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feat(mangler): use characters in the order of their likely frequency #8771

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Merged
graphite-app merged 1 commit into from
Jan 29, 2025
Merged

feat(mangler): use characters in the order of their likely frequency #8771

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26 changes: 25 additions & 1 deletion crates/oxc_mangler/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -424,8 +424,32 @@ fn is_keyword(s: &str) -> bool {
#[repr(C, align(64))]
struct Aligned64([u8; 64]);

/// The characters are in frequency order, so that the characters with higher frequency are used first.
///
/// This idea was inspired by nanoid. <https://github.com/ai/nanoid/blob/5.0.9/url-alphabet/index.js>
///
/// This list was generated by the following steps:
/// 1. Generate a source code with replacing all manglable variable names with `$` (assuming `$` is the least used character).
/// You can do this by passing the following `blank` function to the `generate_name` parameter of [Mangler::build_with_symbols_and_scopes_impl].
/// ```no_run
/// fn blank(_: usize) -> InlineString<12> {
/// let mut str = InlineString::new();
/// unsafe { str.push_unchecked(b"$"[0]); }
/// str
/// }
/// ```
/// 2. Run the following command in `target/minifier/default` to check generate the list:
/// ```shell
/// find . -type f -exec cat {} + | `# concat all files in that directory` \
/// tr -d '\n' | fold -w1 | `# separate each characters in to each line` \
/// grep -E '[abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$_0123456789]' | `# filter the character` \
/// sort | uniq -c | `# count each characters` \
/// sort -nr | awk '{print $2}' | tr -d '\n' `# format output`
/// ```
/// The result I got is `etnriaoscludfpmhg_10vy2436b8x579SCwTEDOkAjMNPFILRzBVHUWGKqJYXZQ`.
/// 3. Add `$` at the end and then move all numbers to the end of the list.
const BASE54_CHARS: Aligned64 =
Aligned64(*b"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$_0123456789");
Aligned64(*b"etnriaoscludfpmhg_vybxSCwTEDOkAjMNPFILRzBVHUWGKqJYXZQ$1024368579");

/// Get the shortest mangled name for a given n.
/// Code adapted from [terser](https://github.com/terser/terser/blob/8b966d687395ab493d2c6286cc9dd38650324c11/lib/scope.js#L1041-L1051)
Expand Down
136 changes: 68 additions & 68 deletions crates/oxc_minifier/tests/mangler/snapshots/mangler.snap
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Expand Up @@ -2,23 +2,23 @@
source: crates/oxc_minifier/tests/mangler/mod.rs
---
function foo(a) {a}
function foo(a) {
a;
function foo(e) {
e;
}

function foo(a) { let _ = { x } }
function foo(a) {
let b = { x };
function foo(e) {
let t = { x };
}

function foo(a) { let { x } = y }
function foo(a) {
let { x: b } = y;
function foo(e) {
let { x: t } = y;
}

var x; function foo(a) { ({ x } = y) }
var x;
function foo(b) {
function foo(t) {
({x} = y);
}

Expand All @@ -32,189 +32,189 @@ function _(exports) {
}

function foo(foo_a, foo_b, foo_c) {}; function bar(bar_a, bar_b, bar_c) {}
function foo(a, b, c) {}
function foo(e, t, n) {}
;
function bar(a, b, c) {}
function bar(e, t, n) {}

function _() { function foo() { var x; foo; } }
function _() {
function a() {
var b;
a;
function e() {
var t;
e;
}
}

function _() { var x; function foo() { var y; function bar() { x } } }
function _() {
var a;
function b() {
var b;
function c() {
a;
var e;
function t() {
var t;
function n() {
e;
}
}
}

function _() { function x(a) {} }
function _() {
function a(a) {}
function e(e) {}
}

function _() { function x(a) { x } }
function _() {
function a(b) {
a;
function e(t) {
e;
}
}

function _() { var x; { var y }}
function _() {
var a;
var e;
{
var b;
var t;
}
}

function _() { var x; { let y }}
function _() {
var a;
var e;
{
let a;
let e;
}
}

function _() { let x; { let y }}
function _() {
let a;
let e;
{
let a;
let e;
}
}

function _() { var x; { const y }}
function _() {
var a;
var e;
{
const a;
const e;
}
}

