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smarter const replacement taking name length into account

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closes #1459
This commit is contained in:
kzc 2017-02-18 19:12:57 +08:00 committed by alexlamsl
parent f0ff6189be
commit 6ffbecb72b
2 changed files with 173 additions and 0 deletions
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12
lib/compress.js
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@ -2784,6 +2784,18 @@ merge(Compressor.prototype, {
} }
} }
} }
if (compressor.option("evaluate") && !isLHS(self, compressor.parent())) {
var d = self.definition();
if (d && d.constant && d.init && d.init.is_constant(compressor)) {
var original_as_string = self.print_to_string();
var const_node = make_node_from_constant(compressor, d.init.constant_value(compressor), self);
var const_node_as_string = const_node.print_to_string();
var per_const_overhead = d.global || !d.references.length ? 0
: (d.name.length + 2 + const_node_as_string.length) / d.references.length;
if (const_node_as_string.length <= original_as_string.length + per_const_overhead)
return const_node;
}
}
return self; return self;
}); });

161
test/compress/const.js Normal file
View File

@ -0,0 +1,161 @@
issue_1191: {
options = {
evaluate : true,
booleans : true,
comparisons : true,
dead_code : true,
conditionals : true,
side_effects : true,
unused : true,
hoist_funs : true,
if_return : true,
join_vars : true,
sequences : false,
collapse_vars : false,
}
input: {
function foo(rot) {
const rotTol = 5;
if (rot < -rotTol || rot > rotTol)
bar();
baz();
}
}
expect: {
function foo(rot) {
(rot < -5 || rot > 5) && bar();
baz();
}
}
}
issue_1194: {
options = {
evaluate : true,
booleans : true,
comparisons : true,
dead_code : true,
conditionals : true,
side_effects : true,
unused : true,
hoist_funs : true,
if_return : true,
join_vars : true,
sequences : false,
collapse_vars : false,
}
input: {
function f1() {const a = "X"; return a + a;}
function f2() {const aa = "X"; return aa + aa;}
function f3() {const aaa = "X"; return aaa + aaa;}
}
expect: {
function f1(){return"XX"}
function f2(){return"XX"}
function f3(){return"XX"}
}
}
issue_1396: {
options = {
evaluate : true,
booleans : true,
comparisons : true,
dead_code : true,
conditionals : true,
side_effects : true,
unused : true,
hoist_funs : true,
if_return : true,
join_vars : true,
sequences : false,
collapse_vars : false,
}
input: {
function foo(a) {
const VALUE = 1;
console.log(2 | VALUE);
console.log(VALUE + 1);
console.log(VALUE);
console.log(a & VALUE);
}
function bar() {
const s = "01234567890123456789";
console.log(s + s + s + s + s);
const CONSTANT = "abc";
console.log(CONSTANT + CONSTANT + CONSTANT + CONSTANT + CONSTANT);
}
}
expect: {
function foo(a) {
console.log(3);
console.log(2);
console.log(1);
console.log(1 & a);
}
function bar() {
const s = "01234567890123456789";
console.log(s + s + s + s + s);
console.log("abcabcabcabcabc");
}
}
}
unused_regexp_literal: {
options = {
evaluate : true,
booleans : true,
comparisons : true,
dead_code : true,
conditionals : true,
side_effects : true,
unused : true,
hoist_funs : true,
if_return : true,
join_vars : true,
sequences : false,
collapse_vars : false,
}
input: {
function f(){ var a = /b/; }
}
expect: {
function f(){}
}
}
regexp_literal_not_const: {
options = {
evaluate : true,
booleans : true,
comparisons : true,
dead_code : true,
conditionals : true,
side_effects : true,
unused : true,
hoist_funs : true,
if_return : true,
join_vars : true,
sequences : false,
collapse_vars : false,
}
input: {
(function(){
var result;
const s = 'acdabcdeabbb';
const REGEXP_LITERAL = /ab*/g;
while (result = REGEXP_LITERAL.exec(s)) {
console.log(result[0]);
}
})();
}
expect: {
(function() {
var result;
const REGEXP_LITERAL = /ab*/g;
while (result = REGEXP_LITERAL.exec("acdabcdeabbb")) console.log(result[0]);
})();
}
}