1 files changed, 100 insertions, 0 deletions
diff --git a/src/js/builtins/codegen/replacements.ts b/src/js/builtins/codegen/replacements.ts
new file mode 100644
index 000000000..05c81b901
--- /dev/null
+++ b/src/js/builtins/codegen/replacements.ts
@@ -0,0 +1,100 @@
+import { LoaderKeys } from "../../../api/schema";
+
+// This is a list of extra syntax replacements to do. Kind of like macros
+// These are only run on code itself, not string contents or comments.
+export const replacements: ReplacementRule[] = [
+  { from: /\bthrow new TypeError\b/g, to: "$throwTypeError" },
+  { from: /\bthrow new RangeError\b/g, to: "$throwRangeError" },
+  { from: /\bthrow new OutOfMemoryError\b/g, to: "$throwOutOfMemoryError" },
+  { from: /\bnew TypeError\b/g, to: "$makeTypeError" },
+];
+
+// These rules are run on the entire file, including within strings.
+export const globalReplacements: ReplacementRule[] = [
+  {
+    from: /\bnotImplementedIssue\(\s*([0-9]+)\s*,\s*((?:"[^"]*"|'[^']+'))\s*\)/g,
+    to: "new TypeError(`${$2} is not implemented yet. See https://github.com/oven-sh/bun/issues/$1`)",
+  },
+  {
+    from: /\bnotImplementedIssueFn\(\s*([0-9]+)\s*,\s*((?:"[^"]*"|'[^']+'))\s*\)/g,
+    to: "() => $throwTypeError(`${$2} is not implemented yet. See https://github.com/oven-sh/bun/issues/$1`)",
+  },
+];
+
+// This is a list of globals we should access using @ notation
+// undefined -> __intrinsic__undefined -> @undefined
+export const globalsToPrefix = [
+  "AbortSignal",
+  "Array",
+  "ArrayBuffer",
+  "Buffer",
+  "Bun",
+  "Infinity",
+  "Loader",
+  "Promise",
+  "ReadableByteStreamController",
+  "ReadableStream",
+  "ReadableStreamBYOBReader",
+  "ReadableStreamBYOBRequest",
+  "ReadableStreamDefaultController",
+  "ReadableStreamDefaultReader",
+  "TransformStream",
+  "TransformStreamDefaultController",
+  "Uint8Array",
+  "WritableStream",
+  "WritableStreamDefaultController",
+  "WritableStreamDefaultWriter",
+  "isFinite",
+  "isNaN",
+  "undefined",
+];
+
+// These enums map to $<enum>IdToLabel and $<enum>LabelToId
+// Make sure to define in ./builtins.d.ts
+export const enums = {
+  Loader: LoaderKeys,
+  ImportKind: [
+    "entry-point",
+    "import-statement",
+    "require-call",
+    "dynamic-import",
+    "require-resolve",
+    "import-rule",
+    "url-token",
+    "internal",
+  ],
+};
+
+// These identifiers have typedef but not present at runtime (converted with replacements)
+// If they are present in the bundle after runtime, we warn at the user.
+// TODO: implement this check.
+export const warnOnIdentifiersNotPresentAtRuntime = [
+  //
+  "OutOfMemoryError",
+  "notImplementedIssue",
+  "notImplementedIssueFn",
+];
+
+export interface ReplacementRule {
+  from: RegExp;
+  to: string;
+  global?: boolean;
+}
+
+/** Applies source code replacements as defined in `replacements` */
+export function applyReplacements(src: string) {
+  let result = src.replace(/\$([a-zA-Z0-9_]+)\b/gm, `__intrinsic__$1`);
+  for (const replacement of replacements) {
+    result = result.replace(replacement.from, replacement.to.replaceAll("$", "__intrinsic__"));
+  }
+  return result;
+}
+
+/** Applies source code replacements as defined in `globalReplacements` */
+export function applyGlobalReplacements(src: string) {
+  let result = src;
+  for (const replacement of globalReplacements) {
+    result = result.replace(replacement.from, replacement.to.replaceAll("$", "__intrinsic__"));
+  }
+  return result;
+}