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compress arguments[index] (#2967)

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- always replace with existing parameter
- only introduce new parameter if `keep_fargs` is disabled
This commit is contained in:
Alex Lam S.L
2018-03-02 11:22:09 +08:00
committed by GitHub
parent 38f2b4579f
commit a75a046abb
4 changed files with 155 additions and 7 deletions
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28
lib/compress.js
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@@ -48,6 +48,7 @@ function Compressor(options, false_by_default) {
return new Compressor(options, false_by_default);
TreeTransformer.call(this, this.before, this.after);
this.options = defaults(options, {
arguments : !false_by_default,
booleans : !false_by_default,
collapse_vars : !false_by_default,
comparisons : !false_by_default,
@@ -3551,7 +3552,7 @@ merge(Compressor.prototype, {
AST_Scope.DEFMETHOD("make_var_name", function(prefix) {
var var_names = this.var_names();
prefix = prefix.replace(/[^a-z_$]+/ig, "_");
prefix = prefix.replace(/(?:^[^a-z_$]|[^a-z0-9_$])/ig, "_");
var name = prefix;
for (var i = 0; var_names[name]; i++) name = prefix + "$" + i;
var_names[name] = true;
@@ -5954,6 +5955,31 @@ merge(Compressor.prototype, {
});
}
}
var fn;
if (compressor.option("arguments")
&& expr instanceof AST_SymbolRef
&& expr.name == "arguments"
&& expr.definition().orig.length == 1
&& (fn = expr.scope) instanceof AST_Lambda
&& prop instanceof AST_Number) {
var index = prop.getValue();
var argname = fn.argnames[index];
if (!argname && !compressor.option("keep_fargs")) {
while (index >= fn.argnames.length) {
argname = make_node(AST_SymbolFunarg, fn, {
name: fn.make_var_name("argument_" + fn.argnames.length),
scope: fn
});
fn.argnames.push(argname);
fn.enclosed.push(fn.def_variable(argname));
}
}
if (argname) {
var sym = make_node(AST_SymbolRef, self, argname);
sym.reference({});
return sym;
}
}
var ev = self.evaluate(compressor);
if (ev !== self) {
ev = make_node_from_constant(ev, self).optimize(compressor);