Really simple Gemtext parser in Typescript

parser.ts

// Gemtext.ts
type TextNode = {
  type: "text";
  content: string;
};

type LinkNode = {
  type: "link";
  url: string;
  title: string;
};

type HeadingNode = {
  type: "heading";
  level: number;
  content: string;
};

type ListItemNode = {
  type: "listItem";
  content: string;
};

type BlockquoteNode = {
  type: "blockquote";
  content: string;
};

type PreformattedNode = {
  type: "preformatted";
  content: string;
};

type GemtextNode =
  | TextNode
  | LinkNode
  | HeadingNode
  | ListItemNode
  | BlockquoteNode
  | PreformattedNode;

function parseGemtext(gemtext: string): GemtextNode[] {
  const lines = gemtext.split("\n");
  const ast: GemtextNode[] = [];

  let preformatted = false;

  for (const line of lines) {
    if (preformatted) {
      if (line === "```") {
        preformatted = false;
        continue;
      }

      ast.push({
        type: "preformatted",
        content: line,
      });
    } else {
      const linkRegex = /^=>\s*(\S+)\s*(.*)$/;
      const headingRegex = /^(#{1,6})\s+(.*)$/;
      const listItemRegex = /^\*\s+(.*)$/;
      const blockquoteRegex = /^>\s+(.*)$/;
      const preformattedRegex = /^```$/;

      if (linkRegex.test(line)) {
        const [, url, title] = line.match(linkRegex) || [];
        ast.push({ type: "link", url, title });
      } else if (headingRegex.test(line)) {
        const [, level, content] = line.match(headingRegex) || [];
        ast.push({ type: "heading", level: level.length, content });
      } else if (listItemRegex.test(line)) {
        const [, content] = line.match(listItemRegex) || [];
        ast.push({ type: "listItem", content });
      } else if (blockquoteRegex.test(line)) {
        const [, content] = line.match(blockquoteRegex) || [];
        ast.push({ type: "blockquote", content });
      } else if (preformattedRegex.test(line)) {
        preformatted = true;
      } else {
        ast.push({ type: "text", content: line });
      }
    }
  }

  return ast;
}

export default parseGemtext;