Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 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 | |
| 12 | var GlobalString = global.String; |
| 13 | var MakeTypeError; |
| 14 | |
| 15 | utils.Import(function(from) { |
| 16 | MakeTypeError = from.MakeTypeError; |
| 17 | }); |
| 18 | |
| 19 | // ------------------------------------------------------------------- |
| 20 | // http://tc39.github.io/proposal-string-pad-start-end/ |
| 21 | |
| 22 | function 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 === "") { |
Ben Murdoch | c561043 | 2016-08-08 18:44:38 +0100 | [diff] [blame^] | 33 | // If filler is the empty String, return S. |
| 34 | return ""; |
Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 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 | |
| 57 | function 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 | |
| 65 | function 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 | |
| 73 | utils.InstallFunctions(GlobalString.prototype, DONT_ENUM, [ |
| 74 | "padStart", StringPadStart, |
| 75 | "padEnd", StringPadEnd |
| 76 | ]); |
| 77 | |
| 78 | }); |