'use strict';

var mdurl = require('mdurl');
var ucmicro = require('uc.micro');
var entities = require('entities');
var LinkifyIt = require('linkify-it');
var punycode = require('punycode.js');

function _interopNamespaceDefault(e) {
  var n = Object.create(null);
  if (e) {
    Object.keys(e).forEach(function (k) {
      if (k !== 'default') {
        var d = Object.getOwnPropertyDescriptor(e, k);
        Object.defineProperty(n, k, d.get ? d : {
          enumerable: true,
          get: function () { return e[k]; }
        });
      }
    });
  }
  n.default = e;
  return Object.freeze(n);
}

var mdurl__namespace = /*#__PURE__*/_interopNamespaceDefault(mdurl);
var ucmicro__namespace = /*#__PURE__*/_interopNamespaceDefault(ucmicro);

// Utilities
//

function _class(obj) {
  return Object.prototype.toString.call(obj);
}
function isString(obj) {
  return _class(obj) === '[object String]';
}
const _hasOwnProperty = Object.prototype.hasOwnProperty;
function has(object, key) {
  return _hasOwnProperty.call(object, key);
}

// Merge objects
//
function assign(obj /* from1, from2, from3, ... */) {
  const sources = Array.prototype.slice.call(arguments, 1);
  sources.forEach(function (source) {
    if (!source) {
      return;
    }
    if (typeof source !== 'object') {
      throw new TypeError(source + 'must be object');
    }
    Object.keys(source).forEach(function (key) {
      obj[key] = source[key];
    });
  });
  return obj;
}

// Remove element from array and put another array at those position.
// Useful for some operations with tokens
function arrayReplaceAt(src, pos, newElements) {
  return [].concat(src.slice(0, pos), newElements, src.slice(pos + 1));
}
function isValidEntityCode(c) {
  /* eslint no-bitwise:0 */
  // broken sequence
  if (c >= 0xD800 && c <= 0xDFFF) {
    return false;
  }
  // never used
  if (c >= 0xFDD0 && c <= 0xFDEF) {
    return false;
  }
  if ((c & 0xFFFF) === 0xFFFF || (c & 0xFFFF) === 0xFFFE) {
    return false;
  }
  // control codes
  if (c >= 0x00 && c <= 0x08) {
    return false;
  }
  if (c === 0x0B) {
    return false;
  }
  if (c >= 0x0E && c <= 0x1F) {
    return false;
  }
  if (c >= 0x7F && c <= 0x9F) {
    return false;
  }
  // out of range
  if (c > 0x10FFFF) {
    return false;
  }
  return true;
}
function fromCodePoint(c) {
  /* eslint no-bitwise:0 */
  if (c > 0xffff) {
    c -= 0x10000;
    const surrogate1 = 0xd800 + (c >> 10);
    const surrogate2 = 0xdc00 + (c & 0x3ff);
    return String.fromCharCode(surrogate1, surrogate2);
  }
  return String.fromCharCode(c);
}
const UNESCAPE_MD_RE = /\\([!"#$%&'()*+,\-./:;<=>?@[\\\]^_`{|}~])/g;
const ENTITY_RE = /&([a-z#][a-z0-9]{1,31});/gi;
const UNESCAPE_ALL_RE = new RegExp(UNESCAPE_MD_RE.source + '|' + ENTITY_RE.source, 'gi');
const DIGITAL_ENTITY_TEST_RE = /^#((?:x[a-f0-9]{1,8}|[0-9]{1,8}))$/i;
function replaceEntityPattern(match, name) {
  if (name.charCodeAt(0) === 0x23 /* # */ && DIGITAL_ENTITY_TEST_RE.test(name)) {
    const code = name[1].toLowerCase() === 'x' ? parseInt(name.slice(2), 16) : parseInt(name.slice(1), 10);
    if (isValidEntityCode(code)) {
      return fromCodePoint(code);
    }
    return match;
  }
  const decoded = entities.decodeHTML(match);
  if (decoded !== match) {
    return decoded;
  }
  return match;
}

/* function replaceEntities(str) {
  if (str.indexOf('&') < 0) { return str; }

  return str.replace(ENTITY_RE, replaceEntityPattern);
} */

function unescapeMd(str) {
  if (str.indexOf('\\') < 0) {
    return str;
  }
  return str.replace(UNESCAPE_MD_RE, '$1');
}
function unescapeAll(str) {
  if (str.indexOf('\\') < 0 && str.indexOf('&') < 0) {
    return str;
  }
  return str.replace(UNESCAPE_ALL_RE, function (match, escaped, entity) {
    if (escaped) {
      return escaped;
    }
    return replaceEntityPattern(match, entity);
  });
}
const HTML_ESCAPE_TEST_RE = /[&<>"]/;
const HTML_ESCAPE_REPLACE_RE = /[&<>"]/g;
const HTML_REPLACEMENTS = {
  '&': '&amp;',
  '<': '&lt;',
  '>': '&gt;',
  '"': '&quot;'
};
function replaceUnsafeChar(ch) {
  return HTML_REPLACEMENTS[ch];
}
function escapeHtml(str) {
  if (HTML_ESCAPE_TEST_RE.test(str)) {
    return str.replace(HTML_ESCAPE_REPLACE_RE, replaceUnsafeChar);
  }
  return str;
}
const REGEXP_ESCAPE_RE = /[.?*+^$[\]\\(){}|-]/g;
function escapeRE(str) {
  return str.replace(REGEXP_ESCAPE_RE, '\\$&');
}
function isSpace(code) {
  switch (code) {
    case 0x09:
    case 0x20:
      return true;
  }
  return false;
}

