.inc.h"
@@ -490,6 +490,13 @@ BUILTIN (ECMA_BUILTIN_ID_ARRAY_ITERATOR_PROTOTYPE,
         ECMA_BUILTIN_ID_ITERATOR_PROTOTYPE,
         true,
         array_iterator_prototype)
+
+/* The %StringIteratorPrototype% object (ECMA-262 v6, 22.1.5.2) */
+BUILTIN (ECMA_BUILTIN_ID_STRING_ITERATOR_PROTOTYPE,
+         ECMA_OBJECT_TYPE_GENERAL,
+         ECMA_BUILTIN_ID_ITERATOR_PROTOTYPE,
+         true,
+         string_iterator_prototype)
 #endif /* ENABLED (JERRY_ES2015_BUILTIN_ITERATOR) */

 #if ENABLED (JERRY_ES2015_BUILTIN_DATAVIEW)
@@ -138,10 +138,8 @@ ecma_op_create_iterator_object (ecma_value_t iterated_value, /**< value from cre
                                uint8_t extra_info) /**< extra information */
 {
  /* 1. */
-  JERRY_ASSERT (ecma_is_value_object (iterated_value));
  JERRY_ASSERT (iterator_type >= ECMA_PSEUDO_ARRAY_ITERATOR && iterator_type <= ECMA_PSEUDO_ARRAY__MAX);

-  ecma_object_t *iterated_obj_p = ecma_get_object_from_value (iterated_value);
  /* 2. */
  ecma_object_t *object_p = ecma_create_object (prototype_obj_p,
                                                sizeof (ecma_extended_object_t),
@@ -151,7 +149,7 @@ ecma_op_create_iterator_object (ecma_value_t iterated_value, /**< value from cre
  ext_obj_p->u.pseudo_array.type = iterator_type;

  /* 3. */
-  ECMA_SET_NON_NULL_POINTER (ext_obj_p->u.pseudo_array.u2.iterated_value_cp, iterated_obj_p);
+  ext_obj_p->u.pseudo_array.u2.iterated_value = iterated_value;
  /* 4. */
  ext_obj_p->u.pseudo_array.u1.iterator_index = 0;
  /* 5. */
@@ -1943,6 +1943,12 @@ ecma_object_get_class_name (ecma_object_t *obj_p) /**< object */
        {
          return LIT_MAGIC_STRING_ARRAY_ITERATOR_UL;
        }
+#endif /* ENABLED (JERRY_ES2015_BUILTIN_ITERATOR) */
+#if ENABLED (JERRY_ES2015_BUILTIN_ITERATOR)
+        case ECMA_PSEUDO_STRING_ITERATOR:
+        {
+          return LIT_MAGIC_STRING_STRING_ITERATOR_UL;
+        }
 #endif /* ENABLED (JERRY_ES2015_BUILTIN_ITERATOR) */
        default:
        {
@@ -651,6 +651,9 @@ LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_SET_PROTOTYPE_OF_UL, "setPrototypeOf")
 LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_SET_UTC_FULL_YEAR_UL, "setUTCFullYear")
 #endif
 LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_TO_LOCALE_STRING_UL, "toLocaleString")
+#if ENABLED (JERRY_ES2015_BUILTIN_ITERATOR)
+LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_STRING_ITERATOR_UL, "String Iterator")
+#endif
 #if ENABLED (JERRY_BUILTIN_DATE)
 LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_GET_MILLISECONDS_UL, "getMilliseconds")
 LIT_MAGIC_STRING_DEF (LIT_MAGIC_STRING_SET_MILLISECONDS_UL, "setMilliseconds")
@@ -778,7 +781,9 @@ LIT_MAGIC_STRING_FIRST_STRING_WITH_SIZE (14, LIT_MAGIC_STRING_REFERENCE_ERROR_UL
 #else
 LIT_MAGIC_STRING_FIRST_STRING_WITH_SIZE (14, LIT_MAGIC_STRING_DEFINE_PROPERTY_UL)
 #endif
-#if ENABLED (JERRY_BUILTIN_DATE)
+#if ENABLED (JERRY_ES2015_BUILTIN_ITERATOR)
+LIT_MAGIC_STRING_FIRST_STRING_WITH_SIZE (15, LIT_MAGIC_STRING_STRING_ITERATOR_UL)
+#elif ENABLED (JERRY_BUILTIN_DATE)
 LIT_MAGIC_STRING_FIRST_STRING_WITH_SIZE (15, LIT_MAGIC_STRING_GET_MILLISECONDS_UL)
 #else
 LIT_MAGIC_STRING_FIRST_STRING_WITH_SIZE (15, LIT_MAGIC_STRING_DEFINE_PROPERTIES_UL)
@@ -289,6 +289,7 @@ LIT_MAGIC_STRING_HAS_OWN_PROPERTY_UL = "hasOwnProperty"
 LIT_MAGIC_STRING_SET_PROTOTYPE_OF_UL = "setPrototypeOf"
 LIT_MAGIC_STRING_SET_UTC_FULL_YEAR_UL = "setUTCFullYear"
 LIT_MAGIC_STRING_TO_LOCALE_STRING_UL = "toLocaleString"
+LIT_MAGIC_STRING_STRING_ITERATOR_UL = "String Iterator"
 LIT_MAGIC_STRING_GET_MILLISECONDS_UL = "getMilliseconds"
 LIT_MAGIC_STRING_SET_MILLISECONDS_UL = "setMilliseconds"
 LIT_MAGIC_STRING_DEFINE_PROPERTIES_UL = "defineProperties"
@@ -0,0 +1,77 @@
+// 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.
+
+try {
+  String.prototype[Symbol.iterator].call(undefined);
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+try {
+  String.prototype[Symbol.iterator].call(Symbol('foo'));
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+var str = 'foobar';
+var iterator = str[Symbol.iterator]();
+
+try {
+  iterator.next.call(5);
+  assert (false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+try {
+  iterator.next.call({});
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+var str = 'Example string.';
+var expected = ['E', 'x', 'a', 'm', 'p', 'l', 'e', ' ', 's', 't', 'r', 'i', 'n', 'g', '.'];
+
+var iterator = str[Symbol.iterator]();
+var next = iterator.next();
+var idx = 0;
+
+while (!next.done) {
+  assert(next.value === expected[idx++]);
+  assert(next.done === false);
+  next = iterator.next();
+}
+
+assert(next.value === undefined);
+
+var str = '^o𓙦һR񼴆]ŭ媖?᯾豼עW򏋁';
+var expected = ['^', 'o', '𓙦', 'һ', 'R', '񼴆', ']', 'ŭ', '媖', '?', '᯾', '豼', 'ע', 'W', '򏋁'];
+
+iterator = str[Symbol.iterator]();
+next = iterator.next();
+idx = 0;
+
+while (!next.done) {
+  assert(next.value === expected[idx++]);
+  assert(next.done === false);
+  next = iterator.next();
+}
+
+assert(next.value === undefined);
+
+assert(iterator.toString() === '[object String Iterator]');
+assert(iterator[Symbol.toStringTag] === 'String Iterator');