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// 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;
// -------------------------------------------------------------------
// 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
]);
});
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