roadmap/quartz/plugins/transformers/toc.ts

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