remark-astro-headings/dist/index.js

A plugin for extracting headings out of MDX files and adding them to the frontmatter.

/// <reference types="mdast-util-mdxjs-esm" />
import GithubSlugger from 'github-slugger';
import { visit } from 'unist-util-visit';
import { readFileSync } from 'node:fs';
import { join } from 'node:path';
import { fromMarkdown } from 'mdast-util-from-markdown';
import { mdxjs } from 'micromark-extension-mdxjs';
import { mdxFromMarkdown } from 'mdast-util-mdx';
const IMPORT_PATH_REGEX = /from\s+['"]([^'"]+)['"]/;
function remarkAstroHeadings(config = {}) {
    const configWithDefaults = {
        minDepth: 2,
        maxDepth: 6,
        createSlugger: () => new GithubSlugger(),
        ...config,
    };
    return generateHeadings(configWithDefaults);
}
function generateHeadings(config) {
    return (root, VFile) => {
        if (!VFile.data.astro) {
            console.warn(`[remark-astro-headings] No astro data found in VFile: ${VFile.path}`);
            return;
        }
        const slugger = config.createSlugger();
        const dir = join(VFile.path, '..');
        const headings = visitDeeply(root, { dir, headings: [], slugger, ...config });
        // @ts-ignore - If `astro` is present then frontmatter is also present
        VFile.data.astro.frontmatter.headings = headings;
    };
}
function visitDeeply(root, config) {
    visit(root, ['heading', 'mdxjsEsm'], (child) => {
        switch (child.type) {
            case 'heading': {
                const content = 'value' in child.children[0] && child.children[0].value;
                if (!content) {
                    break;
                }
                const depth = child.depth;
                if (depth < config.minDepth || depth > config.maxDepth) {
                    break;
                }
                const slug = config.slugger.slug(content);
                config.headings.push({
                    content,
                    slug,
                    depth,
                });
                break;
            }
            case 'mdxjsEsm': {
                const match = child.value.match(IMPORT_PATH_REGEX);
                if (!match) {
                    break;
                }
                const importPath = match[1];
                const file = readFileSync(join(config.dir, importPath), 'utf-8');
                const root = fromMarkdown(file, {
                    extensions: [mdxjs()],
                    mdastExtensions: [mdxFromMarkdown()],
                });
                visitDeeply(root, config);
                break;
            }
        }
    });
    return config.headings;
}
export default remarkAstroHeadings;
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