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enhance conditionals (#3694)
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@alexlamsl
alexlamsl committed Jan 28, 2020
1 parent a478f27 commit b499e03
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Showing 2 changed files with 134 additions and 8 deletions.
85 changes: 77 additions & 8 deletions lib/compress.js
View file
Expand Up @@ -7194,23 +7194,24 @@ merge(Compressor.prototype, {
expressions.push(self);
return make_sequence(self, expressions);
}
var cond = self.condition.is_truthy() || self.condition.tail_node().evaluate(compressor);
if (!cond) {
var condition = self.condition.is_truthy() || self.condition.evaluate(compressor);
if (!condition) {
AST_Node.warn("Condition always false [{file}:{line},{col}]", self.start);
return make_sequence(self, [ self.condition, self.alternative ]).optimize(compressor);
} else if (!(cond instanceof AST_Node)) {
} else if (!(condition instanceof AST_Node)) {
AST_Node.warn("Condition always true [{file}:{line},{col}]", self.start);
return make_sequence(self, [ self.condition, self.consequent ]).optimize(compressor);
}
var negated = cond.negate(compressor, first_in_statement(compressor));
if (best_of(compressor, cond, negated) === negated) {
var negated = condition.negate(compressor, first_in_statement(compressor));
if (best_of(compressor, condition, negated) === negated) {
self = make_node(AST_Conditional, self, {
condition: negated,
consequent: self.alternative,
alternative: self.consequent
});
negated = condition;
condition = self.condition;
}
var condition = self.condition;
var consequent = self.consequent;
var alternative = self.alternative;
// x ? x : y => x || y
Expand Down Expand Up @@ -7298,6 +7299,19 @@ merge(Compressor.prototype, {
alternative: alternative
});
}
// x ? (y ? a : b) : a => !x || y ? a : b
if (consequent instanceof AST_Conditional
&& consequent.consequent.equivalent_to(alternative)) {
return make_node(AST_Conditional, self, {
condition: make_node(AST_Binary, self, {
left: negated,
operator: "||",
right: consequent.condition
}),
consequent: alternative,
alternative: consequent.alternative
});
}
// x ? a : (y ? a : b) => x || y ? a : b
if (alternative instanceof AST_Conditional
&& consequent.equivalent_to(alternative.consequent)) {
Expand All @@ -7311,7 +7325,20 @@ merge(Compressor.prototype, {
alternative: alternative.alternative
});
}
// x ? (y, w) : (z, w) => x ? y : z, w
// x ? b : (y ? a : b) => !x && y ? a : b
if (alternative instanceof AST_Conditional
&& consequent.equivalent_to(alternative.alternative)) {
return make_node(AST_Conditional, self, {
condition: make_node(AST_Binary, self, {
left: negated,
operator: "&&",
right: alternative.condition
}),
consequent: alternative.consequent,
alternative: consequent
});
}
// x ? (a, c) : (b, c) => x ? a : b, c
if ((consequent instanceof AST_Sequence || alternative instanceof AST_Sequence)
&& consequent.tail_node().equivalent_to(alternative.tail_node())) {
return make_sequence(self, [
Expand All @@ -7323,7 +7350,21 @@ merge(Compressor.prototype, {
consequent.tail_node()
]).optimize(compressor);
}
// x ? y || z : z => x && y || z
// x ? y && a : a => (!x || y) && a
if (consequent instanceof AST_Binary
&& consequent.operator == "&&"
&& consequent.right.equivalent_to(alternative)) {
return make_node(AST_Binary, self, {
operator: "&&",
left: make_node(AST_Binary, self, {
operator: "||",
left: negated,
right: consequent.left
}),
right: alternative
}).optimize(compressor);
}
// x ? y || a : a => x && y || a
if (consequent instanceof AST_Binary
&& consequent.operator == "||"
&& consequent.right.equivalent_to(alternative)) {
Expand All @@ -7337,6 +7378,34 @@ merge(Compressor.prototype, {
right: alternative
}).optimize(compressor);
}
// x ? a : y && a => (x || y) && a
if (alternative instanceof AST_Binary
&& alternative.operator == "&&"
&& alternative.right.equivalent_to(consequent)) {
return make_node(AST_Binary, self, {
operator: "&&",
left: make_node(AST_Binary, self, {
operator: "||",
left: condition,
right: alternative.left
}),
right: consequent
}).optimize(compressor);
}
// x ? a : y || a => !x && y || a
if (alternative instanceof AST_Binary
&& alternative.operator == "||"
&& alternative.right.equivalent_to(consequent)) {
return make_node(AST_Binary, self, {
operator: "||",
left: make_node(AST_Binary, self, {
operator: "&&",
left: negated,
right: alternative.left
}),
right: consequent
}).optimize(compressor);
}
var in_bool = compressor.option("booleans") && compressor.in_boolean_context();
if (is_true(consequent)) {
if (is_false(alternative)) {
Expand Down
57 changes: 57 additions & 0 deletions test/compress/conditionals.js
View file
Expand Up @@ -294,6 +294,45 @@ cond_5: {
}
}

cond_6: {
options = {
booleans: true,
conditionals: true,
}
input: {
x ? a : b;
x ? a : a;

x ? y ? a : b : c;
x ? y ? a : a : b;
x ? y ? a : b : b;
x ? y ? a : b : a;
x ? y ? a : a : a;

x ? a : y ? b : c;
x ? a : y ? a : b;
x ? a : y ? b : b;
x ? a : y ? b : a;
x ? a : y ? a : a;
}
expect: {
x ? a : b;
x, a;

x ? y ? a : b : c;
x ? (y, a) : b;
x && y ? a : b;
!x || y ? a : b;
x && y, a;

x ? a : y ? b : c;
x || y ? a : b;
x ? a : (y, b);
!x && y ? b : a;
!x && y, a;
}
}

cond_7: {
options = {
conditionals: true,
Expand Down Expand Up @@ -726,6 +765,24 @@ cond_11: {
expect_stdout: "foo bar"
}

cond_12: {
options = {
conditionals: true,
}
input: {
x ? y && a : a;
x ? y || a : a;
x ? a : y && a;
x ? a : y || a;
}
expect: {
(!x || y) && a;
x && y || a;
(x || y) && a;
!x && y || a;
}
}

ternary_boolean_consequent: {
options = {
booleans: true,
Expand Down

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