JoBoEVD/UglifyJS
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

improve boolean compression (#2548)

Browse Source 
fixes #2535
This commit is contained in:
Alex Lam S.L
2017-12-01 22:41:35 +08:00
committed by GitHub
parent 7ac6fdcc99
commit 9a6b11f8e6
3 changed files with 186 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files

70
lib/compress.js
View File

@@ -158,6 +158,7 @@ merge(Compressor.prototype, {
return true;
}
if (p instanceof AST_Binary && (p.operator == "&&" || p.operator == "||")
|| p instanceof AST_Conditional
|| p.tail_node() === self) {
self = p;
} else {
@@ -4090,49 +4091,72 @@ merge(Compressor.prototype, {
if (compressor.option("evaluate")) {
switch (self.operator) {
case "&&":
var ll = self.left.evaluate(compressor);
var ll = self.left.truthy ? true : self.left.falsy ? false : self.left.evaluate(compressor);
if (!ll) {
compressor.warn("Condition left of && always false [{file}:{line},{col}]", self.start);
return maintain_this_binding(compressor.parent(), compressor.self(), self.left).optimize(compressor);
} else if (ll !== self.left) {
} else if (!(ll instanceof AST_Node)) {
compressor.warn("Condition left of && always true [{file}:{line},{col}]", self.start);
return maintain_this_binding(compressor.parent(), compressor.self(), self.right).optimize(compressor);
return make_sequence(self, [ self.left, self.right ]).optimize(compressor);
}
if (compressor.in_boolean_context()) {
var rr = self.right.evaluate(compressor);
if (!rr) {
var rr = self.right.evaluate(compressor);
if (!rr) {
if (compressor.in_boolean_context()) {
compressor.warn("Boolean && always false [{file}:{line},{col}]", self.start);
return make_sequence(self, [
self.left,
make_node(AST_False, self)
]).optimize(compressor);
} else if (rr !== self.right) {
compressor.warn("Dropping side-effect-free && in boolean context [{file}:{line},{col}]", self.start);
} else self.falsy = true;
} else if (!(rr instanceof AST_Node)) {
var parent = compressor.parent();
if (parent.operator == "&&" && parent.left === compressor.self() || compressor.in_boolean_context()) {
compressor.warn("Dropping side-effect-free && [{file}:{line},{col}]", self.start);
return self.left.optimize(compressor);
}
}
// x || false && y ---> x ? y : false
if (self.left.operator == "||") {
var lr = self.left.right.evaluate(compressor);
if (!lr) return make_node(AST_Conditional, self, {
condition: self.left.left,
consequent: self.right,
alternative: self.left.right
}).optimize(compressor);
}
break;
case "||":
var ll = self.left.evaluate(compressor);
var ll = self.left.truthy ? true : self.left.falsy ? false : self.left.evaluate(compressor);
if (!ll) {
compressor.warn("Condition left of || always false [{file}:{line},{col}]", self.start);
return maintain_this_binding(compressor.parent(), compressor.self(), self.right).optimize(compressor);
} else if (ll !== self.left) {
return make_sequence(self, [ self.left, self.right ]).optimize(compressor);
} else if (!(ll instanceof AST_Node)) {
compressor.warn("Condition left of || always true [{file}:{line},{col}]", self.start);
return maintain_this_binding(compressor.parent(), compressor.self(), self.left).optimize(compressor);
}
if (compressor.in_boolean_context()) {
var rr = self.right.evaluate(compressor);
if (!rr) {
compressor.warn("Dropping side-effect-free || in boolean context [{file}:{line},{col}]", self.start);
var rr = self.right.evaluate(compressor);
if (!rr) {
var parent = compressor.parent();
if (parent.operator == "||" && parent.left === compressor.self() || compressor.in_boolean_context()) {
compressor.warn("Dropping side-effect-free || [{file}:{line},{col}]", self.start);
return self.left.optimize(compressor);
} else if (rr !== self.right) {
}
} else if (!(rr instanceof AST_Node)) {
if (compressor.in_boolean_context()) {
compressor.warn("Boolean || always true [{file}:{line},{col}]", self.start);
return make_sequence(self, [
self.left,
make_node(AST_True, self)
]).optimize(compressor);
}
} else self.truthy = true;
}
if (self.left.operator == "&&") {
var lr = self.left.right.evaluate(compressor);
if (lr && !(lr instanceof AST_Node)) return make_node(AST_Conditional, self, {
condition: self.left.left,
consequent: self.left.right,
alternative: self.right
}).optimize(compressor);
}
break;
}
@@ -4640,7 +4664,7 @@ merge(Compressor.prototype, {
consequent
]).optimize(compressor);
}
var in_bool = compressor.in_boolean_context();
if (is_true(self.consequent)) {
if (is_false(self.alternative)) {
// c ? true : false ---> !!c
@@ -4696,18 +4720,24 @@ merge(Compressor.prototype, {
// AST_True or !0
function is_true(node) {
return node instanceof AST_True
|| in_bool
&& node instanceof AST_Constant
&& node.getValue()
|| (node instanceof AST_UnaryPrefix
&& node.operator == "!"
&& node.expression instanceof AST_Constant
&& !node.expression.value);
&& !node.expression.getValue());
}
// AST_False or !1
function is_false(node) {
return node instanceof AST_False
|| in_bool
&& node instanceof AST_Constant
&& !node.getValue()
|| (node instanceof AST_UnaryPrefix
&& node.operator == "!"
&& node.expression instanceof AST_Constant
&& !!node.expression.value);
&& node.expression.getValue());
}
});