swc_es_parser

swc_es_parser is an ECMAScript parser that builds arena-backed nodes from swc_es_ast.

Goals

• Parse source directly into swc_es_ast handles.
• Expose a small parser API (Lexer, Parser, parse_file_as_*).
• Keep parser errors in a crate-local error model while integrating with swc_common diagnostics.
• Keep runtime dependency graph independent from swc_ecma_parser.

Current Status

• Script/module/program entry points are available.
• Core statements, expressions, module declarations, JSX, and TypeScript constructs are parsed.
• Parity pass/fail behavior is continuously validated against reused swc_ecma_parser fixture corpora.
• Syntax options wired in parser logic include:
  • EsSyntax: decorators_before_export, export_default_from, allow_super_outside_method.
  • TsSyntax: dts, disallow_ambiguous_jsx_like.

Parity Harness

• swc_ecma_parser inputs are reused from crates/swc_ecma_parser/tests.
• Fixture reuse is test-only; importing swc_ecma_parser crate at runtime is disallowed and enforced by tests.
• Run parity checks with:

cargo test -p swc_es_parser --test parity_suite

API Sketch

use swc_common::{input::StringInput, FileName, SourceMap};
use swc_es_parser::{lexer::Lexer, Parser, Syntax};

let cm = SourceMap::default();
let fm = cm.new_source_file(FileName::Custom("a.js".into()).into(), "let a = 1;");
let lexer = Lexer::new(Syntax::default(), StringInput::from(&*fm), None);
let mut parser = Parser::new_from(lexer);
let parsed = parser.parse_program().unwrap();