swc/crates/swc_ecma_codegen/examples/sourcemap.rs

/// Use memory allocator
extern crate swc_node_base;

use std::{
    env,
    fs::{self, File},
    io::BufWriter,
    path::Path,
    time::Instant,
};

use swc_common::input::SourceFileInput;
use swc_ecma_ast::*;
use swc_ecma_codegen::{text_writer::JsWriter, Emitter};
use swc_ecma_parser::{lexer::Lexer, Parser, Syntax};

fn parse_and_gen(entry: &Path) {
    testing::run_test2(false, |cm, _| {
        let fm = cm.load_file(entry).unwrap();

        let lexer = Lexer::new(
            Syntax::Typescript(Default::default()),
            EsVersion::latest(),
            SourceFileInput::from(&*fm),
            None,
        );
        let mut parser = Parser::new_from(lexer);
        let m = parser
            .parse_module()
            .expect("failed to parse input as a module");

        let mut code = vec![];
        let mut srcmap = vec![];

        {
            let mut emitter = Emitter {
                cfg: swc_ecma_codegen::Config {
                    ..Default::default()
                },
                cm: cm.clone(),
                comments: None,
                wr: JsWriter::new(cm.clone(), "\n", &mut code, Some(&mut srcmap)),
            };

            emitter.emit_module(&m).unwrap();
        }

        let srcmap = cm.build_source_map(&srcmap);

        fs::write("output.js", &code).unwrap();

        let srcmap_file = File::create("output.js.map").unwrap();
        let srcmap_wr = BufWriter::new(srcmap_file);
        srcmap.to_writer(srcmap_wr).unwrap();

        Ok(())
    })
    .expect("failed to process a module");
}

/// Usage: ./scripts/instruements path/to/input/file
fn main() {
    let main_file = env::args().nth(1).unwrap();

    let start = Instant::now();
    parse_and_gen(Path::new(&main_file));
    let dur = start.elapsed();
    println!("Took {:?}", dur);
}