Function transform

packages/markmap-lib/src/plugins/frontmatter/index.ts:9–38

(transformHooks: ITransformHooks)

export default definePlugin({
  name,
  transform(transformHooks: ITransformHooks) {
    transformHooks.beforeParse.tap((_md, context) => {
      const { content } = context;
      if (!/^---\r?\n/.test(content)) return;
      const match = /\n---\r?\n/.exec(content);
      if (!match) return;
      const raw = content.slice(4, match.index).trimEnd();
      let frontmatter: typeof context.frontmatter;
      try {
        frontmatter = parse(raw.replace(/\r?\n|\r/g, '\n'));
        if (frontmatter?.markmap) {
          frontmatter.markmap = normalizeMarkmapJsonOptions(
            frontmatter.markmap,
          );
        }
      } catch {
        return;
      }
      context.frontmatter = frontmatter;
      context.parserOptions = {
        ...context.parserOptions,
        ...frontmatter?.markmap?.htmlParser,
      };
      context.frontmatterInfo = {
        lines: content.slice(0, match.index).split('\n').length + 1,
        offset: match.index + match[0].length,
      };
    });
    return {};
  },
});

function normalizeMarkmapJsonOptions(options?: Partial<IMarkmapJSONOptions>) {