Initial commit

quartz/plugins/transformers/toc.ts

@@ -0,0 +1,75 @@
+import { QuartzTransformerPlugin } from "../types"
+import { Root } from "mdast"
+import { visit } from "unist-util-visit"
+import { toString } from "mdast-util-to-string"
+import Slugger from "github-slugger"
+
+export interface Options {
+  maxDepth: 1 | 2 | 3 | 4 | 5 | 6
+  minEntries: number
+  showByDefault: boolean
+  collapseByDefault: boolean
+}
+
+const defaultOptions: Options = {
+  maxDepth: 3,
+  minEntries: 1,
+  showByDefault: true,
+  collapseByDefault: false,
+}
+
+interface TocEntry {
+  depth: number
+  text: string
+  slug: string // this is just the anchor (#some-slug), not the canonical slug
+}
+
+const slugAnchor = new Slugger()
+export const TableOfContents: QuartzTransformerPlugin<Partial<Options> | undefined> = (
+  userOpts,
+) => {
+  const opts = { ...defaultOptions, ...userOpts }
+  return {
+    name: "TableOfContents",
+    markdownPlugins() {
+      return [
+        () => {
+          return async (tree: Root, file) => {
+            const display = file.data.frontmatter?.enableToc ?? opts.showByDefault
+            if (display) {
+              slugAnchor.reset()
+              const toc: TocEntry[] = []
+              let highestDepth: number = opts.maxDepth
+              visit(tree, "heading", (node) => {
+                if (node.depth <= opts.maxDepth) {
+                  const text = toString(node)
+                  highestDepth = Math.min(highestDepth, node.depth)
+                  toc.push({
+                    depth: node.depth,
+                    text,
+                    slug: slugAnchor.slug(text),
+                  })
+                }
+              })
+
+              if (toc.length > 0 && toc.length > opts.minEntries) {
+                file.data.toc = toc.map((entry) => ({
+                  ...entry,
+                  depth: entry.depth - highestDepth,
+                }))
+                file.data.collapseToc = opts.collapseByDefault
+              }
+            }
+          }
+        },
+      ]
+    },
+  }
+}
+
+declare module "vfile" {
+  interface DataMap {
+    toc: TocEntry[]
+    collapseToc: boolean
+  }
+}