// Zs (unicode class) || [\t\f\v\r\n]
function isWhiteSpace(code) {
  if (code >= 0x2000 && code <= 0x200A) {
    return true;
  }
  switch (code) {
    case 0x09: // \t
    case 0x0A: // \n
    case 0x0B: // \v
    case 0x0C: // \f
    case 0x0D: // \r
    case 0x20:
    case 0xA0:
    case 0x1680:
    case 0x202F:
    case 0x205F:
    case 0x3000:
      return true;
  }
  return false;
}

/* eslint-disable max-len */

// Currently without astral characters support.
function isPunctChar(ch) {
  return ucmicro__namespace.P.test(ch) || ucmicro__namespace.S.test(ch);
}

// Markdown ASCII punctuation characters.
//
// !, ", #, $, %, &, ', (, ), *, +, ,, -, ., /, :, ;, <, =, >, ?, @, [, \, ], ^, _, `, {, |, }, or ~
// http://spec.commonmark.org/0.15/#ascii-punctuation-character
//
// Don't confuse with unicode punctuation !!! It lacks some chars in ascii range.
//
function isMdAsciiPunct(ch) {
  switch (ch) {
    case 0x21 /* ! */:
    case 0x22 /* " */:
    case 0x23 /* # */:
    case 0x24 /* $ */:
    case 0x25 /* % */:
    case 0x26 /* & */:
    case 0x27 /* ' */:
    case 0x28 /* ( */:
    case 0x29 /* ) */:
    case 0x2A /* * */:
    case 0x2B /* + */:
    case 0x2C /* , */:
    case 0x2D /* - */:
    case 0x2E /* . */:
    case 0x2F /* / */:
    case 0x3A /* : */:
    case 0x3B /* ; */:
    case 0x3C /* < */:
    case 0x3D /* = */:
    case 0x3E /* > */:
    case 0x3F /* ? */:
    case 0x40 /* @ */:
    case 0x5B /* [ */:
    case 0x5C /* \ */:
    case 0x5D /* ] */:
    case 0x5E /* ^ */:
    case 0x5F /* _ */:
    case 0x60 /* ` */:
    case 0x7B /* { */:
    case 0x7C /* | */:
    case 0x7D /* } */:
    case 0x7E /* ~ */:
      return true;
    default:
      return false;
  }
}

// Hepler to unify [reference labels].
//
function normalizeReference(str) {
  // Trim and collapse whitespace
  //
  str = str.trim().replace(/\s+/g, ' ');

  // In node v10 'ẞ'.toLowerCase() === 'Ṿ', which is presumed to be a bug
  // fixed in v12 (couldn't find any details).
  //
  // So treat this one as a special case
  // (remove this when node v10 is no longer supported).
  //
  if ('ẞ'.toLowerCase() === 'Ṿ') {
    str = str.replace(/ẞ/g, 'ß');
  }

  // .toLowerCase().toUpperCase() should get rid of all differences
  // between letter variants.
  //
  // Simple .toLowerCase() doesn't normalize 125 code points correctly,
  // and .toUpperCase doesn't normalize 6 of them (list of exceptions:
  // İ, ϴ, ẞ, Ω, K, Å - those are already uppercased, but have differently
  // uppercased versions).
  //
  // Here's an example showing how it happens. Lets take greek letter omega:
  // uppercase U+0398 (Θ), U+03f4 (ϴ) and lowercase U+03b8 (θ), U+03d1 (ϑ)
  //
  // Unicode entries:
  // 0398;GREEK CAPITAL LETTER THETA;Lu;0;L;;;;;N;;;;03B8;
  // 03B8;GREEK SMALL LETTER THETA;Ll;0;L;;;;;N;;;0398;;0398
  // 03D1;GREEK THETA SYMBOL;Ll;0;L;<compat> 03B8;;;;N;GREEK SMALL LETTER SCRIPT THETA;;0398;;0398
  // 03F4;GREEK CAPITAL THETA SYMBOL;Lu;0;L;<compat> 0398;;;;N;;;;03B8;
  //
  // Case-insensitive comparison should treat all of them as equivalent.
  //
  // But .toLowerCase() doesn't change ϑ (it's already lowercase),
  // and .toUpperCase() doesn't change ϴ (already uppercase).
  //
  // Applying first lower then upper case normalizes any character:
  // '\u0398\u03f4\u03b8\u03d1'.toLowerCase().toUpperCase() === '\u0398\u0398\u0398\u0398'
  //
  // Note: this is equivalent to unicode case folding; unicode normalization
  // is a different step that is not required here.
  //
  // Final result should be uppercased, because it's later stored in an object
  // (this avoid a conflict with Object.prototype members,
  // most notably, `__proto__`)
  //
  return str.toLowerCase().toUpperCase();
}

// Re-export libraries commonly used in both markdown-it and its plugins,
// so plugins won't have to depend on them explicitly, which reduces their
// bundled size (e.g. a browser build).
//
const lib = {
  mdurl: mdurl__namespace,
  ucmicro: ucmicro__namespace
};

var utils = /*#__PURE__*/Object.freeze({
  __proto__: null,
  arrayReplaceAt: arrayReplaceAt,
  assign: assign,
  escapeHtml: escapeHtml,
  escapeRE: escapeRE,
  fromCodePoint: fromCodePoint,
  has: has,
  isMdAsciiPunct: isMdAsciiPunct,
  isPunctChar: isPunctChar,
  isSpace: isSpace,
  isString: isString,
  isValidEntityCode: isValidEntityCode,
  isWhiteSpace: isWhiteSpace,
  lib: lib,
  normalizeReference: normalizeReference,
  unescapeAll: unescapeAll,
  unescapeMd: unescapeMd
});

