Implement String.prototype.substring()

JerryScript-DCO-1.0-Signed-off-by: Laszlo Vidacs [email protected]

Author: lvidacs

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

@@ -325,6 +325,47 @@ ecma_builtin_helper_array_index_normalize (ecma_number_t index, /**< index */
   return norm_index;
 } /* ecma_builtin_helper_array_index_normalize */
 
+/**
+ * Helper function to normalizing a string index
+ *
+ * This function clamps the given index to the [0, length] range.
+ * If the index is negative, 0 value is used.
+ * If the index is greater than the length of the string, the normalized index will be the length of the string.
+ *
+ * See also:
+ *          ECMA-262 v5, 15.5.4.15
+ *
+ * Used by:
+ *         - The String.prototype.substring routine.
+ *
+ * @return uint32_t - the normalized value of the index
+ */
+uint32_t
+ecma_builtin_helper_string_index_normalize (ecma_number_t index, /**< index */
+                                            uint32_t length) /**< string's length */
+{
+  uint32_t norm_index = 0;
+
+  if (!ecma_number_is_nan (index) && !ecma_number_is_negative (index))
+  {
+    if (ecma_number_is_infinity (index))
+    {
+      norm_index = length;
+    }
+    else
+    {
+      norm_index = ecma_number_to_uint32 (index);
+
+      if (norm_index > length)
+      {
+        norm_index = length;
+      }
+    }
+  }
+
+  return norm_index;
+} /* ecma_builtin_helper_string_index_normalize */
+
 /**
  * @}
  * @}

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

@@ -31,6 +31,7 @@ extern ecma_completion_value_t ecma_builtin_helper_get_to_locale_string_at_index
 extern ecma_completion_value_t ecma_builtin_helper_object_get_properties (ecma_object_t *obj,
                                                                           bool only_enumerable_properties);
 extern uint32_t ecma_builtin_helper_array_index_normalize (ecma_number_t index, uint32_t length);
+extern uint32_t ecma_builtin_helper_string_index_normalize (ecma_number_t index, uint32_t length);
 
 #ifndef CONFIG_ECMA_COMPACT_PROFILE_DISABLE_DATE_BUILTIN
 /* ecma-builtin-helpers-date.cpp */

jerry-core/ecma/builtin-objects/ecma-builtin-string-prototype.cpp

@@ -442,7 +442,69 @@ ecma_builtin_string_prototype_object_substring (ecma_value_t this_arg, /**< this
                                                 ecma_value_t arg1, /**< routine's first argument */
                                                 ecma_value_t arg2) /**< routine's second argument */
 {
-  ECMA_BUILTIN_CP_UNIMPLEMENTED (this_arg, arg1, arg2);
+  ecma_completion_value_t ret_value = ecma_make_empty_completion_value ();
+
+  /* 1 */
+  ECMA_TRY_CATCH (check_coercible_val,
+                  ecma_op_check_object_coercible (this_arg),
+                  ret_value);
+
+  /* 2 */
+  ECMA_TRY_CATCH (to_string_val,
+                  ecma_op_to_string (this_arg),
+                  ret_value);
+
+  /* 3 */
+  ecma_string_t *original_string_p = ecma_get_string_from_value (to_string_val);
+
+  const ecma_length_t len = ecma_string_get_length (original_string_p);
+
+  /* 4, 6 */
+  ECMA_OP_TO_NUMBER_TRY_CATCH (start_num,
+                               arg1,
+                               ret_value);
+
+  ecma_length_t start = 0, end = len;
+
+  start = ecma_builtin_helper_string_index_normalize (start_num, len);
+
+  /* 5, 7 */
+  if (ecma_is_value_undefined (arg2))
+  {
+    end = len;
+  }
+  else
+  {
+    ECMA_OP_TO_NUMBER_TRY_CATCH (end_num,
+                                 arg2,
+                                 ret_value);
+
+    end = ecma_builtin_helper_string_index_normalize (end_num, len);
+
+    ECMA_OP_TO_NUMBER_FINALIZE (end_num);
+  }
+
+  if (ecma_is_completion_value_empty (ret_value))
+  {
+    JERRY_ASSERT (start <= len && end <= len);
+
+    /* 8 */
+    uint32_t from = start < end ? start : end;
+
+    /* 9 */
+    uint32_t to = start > end ? start : end;
+
+    /* 10 */
+    ecma_string_t *new_str_p = ecma_string_substr (original_string_p, from, to);
+    ret_value = ecma_make_normal_completion_value (ecma_make_string_value (new_str_p));
+  }
+
+  ECMA_OP_TO_NUMBER_FINALIZE (start_num);
+
+  ECMA_FINALIZE (to_string_val);
+  ECMA_FINALIZE (check_coercible_val);
+
+  return ret_value;
 } /* ecma_builtin_string_prototype_object_substring */
 
