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possible optimization for AST_Undefined

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if undefined is defined, ;-), we replace AST_Undefined nodes to a reference
to the "undefined" variable; in turn the mangler will compress it to a
single letter; this helps at least on jQuery.
This commit is contained in:
Mihai Bazon
2012-09-17 12:24:21 +03:00
parent 14481de0e9
commit 92e22c460d
1 changed files with 21 additions and 11 deletions
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32
lib/compress.js
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@@ -91,6 +91,12 @@ function Compressor(options, false_by_default) {
self = p;
}
};
function find_parent(type) {
for (var i = stack.length; --i >= 0;) {
var x = stack[i];
if (x instanceof type) return x;
}
};
return {
option : function(key) { return options[key] },
push_node : function(node) { stack.push(node) },
@@ -104,7 +110,8 @@ function Compressor(options, false_by_default) {
if (options.warnings)
AST_Node.warn.apply(AST_Node, arguments);
},
in_boolean_context: in_boolean_context
in_boolean_context: in_boolean_context,
find_parent: find_parent,
};
};
@@ -1499,16 +1506,19 @@ function Compressor(options, false_by_default) {
});
AST_Undefined.DEFMETHOD("optimize", function(compressor){
// if (compressor.option("unsafe") && !(compressor.parent() instanceof AST_Array)) {
// return make_node(AST_Sub, this, {
// expression: make_node(AST_Array, this, {
// elements: []
// }),
// property: make_node(AST_Number, this, {
// value: 0
// })
// });
// }
if (compressor.option("unsafe")) {
var scope = compressor.find_parent(AST_Scope);
var undef = scope.find_variable("undefined");
if (undef) {
var ref = make_node(AST_SymbolRef, this, {
name : "undefined",
scope : scope,
thedef : undef
});
ref.reference();
return ref;
}
}
return this;
});