dan/oxc
1
0
Fork 0
mirror of https://github.com/danbulant/oxc synced 2026-05-19 04:08:41 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

feat(minifier): fold Array::concat into literal (#8442)

Browse source 
Compress `[].concat(a, [b])` into `[a, b]`.

**References**
- [Spec of `Array::concat`](https://tc39.es/ecma262/multipage/indexed-collections.html#sec-array.prototype.concat)
This commit is contained in:
sapphi-red 2025-01-17 06:00:07 +00:00
parent 3dc2d8b8e9
commit 991a22f907
No known key found for this signature in database
GPG key ID: 67631A259A77AC6C
2 changed files with 77 additions and 21 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

96
crates/oxc_minifier/src/ast_passes/peephole_replace_known_methods.rs
View file

@ -62,6 +62,7 @@ impl<'a> PeepholeReplaceKnownMethods {
"indexOf" | "lastIndexOf" => Self::try_fold_string_index_of(ce, name, object, ctx),
"charAt" => Self::try_fold_string_char_at(ce, object, ctx),
"charCodeAt" => Self::try_fold_string_char_code_at(ce, object, ctx),
"concat" => Self::try_fold_concat(ce, ctx),
"replace" | "replaceAll" => Self::try_fold_string_replace(ce, name, object, ctx),
"fromCharCode" => Self::try_fold_string_from_char_code(ce, object, ctx),
"toString" => Self::try_fold_to_string(ce, object, ctx),
@ -420,6 +421,68 @@ impl<'a> PeepholeReplaceKnownMethods {
);
self.changed = true;
}
/// `[].concat(1, 2)` -> `[1, 2]`
fn try_fold_concat(
ce: &mut CallExpression<'a>,
ctx: &mut TraverseCtx<'a>,
) -> Option<Expression<'a>> {
// let concat chaining reduction handle it first
if let Ancestor::StaticMemberExpressionObject(parent_member) = ctx.parent() {
if parent_member.property().name.as_str() == "concat" {
return None;
}
}
let Expression::StaticMemberExpression(member) = &mut ce.callee else { unreachable!() };
let Expression::ArrayExpression(array_expr) = &mut member.object else { return None };
let can_merge_until = ce
.arguments
.iter()
.enumerate()
.take_while(|(_, argument)| match argument {
Argument::SpreadElement(_) => false,
match_expression!(Argument) => {
let argument = argument.to_expression();
if argument.is_literal() {
true
} else {
matches!(argument, Expression::ArrayExpression(_))
}
}
})
.map(|(i, _)| i)
.last();
if let Some(can_merge_until) = can_merge_until {
for argument in ce.arguments.drain(..=can_merge_until) {
let argument = argument.into_expression();
if argument.is_literal() {
array_expr.elements.push(ArrayExpressionElement::from(argument));
} else {
let Expression::ArrayExpression(mut argument_array) = argument else {
unreachable!()
};
array_expr.elements.append(&mut argument_array.elements);
}
}
}
if ce.arguments.is_empty() {
Some(ctx.ast.move_expression(&mut member.object))
} else if can_merge_until.is_some() {
Some(ctx.ast.expression_call(
ce.span,
ctx.ast.move_expression(&mut ce.callee),
Option::<TSTypeParameterInstantiation>::None,
ctx.ast.move_vec(&mut ce.arguments),
false,
))
} else {
None
}
}
}
/// Port from: <https://github.com/google/closure-compiler/blob/v20240609/test/com/google/javascript/jscomp/PeepholeReplaceKnownMethodsTest.java>
@ -1167,52 +1230,45 @@ mod test {
#[test]
fn test_fold_concat_chaining() {
// array
fold("[1,2].concat(1).concat(2,['abc']).concat('abc')", "[1,2].concat(1,2,['abc'],'abc')");
fold("[].concat(['abc']).concat(1).concat([2,3])", "[].concat(['abc'],1,[2,3])");
fold("[1,2].concat(1).concat(2,['abc']).concat('abc')", "[1,2,1,2,'abc','abc']");
fold("[].concat(['abc']).concat(1).concat([2,3])", "['abc',1,2,3]");
fold("var x, y; [1].concat(x).concat(y)", "var x, y; [1].concat(x, y)");
fold("var y; [1].concat(x).concat(y)", "var y; [1].concat(x, y)"); // x might have a getter that updates y, but that side effect is preserved correctly
fold("var x; [1].concat(x.a).concat(x)", "var x; [1].concat(x.a, x)"); // x.a might have a getter that updates x, but that side effect is preserved correctly
fold_same("[].concat(1)");
// string
fold("'1'.concat(1).concat(2,['abc']).concat('abc')", "'1'.concat(1,2,['abc'],'abc')");
fold("''.concat(['abc']).concat(1).concat([2,3])", "''.concat(['abc'],1,[2,3])");
fold_same("''.concat(1)");
fold("var x, y; ''.concat(x).concat(y)", "var x, y; ''.concat(x, y)");
fold("var y; ''.concat(x).concat(y)", "var y; ''.concat(x, y)"); // x might have a getter that updates y, but that side effect is preserved correctly
fold("var x; ''.concat(x.a).concat(x)", "var x; ''.concat(x.a, x)"); // x.a might have a getter that updates x, but that side effect is preserved correctly
fold_same("''.concat(1)");
// other
fold_same("obj.concat([1,2]).concat(1)");
}
#[test]
#[ignore]
fn test_remove_array_literal_from_front_of_concat() {
// enableTypeCheck();
fold("[].concat([1,2,3],1)", "[1,2,3,1]");
fold("[].concat([1,2,3],1)", "[1,2,3].concat(1)");
fold_same("[1,2,3].concat(returnArrayType())");
fold_same("[1,2,3].concat(foo())");
// Call method with the same name as Array.prototype.concat
fold_same("obj.concat([1,2,3])");
fold_same("[].concat(1,[1,2,3])");
fold_same("[].concat(1)");
fold("[].concat([1])", "[1].concat()");
fold("[].concat(1,[1,2,3])", "[1,1,2,3]");
fold("[].concat(1)", "[1]");
fold("[].concat([1])", "[1]");
// Chained folding of empty array lit
fold("[].concat([], [1,2,3], [4])", "[1,2,3].concat([4])");
fold("[].concat([]).concat([1]).concat([2,3])", "[1].concat([2,3])");
fold("[].concat([], [1,2,3], [4])", "[1,2,3,4]");
fold("[].concat([]).concat([1]).concat([2,3])", "[1,2,3]");
// Cannot fold based on type information
fold_same("[].concat(returnArrayType(),1)");
fold_same("[].concat(returnArrayType())");
fold_same("[].concat(returnUnionType())");
fold("[].concat(1, x)", "[1].concat(x)"); // x might be an array or an object with `Symbol.isConcatSpreadable`
fold("[].concat(1, ...x)", "[1].concat(...x)");
fold_same("[].concat(x, 1)");
}
#[test]

2
tasks/minsize/minsize.snap
View file

@ -11,7 +11,7 @@ Original | minified | minified | gzip | gzip | Fixture
544.10 kB | 71.76 kB | 72.48 kB | 26.15 kB | 26.20 kB | lodash.js
555.77 kB | 273.15 kB | 270.13 kB | 90.92 kB | 90.80 kB | d3.js
555.77 kB | 272.91 kB | 270.13 kB | 90.90 kB | 90.80 kB | d3.js
1.01 MB | 460.17 kB | 458.89 kB | 126.76 kB | 126.71 kB | bundle.min.js