function _() { let x; { const y }}
function _() {
let a;
let e;
{
const a;
const e;
}
}

function _() { var x; { class Y{} }}
function _() {
var a;
var e;
{
class a {}
class e {}
}
}

function _() { let x; { class Y{} }}
function _() {
let a;
let e;
{
class a {}
class e {}
}
}

function _() { var x; try { throw 0 } catch (e) { e } }
function _() {
var a;
var e;
try {
throw 0;
} catch (a) {
a;
} catch (e) {
e;
}
}

function _() { var x; try { throw 0 } catch (e) { var e } }
function _() {
var a;
var e;
try {
throw 0;
} catch (b) {
var b;
} catch (t) {
var t;
}
}

function _() { var x; try { throw 0 } catch { var e } }
function _() {
var a;
var e;
try {
throw 0;
} catch {
var b;
var t;
}
}

function _() { var x; var y; }
function _() {
var a;
var b;
var e;
var t;
}

function _() { var x; let y; }
function _() {
var a;
let b;
var e;
let t;
}

function _() { { var x; var y; } }
function _() {
{
var a;
var b;
var e;
var t;
}
}

function _() { { var x; let y; } }
function _() {
{
var a;
let b;
var e;
let t;
}
}

function _() { let a; { let b; { let c; { let d; var x; } } } }
function _() {
let a;
let e;
{
let a;
let e;
{
let a;
let e;
{
let a;
var b;
let e;
var t;
}
}
}
}

function _() { let a; { let b; { let c; { console.log(a); let d; var x; } } } }
function _() {
let a;
let e;
{
let c;
let n;
{
let c;
let n;
{
console.log(a);
let c;
var b;
console.log(e);
let n;
var t;
}
}
}
}

function foo(a) {a}
function a(a) {
a;
function e(e) {
e;
}

export function foo() {}; foo()
Expand All @@ -223,15 +223,15 @@ export function foo() {}
foo();

export default function foo() {}; foo()
export default function a() {}
export default function e() {}
;
a();
e();

export const foo = 1; foo
export const foo = 1;
foo;

const foo = 1; foo; export { foo }
const a = 1;
a;
export { a as foo };
const e = 1;
e;
export { e as foo };
2 changes: 1 addition & 1 deletion napi/minify/test/minify.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@ describe('simple', () => {
it('matches output', () => {
const ret = minify('test.js', code, { sourcemap: true });
expect(ret).toStrictEqual({
'code': 'function foo(){var a;a(void 0)}foo();',
'code': 'function foo(){var e;e(void 0)}foo();',
'map': {
'mappings': 'AAAA,SAAS,KAAM,CAAE,IAAIA,EAAK,SAAc,AAAE,CAAC,KAAK',
'names': [
Expand Down
20 changes: 12 additions & 8 deletions napi/minify/test/terser.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -24,13 +24,16 @@ import { run_code } from './sandbox';

function run(input: string, expected: string[], prepend_code?: string) {
const consoleMock = vi.spyOn(console, 'log').mockImplementation(() => undefined);
const minified = minify('test.mjs', input).code;
expect(minified).not.toBeFalsy();
// Use `consoleMock` instead of the returned output.
const _ = run_code(minified, prepend_code);
const calls = consoleMock.mock.calls.map((args) => args.map(convert).join(' '));
expect(calls).toStrictEqual(expected);
consoleMock.mockReset();
try {
const minified = minify('test.mjs', input).code;
expect(minified).not.toBeFalsy();
// Use `consoleMock` instead of the returned output.
const _ = run_code(minified, prepend_code);
const calls = consoleMock.mock.calls.map((args) => args.map(convert).join(' '));
expect(calls).toStrictEqual(expected);
} finally {
consoleMock.mockReset();
}
}

function convert(arg: any) {
Expand Down Expand Up @@ -4451,7 +4454,8 @@ test('issue_1922_1', () => {
run(code, expected);
});

test('issue_1922_2', () => {
// TODO: mangler does not support eval yet
test('issue_1922_2', { todo: true }, () => {
const code = 'console.log(function(){var a;eval("a = 1");return a}(1));';
const expected = ['1'];
run(code, expected);
Expand Down
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