Add trim, trimLeft and trimRight methods to String

Based on a recent patch for Webkit.
trim is defined in ES 5 section 15.5.4.20.

Author: Jan de Mooij <jandemooij@gmail.com>


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3052 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/runtime.cc

@@ -3584,6 +3584,36 @@ static Object* Runtime_StringToUpperCase(Arguments args) {
   return ConvertCase<unibrow::ToUppercase>(args, &to_upper_mapping);
 }
 
+static inline bool IsTrimWhiteSpace(unibrow::uchar c) {
+  return unibrow::WhiteSpace::Is(c) || c == 0x200b;
+}
+
+static Object* Runtime_StringTrim(Arguments args) {
+  NoHandleAllocation ha;
+  ASSERT(args.length() == 3);
+
+  CONVERT_CHECKED(String, s, args[0]);
+  CONVERT_BOOLEAN_CHECKED(trimLeft, args[1]);
+  CONVERT_BOOLEAN_CHECKED(trimRight, args[2]);
+
+  s->TryFlattenIfNotFlat();
+  int length = s->length();
+
+  int left = 0;
+  if (trimLeft) {
+    while (left < length && IsTrimWhiteSpace(s->Get(left))) {
+      left++;
+    }
+  }
+
+  int right = length;
+  if (trimRight) {
+    while (right > left && IsTrimWhiteSpace(s->Get(right - 1))) {
+      right--;
+    }
+  }
+  return s->Slice(left, right);
+}
 
 bool Runtime::IsUpperCaseChar(uint16_t ch) {
   unibrow::uchar chars[unibrow::ToUppercase::kMaxWidth];

src/runtime.h

@@ -152,6 +152,7 @@ namespace internal {
   F(StringSlice, 3, 1) \
   F(StringReplaceRegExpWithString, 4, 1) \
   F(StringMatch, 3, 1) \
+  F(StringTrim, 3, 1) \
   \
   /* Numbers */ \
   F(NumberToRadixString, 2, 1) \

src/string.js

@@ -680,6 +680,18 @@ function StringToLocaleUpperCase() {
   return %StringToUpperCase(ToString(this));
 }
 
+// ES5, 15.5.4.20
+function StringTrim() {
+  return %StringTrim(ToString(this), true, true);
+}
+
+function StringTrimLeft() {
+  return %StringTrim(ToString(this), true, false);
+}
+
+function StringTrimRight() {
+  return %StringTrim(ToString(this), false, true);
+}
 
 // ECMA-262, section 15.5.3.2
 function StringFromCharCode(code) {
@@ -855,6 +867,9 @@ function SetupString() {
     "toLocaleLowerCase", StringToLocaleLowerCase,
     "toUpperCase", StringToUpperCase,
     "toLocaleUpperCase", StringToLocaleUpperCase,
+    "trim", StringTrim,
+    "trimLeft", StringTrimLeft,
+    "trimRight", StringTrimRight,
     "link", StringLink,
     "anchor", StringAnchor,
     "fontcolor", StringFontcolor,

test/mjsunit/third_party/string-trim.js

@@ -0,0 +1,107 @@
+// Copyright (c) 2009 Apple Computer, Inc. All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+//
+// 1. Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following
+// disclaimer in the documentation and/or other materials provided
+// with the distribution.
+//
+// 3. Neither the name of the copyright holder(s) nor the names of any
+// contributors may be used to endorse or promote products derived
+// from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+// OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Based on LayoutTests/fast/js/script-tests/string-trim.js
+
+// References to trim(), trimLeft() and trimRight() functions for 
+// testing Function's *.call() and *.apply() methods.
+
+var trim            = String.prototype.trim;
+var trimLeft        = String.prototype.trimLeft;
+var trimRight       = String.prototype.trimRight;
+
+var testString      = 'foo bar';
+var trimString      = '';
+var leftTrimString  = '';
+var rightTrimString = '';
+var wsString        = '';
+
+var whitespace      = [
+  {s : '\u0009', t : 'HORIZONTAL TAB'},
+  {s : '\u000A', t : 'LINE FEED OR NEW LINE'},
+  {s : '\u000B', t : 'VERTICAL TAB'},
+  {s : '\u000C', t : 'FORMFEED'},
+  {s : '\u000D', t : 'CARRIAGE RETURN'},
+  {s : '\u0020', t : 'SPACE'},
+  {s : '\u00A0', t : 'NO-BREAK SPACE'},
+  {s : '\u2000', t : 'EN QUAD'},
+  {s : '\u2001', t : 'EM QUAD'},
+  {s : '\u2002', t : 'EN SPACE'},
+  {s : '\u2003', t : 'EM SPACE'},
+  {s : '\u2004', t : 'THREE-PER-EM SPACE'},
+  {s : '\u2005', t : 'FOUR-PER-EM SPACE'},
+  {s : '\u2006', t : 'SIX-PER-EM SPACE'},
+  {s : '\u2007', t : 'FIGURE SPACE'},
+  {s : '\u2008', t : 'PUNCTUATION SPACE'},
+  {s : '\u2009', t : 'THIN SPACE'},
+  {s : '\u200A', t : 'HAIR SPACE'},
+  {s : '\u3000', t : 'IDEOGRAPHIC SPACE'},
+  {s : '\u2028', t : 'LINE SEPARATOR'},
+  {s : '\u2029', t : 'PARAGRAPH SEPARATOR'},
+  {s : '\u200B', t : 'ZERO WIDTH SPACE (category Cf)'}
+];
+
+for (var i = 0; i < whitespace.length; i++) {
+  assertEquals(whitespace[i].s.trim(), '');
+  assertEquals(whitespace[i].s.trimLeft(), '');
+  assertEquals(whitespace[i].s.trimRight(), '');
+  wsString += whitespace[i].s;
+}
+
+trimString      = wsString   + testString + wsString;
+leftTrimString  = testString + wsString;  // Trimmed from the left.
+rightTrimString = wsString   + testString;  // Trimmed from the right.
+
+assertEquals(wsString.trim(),      '');
+assertEquals(wsString.trimLeft(),  '');
+assertEquals(wsString.trimRight(), '');
+
+assertEquals(trimString.trim(),      testString);
+assertEquals(trimString.trimLeft(),  leftTrimString);
+assertEquals(trimString.trimRight(), rightTrimString);
+
+assertEquals(leftTrimString.trim(),      testString);
+assertEquals(leftTrimString.trimLeft(),  leftTrimString);
+assertEquals(leftTrimString.trimRight(), testString);
+
+assertEquals(rightTrimString.trim(),      testString);
+assertEquals(rightTrimString.trimLeft(),  testString);
+assertEquals(rightTrimString.trimRight(), rightTrimString);
+
+var testValues = [0, Infinity, NaN, true, false, ({}), ['an','array']
+  ({toString:function(){return 'wibble'}})
+];
+
+for (var i = 0; i < testValues.length; i++) {
+  assertEquals(trim.call(testValues[i]), String(testValues[i]));
+  assertEquals(trimLeft.call(testValues[i]), String(testValues[i]));
+  assertEquals(trimRight.call(testValues[i]), String(testValues[i]));
+}