1// Copyright 2016 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5(function(global, utils) {
6
7%CheckIsBootstrapping();
8
9// -------------------------------------------------------------------
10// Imports
11
12var GlobalString = global.String;
13
14// -------------------------------------------------------------------
15// http://tc39.github.io/proposal-string-pad-start-end/
16
17function StringPad(thisString, maxLength, fillString) {
18  maxLength = TO_LENGTH(maxLength);
19  var stringLength = thisString.length;
20
21  if (maxLength <= stringLength) return "";
22
23  if (IS_UNDEFINED(fillString)) {
24    fillString = " ";
25  } else {
26    fillString = TO_STRING(fillString);
27    if (fillString === "") {
28      // If filler is the empty String, return S.
29      return "";
30    }
31  }
32
33  var fillLength = maxLength - stringLength;
34  var repetitions = (fillLength / fillString.length) | 0;
35  var remainingChars = (fillLength - fillString.length * repetitions) | 0;
36
37  var filler = "";
38  while (true) {
39    if (repetitions & 1) filler += fillString;
40    repetitions >>= 1;
41    if (repetitions === 0) break;
42    fillString += fillString;
43  }
44
45  if (remainingChars) {
46    filler += %_SubString(fillString, 0, remainingChars);
47  }
48
49  return filler;
50}
51
52function StringPadStart(maxLength, fillString) {
53  CHECK_OBJECT_COERCIBLE(this, "String.prototype.padStart")
54  var thisString = TO_STRING(this);
55
56  return StringPad(thisString, maxLength, fillString) + thisString;
57}
58%FunctionSetLength(StringPadStart, 1);
59
60function StringPadEnd(maxLength, fillString) {
61  CHECK_OBJECT_COERCIBLE(this, "String.prototype.padEnd")
62  var thisString = TO_STRING(this);
63
64  return thisString + StringPad(thisString, maxLength, fillString);
65}
66%FunctionSetLength(StringPadEnd, 1);
67
68utils.InstallFunctions(GlobalString.prototype, DONT_ENUM, [
69  "padStart", StringPadStart,
70  "padEnd", StringPadEnd
71]);
72
73});
74