Implement String.prototype.charAt()

JerryScript-DCO-1.0-Signed-off-by: Laszlo Vidacs lvidacs.u-szeged@partner.samsung.com

Author: lvidacs

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

@@ -112,7 +112,47 @@ static ecma_completion_value_t
 ecma_builtin_string_prototype_object_char_at (ecma_value_t this_arg, /**< this argument */
                                               ecma_value_t arg) /**< routine's argument */
 {
-  ECMA_BUILTIN_CP_UNIMPLEMENTED (this_arg, arg);
+  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);
+
+  /* 4 */
+  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);
+
+  /* 3 */
+  ECMA_OP_TO_NUMBER_TRY_CATCH (index_num,
+                               arg,
+                               ret_value);
+
+  /* 5 */
+  if (index_num < 0 || index_num >= len || !len)
+  {
+    ret_value = ecma_make_normal_completion_value (ecma_make_string_value (
+                                                   ecma_get_magic_string (LIT_MAGIC_STRING__EMPTY)));
+  }
+  else
+  {
+    /* 6 */
+    ecma_char_t new_ecma_char = ecma_string_get_char_at_pos (original_string_p, ecma_number_to_uint32 (index_num));
+    ret_value = ecma_make_normal_completion_value (ecma_make_string_value (
+                                                   ecma_new_ecma_string_from_code_unit (new_ecma_char)));
+  }
+
+  ECMA_OP_TO_NUMBER_FINALIZE (index_num);
+
+  ECMA_FINALIZE (to_string_val);
+  ECMA_FINALIZE (check_coercible_val);
+
+  return ret_value;
 } /* ecma_builtin_string_prototype_object_char_at */
 
 /**

tests/jerry/string-prototype-charat.js

@@ -0,0 +1,103 @@
+// 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.charAt, 'length').configurable === false);
+
+assert(Object.getOwnPropertyDescriptor(String.prototype.charAt, 'length').enumerable === false);
+
+assert(Object.getOwnPropertyDescriptor(String.prototype.charAt, 'length').writable === false);
+
+assert(String.prototype.charAt.length === 1);
+
+// check empty string
+assert(String.prototype.charAt.call(new String()) === "");
+
+// check NaN
+assert("hello world!".charAt(NaN) === "h");
+
+// check Object
+assert(String.prototype.charAt.call({})  === "[");
+
+// simple checks
+assert("hello world!".charAt(0) === "h");
+
+assert("hello world!".charAt(1) === "e");
+
+// check +-Inf
+assert("hello world!".charAt(-Infinity) === "");
+
+assert("hello world!".charAt(Infinity) === "");
+
+assert("hello world!".charAt(11) === "!");
+
+assert("hello world!".charAt(12) === "");
+
+// check negative
+assert("hello world!".charAt(-1) === "");
+
+assert("hello world!".charAt(-9999999) === "");
+
+assert("hello world!".charAt(-0) === "h");
+
+// check undefined
+assert("hello world!".charAt(undefined) === "h");
+
+// check booleans
+assert("hello world!".charAt(true) === "e");
+
+assert("hello world!".charAt(false) === "h");
+
+// check this is undefined
+try {
+  String.prototype.charAt.call(undefined);
+  assert(false);
+} catch(e) {
+  assert(e instanceof TypeError);
+}
+
+// check this is null
+try {
+  String.prototype.charAt.call(null);
+  assert(false);
+} catch(e) {
+  assert(e instanceof TypeError);
+}
+
+// check coercible - undefined
+try {
+  assert(true.charAt() === "");
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+// check coercible - null
+try {
+  assert(String.prototype.charAt.call(null, 0) === "");
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+// check coercible - Boolean
+assert(String.prototype.charAt.call(true, 1) === "r");
+
+// check coercible - Object
+var test_object = {firstName:"John", lastName:"Doe"};
+assert(String.prototype.charAt.call(test_object, 1) === "o");
+
+// check coercible - Number
+assert(String.prototype.charAt.call(123, 2) === "3");