feat(span): introduce format_atom! macro
#10722
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CodSpeed Instrumentation Performance ReportMerging #10722 will not alter performanceComparing Summary
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WalkthroughA new macro named 📜 Recent review detailsConfiguration used: CodeRabbit UI 📒 Files selected for processing (2)
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Pull Request Overview
This PR introduces the new macro format_atom! to create an Atom directly in the arena without intermediate String allocation.
- Adds a re-export of the arena-specific String (ArenaString) in lib.rs for internal use.
- Implements and documents the format_atom! macro in atom.rs.
Reviewed Changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| crates/oxc_span/src/lib.rs | Adds a re-export for ArenaString to support the new macro. |
| crates/oxc_span/src/atom.rs | Implements and documents the format_atom! macro. |
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Actionable comments posted: 0
🧹 Nitpick comments (1)
crates/oxc_span/src/atom.rs (1)
234-269: Well-designed macro with clear documentation.The implementation is clean and follows Rust best practices:
- Takes an allocator as first argument, consistent with other allocator-based APIs
- Directly constructs the string in the arena without intermediate allocations
- Error handling matches the standard
format!macro (panics on errors)- Documentation is clear and includes a usage example
Consider enhancing the documentation example to specifically demonstrate the efficiency improvement mentioned in the PR objectives - showing how this avoids an intermediate
Stringwhen converting a type implementingDisplayto anAtom:/// # Example /// /// ``` /// use oxc_allocator::Allocator; /// use oxc_span::format_atom; /// let allocator = Allocator::new(); /// /// let s1 = "foo"; /// let s2 = "bar"; /// let formatted = format_atom!(&allocator, "{s1}.{s2}"); /// assert_eq!(formatted, "foo.bar"); +/// +/// // More efficient than creating an intermediate String +/// struct MyType(i32); +/// impl std::fmt::Display for MyType { +/// fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { +/// write!(f, "MyType({})", self.0) +/// } +/// } +/// +/// let my_value = MyType(42); +/// // Avoid intermediate String allocation +/// let atom = format_atom!(&allocator, "{my_value}"); +/// assert_eq!(atom, "MyType(42)"); /// ```
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crates/oxc_span/src/atom.rs(1 hunks)crates/oxc_span/src/lib.rs(1 hunks)
🔇 Additional comments (1)
crates/oxc_span/src/lib.rs (1)
35-36: Well structured internal re-export for the new macro.Clean implementation that follows the existing pattern in this module (similar to line 34 for
format_compact_str!). Appropriately placed within the#[doc(hidden)]__internalmodule, indicating this is not part of the public API.
Merge activity
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Introduce a `format_atom!` macro. This behaves the same as `std`'s `format!` macro, but constructs the string directly in arena, and returns an `Atom` instead of a `String`.
```rs
let foo_dot_bar: Atom = format_atom!(&allocator, "{}.{}", foo, bar);
```
Can also be used to avoid creating a temp `String` when creating an `Atom` using a `Display` impl:
```rs
// Before
let atom = ctx.ast.atom(&my_display_type.to_string());
// After
let atom = format_atom!(ctx.ast.allocator, "{my_display_type}");
```
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…#10723) Avoid temp `String` and copying string data by: 1. Reusing existing `Atom` where possible, instead of copying the string data and creating a new `Atom`. 2. Use `format_atom!` macro (introduced in #10722) to avoid creating a temporary `String` when converting `oxc_regular_expression::Pattern` to a string.
Introduce a
format_atom!macro. This behaves the same asstd'sformat!macro, but constructs the string directly in arena, and returns anAtominstead of aString.Can also be used to avoid creating a temp
Stringwhen creating anAtomusing aDisplayimpl: