feat(traverse): CombinedTraverse type to compose Traverses

[overlookmotel]

Implements the CombinedTraverse type discussed in #3216 (comment). This type and the accompanying combine_traverses! macro allow composing multiple traverses/transforms with minimal boilerplate.

I am actually not sure if this is a good idea or not. The API is nice I think, but it may blow up compile times.

[overlookmotel]

• feat(traverse): CombinedTraverse type to compose Traverses #3219 👈
• main

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[codspeed-hq]

CodSpeed Performance Report

Merging #3219 will not alter performance

_{Comparing 05-10-feat_traverse_combinedtraverse_type_to_compose_traverse_s (16abdc7) with main (2064ae9)}

Summary

✅ 27 untouched benchmarks

[Dunqing]

Can we combine multiple Traversers ( >2 )?

[overlookmotel]

Can we combine multiple Traversers ( >2 )?

Yes!

let all_five = combine_traverses!(
    MyTraverse1::new(),
    MyTraverse2::new(),
    MyTraverse3::new(),
    MyTraverse4::new(),
    MyTraverse5::new(), 
);

oxc/crates/oxc_traverse/src/lib.rs

Lines 210 to 287 in 2ff2eb8

	/// Macro to compose multiple traverses.
	///
	/// The traverses will run:
	/// * `enter_*` methods in order.
	/// * `exit_*` methods in reverse order.
	///
	/// Each `Traverse` does NOT run one after another on the whole AST in a series of passes.
	/// Visitation is interleaved. The AST is only visited once.
	///
	/// i.e. with 3 `Traverse`s provided, execution order is:
	///
	/// * `Tr1::enter_program`
	/// * `Tr2::enter_program`
	/// * `Tr3::enter_program`
	/// * `Tr1::enter_statements`
	/// * `Tr2::enter_statements`
	/// * `Tr3::enter_statements`
	/// * ...and so on all the way down AST
	/// * `Tr3::exit_statements`
	/// * `Tr2::exit_statements`
	/// * `Tr1::exit_statements`
	/// * `Tr3::exit_program`
	/// * `Tr2::exit_program`
	/// * `Tr1::exit_program`
	///
	/// # Example
	///
	/// ```
	/// use oxc_traverse::{combine_traverses, Traverse};
	///
	/// struct MyTraverse1;
	/// impl MyTraverse1 { fn new() -> Self { Self } }
	/// impl<'a> Traverse<'a> for MyTraverse1 {}
	///
	/// struct MyTraverse2;
	/// impl MyTraverse2 { fn new() -> Self { Self } }
	/// impl<'a> Traverse<'a> for MyTraverse2 {}
	///
	/// struct MyTraverse3;
	/// impl MyTraverse3 { fn new() -> Self { Self } }
	/// impl<'a> Traverse<'a> for MyTraverse3 {}
	///
	/// let all_three = combine_traverses!(
	/// MyTraverse1::new(),
	/// MyTraverse2::new(),
	/// MyTraverse3::new(),
	/// );
	/// ```
	///
	/// # Expansion
	///
	/// `combine_traverses!` in above example expands to:
	///
	/// ```nocompile
	/// let all_three = CombinedTraverse::new(
	/// MyTraverse1::new(),
	/// CombinedTraverse::new(
	/// MyTraverse2::new(),
	/// MyTraverse3::new(),
	/// ),
	/// );
	/// ```
	#[macro_export]
	macro_rules! combine_traverses {
	($t1:expr, $t2:expr $(,)?) => {
	$crate::CombinedTraverse::new($t1, $t2)
	};
	($t1:expr, $t2:expr, $($rest:expr),+ $(,)?) => {
	$crate::CombinedTraverse::new(
	$t1,
	$crate::combine_traverses!(
	$t2,
	$($rest),+
	)
	)
	};
	}

[Boshen]

Crazy! Let's hop on a call every time we gonna add 3000 lines of code 😛

[overlookmotel]

Crazy!

Can I take that as "no way we're going to merge this nonsense"?

Well I did say "I am actually not sure if this is a good idea". It's just responding to Dunqing's request for a less verbose API in #3216.

And the joy of codegens is it only takes about 20 mins to generate 3000 lines of code! 😂

[Boshen]

Let's refine the infra once all tests passes so we have the whole picture of the current infra.