Index: src/js/harmony-string-padding.js |
diff --git a/src/js/harmony-string-padding.js b/src/js/harmony-string-padding.js |
new file mode 100644 |
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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; |
+var MakeTypeError; |
+ |
+utils.Import(function(from) { |
+ MakeTypeError = from.MakeTypeError; |
+}); |
+ |
+// ------------------------------------------------------------------- |
+// http://tc39.github.io/proposal-string-pad-start-end/ |
+ |
+macro STRING_PAD_COMMON(NAME, MAXLENGTH, FILLSTRING, S, FILLER) |
Dan Ehrenberg
2016/03/23 15:59:50
Can you use a function rather than a macro here?
caitp (gmail)
2016/03/23 17:00:41
I've made a function for the "repeat the filler" s
Dan Ehrenberg
2016/03/23 17:30:17
I think there could be a middle point here, which
caitp (gmail)
2016/03/23 20:45:45
done
|
+ CHECK_OBJECT_COERCIBLE(this, "String.prototype.NAME") |
+ |
+ var S = TO_STRING(TO_OBJECT(this)); |
+ MAXLENGTH = TO_LENGTH(maxLength); |
+ var stringLength = S.length; |
+ |
+ if (MAXLENGTH <= stringLength) return S; |
+ |
+ if (IS_UNDEFINED(FILLSTRING)) { |
+ FILLSTRING = " "; |
+ } else { |
+ FILLSTRING = TO_STRING(FILLSTRING); |
+ if (FILLSTRING === "") { |
+ FILLSTRING = " "; |
+ } |
+ } |
+ |
+ 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); |
+ } |
+endmacro |
+ |
+function StringPadStart(maxLength, fillString) { |
+ STRING_PAD_COMMON(padStart, maxLength, fillString, S, filler) |
+ return filler + S; |
+} |
+%FunctionSetLength(StringPadStart, 1); |
+ |
+function StringPadEnd(maxLength, fillString) { |
+ STRING_PAD_COMMON(padEnd, maxLength, fillString, S, filler) |
+ return S + filler; |
+} |
+%FunctionSetLength(StringPadEnd, 1); |
+ |
+utils.InstallFunctions(GlobalString.prototype, DONT_ENUM, [ |
+ "padStart", StringPadStart, |
+ "padEnd", StringPadEnd |
+]); |
+ |
+}); |