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;
13var MakeTypeError;
14
15utils.Import(function(from) {
16  MakeTypeError = from.MakeTypeError;
17});
18
19// -------------------------------------------------------------------
20// http://tc39.github.io/proposal-string-pad-start-end/
21
22function StringPad(thisString, maxLength, fillString) {
23  maxLength = TO_LENGTH(maxLength);
24  var stringLength = thisString.length;
25
26  if (maxLength <= stringLength) return "";
27
28  if (IS_UNDEFINED(fillString)) {
29    fillString = " ";
30  } else {
31    fillString = TO_STRING(fillString);
32    if (fillString === "") {
33      // If filler is the empty String, return S.
34      return "";
35    }
36  }
37
38  var fillLength = maxLength - stringLength;
39  var repetitions = (fillLength / fillString.length) | 0;
40  var remainingChars = (fillLength - fillString.length * repetitions) | 0;
41
42  var filler = "";
43  while (true) {
44    if (repetitions & 1) filler += fillString;
45    repetitions >>= 1;
46    if (repetitions === 0) break;
47    fillString += fillString;
48  }
49
50  if (remainingChars) {
51    filler += %_SubString(fillString, 0, remainingChars);
52  }
53
54  return filler;
55}
56
57function StringPadStart(maxLength, fillString) {
58  CHECK_OBJECT_COERCIBLE(this, "String.prototype.padStart")
59  var thisString = TO_STRING(this);
60
61  return StringPad(thisString, maxLength, fillString) + thisString;
62}
63%FunctionSetLength(StringPadStart, 1);
64
65function StringPadEnd(maxLength, fillString) {
66  CHECK_OBJECT_COERCIBLE(this, "String.prototype.padEnd")
67  var thisString = TO_STRING(this);
68
69  return thisString + StringPad(thisString, maxLength, fillString);
70}
71%FunctionSetLength(StringPadEnd, 1);
72
73utils.InstallFunctions(GlobalString.prototype, DONT_ENUM, [
74  "padStart", StringPadStart,
75  "padEnd", StringPadEnd
76]);
77
78});
79