micromark-extension-lemmy-supersub/lib/syntax.js

micromark extension to support lemmy supersub format

/**
 * @typedef {import('micromark-util-types').Construct} Construct
 * @typedef {import('micromark-util-types').Extension} Extension
 * @typedef {import('micromark-util-types').State} State
 * @typedef {import('micromark-util-types').Token} Token
 * @typedef {import('micromark-util-types').TokenizeContext} TokenizeContext
 * @typedef {import('micromark-util-types').Tokenizer} Tokenizer
 * @typedef {import('micromark-util-types').TokenType} TokenType
 * @typedef {import('micromark-util-types').Code} Code
 */

import { markdownLineEndingOrSpace } from 'micromark-util-character';
const codeFor = {
  sup: 94,
  sub: 126
};

/** @type {Extension} */
export const supersub = {
  text: {
    [codeFor.sub]: {
      tokenize: tokenizeSupersub
    },
    [codeFor.sup]: {
      tokenize: tokenizeSupersub
    }
  }
};

/**
 * @this {TokenizeContext}
 * @type {Tokenizer}
 */
function tokenizeSupersub(effects, ok, nok) {
  /** @type {'sub' | 'sup'} */
  let type;
  return start;

  /** @type {State} */
  function start(code) {
    if (code === codeFor.sup) {
      type = 'sup';
    } else if (code === codeFor.sub) {
      type = 'sub';
    } else {
      return nok(code);
    }
    effects.enter(type);
    effects.enter(`${type}Marker`);
    effects.consume(code);
    effects.exit(`${type}Marker`);
    return data;
  }

  /** @type {State} */
  function data(code) {
    if (code === null || markdownLineEndingOrSpace(code)) {
      return nok(code);
    }
    effects.enter("chunkText", {
      contentType: "text"
    });
    effects.consume(code);
    return content;
  }

  /** @type {State} */
  function content(code) {
    if (code === null || markdownLineEndingOrSpace(code)) {
      return nok(code);
    }
    if (code === 92) {
      effects.consume(code);
      return escaped;
    }
    if (code === codeFor[type]) {
      effects.exit("chunkText");
      effects.enter(`${type}Marker`);
      effects.consume(code);
      effects.exit(`${type}Marker`);
      effects.exit(type);
      return ok;
    }
    effects.consume(code);
    return content;
  }

  /** @type {State} */
  function escaped(code) {
    if (code === codeFor[type]) {
      effects.consume(code);
      return content;
    }
    effects.consume(code);
    return content;
  }
}