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Implement string literal trim() folding #2900

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Implement string literal trim() folding #2900

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ec7dce2
Implemented String.prototype.trim() folding.
puddly Apr 19, 2018
93281ac
Fixed typo in whitespace regex.
puddly Apr 19, 2018
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16 changes: 16 additions & 0 deletions src/com/google/javascript/jscomp/PeepholeReplaceKnownMethods.java
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Original file line number Diff line number Diff line change
Expand Up @@ -218,6 +218,8 @@ private Node tryFoldKnownStringMethods(Node subtree, Node callTarget) {
return tryFoldStringToLowerCase(subtree, stringNode);
case "toUpperCase":
return tryFoldStringToUpperCase(subtree, stringNode);
case "trim":
return tryFoldStringTrim(subtree, stringNode);
default: // fall out
}
} else {
Expand Down Expand Up @@ -319,6 +321,20 @@ private Node tryFoldStringToUpperCase(Node subtree, Node stringNode) {
return replacement;
}

/**
* @return The trimmed string Node.
*/
private Node tryFoldStringTrim(Node subtree, Node stringNode) {
// See ECMA 15.5.4.20, 7.2, and 7.3
// All Unicode 10.0 whitespace + BOM
String whitespace = "[ \t\n-\r\\u0085\\u00A0\\u1680\\u2000-\\u200A\\u2028\\u2029\\u202F\\u205F\\u3000\\uFEFF]+";
String trimmed = stringNode.getString().replaceAll("^" + whitespace + "|" + whitespace + "$", "");
Node replacement = IR.string(trimmed);
subtree.replaceWith(replacement);
compiler.reportChangeToEnclosingScope(replacement);
return replacement;
}

/**
* @param input string representation of a number
* @return string with leading and trailing zeros removed
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1 change: 1 addition & 0 deletions test/com/google/javascript/jscomp/PeepholeIntegrationTest.java
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Expand Up @@ -377,6 +377,7 @@ public void testTemplateStringsKnownMethods() {
test("x = `abcdef`.charCodeAt(0)", "x = 97");
test("x = `abc`.toUpperCase()", "x = 'ABC'");
test("x = `ABC`.toLowerCase()", "x = 'abc'");
test("x = `\t\n\uFEFF\t asd foo bar \r\n`.trim()", "x = 'asd foo bar'");
test("x = parseInt(`123`)", "x = 123");
test("x = parseFloat(`1.23`)", "x = 1.23");
}
Expand Down