rehype-collect-headings.ts — astro Source File

Source Code

import type { Expression, Super } from 'estree';
import Slugger from 'github-slugger';
import type { MdxTextExpression } from 'mdast-util-mdx-expression';
import type { Node } from 'unist';
import { visit } from 'unist-util-visit';
import type { VFile } from 'vfile';
import type { MarkdownHeading, RehypePlugin } from './types.js';

const rawNodeTypes = new Set(['text', 'raw', 'mdxTextExpression']);
const codeTagNames = new Set(['code', 'pre']);

/**
 * Rehype plugin that adds `id` attributes to headings based on their text content.
 *
 * @see https://docs.astro.build/en/guides/markdown-content/#heading-ids-and-plugins
 */
export function rehypeHeadingIds(): ReturnType<RehypePlugin> {
	return function (tree, file) {
		const headings: MarkdownHeading[] = [];
		const frontmatter = file.data.astro?.frontmatter;
		const slugger = new Slugger();
		const isMDX = isMDXFile(file);
		visit(tree, (node) => {
			if (node.type !== 'element') return;
			const { tagName } = node;
			if (tagName[0] !== 'h') return;
			const [, level] = /h([0-6])/.exec(tagName) ?? [];
			if (!level) return;
			const depth = Number.parseInt(level);

			let text = '';
			visit(node, (child, __, parent) => {
				if (child.type === 'element' || parent == null) {
					return;
				}
				if (child.type === 'raw') {
					if (/^\n?<.*>\n?$/.test(child.value)) {
						return;
					}
				}
				if (rawNodeTypes.has(child.type)) {
					if (isMDX || codeTagNames.has(parent.tagName)) {
						let value = child.value;
						if (isMdxTextExpression(child) && frontmatter) {
							const frontmatterPath = getMdxFrontmatterVariablePath(child);
							if (Array.isArray(frontmatterPath) && frontmatterPath.length > 0) {
								const frontmatterValue = getMdxFrontmatterVariableValue(
									frontmatter,
									frontmatterPath,
								);
								if (typeof frontmatterValue === 'string') {
									value = frontmatterValue;
								}
							}
						}
						text += value;
					} else {
						text += child.value.replace(/\{/g, '${');
					}
				}
// ... (71 more lines)