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enhance booleans (#3661)

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Alex Lam S.L 2019-12-31 13:10:05 +08:00 committed by GitHub
parent a2e4c2fd97
commit 99ac73a635
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 23 additions and 16 deletions
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5
lib/ast.js
View File

@ -964,12 +964,13 @@ TreeWalker.prototype = {
in_boolean_context: function() { in_boolean_context: function() {
var self = this.self(); var self = this.self();
for (var i = 0, p; p = this.parent(i); i++) { for (var i = 0, p; p = this.parent(i); i++) {
if (p instanceof AST_SimpleStatement if (p instanceof AST_Conditional && p.condition === self
|| p instanceof AST_Conditional && p.condition === self
|| p instanceof AST_DWLoop && p.condition === self || p instanceof AST_DWLoop && p.condition === self
|| p instanceof AST_For && p.condition === self || p instanceof AST_For && p.condition === self
|| p instanceof AST_If && p.condition === self || p instanceof AST_If && p.condition === self
|| p instanceof AST_Return && p.in_bool || p instanceof AST_Return && p.in_bool
|| p instanceof AST_Sequence && p.tail_node() !== self
|| p instanceof AST_SimpleStatement
|| p instanceof AST_UnaryPrefix && p.operator == "!" && p.expression === self) { || p instanceof AST_UnaryPrefix && p.operator == "!" && p.expression === self) {
return true; return true;
} }

29
lib/compress.js
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@ -2021,6 +2021,7 @@ merge(Compressor.prototype, {
if (stat instanceof AST_If && stat.body instanceof AST_Return) { if (stat instanceof AST_If && stat.body instanceof AST_Return) {
var value = stat.body.value; var value = stat.body.value;
var in_bool = stat.body.in_bool || next instanceof AST_Return && next.in_bool;
//--- //---
// pretty silly case, but: // pretty silly case, but:
// if (foo()) return; return; => foo(); return; // if (foo()) return; return; => foo(); return;
@ -2034,7 +2035,7 @@ merge(Compressor.prototype, {
} }
//--- //---
// if (foo()) return x; return y; => return foo() ? x : y; // if (foo()) return x; return y; => return foo() ? x : y;
if (value && !stat.alternative && next instanceof AST_Return && next.value) { if ((in_bool || value) && !stat.alternative && next instanceof AST_Return) {
CHANGED = true; CHANGED = true;
stat = stat.clone(); stat = stat.clone();
stat.alternative = next; stat.alternative = next;
@ -2044,16 +2045,13 @@ merge(Compressor.prototype, {
} }
//--- //---
// if (foo()) return x; [ return ; ] => return foo() ? x : undefined; // if (foo()) return x; [ return ; ] => return foo() ? x : undefined;
if (value && !stat.alternative if (!stat.alternative && !next && in_lambda && (in_bool || value && multiple_if_returns)) {
&& (!next && in_lambda && multiple_if_returns
|| next instanceof AST_Return)) {
CHANGED = true; CHANGED = true;
stat = stat.clone(); stat = stat.clone();
stat.alternative = next || make_node(AST_Return, stat, { stat.alternative = make_node(AST_Return, stat, {
value: null value: null
}); });
statements.splice(i, 1, stat.transform(compressor)); statements.splice(i, 1, stat.transform(compressor));
if (next) statements.splice(j, 1);
continue; continue;
} }
//--- //---
@ -5104,13 +5102,17 @@ merge(Compressor.prototype, {
if (self.body instanceof AST_Exit if (self.body instanceof AST_Exit
&& self.alternative instanceof AST_Exit && self.alternative instanceof AST_Exit
&& self.body.TYPE == self.alternative.TYPE) { && self.body.TYPE == self.alternative.TYPE) {
return make_node(self.body.CTOR, self, { var exit = make_node(self.body.CTOR, self, {
value: make_node(AST_Conditional, self, { value: make_node(AST_Conditional, self, {
condition : self.condition, condition : self.condition,
consequent : self.body.value || make_node(AST_Undefined, self.body), consequent : self.body.value || make_node(AST_Undefined, self.body),
alternative : self.alternative.value || make_node(AST_Undefined, self.alternative) alternative : self.alternative.value || make_node(AST_Undefined, self.alternative)
}).transform(compressor) })
}).optimize(compressor); });
if (exit instanceof AST_Return) {
exit.in_bool = self.body.in_bool || self.alternative.in_bool;
}
return exit;
} }
if (self.body instanceof AST_If if (self.body instanceof AST_If
&& !self.body.alternative && !self.body.alternative
@ -7321,12 +7323,15 @@ merge(Compressor.prototype, {
&& node.expression instanceof AST_Constant && node.expression instanceof AST_Constant
&& !node.expression.value); && !node.expression.value);
} }
// AST_False or !1 // AST_False or !1 or void 0
function is_false(node) { function is_false(node) {
return node instanceof AST_False return node instanceof AST_False
|| in_bool || in_bool
&& node instanceof AST_Constant && (node instanceof AST_Constant
&& !node.value && !node.value
|| node instanceof AST_UnaryPrefix
&& node.operator == "void"
&& !node.expression.has_side_effects(compressor))
|| (node instanceof AST_UnaryPrefix || (node instanceof AST_UnaryPrefix
&& node.operator == "!" && node.operator == "!"
&& node.expression instanceof AST_Constant && node.expression instanceof AST_Constant

4
test/compress/collapse_vars.js
View File

@ -5863,8 +5863,8 @@ issue_2974: {
var c = 0; var c = 0;
(function(b) { (function(b) {
var a = 2; var a = 2;
for (; b.null = -4, c++, b.null && --a > 0;); for (;c++, (!0).null && --a > 0;);
})(!0), })(),
console.log(c); console.log(c);
} }
expect_stdout: "1" expect_stdout: "1"

1
test/compress/transform.js
View File

@ -103,6 +103,7 @@ if_return: {
booleans: true, booleans: true,
conditionals: true, conditionals: true,
if_return: true, if_return: true,
passes: 2,
sequences: true, sequences: true,
side_effects: true, side_effects: true,
} }