added ast-grep code patcher

Author: conico974

packages/open-next/package.json

@@ -37,6 +37,7 @@
     "README.md"
   ],
   "dependencies": {
+    "@ast-grep/napi": "^0.35.0",
     "@aws-sdk/client-cloudfront": "3.398.0",
     "@aws-sdk/client-dynamodb": "^3.398.0",
     "@aws-sdk/client-lambda": "^3.398.0",

packages/open-next/src/build/patch/astCodePatcher.ts

@@ -0,0 +1,114 @@
+// Mostly copied from the cloudflare adapter
+import { readFileSync } from "node:fs";
+
+import {
+  type Edit,
+  Lang,
+  type NapiConfig,
+  type SgNode,
+  parse,
+} from "@ast-grep/napi";
+import yaml from "yaml";
+import type { PatchCodeFn } from "./codePatcher";
+
+/**
+ * fix has the same meaning as in yaml rules
+ * see https://ast-grep.github.io/guide/rewrite-code.html#using-fix-in-yaml-rule
+ */
+export type RuleConfig = NapiConfig & { fix?: string };
+
+/**
+ * Returns the `Edit`s and `Match`es for an ast-grep rule in yaml format
+ *
+ * The rule must have a `fix` to rewrite the matched node.
+ *
+ * Tip: use https://ast-grep.github.io/playground.html to create rules.
+ *
+ * @param rule The rule. Either a yaml string or an instance of `RuleConfig`
+ * @param root The root node
+ * @param once only apply once
+ * @returns A list of edits and a list of matches.
+ */
+export function applyRule(
+  rule: string | RuleConfig,
+  root: SgNode,
+  { once = false } = {},
+) {
+  const ruleConfig: RuleConfig =
+    typeof rule === "string" ? yaml.parse(rule) : rule;
+  if (ruleConfig.transform) {
+    throw new Error("transform is not supported");
+  }
+  if (!ruleConfig.fix) {
+    throw new Error("no fix to apply");
+  }
+
+  const fix = ruleConfig.fix;
+
+  const matches = once
+    ? [root.find(ruleConfig)].filter((m) => m !== null)
+    : root.findAll(ruleConfig);
+
+  const edits: Edit[] = [];
+
+  matches.forEach((match) => {
+    edits.push(
+      match.replace(
+        // Replace known placeholders by their value
+        fix
+          .replace(/\$\$\$([A-Z0-9_]+)/g, (_m, name) =>
+            match
+              .getMultipleMatches(name)
+              .map((n) => n.text())
+              .join(""),
+          )
+          .replace(
+            /\$([A-Z0-9_]+)/g,
+            (m, name) => match.getMatch(name)?.text() ?? m,
+          ),
+      ),
+    );
+  });
+
+  return { edits, matches };
+}
+
+/**
+ * Parse a file and obtain its root.
+ *
+ * @param path The file path
+ * @param lang The language to parse. Defaults to TypeScript.
+ * @returns The root for the file.
+ */
+export function parseFile(path: string, lang = Lang.TypeScript) {
+  return parse(lang, readFileSync(path, { encoding: "utf-8" })).root();
+}
+
+/**
+ * Patches the code from by applying the rule.
+ *
+ * This function is mainly for on off edits and tests,
+ * use `getRuleEdits` to apply multiple rules.
+ *
+ * @param code The source code
+ * @param rule The astgrep rule (yaml or NapiConfig)
+ * @param lang The language used by the source code
+ * @param lang Whether to apply the rule only once
+ * @returns The patched code
+ */
+export function patchCode(
+  code: string,
+  rule: string | RuleConfig,
+  { lang = Lang.TypeScript, once = false } = {},
+): string {
+  const node = parse(lang, code).root();
+  const { edits } = applyRule(rule, node, { once });
+  return node.commitEdits(edits);
+}
+
+export function createPatchCode(
+  rule: string | RuleConfig,
+  lang = Lang.TypeScript,
+): PatchCodeFn {
+  return async ({ code }) => patchCode(code, rule, { lang });
+}

packages/open-next/src/build/patch/codePatcher.ts

@@ -11,8 +11,7 @@ export interface VersionedField<T> {
   field: T;
 }
 
-//TODO: create a version of this that would use ast-grep
-type PatchCodeFn = (args: {
+export type PatchCodeFn = (args: {
   // The content of the file that needs to be patched
   code: string;
   // The final path of the file that needs to be patched