JoBoEVD/UglifyJS
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other small optimization:

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if (foo) continue;
...body...

==>

if (!foo) { ...body ... }

Only when the parent block is the target loop of the `continue` statement.
This commit is contained in:
Mihai Bazon
2012-09-15 16:06:09 +03:00
parent 4e0262bdfb
commit 397bf56d25
1 changed files with 40 additions and 2 deletions
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42
lib/compress.js
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@@ -184,10 +184,44 @@ function Compressor(options, false_by_default) {
} while (CHANGED);
return statements;
/// XXX: this function is UGLY and kinda wrong.
/// I think it would be cleaner if it operates backwards.
function handle_if_return(statements, compressor) {
var in_lambda = compressor.self() instanceof AST_Lambda;
var self = compressor.self();
var in_lambda = self instanceof AST_Lambda;
var last = statements.length - 1;
return MAP(statements, function(stat, i){
if (stat instanceof AST_If
&& stat.body instanceof AST_Continue
&& !stat.alternative
&& self === stat.body.target()) {
CHANGED = true;
if (i < last) {
var rest = statements.slice(i + 1);
var cond = stat.condition;
while (rest[0] instanceof AST_If
&& rest[0].body instanceof AST_Continue
&& self === rest[0].body.target()
&& !rest[0].alternative) {
cond = make_node(AST_Binary, rest[0], {
operator: "||",
left: cond,
right: rest[0].condition
});
rest.shift();
}
return MAP.last(make_node(AST_If, stat, {
condition: cond.negate(compressor),
body: make_node(AST_BlockStatement, stat, {
body: rest
}).optimize(compressor)
}).optimize(compressor))
} else {
return make_node(AST_SimpleStatement, stat, {
body: stat.condition
}).optimize(compressor);
}
}
if (stat instanceof AST_If
&& stat.body instanceof AST_Return
&& !stat.alternative
@@ -199,6 +233,7 @@ function Compressor(options, false_by_default) {
var cond = stat.condition;
while (rest[0] instanceof AST_If
&& rest[0].body instanceof AST_Return
&& !rest[0].body.value
&& !rest[0].alternative) {
cond = make_node(AST_Binary, rest[0], {
operator: "||",
@@ -645,7 +680,10 @@ function Compressor(options, false_by_default) {
(function(def){
def(AST_StatementBase, function(){ return null });
def(AST_Jump, function(){ return this });
def(AST_BlockStatement, function(){ return this.body[this.body.length - 1].aborts() });
def(AST_BlockStatement, function(){
var n = this.body.length;
return n > 0 && this.body[n - 1].aborts();
});
})(function(node, func){
node.DEFMETHOD("aborts", func);
});