// Parse link label
//
// this function assumes that first character ("[") already matches;
// returns the end of the label
//

function parseLinkLabel(state, start, disableNested) {
  let level, found, marker, prevPos;
  const max = state.posMax;
  const oldPos = state.pos;
  state.pos = start + 1;
  level = 1;
  while (state.pos < max) {
    marker = state.src.charCodeAt(state.pos);
    if (marker === 0x5D /* ] */) {
      level--;
      if (level === 0) {
        found = true;
        break;
      }
    }
    prevPos = state.pos;
    state.md.inline.skipToken(state);
    if (marker === 0x5B /* [ */) {
      if (prevPos === state.pos - 1) {
        // increase level if we find text `[`, which is not a part of any token
        level++;
      } else if (disableNested) {
        state.pos = oldPos;
        return -1;
      }
    }
  }
  let labelEnd = -1;
  if (found) {
    labelEnd = state.pos;
  }

  // restore old state
  state.pos = oldPos;
  return labelEnd;
}

// Parse link destination
//

function parseLinkDestination(str, start, max) {
  let code;
  let pos = start;
  const result = {
    ok: false,
    pos: 0,
    str: ''
  };
  if (str.charCodeAt(pos) === 0x3C /* < */) {
    pos++;
    while (pos < max) {
      code = str.charCodeAt(pos);
      if (code === 0x0A /* \n */) {
        return result;
      }
      if (code === 0x3C /* < */) {
        return result;
      }
      if (code === 0x3E /* > */) {
        result.pos = pos + 1;
        result.str = unescapeAll(str.slice(start + 1, pos));
        result.ok = true;
        return result;
      }
      if (code === 0x5C /* \ */ && pos + 1 < max) {
        pos += 2;
        continue;
      }
      pos++;
    }

    // no closing '>'
    return result;
  }

  // this should be ... } else { ... branch

  let level = 0;
  while (pos < max) {
    code = str.charCodeAt(pos);
    if (code === 0x20) {
      break;
    }

    // ascii control characters
    if (code < 0x20 || code === 0x7F) {
      break;
    }
    if (code === 0x5C /* \ */ && pos + 1 < max) {
      if (str.charCodeAt(pos + 1) === 0x20) {
        break;
      }
      pos += 2;
      continue;
    }
    if (code === 0x28 /* ( */) {
      level++;
      if (level > 32) {
        return result;
      }
    }
    if (code === 0x29 /* ) */) {
      if (level === 0) {
        break;
      }
      level--;
    }
    pos++;
  }
  if (start === pos) {
    return result;
  }
  if (level !== 0) {
    return result;
  }
  result.str = unescapeAll(str.slice(start, pos));
  result.pos = pos;
  result.ok = true;
  return result;
}

// Parse link title
//


// Parse link title within `str` in [start, max] range,
// or continue previous parsing if `prev_state` is defined (equal to result of last execution).
//
function parseLinkTitle(str, start, max, prev_state) {
  let code;
  let pos = start;
  const state = {
    // if `true`, this is a valid link title
    ok: false,
    // if `true`, this link can be continued on the next line
    can_continue: false,
    // if `ok`, it's the position of the first character after the closing marker
    pos: 0,
    // if `ok`, it's the unescaped title
    str: '',
    // expected closing marker character code
    marker: 0
  };
  if (prev_state) {
    // this is a continuation of a previous parseLinkTitle call on the next line,
    // used in reference links only
    state.str = prev_state.str;
    state.marker = prev_state.marker;
  } else {
    if (pos >= max) {
      return state;
    }
    let marker = str.charCodeAt(pos);
    if (marker !== 0x22 /* " */ && marker !== 0x27 /* ' */ && marker !== 0x28 /* ( */) {
      return state;
    }
    start++;
    pos++;

    // if opening marker is "(", switch it to closing marker ")"
    if (marker === 0x28) {
      marker = 0x29;
    }
    state.marker = marker;
  }
  while (pos < max) {
    code = str.charCodeAt(pos);
    if (code === state.marker) {
      state.pos = pos + 1;
      state.str += unescapeAll(str.slice(start, pos));
      state.ok = true;
      return state;
    } else if (code === 0x28 /* ( */ && state.marker === 0x29 /* ) */) {
      return state;
    } else if (code === 0x5C /* \ */ && pos + 1 < max) {
      pos++;
    }
    pos++;
  }

  // no closing marker found, but this link title may continue on the next line (for references)
  state.can_continue = true;
  state.str += unescapeAll(str.slice(start, pos));
  return state;
}

// Just a shortcut for bulk export

var helpers = /*#__PURE__*/Object.freeze({
  __proto__: null,
  parseLinkDestination: parseLinkDestination,
  parseLinkLabel: parseLinkLabel,
  parseLinkTitle: parseLinkTitle
});

