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overlookmotel
7e9b84a1dc
Add an `implements!` macro which answers "does type X implement trait Y?". Primarily this is useful in tests, but can also be used in macros to produce specialized code paths. ```rust assert!(implements!(Ident: Send)); assert!(implements!(Ident: Sync)); assert!(implements!(Allocator: !Sync)); ``` Also works in const context: ```rust const U32_IS_COPY: bool = implements!(u32: Copy); const _: () = assert!(U32_IS_COPY); ``` Particularly useful for checking that a type does _not_ implement a trait. Without this macro, that requires a `compile_fail` doctest, which is fragile - when code changes, the doctest can easily start failing for _different_ reasons, which means it's no longer testing what it's meant to, and there's no way to spot that. This is a primitive required for forthcoming `MultiVec` SoA vec type. Putting it in `oxc_data_structures` as it can be useful in other places too.
34 lines
1.9 KiB
Markdown
34 lines
1.9 KiB
Markdown
# Oxc Data Structures
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Common data structures and utilities used across oxc crates.
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## Overview
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This crate provides specialized data structures and utilities that are used throughout the oxc toolchain. These structures are optimized for the specific needs of compiler and tooling workloads.
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## Key Features
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- **Stacks**: Efficient stack types, optimized for fast `push`, `pop`, and `last`
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- **Code buffer**: Efficient string building with segment tracking
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- **Inline strings**: Memory-efficient string storage for short strings
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- **Slice iterators**: Enhanced iteration capabilities for slices
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- **Rope data structure**: Efficient text manipulation for large documents
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- **Box macros**: Macros for creating boxed arrays / slices (similar to `vec!` macro)
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- **Fieldless enums macro**: Macro for creating enums with a `VARIANTS` constant listing all variants
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- **Non-null pointers**: `NonNullConst<T>` and `NonNullMut<T>` - non-null pointer types with explicit const/mut permissions
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- **Branch prediction hints**: `likely` and `unlikely` functions to hint to the compiler whether a branch is likely to be taken (also re-exports `std::hint::cold_path`)
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- **`StringExt` trait**: Add methods to `String` to push without capacity checks
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- **String utilities**: `const`-compatible string helpers (e.g. `const_str_eq` for comparing strings in a `const` context)
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- **Type utilities**: `implements!` macro to determine if a type implements a trait
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## Architecture
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These data structures are designed with specific compiler requirements in mind:
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- **Performance**: Optimized for common patterns in parsing and code generation
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- **Memory efficiency**: Minimize allocations and memory overhead
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- **Safety**: Provide safe abstractions over potentially unsafe operations
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- **Ergonomics**: Easy to use APIs that integrate well with other oxc components
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The structures complement Rust's standard library with domain-specific optimizations for JavaScript/TypeScript tooling.
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