解析器架构

🌐 Parser Architecture

Oxc 维护着自己的抽象语法树（AST）和解析器，它是迄今为止用 Rust 编写的速度最快、最符合规范的 JavaScript 和 TypeScript（包括 JSX 和 TSX）解析器。

🌐 Oxc maintains its own AST and parser, which is by far the fastest and most conformant JavaScript and TypeScript (including JSX and TSX) parser written in Rust.

由于解析器往往是 JavaScript 工具中的关键性能瓶颈，任何细微的改进都可能对我们的下游工具产生连锁效应。通过开发我们的解析器，我们有机会探索和实现经过充分研究的性能优化技术。

🌐 As the parser often represents a key performance bottleneck in JavaScript tooling, any minor improvements can have a cascading effect on our downstream tools. By developing our parser, we have the opportunity to explore and implement well-researched performance techniques.

AST设计理念

🌐 AST Design Philosophy

虽然许多现有的 JavaScript 工具依赖 estree 作为它们的 AST 规范，但一个显著的缺点是它存在大量模糊的节点。这种模糊性经常导致在使用 estree 开发时产生混淆。

🌐 While many existing JavaScript tools rely on estree as their AST specification, a notable drawback is its abundance of ambiguous nodes. This ambiguity often leads to confusion during development with estree.

Oxc AST 与 estree AST 的不同在于，它移除了模糊的节点并引入了不同的类型。例如，Oxc AST 不再使用通用的 estree Identifier，而是提供了具体类型，如 BindingIdentifier、IdentifierReference 和 IdentifierName。

🌐 The Oxc AST differs from the estree AST by removing ambiguous nodes and introducing distinct types. For example, instead of using a generic estree Identifier, the Oxc AST provides specific types such as BindingIdentifier, IdentifierReference, and IdentifierName.

这种明确的区分通过更紧密地与 ECMAScript 规范对齐，大大提升了开发体验。

🌐 This clear distinction greatly enhances the development experience by aligning more closely with the ECMAScript specification.

AST 节点类型

🌐 AST Node Types

rust

// Instead of generic Identifier
pub struct BindingIdentifier<'a> {
    pub span: Span,
    pub name: Atom<'a>,
}

pub struct IdentifierReference<'a> {
    pub span: Span,
    pub name: Atom<'a>,
    pub reference_id: Cell<Option<ReferenceId>>,
}

pub struct IdentifierName<'a> {
    pub span: Span,
    pub name: Atom<'a>,
}

语义清晰

🌐 Semantic Clarity

这种方法提供了语义上的清晰性：

🌐 This approach provides semantic clarity:

BindingIdentifier：变量声明（let x = 1）
IdentifierReference：变量使用（console.log(x)）
IdentifierName：属性名称（obj.property）

性能架构

🌐 Performance Architecture

它怎么这么快

🌐 How is it so fast

内存区：AST 分配在内存区中，以实现快速分配和释放
字符串优化：短字符串由 CompactString 内联
最小堆使用：除了上述两个之外，不进行其他堆分配
关注点分离：作用域绑定、符号解析以及部分语法错误被委派给语义分析器处理

内存管理详情

🌐 Memory Management Details

竞技场分配

🌐 Arena Allocation

rust

use oxc_allocator::Allocator;

// All AST nodes are allocated in this arena
let allocator = Allocator::default();
let ast_node = allocator.alloc(Expression::NumericLiteral(
    allocator.alloc(NumericLiteral { value: 42.0, span: SPAN })
));

好处：

🌐 Benefits:

O(1) 分配：简单的指针增加
O(1) 释放：一次性丢弃整个区域
缓存友好：线性内存布局
无碎片化：连续的内存使用

使用 CompactString 的字符串驻留

🌐 String Interning with CompactString

rust

// Strings ≤ 24 bytes are stored inline (no heap allocation)
let short_name = CompactString::from("variableName");  // Stack allocated
let long_name = CompactString::from("a_very_long_variable_name_that_exceeds_limit");  // Heap allocated

这减少了大多数 JavaScript 标识符和字符串字面量的内存分配。

🌐 This reduces memory allocations for the majority of JavaScript identifiers and string literals.