/**
 * class Renderer
 *
 * Generates HTML from parsed token stream. Each instance has independent
 * copy of rules. Those can be rewritten with ease. Also, you can add new
 * rules if you create plugin and adds new token types.
 **/

const default_rules = {};
default_rules.code_inline = function (tokens, idx, options, env, slf) {
  const token = tokens[idx];
  return '<code' + slf.renderAttrs(token) + '>' + escapeHtml(token.content) + '</code>';
};
default_rules.code_block = function (tokens, idx, options, env, slf) {
  const token = tokens[idx];
  return '<pre' + slf.renderAttrs(token) + '><code>' + escapeHtml(tokens[idx].content) + '</code></pre>\n';
};
default_rules.fence = function (tokens, idx, options, env, slf) {
  const token = tokens[idx];
  const info = token.info ? unescapeAll(token.info).trim() : '';
  let langName = '';
  let langAttrs = '';
  if (info) {
    const arr = info.split(/(\s+)/g);
    langName = arr[0];
    langAttrs = arr.slice(2).join('');
  }
  let highlighted;
  if (options.highlight) {
    highlighted = options.highlight(token.content, langName, langAttrs) || escapeHtml(token.content);
  } else {
    highlighted = escapeHtml(token.content);
  }
  if (highlighted.indexOf('<pre') === 0) {
    return highlighted + '\n';
  }

  // If language exists, inject class gently, without modifying original token.
  // May be, one day we will add .deepClone() for token and simplify this part, but
  // now we prefer to keep things local.
  if (info) {
    const i = token.attrIndex('class');
    const tmpAttrs = token.attrs ? token.attrs.slice() : [];
    if (i < 0) {
      tmpAttrs.push(['class', options.langPrefix + langName]);
    } else {
      tmpAttrs[i] = tmpAttrs[i].slice();
      tmpAttrs[i][1] += ' ' + options.langPrefix + langName;
    }

    // Fake token just to render attributes
    const tmpToken = {
      attrs: tmpAttrs
    };
    return `<pre><code${slf.renderAttrs(tmpToken)}>${highlighted}</code></pre>\n`;
  }
  return `<pre><code${slf.renderAttrs(token)}>${highlighted}</code></pre>\n`;
};
default_rules.image = function (tokens, idx, options, env, slf) {
  const token = tokens[idx];

  // "alt" attr MUST be set, even if empty. Because it's mandatory and
  // should be placed on proper position for tests.
  //
  // Replace content with actual value

  token.attrs[token.attrIndex('alt')][1] = slf.renderInlineAsText(token.children, options, env);
  return slf.renderToken(tokens, idx, options);
};
default_rules.hardbreak = function (tokens, idx, options /*, env */) {
  return options.xhtmlOut ? '<br />\n' : '<br>\n';
};
default_rules.softbreak = function (tokens, idx, options /*, env */) {
  return options.breaks ? options.xhtmlOut ? '<br />\n' : '<br>\n' : '\n';
};
default_rules.text = function (tokens, idx /*, options, env */) {
  return escapeHtml(tokens[idx].content);
};
default_rules.html_block = function (tokens, idx /*, options, env */) {
  return tokens[idx].content;
};
default_rules.html_inline = function (tokens, idx /*, options, env */) {
  return tokens[idx].content;
};

/**
 * new Renderer()
 *
 * Creates new [[Renderer]] instance and fill [[Renderer#rules]] with defaults.
 **/
function Renderer() {
  /**
   * Renderer#rules -> Object
   *
   * Contains render rules for tokens. Can be updated and extended.
   *
   * ##### Example
   *
   * ```javascript
   * var md = require('markdown-it')();
   *
   * md.renderer.rules.strong_open  = function () { return '<b>'; };
   * md.renderer.rules.strong_close = function () { return '</b>'; };
   *
   * var result = md.renderInline(...);
   * ```
   *
   * Each rule is called as independent static function with fixed signature:
   *
   * ```javascript
   * function my_token_render(tokens, idx, options, env, renderer) {
   *   // ...
   *   return renderedHTML;
   * }
   * ```
   *
   * See [source code](https://github.com/markdown-it/markdown-it/blob/master/lib/renderer.mjs)
   * for more details and examples.
   **/
  this.rules = assign({}, default_rules);
}

/**
 * Renderer.renderAttrs(token) -> String
 *
 * Render token attributes to string.
 **/
Renderer.prototype.renderAttrs = function renderAttrs(token) {
  let i, l, result;
  if (!token.attrs) {
    return '';
  }
  result = '';
  for (i = 0, l = token.attrs.length; i < l; i++) {
    result += ' ' + escapeHtml(token.attrs[i][0]) + '="' + escapeHtml(token.attrs[i][1]) + '"';
  }
  return result;
};

/**
 * Renderer.renderToken(tokens, idx, options) -> String
 * - tokens (Array): list of tokens
 * - idx (Numbed): token index to render
 * - options (Object): params of parser instance
 *
 * Default token renderer. Can be overriden by custom function
 * in [[Renderer#rules]].
 **/
Renderer.prototype.renderToken = function renderToken(tokens, idx, options) {
  const token = tokens[idx];
  let result = '';

  // Tight list paragraphs
  if (token.hidden) {
    return '';
  }

  // Insert a newline between hidden paragraph and subsequent opening
  // block-level tag.
  //
  // For example, here we should insert a newline before blockquote:
  //  - a
  //    >
  //
  if (token.block && token.nesting !== -1 && idx && tokens[idx - 1].hidden) {
    result += '\n';
  }

  // Add token name, e.g. `<img`
  result += (token.nesting === -1 ? '</' : '<') + token.tag;

