oxc / Explore crates

https://github.com/oxc-project/oxc

oxc_ast

Printing an AST

For this one, you will need to read oxc_codegen before.

oxc_codegen

oxc:oxc_codegen::Codegen is the struct that holds everything needed to transform an oxc::oxc_ast::ast::Program into a CodegenReturn thanks to its build method.

The CodegenReturn contains:

• code: String (the code generated from the ast)
• map: Option<oxc_sourcemap::SourceMap> (the sourcemap if activated)

Codegen::build

• prepares a buffer for the code that will be generated - self.code.reserve(program.source_text.len())
• creates a HashMap of the comments contained in the AST (if the comments are to be printed - like not in minified code)
• creates a oxc::oxc_codegen::SourcemapBuilder (if sourcemaps are active)

Finally, calls the print method on the AST, passing itself &mut Codegen and a default oxc::oxc_codegen::Context which will be passed to each print calls of each AST node.

Codegen::gen

Each kind of of AST nodes needs to implement the following traits (according to their behavior)

#![allow(unused)]
fn main() {
/// Generate source code for an AST node.
pub trait Gen: GetSpan {
    /// Generate code for an AST node.
    fn gen(&self, p: &mut Codegen, ctx: Context);

    /// Generate code for an AST node. Alias for `gen`.
    fn print(&self, p: &mut Codegen, ctx: Context) {
        self.gen(p, ctx);
    }
}
}

#![allow(unused)]
fn main() {
/// Generate source code for an expression.
pub trait GenExpr: GetSpan {
    /// Generate code for an expression, respecting operator precedence.
    fn gen_expr(&self, p: &mut Codegen, precedence: Precedence, ctx: Context);

    /// Generate code for an expression, respecting operator precedence. Alias for `gen_expr`.
    fn print_expr(&self, p: &mut Codegen, precedence: Precedence, ctx: Context) {
        self.gen_expr(p, precedence, ctx);
    }
}
}

See the follow-up in oxc_ast.

See more about sourcemaps on oxc::oxc_sourcemaps.

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oxc_sourcemap

The sourcemap implement port from rust-sourcemap, but has some different with it.

Encode sourcemap at parallel, including quote sourceContent and encode token to vlq mappings. Avoid Sourcemap some methods overhead, like SourceMap::tokens().

The main interface for creating sourcemaps from existing files seems to be oxc::oxc_codegen::CodeGen::new().enable_source_map(&filename, &source_text).build() (or any other options allowed by the builder pattern).

Understand the relation about SourceMap between oxc_codegen and oxc_sourcemap

• oxc::oxc_codegen::SourcemapBuilder vs oxc::oxc_sourcemap::SourceMapBuilder (map vs Map - may be a typo ?)
  • oxc::oxc_codegen::Codegen contains a field sourcemap_builder: Option<oxc::oxc_codegen::SourcemapBuilder>
  • oxc::oxc_codegen::SourcemapBuilder contains a field sourcemap_builder: oxc::oxc_sourcemap::SourceMapBuilder
• oxc::oxc_codegen::SourcemapBuilder has into_sourcemap(self) -> oxc::oxc_sourcemap::SourceMap, which calls:
  • oxc::oxc_sourcemap::SourceMapBuilder with into_sourcemap(self) -> SourceMap

See more in oxc::oxc_codegen.

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oxc_span

oxc::oxc_span::span::types

A range in text, represented by a zero-indexed start and end offset.

#![allow(unused)]
fn main() {
use oxc_span::Span;
let text = "foo bar baz";
let span = Span::new(4, 7);
assert_eq!(&text[span], "bar");
}

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