new_tags_ex.ts

// Tag Management: Define functions describing what to do with HTML tags in our
// comments.
interface OnTag {
  open(attrs: {[key: string]: string}): string;
  close(): string;
}

// Some handlers for behaviors that apply to multiple tags:
const em: OnTag = { open: () => '_', close: () => '_' };
const strong = { open: () => '__', close: () => '__' };
// ...

// Our top-level tag handler.
const onTag = new Map<string, OnTag>([
  ['a', {open: (attrs) => `{@link ${attrs['href']} `, close: () => '}'}],
  ['em', em], ['i', em],
  ['strong', strong], ['b', strong],
  // ...
]);

function parseComment(comment: string): string {
  const result: string[] = [];
  const parser = new Parser({
    ontext: (text: string) => result.push(replace(text)),
    onopentag: (tag: string, attrs: {[key: string]: string}) => {
      const handler = onTag.get(tag);
      if (!handler) {
        throw new Error(`Unknown tag "${tag}".`);
      }

      if (handler.open) {
        result.push(handler.open(attrs));
      }
    },
    onclosetag: (tag: string) => {
      const handler = onTag.get(tag);
      assert(handler);

      if (handler.close) {
        result.push(handler.close());
      }
    }
  });
  parser.write(comment);
  parser.end();

  // ... turn result into 'lines'
  return lines.length === 1 ? `* ${lines[0]} ` :
                              ('*\n * ' + lines.join('\n * ') + '\n ');
}