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optimizations for && and || where left side is constant expression

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kzc
2015-06-11 23:22:38 -04:00
parent 5bf617ebde
commit fedb6191a1
2 changed files with 189 additions and 0 deletions
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28
lib/compress.js
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@@ -2104,6 +2104,34 @@ merge(Compressor.prototype, {
}
break;
}
if (compressor.option("conditionals")) {
if (self.operator == "&&") {
var ll = self.left.evaluate(compressor);
var rr = self.right.evaluate(compressor);
if (ll.length > 1) {
if (ll[1]) {
compressor.warn("Condition left of && always true [{file}:{line},{col}]", self.start);
return rr[0];
} else {
compressor.warn("Condition left of && always false [{file}:{line},{col}]", self.start);
return ll[0];
}
}
}
if (self.operator == "||") {
var ll = self.left.evaluate(compressor);
var rr = self.right.evaluate(compressor);
if (ll.length > 1) {
if (ll[1]) {
compressor.warn("Condition left of || always true [{file}:{line},{col}]", self.start);
return ll[0];
} else {
compressor.warn("Condition left of || always false [{file}:{line},{col}]", self.start);
return rr[0];
}
}
}
}
if (compressor.option("booleans") && compressor.in_boolean_context()) switch (self.operator) {
case "&&":
var ll = self.left.evaluate(compressor);