MZC/KnowMathBot/frontend/node_modules/micromark-core-commonmark/lib/character-reference.js

/**
 * @import {
 *   Code,
 *   Construct,
 *   State,
 *   TokenizeContext,
 *   Tokenizer
 * } from 'micromark-util-types'
 */

import { decodeNamedCharacterReference } from 'decode-named-character-reference';
import { asciiAlphanumeric, asciiDigit, asciiHexDigit } from 'micromark-util-character';
/** @type {Construct} */
export const characterReference = {
  name: 'characterReference',
  tokenize: tokenizeCharacterReference
};

/**
 * @this {TokenizeContext}
 *   Context.
 * @type {Tokenizer}
 */
function tokenizeCharacterReference(effects, ok, nok) {
  const self = this;
  let size = 0;
  /** @type {number} */
  let max;
  /** @type {(code: Code) => boolean} */
  let test;
  return start;

  /**
   * Start of character reference.
   *
   * ```markdown
   * > | a&b
   *      ^
   * > | a{b
   *      ^
   * > | a	b
   *      ^
   * ```
   *
   * @type {State}
   */
  function start(code) {
    effects.enter("characterReference");
    effects.enter("characterReferenceMarker");
    effects.consume(code);
    effects.exit("characterReferenceMarker");
    return open;
  }

  /**
   * After `&`, at `#` for numeric references or alphanumeric for named
   * references.
   *
   * ```markdown
   * > | a&b
   *       ^
   * > | a{b
   *       ^
   * > | a	b
   *       ^
   * ```
   *
   * @type {State}
   */
  function open(code) {
    if (code === 35) {
      effects.enter("characterReferenceMarkerNumeric");
      effects.consume(code);
      effects.exit("characterReferenceMarkerNumeric");
      return numeric;
    }
    effects.enter("characterReferenceValue");
    max = 31;
    test = asciiAlphanumeric;
    return value(code);
  }

  /**
   * After `#`, at `x` for hexadecimals or digit for decimals.
   *
   * ```markdown
   * > | a{b
   *        ^
   * > | a	b
   *        ^
   * ```
   *
   * @type {State}
   */
  function numeric(code) {
    if (code === 88 || code === 120) {
      effects.enter("characterReferenceMarkerHexadecimal");
      effects.consume(code);
      effects.exit("characterReferenceMarkerHexadecimal");
      effects.enter("characterReferenceValue");
      max = 6;
      test = asciiHexDigit;
      return value;
    }
    effects.enter("characterReferenceValue");
    max = 7;
    test = asciiDigit;
    return value(code);
  }

  /**
   * After markers (`&#x`, `&#`, or `&`), in value, before `;`.
   *
   * The character reference kind defines what and how many characters are
   * allowed.
   *
   * ```markdown
   * > | a&b
   *       ^^^
   * > | a{b
   *        ^^^
   * > | a	b
   *         ^
   * ```
   *
   * @type {State}
   */
  function value(code) {
    if (code === 59 && size) {
      const token = effects.exit("characterReferenceValue");
      if (test === asciiAlphanumeric && !decodeNamedCharacterReference(self.sliceSerialize(token))) {
        return nok(code);
      }

      // To do: `markdown-rs` uses a different name:
      // `CharacterReferenceMarkerSemi`.
      effects.enter("characterReferenceMarker");
      effects.consume(code);
      effects.exit("characterReferenceMarker");
      effects.exit("characterReference");
      return ok;
    }
    if (test(code) && size++ < max) {
      effects.consume(code);
      return value;
    }
    return nok(code);
  }
}