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https://github.com/danbulant/oxc
synced 2026-05-22 05:38:54 +00:00
feat(minifier): compress array of string literals to 'str1,str2'.split(',') (#8786)
Ported `["str1", "str2", ...]` => `"str1 str2".split(" ")` compression from closure compiler with some tweaks.
This commit is contained in:
sapphi-red
parent
2eac9c0370
commit
7ea99f40ac
2 changed files with 104 additions and 18 deletions
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@ -907,6 +907,7 @@ impl<'a> LatePeepholeOptimizations {
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if let Some(folded_expr) = match expr {
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Expression::BooleanLiteral(_) => Self::try_compress_boolean(expr, ctx),
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Expression::ArrayExpression(_) => Self::try_compress_array_expression(expr, ctx),
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_ => None,
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} {
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*expr = folded_expr;
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@ -939,6 +940,78 @@ impl<'a> LatePeepholeOptimizations {
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Some(ctx.ast.expression_unary(lit.span, UnaryOperator::LogicalNot, num))
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}
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/// Transforms long array expression with string literals to `"str1,str2".split(',')`
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fn try_compress_array_expression(
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expr: &mut Expression<'a>,
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ctx: Ctx<'a, '_>,
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) -> Option<Expression<'a>> {
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// this threshold is chosen by hand by checking the minsize output
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const THRESHOLD: usize = 40;
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let Expression::ArrayExpression(array) = expr else { unreachable!() };
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let is_all_string = array
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.elements
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.iter()
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.all(|element| element.as_expression().is_some_and(Expression::is_string_literal));
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if !is_all_string {
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return None;
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}
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let element_count = array.elements.len();
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// replace with `.split` only when the saved size is great enough
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// because using `.split` in some places and not in others may cause gzipped size to be bigger
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let can_save = element_count * 2 > ".split('.')".len() + THRESHOLD;
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if !can_save {
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return None;
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}
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let strings = array.elements.iter().map(|element| {
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let Expression::StringLiteral(str) = element.to_expression() else { unreachable!() };
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str.value.as_str()
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});
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let delimiter = Self::pick_delimiter(&strings)?;
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let concatenated_string = strings.collect::<std::vec::Vec<_>>().join(delimiter);
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// "str1,str2".split(',')
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Some(ctx.ast.expression_call(
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expr.span(),
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Expression::StaticMemberExpression(ctx.ast.alloc_static_member_expression(
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expr.span(),
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ctx.ast.expression_string_literal(
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expr.span(),
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ctx.ast.atom(&concatenated_string),
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None,
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),
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ctx.ast.identifier_name(expr.span(), "split"),
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false,
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)),
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Option::<TSTypeParameterInstantiation>::None,
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ctx.ast.vec1(Argument::from(ctx.ast.expression_string_literal(
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expr.span(),
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ctx.ast.atom(delimiter),
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None,
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))),
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false,
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))
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}
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fn pick_delimiter<'s>(
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strings: &(impl Iterator<Item = &'s str> + Clone),
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) -> Option<&'static str> {
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// These delimiters are chars that appears a lot in the program
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// therefore probably have a small Huffman encoding.
