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enhance conditionals (#3243)

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This commit is contained in:
Alex Lam S.L
2018-08-30 01:06:34 +08:00
committed by GitHub
parent aa0029204e
commit 2bdaca10ae
2 changed files with 105 additions and 24 deletions
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57
lib/compress.js
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@@ -6047,20 +6047,22 @@ merge(Compressor.prototype, {
// |
// v
// exp = foo ? something : something_else;
if (consequent instanceof AST_Assign
&& alternative instanceof AST_Assign
&& consequent.operator == alternative.operator
&& consequent.left.equivalent_to(alternative.left)
&& (!self.condition.has_side_effects(compressor)
|| consequent.operator == "="
&& !consequent.left.has_side_effects(compressor))) {
var seq_tail = consequent.tail_node();
var alt_tail = alternative.tail_node();
if (seq_tail instanceof AST_Assign
&& alt_tail instanceof AST_Assign
&& seq_tail.operator == alt_tail.operator
&& seq_tail.left.equivalent_to(alt_tail.left)
&& (!condition.has_side_effects(compressor)
|| seq_tail.operator == "="
&& !seq_tail.left.has_side_effects(compressor))) {
return make_node(AST_Assign, self, {
operator: consequent.operator,
left: consequent.left,
operator: seq_tail.operator,
left: seq_tail.left,
right: make_node(AST_Conditional, self, {
condition: self.condition,
consequent: consequent.right,
alternative: alternative.right
condition: condition,
consequent: pop_lhs(consequent),
alternative: pop_lhs(alternative)
})
});
}
@@ -6071,12 +6073,12 @@ merge(Compressor.prototype, {
&& consequent.args.length > 0
&& consequent.args.length == alternative.args.length
&& consequent.expression.equivalent_to(alternative.expression)
&& !self.condition.has_side_effects(compressor)
&& !condition.has_side_effects(compressor)
&& !consequent.expression.has_side_effects(compressor)
&& typeof (arg_index = single_arg_diff()) == "number") {
var node = consequent.clone();
node.args[arg_index] = make_node(AST_Conditional, self, {
condition: self.condition,
condition: condition,
consequent: consequent.args[arg_index],
alternative: alternative.args[arg_index]
});
@@ -6087,7 +6089,7 @@ merge(Compressor.prototype, {
&& consequent.alternative.equivalent_to(alternative)) {
return make_node(AST_Conditional, self, {
condition: make_node(AST_Binary, self, {
left: self.condition,
left: condition,
operator: "&&",
right: consequent.condition
}),
@@ -6098,7 +6100,7 @@ merge(Compressor.prototype, {
// x ? y : y --> x, y
if (consequent.equivalent_to(alternative)) {
return make_sequence(self, [
self.condition,
condition,
consequent
]).optimize(compressor);
}
@@ -6107,7 +6109,7 @@ merge(Compressor.prototype, {
&& consequent.tail_node().equivalent_to(alternative.tail_node())) {
return make_sequence(self, [
make_node(AST_Conditional, self, {
condition: self.condition,
condition: condition,
consequent: pop_seq(consequent),
alternative: pop_seq(alternative)
}),
@@ -6122,7 +6124,7 @@ merge(Compressor.prototype, {
operator: "||",
left: make_node(AST_Binary, self, {
operator: "&&",
left: self.condition,
left: condition,
right: consequent.left
}),
right: alternative
@@ -6132,24 +6134,24 @@ merge(Compressor.prototype, {
if (is_true(self.consequent)) {
if (is_false(self.alternative)) {
// c ? true : false ---> !!c
return booleanize(self.condition);
return booleanize(condition);
}
// c ? true : x ---> !!c || x
return make_node(AST_Binary, self, {
operator: "||",
left: booleanize(self.condition),
left: booleanize(condition),
right: self.alternative
});
}
if (is_false(self.consequent)) {
if (is_true(self.alternative)) {
// c ? false : true ---> !c
return booleanize(self.condition.negate(compressor));
return booleanize(condition.negate(compressor));
}
// c ? false : x ---> !c && x
return make_node(AST_Binary, self, {
operator: "&&",
left: booleanize(self.condition.negate(compressor)),
left: booleanize(condition.negate(compressor)),
right: self.alternative
});
}
@@ -6157,7 +6159,7 @@ merge(Compressor.prototype, {
// c ? x : true ---> !c || x
return make_node(AST_Binary, self, {
operator: "||",
left: booleanize(self.condition.negate(compressor)),
left: booleanize(condition.negate(compressor)),
right: self.consequent
});
}
@@ -6165,7 +6167,7 @@ merge(Compressor.prototype, {
// c ? x : false ---> !!c && x
return make_node(AST_Binary, self, {
operator: "&&",
left: booleanize(self.condition),
left: booleanize(condition),
right: self.consequent
});
}
@@ -6217,6 +6219,13 @@ merge(Compressor.prototype, {
}
}
function pop_lhs(node) {
if (!(node instanceof AST_Sequence)) return node.right;
var exprs = node.expressions.slice();
exprs.push(exprs.pop().right);
return make_sequence(node, exprs);
}
function pop_seq(node) {
if (!(node instanceof AST_Sequence)) return make_node(AST_Number, node, {
value: 0