  // Encode attributes, e.g. `<img src="foo"`
  result += this.renderAttrs(token);

  // Add a slash for self-closing tags, e.g. `<img src="foo" /`
  if (token.nesting === 0 && options.xhtmlOut) {
    result += ' /';
  }

  // Check if we need to add a newline after this tag
  let needLf = false;
  if (token.block) {
    needLf = true;
    if (token.nesting === 1) {
      if (idx + 1 < tokens.length) {
        const nextToken = tokens[idx + 1];
        if (nextToken.type === 'inline' || nextToken.hidden) {
          // Block-level tag containing an inline tag.
          //
          needLf = false;
        } else if (nextToken.nesting === -1 && nextToken.tag === token.tag) {
          // Opening tag + closing tag of the same type. E.g. `<li></li>`.
          //
          needLf = false;
        }
      }
    }
  }
  result += needLf ? '>\n' : '>';
  return result;
};

/**
 * Renderer.renderInline(tokens, options, env) -> String
 * - tokens (Array): list on block tokens to render
 * - options (Object): params of parser instance
 * - env (Object): additional data from parsed input (references, for example)
 *
 * The same as [[Renderer.render]], but for single token of `inline` type.
 **/
Renderer.prototype.renderInline = function (tokens, options, env) {
  let result = '';
  const rules = this.rules;
  for (let i = 0, len = tokens.length; i < len; i++) {
    const type = tokens[i].type;
    if (typeof rules[type] !== 'undefined') {
      result += rules[type](tokens, i, options, env, this);
    } else {
      result += this.renderToken(tokens, i, options);
    }
  }
  return result;
};

/** internal
 * Renderer.renderInlineAsText(tokens, options, env) -> String
 * - tokens (Array): list on block tokens to render
 * - options (Object): params of parser instance
 * - env (Object): additional data from parsed input (references, for example)
 *
 * Special kludge for image `alt` attributes to conform CommonMark spec.
 * Don't try to use it! Spec requires to show `alt` content with stripped markup,
 * instead of simple escaping.
 **/
Renderer.prototype.renderInlineAsText = function (tokens, options, env) {
  let result = '';
  for (let i = 0, len = tokens.length; i < len; i++) {
    switch (tokens[i].type) {
      case 'text':
        result += tokens[i].content;
        break;
      case 'image':
        result += this.renderInlineAsText(tokens[i].children, options, env);
        break;
      case 'html_inline':
      case 'html_block':
        result += tokens[i].content;
        break;
      case 'softbreak':
      case 'hardbreak':
        result += '\n';
        break;
      // all other tokens are skipped
    }
  }
  return result;
};

/**
 * Renderer.render(tokens, options, env) -> String
 * - tokens (Array): list on block tokens to render
 * - options (Object): params of parser instance
 * - env (Object): additional data from parsed input (references, for example)
 *
 * Takes token stream and generates HTML. Probably, you will never need to call
 * this method directly.
 **/
Renderer.prototype.render = function (tokens, options, env) {
  let result = '';
  const rules = this.rules;
  for (let i = 0, len = tokens.length; i < len; i++) {
    const type = tokens[i].type;
    if (type === 'inline') {
      result += this.renderInline(tokens[i].children, options, env);
    } else if (typeof rules[type] !== 'undefined') {
      result += rules[type](tokens, i, options, env, this);
    } else {
      result += this.renderToken(tokens, i, options, env);
    }
  }
  return result;
};

/**
 * class Ruler
 *
 * Helper class, used by [[MarkdownIt#core]], [[MarkdownIt#block]] and
 * [[MarkdownIt#inline]] to manage sequences of functions (rules):
 *
 * - keep rules in defined order
 * - assign the name to each rule
 * - enable/disable rules
 * - add/replace rules
 * - allow assign rules to additional named chains (in the same)
 * - cacheing lists of active rules
 *
 * You will not need use this class directly until write plugins. For simple
 * rules control use [[MarkdownIt.disable]], [[MarkdownIt.enable]] and
 * [[MarkdownIt.use]].
 **/

/**
 * new Ruler()
 **/
function Ruler() {
  // List of added rules. Each element is:
  //
  // {
  //   name: XXX,
  //   enabled: Boolean,
  //   fn: Function(),
  //   alt: [ name2, name3 ]
  // }
  //
  this.__rules__ = [];

  // Cached rule chains.
  //
  // First level - chain name, '' for default.
  // Second level - diginal anchor for fast filtering by charcodes.
  //
  this.__cache__ = null;
}

// Helper methods, should not be used directly

// Find rule index by name
//
Ruler.prototype.__find__ = function (name) {
  for (let i = 0; i < this.__rules__.length; i++) {
    if (this.__rules__[i].name === name) {
      return i;
    }
  }
  return -1;
};

// Build rules lookup cache
//
Ruler.prototype.__compile__ = function () {
  const self = this;
  const chains = [''];

  // collect unique names
  self.__rules__.forEach(function (rule) {
    if (!rule.enabled) {
      return;
    }
    rule.alt.forEach(function (altName) {
      if (chains.indexOf(altName) < 0) {
        chains.push(altName);
      }
    });
  });
  self.__cache__ = {};
  chains.forEach(function (chain) {
    self.__cache__[chain] = [];
    self.__rules__.forEach(function (rule) {
      if (!rule.enabled) {
        return;
      }
      if (chain && rule.alt.indexOf(chain) < 0) {
        return;
      }
      self.__cache__[chain].push(rule.fn);
    });
  });
};

