feat: toc generator

.gitignore

@@ -6,3 +6,4 @@ dist
 .eslintcache
 *.log*
 *.env*
+.pnpm-store

package.json

@@ -40,6 +40,7 @@
     "defu": "^6.1.4",
     "destr": "^2.0.3",
     "didyoumean2": "^6.0.1",
+    "github-slugger": "^2.0.0",
     "globby": "^14.0.2",
     "magic-string": "^0.30.11",
     "mdbox": "^0.1.0",

src/generators/index.ts

@@ -7,6 +7,7 @@ import { jsimport } from "./jsimport";
 import { withAutomd } from "./with-automd";
 import { file } from "./file";
 import { contributors } from "./contributors";
+import { toc } from "./toc";
 
 export default {
   jsdocs,
@@ -19,4 +20,5 @@ export default {
   jsimport,
   "with-automd": withAutomd,
   contributors,
+  toc,
 } as Record<string, Generator>;

src/generators/toc.ts

@@ -0,0 +1,62 @@
+import { readFile } from "node:fs/promises";
+import { md } from "mdbox";
+import { initMdAstParser } from "mdbox/parser";
+import type { ParsedTree } from "mdbox/parser";
+import { fileURLToPath } from "mlly";
+import { defineGenerator } from "../generator";
+import { slug } from "github-slugger";
+
+function getTextContentFromAst(tree: ParsedTree): string {
+  let content = "";
+  for (const node of tree) {
+    if (typeof node === "string") {
+      content += node;
+      continue;
+    }
+    content += getTextContentFromAst(node.children ?? []);
+  }
+  return content;
+}
+
+export const toc = defineGenerator({
+  name: "toc",
+  async generate({ args, url }) {
+    const minLevel: number = Number.parseInt(args.minLevel ?? 2);
+    const maxLevel: number = Number.parseInt(args.maxLevel ?? 3);
+
+    if (url === undefined) {
+      throw new Error("URL is required for toc generator");
+    }
+
+    const contents = await readFile(fileURLToPath(url), "utf8");
+    const parser = await initMdAstParser();
+    const { tree } = parser.parse(contents);
+
+    const toc = [];
+    const allowedNodeTypes = new Set(
+      ["h1", "h2", "h3", "h4", "h5", "h6"].slice(minLevel - 1, maxLevel),
+    );
+    for (const node of tree) {
+      if (typeof node === "string") {
+        continue;
+      }
+      if (allowedNodeTypes.has(node.type)) {
+        toc.push({
+          level: Number.parseInt(node.type.slice(1)) - minLevel,
+          text: getTextContentFromAst(node.children ?? []),
+        });
+      }
+    }
+
+    const tocMd = toc
+      .map(({ level, text }) => {
+        const content = md.link(`#${slug(text)}`, text);
+        return `${"  ".repeat(level)}- ${content}`;
+      })
+      .join("\n");
+
+    return {
+      contents: tocMd,
+    };
+  },
+});

test/fixture/INPUT.md

@@ -1,5 +1,30 @@
 # Automd built-in generator fixtures
 
+## Table of Contents
+
+<!-- automd:toc max-level="4" -->
+<!-- /automd -->
+
+## Heading test
+
+### sub heading 1
+
+#### sub sub heading
+
+### sub heading 2
+
+#### sub sub heading 1
+
+#### sub sub heading 2
+
+##### do you really need this many headings?
+
+## heading with [link](#)
+
+## heading with footnote[^1]
+
+[^1]: this is a footnote
+
 ## `badges`
 
 <!-- automd:badges bundlephobia packagephobia  -->

test/fixture/OUTPUT.md

@@ -1,5 +1,50 @@
 # Automd built-in generator fixtures
 
+## Table of Contents
+
+<!-- automd:toc max-level="4" -->
+
+- [Table of Contents](#table-of-contents)
+- [Heading test](#heading-test)
+  - [sub heading 1](#sub-heading-1)
+    - [sub sub heading](#sub-sub-heading)
+  - [sub heading 2](#sub-heading-2)
+    - [sub sub heading 1](#sub-sub-heading-1)
+    - [sub sub heading 2](#sub-sub-heading-2)
+- [heading with link](#heading-with-link)
+- [heading with footnote](#heading-with-footnote)
+- [badges](#badges)
+- [pm-x](#pm-x)
+- [pm-install](#pm-install)
+- [jsdocs](#jsdocs)
+- [jsimport](#jsimport)
+- [with-automd](#with-automd)
+- [fetch](#fetch)
+- [file](#file)
+- [contributors](#contributors)
+
+<!-- /automd -->
+
+## Heading test
+
+### sub heading 1
+
+#### sub sub heading
+
+### sub heading 2
+
+#### sub sub heading 1
+
+#### sub sub heading 2
+
+##### do you really need this many headings?
+
+## heading with [link](#)
+
+## heading with footnote[^1]
+
+[^1]: this is a footnote
+
 ## `badges`
 
 <!-- automd:badges bundlephobia packagephobia  -->