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Preserve ThisBinding in conditionals & collapse_vars

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Fixes #973
This commit is contained in:
alexlamsl
2016-02-16 18:15:59 +08:00
committed by Richard van Velzen
parent 63b01fe8f9
commit 31a9b05c96
3 changed files with 78 additions and 19 deletions
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39
lib/compress.js
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@@ -176,6 +176,21 @@ merge(Compressor.prototype, {
}
};
// we shouldn't compress (1,func)(something) to
// func(something) because that changes the meaning of
// the func (becomes lexical instead of global).
function maintain_this_binding(parent, orig, val) {
if (parent instanceof AST_Call && parent.expression === orig && val instanceof AST_PropAccess) {
return make_node(AST_Seq, orig, {
car: make_node(AST_Number, orig, {
value: 0
}),
cdr: val
});
}
return val;
}
function as_statement_array(thing) {
if (thing === null) return [];
if (thing instanceof AST_BlockStatement) return thing.body;
@@ -366,7 +381,7 @@ merge(Compressor.prototype, {
if (is_lvalue(node, parent)) return node;
// Remove var definition and return its value to the TreeTransformer to replace.
var value = var_decl.value;
var value = maintain_this_binding(parent, node, var_decl.value);
var_decl.value = null;
var_defs.splice(var_defs_index, 1);
@@ -2108,13 +2123,7 @@ merge(Compressor.prototype, {
if (!compressor.option("side_effects"))
return self;
if (!self.car.has_side_effects(compressor)) {
// we shouldn't compress (1,func)(something) to
// func(something) because that changes the meaning of
// the func (becomes lexical instead of global).
var p = compressor.parent();
if (!(p instanceof AST_Call && p.expression === self)) {
return self.cdr;
}
return maintain_this_binding(compressor.parent(), self, self.cdr);
}
if (compressor.option("cascade")) {
if (self.car instanceof AST_Assign
@@ -2304,11 +2313,10 @@ merge(Compressor.prototype, {
if (ll.length > 1) {
if (ll[1]) {
compressor.warn("Condition left of && always true [{file}:{line},{col}]", self.start);
var rr = self.right.evaluate(compressor);
return rr[0];
return maintain_this_binding(compressor.parent(), self, self.right.evaluate(compressor)[0]);
} else {
compressor.warn("Condition left of && always false [{file}:{line},{col}]", self.start);
return ll[0];
return maintain_this_binding(compressor.parent(), self, ll[0]);
}
}
}
@@ -2317,11 +2325,10 @@ merge(Compressor.prototype, {
if (ll.length > 1) {
if (ll[1]) {
compressor.warn("Condition left of || always true [{file}:{line},{col}]", self.start);
return ll[0];
return maintain_this_binding(compressor.parent(), self, ll[0]);
} else {
compressor.warn("Condition left of || always false [{file}:{line},{col}]", self.start);
var rr = self.right.evaluate(compressor);
return rr[0];
return maintain_this_binding(compressor.parent(), self, self.right.evaluate(compressor)[0]);
}
}
}
@@ -2546,10 +2553,10 @@ merge(Compressor.prototype, {
if (cond.length > 1) {
if (cond[1]) {
compressor.warn("Condition always true [{file}:{line},{col}]", self.start);
return self.consequent;
return maintain_this_binding(compressor.parent(), self, self.consequent);
} else {
compressor.warn("Condition always false [{file}:{line},{col}]", self.start);
return self.alternative;
return maintain_this_binding(compressor.parent(), self, self.alternative);
}
}
var negated = cond[0].negate(compressor);