/**
 * Ruler.at(name, fn [, options])
 * - name (String): rule name to replace.
 * - fn (Function): new rule function.
 * - options (Object): new rule options (not mandatory).
 *
 * Replace rule by name with new function & options. Throws error if name not
 * found.
 *
 * ##### Options:
 *
 * - __alt__ - array with names of "alternate" chains.
 *
 * ##### Example
 *
 * Replace existing typographer replacement rule with new one:
 *
 * ```javascript
 * var md = require('markdown-it')();
 *
 * md.core.ruler.at('replacements', function replace(state) {
 *   //...
 * });
 * ```
 **/
Ruler.prototype.at = function (name, fn, options) {
  const index = this.__find__(name);
  const opt = options || {};
  if (index === -1) {
    throw new Error('Parser rule not found: ' + name);
  }
  this.__rules__[index].fn = fn;
  this.__rules__[index].alt = opt.alt || [];
  this.__cache__ = null;
};

/**
 * Ruler.before(beforeName, ruleName, fn [, options])
 * - beforeName (String): new rule will be added before this one.
 * - ruleName (String): name of added rule.
 * - fn (Function): rule function.
 * - options (Object): rule options (not mandatory).
 *
 * Add new rule to chain before one with given name. See also
 * [[Ruler.after]], [[Ruler.push]].
 *
 * ##### Options:
 *
 * - __alt__ - array with names of "alternate" chains.
 *
 * ##### Example
 *
 * ```javascript
 * var md = require('markdown-it')();
 *
 * md.block.ruler.before('paragraph', 'my_rule', function replace(state) {
 *   //...
 * });
 * ```
 **/
Ruler.prototype.before = function (beforeName, ruleName, fn, options) {
  const index = this.__find__(beforeName);
  const opt = options || {};
  if (index === -1) {
    throw new Error('Parser rule not found: ' + beforeName);
  }
  this.__rules__.splice(index, 0, {
    name: ruleName,
    enabled: true,
    fn,
    alt: opt.alt || []
  });
  this.__cache__ = null;
};

/**
 * Ruler.after(afterName, ruleName, fn [, options])
 * - afterName (String): new rule will be added after this one.
 * - ruleName (String): name of added rule.
 * - fn (Function): rule function.
 * - options (Object): rule options (not mandatory).
 *
 * Add new rule to chain after one with given name. See also
 * [[Ruler.before]], [[Ruler.push]].
 *
 * ##### Options:
 *
 * - __alt__ - array with names of "alternate" chains.
 *
 * ##### Example
 *
 * ```javascript
 * var md = require('markdown-it')();
 *
 * md.inline.ruler.after('text', 'my_rule', function replace(state) {
 *   //...
 * });
 * ```
 **/
Ruler.prototype.after = function (afterName, ruleName, fn, options) {
  const index = this.__find__(afterName);
  const opt = options || {};
  if (index === -1) {
    throw new Error('Parser rule not found: ' + afterName);
  }
  this.__rules__.splice(index + 1, 0, {
    name: ruleName,
    enabled: true,
    fn,
    alt: opt.alt || []
  });
  this.__cache__ = null;
};

/**
 * Ruler.push(ruleName, fn [, options])
 * - ruleName (String): name of added rule.
 * - fn (Function): rule function.
 * - options (Object): rule options (not mandatory).
 *
 * Push new rule to the end of chain. See also
 * [[Ruler.before]], [[Ruler.after]].
 *
 * ##### Options:
 *
 * - __alt__ - array with names of "alternate" chains.
 *
 * ##### Example
 *
 * ```javascript
 * var md = require('markdown-it')();
 *
 * md.core.ruler.push('my_rule', function replace(state) {
 *   //...
 * });
 * ```
 **/
Ruler.prototype.push = function (ruleName, fn, options) {
  const opt = options || {};
  this.__rules__.push({
    name: ruleName,
    enabled: true,
    fn,
    alt: opt.alt || []
  });
  this.__cache__ = null;
};

/**
 * Ruler.enable(list [, ignoreInvalid]) -> Array
 * - list (String|Array): list of rule names to enable.
 * - ignoreInvalid (Boolean): set `true` to ignore errors when rule not found.
 *
 * Enable rules with given names. If any rule name not found - throw Error.
 * Errors can be disabled by second param.
 *
 * Returns list of found rule names (if no exception happened).
 *
 * See also [[Ruler.disable]], [[Ruler.enableOnly]].
 **/
Ruler.prototype.enable = function (list, ignoreInvalid) {
  if (!Array.isArray(list)) {
    list = [list];
  }
  const result = [];

  // Search by name and enable
  list.forEach(function (name) {
    const idx = this.__find__(name);
    if (idx < 0) {
      if (ignoreInvalid) {
        return;
      }
      throw new Error('Rules manager: invalid rule name ' + name);
    }
    this.__rules__[idx].enabled = true;
    result.push(name);
  }, this);
  this.__cache__ = null;
  return result;
};

/**
 * Ruler.enableOnly(list [, ignoreInvalid])
 * - list (String|Array): list of rule names to enable (whitelist).
 * - ignoreInvalid (Boolean): set `true` to ignore errors when rule not found.
 *
 * Enable rules with given names, and disable everything else. If any rule name
 * not found - throw Error. Errors can be disabled by second param.
 *
 * See also [[Ruler.disable]], [[Ruler.enable]].
 **/
Ruler.prototype.enableOnly = function (list, ignoreInvalid) {
  if (!Array.isArray(list)) {
    list = [list];
  }
  this.__rules__.forEach(function (rule) {
    rule.enabled = false;
  });
  this.enable(list, ignoreInvalid);
};

