node-syntax-tree and synckit

package.json

@@ -19,7 +19,9 @@
   },
   "homepage": "https://github.com/prettier/plugin-ruby#readme",
   "dependencies": {
-    "prettier": ">=2.3.0"
+    "node-syntax-tree": "^0.2.0",
+    "prettier": ">=2.3.0",
+    "synckit": "^0.8.1"
   },
   "devDependencies": {
     "eslint": "^8.15.0",

src/plugin.js

@@ -1,4 +1,10 @@
-const { parseSync } = require("./parseSync");
+const { createSyncFn } = require("synckit");
+const parseSyncFn = createSyncFn(require.resolve("./worker"));
+
+function parseSync(kind, source, options) {
+  const { locStart, locEnd, plugins, preprocess, printer, ...cloneableOptions } = options;
+  return parseSyncFn(kind, source, cloneableOptions);
+}
 
 /*
  * metadata mostly pulled from linguist and rubocop:

src/worker.js

@@ -0,0 +1,21 @@
+const { runAsWorker } = require("synckit/lib/index.cjs");
+const { default: createSyntaxTree } = require("node-syntax-tree");
+
+let cachedSyntaxTree = null;
+
+function fetchSyntaxTree() {
+  if (cachedSyntaxTree == null) {
+    return createSyntaxTree().then((syntaxTree) => {
+      cachedSyntaxTree = syntaxTree;
+      return cachedSyntaxTree;
+    });
+  } else {
+    return Promise.resolve(cachedSyntaxTree);
+  }
+}
+
+runAsWorker((kind, source, options) => {
+  return fetchSyntaxTree().then((syntaxTree) => {
+    return syntaxTree.handlers[kind].format(source);
+  });
+});