text: // Copyright 2014 the V8 project authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  'use strict';
  
  // This file relies on the fact that the following declaration has been made
  // in runtime.js:
  // var $String = global.String;
  // var $Array = global.Array;
  
  // -------------------------------------------------------------------
  
  // ES6 draft 01-20-14, section 21.1.3.13
  function StringRepeat(count) {
    CHECK_OBJECT_COERCIBLE(this, "String.prototype.repeat");
  
    var s = TO_STRING_INLINE(this);
    var n = ToInteger(count);
    // The maximum string length is stored in a smi, so a longer repeat
    // must result in a range error.
    if (n < 0 || n > %_MaxSmi()) {
      throw MakeRangeError("invalid_count_value", []);
    }
  
    var r = "";
    while (true) {
      if (n & 1) r += s;
      n >>= 1;
      if (n === 0) return r;
      s += s;
    }
  }
  
  
  // ES6 draft 04-05-14, section 21.1.3.18
  function StringStartsWith(searchString /* position */) {  // length == 1
    CHECK_OBJECT_COERCIBLE(this, "String.prototype.startsWith");
  
    var s = TO_STRING_INLINE(this);
  
    if (IS_REGEXP(searchString)) {
      throw MakeTypeError("first_argument_not_regexp",
                          ["String.prototype.startsWith"]);
    }
  
    var ss = TO_STRING_INLINE(searchString);
    var pos = 0;
    if (%_ArgumentsLength() > 1) {
      pos = %_Arguments(1);  // position
      pos = ToInteger(pos);
    }
  
    var s_len = s.length;
    var start = MathMin(MathMax(pos, 0), s_len);
    var ss_len = ss.length;
    if (ss_len + start > s_len) {
      return false;
    }
  
    return %StringIndexOf(s, ss, start) === start;
  }
  
  
  // ES6 draft 04-05-14, section 21.1.3.7
  function StringEndsWith(searchString /* position */) {  // length == 1
    CHECK_OBJECT_COERCIBLE(this, "String.prototype.endsWith");
  
    var s = TO_STRING_INLINE(this);
  
    if (IS_REGEXP(searchString)) {
      throw MakeTypeError("first_argument_not_regexp",
                          ["String.prototype.endsWith"]);
    }
  
    var ss = TO_STRING_INLINE(searchString);
    var s_len = s.length;
    var pos = s_len;
    if (%_ArgumentsLength() > 1) {
      var arg = %_Arguments(1);  // position
      if (!IS_UNDEFINED(arg)) {
        pos = ToInteger(arg);
      }
    }
  
    var end = MathMin(MathMax(pos, 0), s_len);
    var ss_len = ss.length;
    var start = end - ss_len;
    if (start < 0) {
      return false;
    }
  
    return %StringLastIndexOf(s, ss, start) === start;
  }
  
  
  // ES6 draft 04-05-14, section 21.1.3.6
  function StringIncludes(searchString /* position */) {  // length == 1
    CHECK_OBJECT_COERCIBLE(this, "String.prototype.includes");
  
    var s = TO_STRING_INLINE(this);
  
    if (IS_REGEXP(searchString)) {
      throw MakeTypeError("first_argument_not_regexp",
                          ["String.prototype.includes"]);
    }
  
    var ss = TO_STRING_INLINE(searchString);
    var pos = 0;
    if (%_ArgumentsLength() > 1) {
      pos = %_Arguments(1);  // position
      pos = ToInteger(pos);
    }
  
    var s_len = s.length;
    var start = MathMin(MathMax(pos, 0), s_len);
    var ss_len = ss.length;
    if (ss_len + start > s_len) {
      return false;
    }
  
    return %StringIndexOf(s, ss, start) !== -1;
  }
  
  
  // ES6 Draft 05-22-2014, section 21.1.3.3
  function StringCodePointAt(pos) {
    CHECK_OBJECT_COERCIBLE(this, "String.prototype.codePointAt");
  
    var string = TO_STRING_INLINE(this);
    var size = string.length;
    pos = TO_INTEGER(pos);
    if (pos < 0 || pos >= size) {
      return UNDEFINED;
    }
    var first = %_StringCharCodeAt(string, pos);
    if (first < 0xD800 || first > 0xDBFF || pos + 1 == size) {
      return first;
    }
    var second = %_StringCharCodeAt(string, pos + 1);
    if (second < 0xDC00 || second > 0xDFFF) {
      return first;
    }
    return (first - 0xD800) * 0x400 + second + 0x2400;
  }
  
  
  // ES6 Draft 05-22-2014, section 21.1.2.2
  function StringFromCodePoint(_) {  // length = 1
    var code;
    var length = %_ArgumentsLength();
    var index;
    var result = "";
    for (index = 0; index < length; index++) {
      code = %_Arguments(index);
      if (!%_IsSmi(code)) {
        code = ToNumber(code);
      }
      if (code < 0 || code > 0x10FFFF || code !== TO_INTEGER(code)) {
        throw MakeRangeError("invalid_code_point", [code]);
      }
      if (code <= 0xFFFF) {
        result += %_StringCharFromCode(code);
      } else {
        code -= 0x10000;
        result += %_StringCharFromCode((code >>> 10) & 0x3FF | 0xD800);
        result += %_StringCharFromCode(code & 0x3FF | 0xDC00);
      }
    }
    return result;
  }
  
  
  // -------------------------------------------------------------------
  
  function ExtendStringPrototype() {
    %CheckIsBootstrapping();
  
    // Set up the non-enumerable functions on the String object.
    InstallFunctions($String, DONT_ENUM, $Array(
      "fromCodePoint", StringFromCodePoint
    ));
  
    // Set up the non-enumerable functions on the String prototype object.
    InstallFunctions($String.prototype, DONT_ENUM, $Array(
      "codePointAt", StringCodePointAt,
      "includes", StringIncludes,
      "endsWith", StringEndsWith,
      "repeat", StringRepeat,
      "startsWith", StringStartsWith
    ));
  }
  
  ExtendStringPrototype();
  