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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.//! This example shows how to use swc to transpile TypeScript and JSX/TSX//! modules.//!//! It will only transpile, not typecheck (like Deno's `--no-check` flag).
use std::pin::Pin;use std::rc::Rc;
use anyhow::anyhow;use anyhow::bail;use anyhow::Error;use deno_ast::MediaType;use deno_ast::ParseParams;use deno_ast::SourceTextInfo;use deno_core::resolve_import;use deno_core::resolve_path;use deno_core::JsRuntime;use deno_core::ModuleLoader;use deno_core::ModuleSource;use deno_core::ModuleSourceFuture;use deno_core::ModuleSpecifier;use deno_core::ModuleType;use deno_core::RuntimeOptions;use futures::FutureExt;
struct TypescriptModuleLoader;
impl ModuleLoader for TypescriptModuleLoader {  fn resolve(    &self,    specifier: &str,    referrer: &str,    _is_main: bool,  ) -> Result<ModuleSpecifier, Error> {    Ok(resolve_import(specifier, referrer)?)  }
  fn load(    &self,    module_specifier: &ModuleSpecifier,    _maybe_referrer: Option<ModuleSpecifier>,    _is_dyn_import: bool,  ) -> Pin<Box<ModuleSourceFuture>> {    let module_specifier = module_specifier.clone();    async move {      let path = module_specifier        .to_file_path()        .map_err(|_| anyhow!("Only file: URLs are supported."))?;
      let media_type = MediaType::from(&path);      let (module_type, should_transpile) = match MediaType::from(&path) {        MediaType::JavaScript | MediaType::Mjs | MediaType::Cjs => {          (ModuleType::JavaScript, false)        }        MediaType::Jsx => (ModuleType::JavaScript, true),        MediaType::TypeScript        | MediaType::Mts        | MediaType::Cts        | MediaType::Dts        | MediaType::Dmts        | MediaType::Dcts        | MediaType::Tsx => (ModuleType::JavaScript, true),        MediaType::Json => (ModuleType::Json, false),        _ => bail!("Unknown extension {:?}", path.extension()),      };
      let code = std::fs::read_to_string(&path)?;      let code = if should_transpile {        let parsed = deno_ast::parse_module(ParseParams {          specifier: module_specifier.to_string(),          text_info: SourceTextInfo::from_string(code),          media_type,          capture_tokens: false,          scope_analysis: false,          maybe_syntax: None,        })?;        parsed.transpile(&Default::default())?.text      } else {        code      };      let module = ModuleSource {        code: code.into_bytes().into_boxed_slice(),        module_type,        module_url_specified: module_specifier.to_string(),        module_url_found: module_specifier.to_string(),      };      Ok(module)    }    .boxed_local()  }}
fn main() -> Result<(), Error> {  let args: Vec<String> = std::env::args().collect();  if args.len() < 2 {    println!("Usage: target/examples/debug/ts_module_loader <path_to_module>");    std::process::exit(1);  }  let main_url = args[1].clone();  println!("Run {}", main_url);
  let mut js_runtime = JsRuntime::new(RuntimeOptions {    module_loader: Some(Rc::new(TypescriptModuleLoader)),    ..Default::default()  });
  let main_module = resolve_path(&main_url)?;
  let future = async move {    let mod_id = js_runtime.load_main_module(&main_module, None).await?;    let result = js_runtime.mod_evaluate(mod_id);    js_runtime.run_event_loop(false).await?;    result.await?  };
  tokio::runtime::Builder::new_current_thread()    .enable_all()    .build()    .unwrap()    .block_on(future)}