code generator checks timestamps. totally useless

Author: thejoshwolfe

.gitignore

@@ -2,3 +2,4 @@ node_modules/
 *.js
 *.js.map
 *.d.ts
+*.cache.json

src/shared/generate-typescript-interfaces.ts

@@ -0,0 +1,47 @@
+import {writeFileSync, statSync, readFileSync} from "fs";
+
+const selfPath = "generate-typescript-interfaces.js"; // we don't have __filename for some reason.
+const inPath = "schema.js";
+const outPath = "schema.d.ts";
+const cachePath = "schema.cache.json";
+
+let cache: {[index: string]: string} = function() {
+  try {
+    return JSON.parse(readFileSync(cachePath, {encoding: "utf8"}));
+  } catch {
+    return {};
+  }
+}();
+
+function checkCache(path: string): boolean {
+  let stats = statSync(path, {throwIfNoEntry: false});
+  if (stats == null) return false;
+  const entry = JSON.stringify([stats.ino, stats.size, stats.mtime]);
+  if (cache[path] === entry) return true;
+
+  // Optimistically put the new entry in case we get around to writing the cache.
+  cache[path] = entry;
+  return false;
+}
+function writeCache() {
+  writeFileSync(cachePath, JSON.stringify(cache) + "\n");
+}
+
+if (checkCache(selfPath) && checkCache(inPath) && checkCache(outPath)) {
+  // up to date.
+  process.exit(0);
+}
+
+// Need to generate.
+console.log("generating schema types");
+import {protocolSchema} from "./schema.js"
+
+// tsc chokes analyzing this dependency, but it works at runtime.
+// Obfuscate the import to disable typescript compile-time analysis.
+const {compile} = await import("" + "json-schema-to-typescript");
+
+let content = await compile(protocolSchema, "ProtocolMessage");
+writeFileSync(outPath, content);
+
+checkCache(outPath);
+writeCache();