/**
 * Ruler.disable(list [, ignoreInvalid]) -> Array
 * - list (String|Array): list of rule names to disable.
 * - ignoreInvalid (Boolean): set `true` to ignore errors when rule not found.
 *
 * Disable rules with given names. If any rule name not found - throw Error.
 * Errors can be disabled by second param.
 *
 * Returns list of found rule names (if no exception happened).
 *
 * See also [[Ruler.enable]], [[Ruler.enableOnly]].
 **/
Ruler.prototype.disable = function (list, ignoreInvalid) {
  if (!Array.isArray(list)) {
    list = [list];
  }
  const result = [];

  // Search by name and disable
  list.forEach(function (name) {
    const idx = this.__find__(name);
    if (idx < 0) {
      if (ignoreInvalid) {
        return;
      }
      throw new Error('Rules manager: invalid rule name ' + name);
    }
    this.__rules__[idx].enabled = false;
    result.push(name);
  }, this);
  this.__cache__ = null;
  return result;
};

/**
 * Ruler.getRules(chainName) -> Array
 *
 * Return array of active functions (rules) for given chain name. It analyzes
 * rules configuration, compiles caches if not exists and returns result.
 *
 * Default chain name is `''` (empty string). It can't be skipped. That's
 * done intentionally, to keep signature monomorphic for high speed.
 **/
Ruler.prototype.getRules = function (chainName) {
  if (this.__cache__ === null) {
    this.__compile__();
  }

  // Chain can be empty, if rules disabled. But we still have to return Array.
  return this.__cache__[chainName] || [];
};

// Token class

/**
 * class Token
 **/

/**
 * new Token(type, tag, nesting)
 *
 * Create new token and fill passed properties.
 **/
function Token(type, tag, nesting) {
  /**
   * Token#type -> String
   *
   * Type of the token (string, e.g. "paragraph_open")
   **/
  this.type = type;

  /**
   * Token#tag -> String
   *
   * html tag name, e.g. "p"
   **/
  this.tag = tag;

  /**
   * Token#attrs -> Array
   *
   * Html attributes. Format: `[ [ name1, value1 ], [ name2, value2 ] ]`
   **/
  this.attrs = null;

  /**
   * Token#map -> Array
   *
   * Source map info. Format: `[ line_begin, line_end ]`
   **/
  this.map = null;

  /**
   * Token#nesting -> Number
   *
   * Level change (number in {-1, 0, 1} set), where:
   *
   * -  `1` means the tag is opening
   * -  `0` means the tag is self-closing
   * - `-1` means the tag is closing
   **/
  this.nesting = nesting;

  /**
   * Token#level -> Number
   *
   * nesting level, the same as `state.level`
   **/
  this.level = 0;

  /**
   * Token#children -> Array
   *
   * An array of child nodes (inline and img tokens)
   **/
  this.children = null;

  /**
   * Token#content -> String
   *
   * In a case of self-closing tag (code, html, fence, etc.),
   * it has contents of this tag.
   **/
  this.content = '';

  /**
   * Token#markup -> String
   *
   * '*' or '_' for emphasis, fence string for fence, etc.
   **/
  this.markup = '';

  /**
   * Token#info -> String
   *
   * Additional information:
   *
   * - Info string for "fence" tokens
   * - The value "auto" for autolink "link_open" and "link_close" tokens
   * - The string value of the item marker for ordered-list "list_item_open" tokens
   **/
  this.info = '';

  /**
   * Token#meta -> Object
   *
   * A place for plugins to store an arbitrary data
   **/
  this.meta = null;

  /**
   * Token#block -> Boolean
   *
   * True for block-level tokens, false for inline tokens.
   * Used in renderer to calculate line breaks
   **/
  this.block = false;

  /**
   * Token#hidden -> Boolean
   *
   * If it's true, ignore this element when rendering. Used for tight lists
   * to hide paragraphs.
   **/
  this.hidden = false;
}

/**
 * Token.attrIndex(name) -> Number
 *
 * Search attribute index by name.
 **/
Token.prototype.attrIndex = function attrIndex(name) {
  if (!this.attrs) {
    return -1;
  }
  const attrs = this.attrs;
  for (let i = 0, len = attrs.length; i < len; i++) {
    if (attrs[i][0] === name) {
      return i;
    }
  }
  return -1;
};

/**
 * Token.attrPush(attrData)
 *
 * Add `[ name, value ]` attribute to list. Init attrs if necessary
 **/
Token.prototype.attrPush = function attrPush(attrData) {
  if (this.attrs) {
    this.attrs.push(attrData);
  } else {
    this.attrs = [attrData];
  }
};

/**
 * Token.attrSet(name, value)
 *
 * Set `name` attribute to `value`. Override old value if exists.
 **/
Token.prototype.attrSet = function attrSet(name, value) {
  const idx = this.attrIndex(name);
  const attrData = [name, value];
  if (idx < 0) {
    this.attrPush(attrData);
  } else {
    this.attrs[idx] = attrData;
  }
};

/**
 * Token.attrGet(name)
 *
 * Get the value of attribute `name`, or null if it does not exist.
 **/
Token.prototype.attrGet = function attrGet(name) {
  const idx = this.attrIndex(name);
  let value = null;
  if (idx >= 0) {
    value = this.attrs[idx][1];
  }
  return value;
};