 /**

tests/jerry/string-prototype-substring.js

@@ -0,0 +1,140 @@
+// Copyright 2015 Samsung Electronics Co., Ltd.
+// Copyright 2015 University of Szeged.
+//
+// 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.
+
+// check properties
+assert(Object.getOwnPropertyDescriptor(String.prototype.substring, 'length').configurable === false);
+
+assert(Object.getOwnPropertyDescriptor(String.prototype.substring, 'length').enumerable === false);
+
+assert(Object.getOwnPropertyDescriptor(String.prototype.substring, 'length').writable === false);
+
+assert(String.prototype.substring.length === 2);
+
+assert(String.prototype.substring.call(new String()) === "");
+
+assert(String.prototype.substring.call({}) === "[object Object]");
+
+// check this is undefined
+try {
+  String.prototype.substring.call(undefined);
+  assert(false);
+} catch(e) {
+  assert(e instanceof TypeError);
+}
+
+// check this is null
+try {
+  String.prototype.substring.call(null);
+  assert(false);
+} catch(e) {
+  assert(e instanceof TypeError);
+}
+
+// simple checks
+assert("hello world!".substring(0, 11) === "hello world");
+
+assert("hello world!".substring(11, 0) === "hello world");
+
+assert("hello world!".substring(0, 12) === "hello world!");
+
+assert("hello world!".substring(12, 0) === "hello world!");
+
+// check NaN
+assert("hello world!".substring(NaN, 12) === "hello world!");
+
+// check NaN
+assert("hello world!".substring(2, NaN) === "he");
+
+// check end undefined
+assert("hello world!".substring(2, undefined) === "llo world!");
+
+// check negative
+assert("hello world!".substring(-1,8) === "hello wo");
+
+// check negative
+assert("hello\tworld!".substring(5,-8) === "hello");
+
+// check negative
+assert("hello world!".substring(-1,-8) === "");
+
+// check ranges
+assert("hello world!".substring(-1,10000) === "hello world!");
+
+assert("hello world!".substring(10000,1000000) === "");
+
+assert("hello world!".substring(100000,1) === "ello world!");
+
+// check both undefined
+assert("hello world!".substring(undefined, undefined) === "hello world!");
+
+var undef_var;
+assert("hello world!".substring(undef_var, undef_var) === "hello world!");
+
+// check integer conversion
+assert("hello world!".substring(undefined, 5) === "hello");
+
+assert("hello world!".substring(undefined, "bar") === "");
+
+assert("hello world!".substring(2, true) === "e");
+
+assert("hello world!".substring(2, false) === "he");
+
+assert("hello world!".substring(5, obj) === " world!");
+
+// check other objects
+var obj = { substring : String.prototype.substring }
+
+obj.toString = function() {
+    return "Iam";
+}
+assert(obj.substring(100000,1) === "am");
+
+obj.toString = function() {
+  throw new ReferenceError ("foo");
+};
+
+try {
+  assert(obj.substring(100000,1));
+  assert(false);
+} catch (e) {
+  assert(e.message === "foo");
+  assert(e instanceof ReferenceError);
+}
+
+// check coercible - undefined
+try {
+  assert(true.substring() === "");
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+// check coercible - null
+try {
+  assert(String.prototype.substring.call(null, 0, 1) === "");
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+// check coercible - Boolean
+assert(String.prototype.substring.call(true, 0, 1) === "t");
+
+// check coercible - Object
+var test_object = {firstName:"John", lastName:"Doe"};
+assert(String.prototype.substring.call(test_object, 0, 7) === "[object");
+
+// check coercible - Number
+assert(String.prototype.substring.call(123, 0, 3) === "123");