3 files changed, 48 insertions, 20 deletions

diff --git a/deno_typescript/compiler_main.js b/deno_typescript/compiler_main.js
index 94b38e070..013d6e157 100644
--- a/deno_typescript/compiler_main.js
+++ b/deno_typescript/compiler_main.js
@@ -184,8 +184,8 @@ class Host {
       fileName = moduleMap.get(fileName);
     }
 
-    const { sourceCode, moduleName } = dispatch("readFile", {
-      fileName,
+    const { sourceCode, moduleName } = dispatch("loadModule", {
+      moduleUrl: fileName,
       languageVersion,
       shouldCreateNewSourceFile
     });
diff --git a/deno_typescript/lib.rs b/deno_typescript/lib.rs
index 1bf6eb351..7977b7cfe 100644
--- a/deno_typescript/lib.rs
+++ b/deno_typescript/lib.rs
@@ -16,6 +16,7 @@ use deno_core::StartupData;
 use deno_core::ZeroCopyBuf;
 pub use ops::EmitResult;
 use ops::WrittenFile;
+use std::collections::HashMap;
 use std::fs;
 use std::path::Path;
 use std::path::PathBuf;
@@ -32,6 +33,8 @@ pub fn ts_version() -> String {
   pkg["version"].as_str().unwrap().to_string()
 }
 
+type ExternCrateModules = HashMap<String, String>;
+
 #[derive(Debug)]
 pub struct TSState {
   bundle: bool,
@@ -40,6 +43,7 @@ pub struct TSState {
   /// A list of files emitted by typescript. WrittenFile is tuple of the form
   /// (url, corresponding_module, source_code)
   written_files: Vec<WrittenFile>,
+  extern_crate_modules: ExternCrateModules,
 }
 
 fn compiler_op<D>(
@@ -62,21 +66,27 @@ pub struct TSIsolate {
 }
 
 impl TSIsolate {
-  fn new(bundle: bool) -> TSIsolate {
+  fn new(
+    bundle: bool,
+    maybe_extern_crate_modules: Option<ExternCrateModules>,
+  ) -> TSIsolate {
     let mut isolate = Isolate::new(StartupData::None, false);
     js_check(isolate.execute("assets/typescript.js", TYPESCRIPT_CODE));
     js_check(isolate.execute("compiler_main.js", COMPILER_CODE));
 
+    let extern_crate_modules = maybe_extern_crate_modules.unwrap_or_default();
+
     let state = Arc::new(Mutex::new(TSState {
       bundle,
       exit_code: 0,
       emit_result: None,
       written_files: Vec::new(),
+      extern_crate_modules,
     }));
 
     isolate.register_op(
-      "readFile",
-      compiler_op(state.clone(), ops::json_op(ops::read_file)),
+      "loadModule",
+      compiler_op(state.clone(), ops::json_op(ops::load_module)),
     );
     isolate
       .register_op("exit", compiler_op(state.clone(), ops::json_op(ops::exit)));
@@ -125,8 +135,9 @@ impl TSIsolate {
 pub fn compile_bundle(
   bundle_filename: &Path,
   root_names: Vec<PathBuf>,
+  extern_crate_modules: Option<ExternCrateModules>,
 ) -> Result<String, ErrBox> {
-  let ts_isolate = TSIsolate::new(true);
+  let ts_isolate = TSIsolate::new(true, extern_crate_modules);
 
   let config_json = serde_json::json!({
     "compilerOptions": {
diff --git a/deno_typescript/ops.rs b/deno_typescript/ops.rs
index f76662620..f9b244397 100644
--- a/deno_typescript/ops.rs
+++ b/deno_typescript/ops.rs
@@ -35,16 +35,16 @@ pub fn json_op(d: Dispatcher) -> impl Fn(&mut TSState, &[u8]) -> CoreOp {
 
 #[derive(Debug, Deserialize)]
 #[serde(rename_all = "camelCase")]
-struct ReadFile {
-  file_name: String,
+struct LoadModule {
+  module_url: String,
   language_version: Option<i32>,
   should_create_new_source_file: bool,
 }
 
-pub fn read_file(_s: &mut TSState, v: Value) -> Result<Value, ErrBox> {
-  let v: ReadFile = serde_json::from_value(v)?;
-  let (module_name, source_code) = if v.file_name.starts_with("$asset$/") {
-    let asset = v.file_name.replace("$asset$/", "");
+pub fn load_module(s: &mut TSState, v: Value) -> Result<Value, ErrBox> {
+  let v: LoadModule = serde_json::from_value(v)?;
+  let (module_name, source_code) = if v.module_url.starts_with("$asset$/") {
+    let asset = v.module_url.replace("$asset$/", "");
 
     let source_code = match crate::get_asset(&asset) {
       Some(code) => code.to_string(),
@@ -58,14 +58,31 @@ pub fn read_file(_s: &mut TSState, v: Value) -> Result<Value, ErrBox> {
 
     (asset, source_code)
   } else {
-    assert!(!v.file_name.starts_with("$assets$"), "you meant $asset$");
-    let module_specifier = ModuleSpecifier::resolve_url_or_path(&v.file_name)?;
-    let path = module_specifier.as_url().to_file_path().unwrap();
-    println!("cargo:rerun-if-changed={}", path.display());
-    (
-      module_specifier.as_str().to_string(),
-      std::fs::read_to_string(&path)?,
-    )
+    assert!(!v.module_url.starts_with("$assets$"), "you meant $asset$");
+    let module_specifier = ModuleSpecifier::resolve_url_or_path(&v.module_url)?;
+    let module_url = module_specifier.as_url();
+    match module_url.scheme() {
+      "file" => {
+        let path = module_url.to_file_path().unwrap();
+        println!("cargo:rerun-if-changed={}", path.display());
+        (
+          module_specifier.as_str().to_string(),
+          std::fs::read_to_string(&path)?,
+        )
+      }
+      "crate" => {
+        let crate_name = module_url.host_str().unwrap();
+        // TODO(afinch7) turn failures here into real error messages.
+        let path_prefix = s.extern_crate_modules.get(crate_name).unwrap();
+        let path =
+          std::path::Path::new(path_prefix).join(&module_url.path()[1..]);
+        (
+          module_specifier.as_str().to_string(),
+          std::fs::read_to_string(&path)?,
+        )
+      }
+      _ => unimplemented!(),
+    }
   };
   Ok(json!({
     "moduleName": module_name,