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const DELIMITERS: [&str; 5] = [".", ",", "(", ")", " "];
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let is_all_length_1 = strings.clone().all(|s| s.len() == 1);
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if is_all_length_1 {
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return Some("");
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}
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DELIMITERS.into_iter().find(|&delimiter| strings.clone().all(|s| !s.contains(delimiter)))
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}
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pub fn substitute_catch_clause(&mut self, catch: &mut CatchClause<'a>, ctx: Ctx<'a, '_>) {
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if self.target >= ESTarget::ES2019 {
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if let Some(param) = &catch.param {
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@ -1233,20 +1306,33 @@ mod test {
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}
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#[test]
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#[ignore]
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fn test_string_array_splitting() {
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test_same("var x=['1','2','3','4']");
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test_same("var x=['1','2','3','4','5']");
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test("var x=['1','2','3','4','5','6']", "var x='123456'.split('')");
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test("var x=['1','2','3','4','5','00']", "var x='1 2 3 4 5 00'.split(' ')");
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test("var x=['1','2','3','4','5','6','7']", "var x='1234567'.split('')");
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test("var x=['1','2','3','4','5','6','00']", "var x='1 2 3 4 5 6 00'.split(' ')");
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test("var x=[' ,',',',',',',',',',',']", "var x=' ,;,;,;,;,;,'.split(';')");
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test("var x=[',,',' ',',',',',',',',']", "var x=',,; ;,;,;,;,'.split(';')");
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test("var x=['a,',' ',',',',',',',',']", "var x='a,; ;,;,;,;,'.split(';')");
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const REPEAT: usize = 20;
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let additional_args = ",'1'".repeat(REPEAT);
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let test_with_longer_args =
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|source_text_partial: &str, expected_partial: &str, delimiter: &str| {
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let expected = &format!(
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"var x='{expected_partial}{}'.split('{delimiter}')",
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format!("{delimiter}1").repeat(REPEAT)
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);
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test(&format!("var x=[{source_text_partial}{additional_args}]"), expected);
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};
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let test_same_with_longer_args = |source_text_partial: &str| {
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test_same(&format!("var x=[{source_text_partial}{additional_args}]"));
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};
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test_same_with_longer_args("'1','2','3','4'");
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test_same_with_longer_args("'1','2','3','4','5'");
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test_with_longer_args("'1','2','3','4','5','6'", "123456", "");
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test_with_longer_args("'1','2','3','4','5','00'", "1.2.3.4.5.00", ".");
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test_with_longer_args("'1','2','3','4','5','6','7'", "1234567", "");
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test_with_longer_args("'1','2','3','4','5','6','00'", "1.2.3.4.5.6.00", ".");
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test_with_longer_args("'.,',',',',',',',',',','", ".,(,(,(,(,(,", "(");
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test_with_longer_args("',,','.',',',',',',',','", ",,(.(,(,(,(,", "(");
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test_with_longer_args("'a,','.',',',',',',',','", "a,(.(,(,(,(,", "(");
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// all possible delimiters used, leave it alone
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test_same("var x=[',', ' ', ';', '{', '}']");
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test_same_with_longer_args("'.', ',', '(', ')', ' '");
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}
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#[test]
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@ -9,19 +9,19 @@ Original | minified | minified | gzip | gzip | Fixture
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342.15 kB | 117.69 kB | 118.14 kB | 43.55 kB | 44.37 kB | vue.js
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544.10 kB | 71.49 kB | 72.48 kB | 25.89 kB | 26.20 kB | lodash.js
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544.10 kB | 71.44 kB | 72.48 kB | 25.87 kB | 26.20 kB | lodash.js
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555.77 kB | 271.48 kB | 270.13 kB | 88.38 kB | 90.80 kB | d3.js
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1.01 MB | 457.63 kB | 458.89 kB | 123.53 kB | 126.71 kB | bundle.min.js
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1.01 MB | 441.51 kB | 458.89 kB | 122.54 kB | 126.71 kB | bundle.min.js
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1.25 MB | 650.59 kB | 646.76 kB | 161.11 kB | 163.73 kB | three.js
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1.25 MB | 650.46 kB | 646.76 kB | 161 kB | 163.73 kB | three.js
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2.14 MB | 718.83 kB | 724.14 kB | 162.15 kB | 181.07 kB | victory.js
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2.14 MB | 718.76 kB | 724.14 kB | 162.15 kB | 181.07 kB | victory.js
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3.20 MB | 1.01 MB | 1.01 MB | 324.36 kB | 331.56 kB | echarts.js
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3.20 MB | 1.01 MB | 1.01 MB | 324.35 kB | 331.56 kB | echarts.js
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6.69 MB | 2.30 MB | 2.31 MB | 469.42 kB | 488.28 kB | antd.js
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6.69 MB | 2.30 MB | 2.31 MB | 469.30 kB | 488.28 kB | antd.js
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10.95 MB | 3.37 MB | 3.49 MB | 864.74 kB | 915.50 kB | typescript.js
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10.95 MB | 3.37 MB | 3.49 MB | 864.70 kB | 915.50 kB | typescript.js
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