Function transformFootnotes

packages/muya/src/state/renderToStaticHTML.ts:92–151

(html: string)

const CODE_PLACEHOLDER_RESTORE_RE = /_MUYA_FN_GUARD_(\d+)_/g;

function transformFootnotes(html: string): string {
    // 1. Lift every footnote-block out of the body, remembering the rendered
    //    definition html keyed by identifier. The body of the def is the inner
    //    html marked already produced — paragraphs, lists, code, etc.
    const definitions = new Map<string, string>();
    let body = html.replace(FOOTNOTE_DEF_RE, (_, id: string, inner: string) => {
        // First definition wins for duplicate identifiers — matches the way
        // pandoc / GFM linkrefs treat repeated labels and what the plan asks
        // for (Section 十, risk #2).
        if (!definitions.has(id))
            definitions.set(id, inner);
        return '';
    });

    if (definitions.size === 0)
        return html;

    // 2. Stash code spans / blocks so step 3 only scans live prose.
    const codeSlots: string[] = [];
    body = body.replace(CODE_GUARD_RE, (m) => {
        codeSlots.push(m);
        return `${CODE_PLACEHOLDER_PREFIX}${codeSlots.length - 1}_`;
    });

    // 3. Find inline `[^id]` references in source order. Numbering follows
    //    inline order (pandoc / GFM convention), not the order definitions
    //    appear in source. Orphan refs (no matching def) stay as plain text;
    //    repeats reuse the first-seen number.
    const refNumber = new Map<string, number>();
    let nextN = 1;
    body = body.replace(FOOTNOTE_REF_RE, (match, id: string) => {
        if (!definitions.has(id))
            return match;
        if (!refNumber.has(id))
            refNumber.set(id, nextN++);
        const n = refNumber.get(id)!;
        return `<sup class="footnote-ref"><a href="#fn-${n}" id="fnref-${n}">${n}</a></sup>`;
    });

    // 4. Restore the protected code regions.
    body = body.replace(CODE_PLACEHOLDER_RESTORE_RE, (_, i) => codeSlots[Number(i)]);

    if (refNumber.size === 0)
        return body;

    // 5. Build the footnotes section in numeric order. Orphan definitions
    //    (defined but never referenced inline) are dropped — same as the
    //    parser-extension behaviour marktext shipped.
    const orderedRefs = Array.from(refNumber.entries()).sort(
        (a, b) => a[1] - b[1],
    );
    const items: string[] = [];
    for (const [id, n] of orderedRefs) {
        const inner = definitions.get(id) ?? '';
        items.push(`<li id="fn-${n}">${appendBackref(inner, n)}</li>`);
    }

    const section = `\n<section class="footnotes">\n<ol>\n${items.join('\n')}\n</ol>\n</section>\n`;