1 files changed, 103 insertions, 0 deletions
diff --git a/cli/js/compiler/bundler.ts b/cli/js/compiler/bundler.ts
new file mode 100644
index 000000000..ab987a7fc
--- /dev/null
+++ b/cli/js/compiler/bundler.ts
@@ -0,0 +1,103 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import { SYSTEM_LOADER } from "./bootstrap.ts";
+import { commonPath, normalizeString, CHAR_FORWARD_SLASH } from "./util.ts";
+import { assert } from "../util.ts";
+
+/** Local state of what the root exports are of a root module. */
+let rootExports: string[] | undefined;
+
+/** Take a URL and normalize it, resolving relative path parts. */
+function normalizeUrl(rootName: string): string {
+  const match = /^(\S+:\/{2,3})(.+)$/.exec(rootName);
+  if (match) {
+    const [, protocol, path] = match;
+    return `${protocol}${normalizeString(
+      path,
+      false,
+      "/",
+      code => code === CHAR_FORWARD_SLASH
+    )}`;
+  } else {
+    return rootName;
+  }
+}
+
+/** Given a root name, contents, and source files, enrich the data of the
+ * bundle with a loader and re-export the exports of the root name. */
+export function buildBundle(
+  rootName: string,
+  data: string,
+  sourceFiles: readonly ts.SourceFile[]
+): string {
+  // when outputting to AMD and a single outfile, TypeScript makes up the module
+  // specifiers which are used to define the modules, and doesn't expose them
+  // publicly, so we have to try to replicate
+  const sources = sourceFiles.map(sf => sf.fileName);
+  const sharedPath = commonPath(sources);
+  rootName = normalizeUrl(rootName)
+    .replace(sharedPath, "")
+    .replace(/\.\w+$/i, "");
+  // If one of the modules requires support for top-level-await, TypeScript will
+  // emit the execute function as an async function.  When this is the case we
+  // need to bubble up the TLA to the instantiation, otherwise we instantiate
+  // synchronously.
+  const hasTla = data.match(/execute:\sasync\sfunction\s/);
+  let instantiate: string;
+  if (rootExports && rootExports.length) {
+    instantiate = hasTla
+      ? `const __exp = await __instantiateAsync("${rootName}");\n`
+      : `const __exp = __instantiate("${rootName}");\n`;
+    for (const rootExport of rootExports) {
+      if (rootExport === "default") {
+        instantiate += `export default __exp["${rootExport}"];\n`;
+      } else {
+        instantiate += `export const ${rootExport} = __exp["${rootExport}"];\n`;
+      }
+    }
+  } else {
+    instantiate = hasTla
+      ? `await __instantiateAsync("${rootName}");\n`
+      : `__instantiate("${rootName}");\n`;
+  }
+  return `${SYSTEM_LOADER}\n${data}\n${instantiate}`;
+}
+
+/** Set the rootExports which will by the `emitBundle()` */
+export function setRootExports(program: ts.Program, rootModule: string): void {
+  // get a reference to the type checker, this will let us find symbols from
+  // the AST.
+  const checker = program.getTypeChecker();
+  // get a reference to the main source file for the bundle
+  const mainSourceFile = program.getSourceFile(rootModule);
+  assert(mainSourceFile);
+  // retrieve the internal TypeScript symbol for this AST node
+  const mainSymbol = checker.getSymbolAtLocation(mainSourceFile);
+  if (!mainSymbol) {
+    return;
+  }
+  rootExports = checker
+    .getExportsOfModule(mainSymbol)
+    // .getExportsOfModule includes type only symbols which are exported from
+    // the module, so we need to try to filter those out.  While not critical
+    // someone looking at the bundle would think there is runtime code behind
+    // that when there isn't.  There appears to be no clean way of figuring that
+    // out, so inspecting SymbolFlags that might be present that are type only
+    .filter(
+      sym =>
+        sym.flags & ts.SymbolFlags.Class ||
+        !(
+          sym.flags & ts.SymbolFlags.Interface ||
+          sym.flags & ts.SymbolFlags.TypeLiteral ||
+          sym.flags & ts.SymbolFlags.Signature ||
+          sym.flags & ts.SymbolFlags.TypeParameter ||
+          sym.flags & ts.SymbolFlags.TypeAlias ||
+          sym.flags & ts.SymbolFlags.Type ||
+          sym.flags & ts.SymbolFlags.Namespace ||
+          sym.flags & ts.SymbolFlags.InterfaceExcludes ||
+          sym.flags & ts.SymbolFlags.TypeParameterExcludes ||
+          sym.flags & ts.SymbolFlags.TypeAliasExcludes
+        )
+    )
+    .map(sym => sym.getName());
+}