| // Copyright 2016 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. |
| |
| (function(global, utils) { |
| |
| %CheckIsBootstrapping(); |
| |
| // ------------------------------------------------------------------- |
| // Imports |
| |
| var GlobalString = global.String; |
| var MakeTypeError; |
| |
| utils.Import(function(from) { |
| MakeTypeError = from.MakeTypeError; |
| }); |
| |
| // ------------------------------------------------------------------- |
| // http://tc39.github.io/proposal-string-pad-start-end/ |
| |
| function StringPad(thisString, maxLength, fillString) { |
| maxLength = TO_LENGTH(maxLength); |
| var stringLength = thisString.length; |
| |
| if (maxLength <= stringLength) return ""; |
| |
| if (IS_UNDEFINED(fillString)) { |
| fillString = " "; |
| } else { |
| fillString = TO_STRING(fillString); |
| if (fillString === "") { |
| // If filler is the empty String, return S. |
| return ""; |
| } |
| } |
| |
| var fillLength = maxLength - stringLength; |
| var repetitions = (fillLength / fillString.length) | 0; |
| var remainingChars = (fillLength - fillString.length * repetitions) | 0; |
| |
| var filler = ""; |
| while (true) { |
| if (repetitions & 1) filler += fillString; |
| repetitions >>= 1; |
| if (repetitions === 0) break; |
| fillString += fillString; |
| } |
| |
| if (remainingChars) { |
| filler += %_SubString(fillString, 0, remainingChars); |
| } |
| |
| return filler; |
| } |
| |
| function StringPadStart(maxLength, fillString) { |
| CHECK_OBJECT_COERCIBLE(this, "String.prototype.padStart") |
| var thisString = TO_STRING(this); |
| |
| return StringPad(thisString, maxLength, fillString) + thisString; |
| } |
| %FunctionSetLength(StringPadStart, 1); |
| |
| function StringPadEnd(maxLength, fillString) { |
| CHECK_OBJECT_COERCIBLE(this, "String.prototype.padEnd") |
| var thisString = TO_STRING(this); |
| |
| return thisString + StringPad(thisString, maxLength, fillString); |
| } |
| %FunctionSetLength(StringPadEnd, 1); |
| |
| utils.InstallFunctions(GlobalString.prototype, DONT_ENUM, [ |
| "padStart", StringPadStart, |
| "padEnd", StringPadEnd |
| ]); |
| |
| }); |