refactor file loading

src/loader.ts

@@ -0,0 +1,77 @@
+import { DepCrate } from "./ast";
+import { CrateLoader, GlobalContext } from "./context";
+import { CompilerError, LoadedFile, Span, withErrorPrinter } from "./error";
+import fs from "fs";
+import path from "path";
+import { tokenize } from "./lexer";
+import { ParseState, parse } from "./parser";
+import { resolve } from "./resolve";
+import { typeck } from "./typeck";
+
+export function loadModuleFile(
+  relativeTo: string,
+  moduleName: string,
+  span: Span
+): LoadedFile {
+  const options = [
+    path.join(relativeTo, `${moduleName}.nil`),
+    path.join(relativeTo, moduleName, `${moduleName}.mod.nil`),
+  ];
+
+  let content: string | undefined = undefined;
+  let filePath: string | undefined = undefined;
+  options.forEach((tryPath) => {
+    try {
+      content = fs.readFileSync(tryPath, { encoding: "utf-8" });
+      filePath = tryPath;
+    } catch (e) {}
+  });
+
+  if (content === undefined || filePath === undefined) {
+    throw new CompilerError(
+      `failed to load ${moduleName}, could not find ${options.join(" or ")}`,
+      span
+    );
+  }
+
+  return { content, path: filePath };
+}
+
+export const loadCrate: CrateLoader = (
+  gcx: GlobalContext,
+  name: string,
+  span: Span
+): DepCrate => {
+  // We really, really want a good algorithm for finding crates.
+  // But right now we just look for files in the CWD.
+
+  const existing = gcx.depCrates.find((crate) => crate.packageName === name);
+  if (existing) {
+    return existing;
+  }
+
+  const file = loadModuleFile(".", name, span);
+
+  return withErrorPrinter(
+    (): DepCrate => {
+      const crateId = gcx.crateId.next();
+
+      const tokens = tokenize(file);
+      const parseState: ParseState = { tokens, file };
+      const ast = parse(name, parseState, crateId);
+      const resolved = resolve(gcx, ast);
+      console.log(resolved);
+
+      const typecked = typeck(gcx, resolved);
+
+      gcx.depCrates.push(typecked);
+      return typecked;
+    },
+    () => {
+      throw new CompilerError(
+        `failed to load crate ${name}: crate contains errors`,
+        span
+      );
+    }
+  );
+};