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| 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 === "") { |
| 33 fillString = " "; |
| 34 } |
| 35 } |
| 36 |
| 37 var fillLength = maxLength - stringLength; |
| 38 var repetitions = (fillLength / fillString.length) | 0; |
| 39 var remainingChars = (fillLength - fillString.length * repetitions) | 0; |
| 40 |
| 41 var filler = ""; |
| 42 while (true) { |
| 43 if (repetitions & 1) filler += fillString; |
| 44 repetitions >>= 1; |
| 45 if (repetitions === 0) break; |
| 46 fillString += fillString; |
| 47 } |
| 48 |
| 49 if (remainingChars) { |
| 50 filler += %_SubString(fillString, 0, remainingChars); |
| 51 } |
| 52 |
| 53 return filler; |
| 54 } |
| 55 |
| 56 function StringPadStart(maxLength, fillString) { |
| 57 CHECK_OBJECT_COERCIBLE(this, "String.prototype.padStart") |
| 58 var thisString = TO_STRING(this); |
| 59 |
| 60 return StringPad(thisString, maxLength, fillString) + thisString; |
| 61 } |
| 62 %FunctionSetLength(StringPadStart, 1); |
| 63 |
| 64 function StringPadEnd(maxLength, fillString) { |
| 65 CHECK_OBJECT_COERCIBLE(this, "String.prototype.padEnd") |
| 66 var thisString = TO_STRING(this); |
| 67 |
| 68 return thisString + StringPad(thisString, maxLength, fillString); |
| 69 } |
| 70 %FunctionSetLength(StringPadEnd, 1); |
| 71 |
| 72 utils.InstallFunctions(GlobalString.prototype, DONT_ENUM, [ |
| 73 "padStart", StringPadStart, |
| 74 "padEnd", StringPadEnd |
| 75 ]); |
| 76 |
| 77 }); |
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