/**
 * Token.attrJoin(name, value)
 *
 * Join value to existing attribute via space. Or create new attribute if not
 * exists. Useful to operate with token classes.
 **/
Token.prototype.attrJoin = function attrJoin(name, value) {
  const idx = this.attrIndex(name);
  if (idx < 0) {
    this.attrPush([name, value]);
  } else {
    this.attrs[idx][1] = this.attrs[idx][1] + ' ' + value;
  }
};

// Core state object
//

function StateCore(src, md, env) {
  this.src = src;
  this.env = env;
  this.tokens = [];
  this.inlineMode = false;
  this.md = md; // link to parser instance
}

// re-export Token class to use in core rules
StateCore.prototype.Token = Token;

// Normalize input string

// https://spec.commonmark.org/0.29/#line-ending
const NEWLINES_RE = /\r\n?|\n/g;
const NULL_RE = /\0/g;
function normalize(state) {
  let str;

  // Normalize newlines
  str = state.src.replace(NEWLINES_RE, '\n');

  // Replace NULL characters
  str = str.replace(NULL_RE, '\uFFFD');
  state.src = str;
}

function block(state) {
  let token;
  if (state.inlineMode) {
    token = new state.Token('inline', '', 0);
    token.content = state.src;
    token.map = [0, 1];
    token.children = [];
    state.tokens.push(token);
  } else {
    state.md.block.parse(state.src, state.md, state.env, state.tokens);
  }
}

function inline(state) {
  const tokens = state.tokens;

  // Parse inlines
  for (let i = 0, l = tokens.length; i < l; i++) {
    const tok = tokens[i];
    if (tok.type === 'inline') {
      state.md.inline.parse(tok.content, state.md, state.env, tok.children);
    }
  }
}

// Replace link-like texts with link nodes.
//
// Currently restricted by `md.validateLink()` to http/https/ftp
//

function isLinkOpen$1(str) {
  return /^<a[>\s]/i.test(str);
}
function isLinkClose$1(str) {
  return /^<\/a\s*>/i.test(str);
}
function linkify$1(state) {
  const blockTokens = state.tokens;
  if (!state.md.options.linkify) {
    return;
  }
  for (let j = 0, l = blockTokens.length; j < l; j++) {
    if (blockTokens[j].type !== 'inline' || !state.md.linkify.pretest(blockTokens[j].content)) {
      continue;
    }
    let tokens = blockTokens[j].children;
    let htmlLinkLevel = 0;

    // We scan from the end, to keep position when new tags added.
    // Use reversed logic in links start/end match
    for (let i = tokens.length - 1; i >= 0; i--) {
      const currentToken = tokens[i];

      // Skip content of markdown links
      if (currentToken.type === 'link_close') {
        i--;
        while (tokens[i].level !== currentToken.level && tokens[i].type !== 'link_open') {
          i--;
        }
        continue;
      }

      // Skip content of html tag links
      if (currentToken.type === 'html_inline') {
        if (isLinkOpen$1(currentToken.content) && htmlLinkLevel > 0) {
          htmlLinkLevel--;
        }
        if (isLinkClose$1(currentToken.content)) {
          htmlLinkLevel++;
        }
      }
      if (htmlLinkLevel > 0) {
        continue;
      }
      if (currentToken.type === 'text' && state.md.linkify.test(currentToken.content)) {
        const text = currentToken.content;
        let links = state.md.linkify.match(text);

        // Now split string to nodes
        const nodes = [];
        let level = currentToken.level;
        let lastPos = 0;

        // forbid escape sequence at the start of the string,
        // this avoids http\://example.com/ from being linkified as
        // http:<a href="//example.com/">//example.com/</a>
        if (links.length > 0 && links[0].index === 0 && i > 0 && tokens[i - 1].type === 'text_special') {
          links = links.slice(1);
        }
        for (let ln = 0; ln < links.length; ln++) {
          const url = links[ln].url;
          const fullUrl = state.md.normalizeLink(url);
          if (!state.md.validateLink(fullUrl)) {
            continue;
          }
          let urlText = links[ln].text;

          // Linkifier might send raw hostnames like "example.com", where url
          // starts with domain name. So we prepend http:// in those cases,
          // and remove it afterwards.
          //
          if (!links[ln].schema) {
            urlText = state.md.normalizeLinkText('http://' + urlText).replace(/^http:\/\//, '');
          } else if (links[ln].schema === 'mailto:' && !/^mailto:/i.test(urlText)) {
            urlText = state.md.normalizeLinkText('mailto:' + urlText).replace(/^mailto:/, '');
          } else {
            urlText = state.md.normalizeLinkText(urlText);
          }
          const pos = links[ln].index;
          if (pos > lastPos) {
            const token = new state.Token('text', '', 0);
            token.content = text.slice(lastPos, pos);
            token.level = level;
            nodes.push(token);
          }
          const token_o = new state.Token('link_open', 'a', 1);
          token_o.attrs = [['href', fullUrl]];
          token_o.level = level++;
          token_o.markup = 'linkify';
          token_o.info = 'auto';
          nodes.push(token_o);
          const token_t = new state.Token('text', '', 0);
          token_t.content = urlText;
          token_t.level = level;
          nodes.push(token_t);
          const token_c = new state.Token('link_close', 'a', -1);
          token_c.level = --level;
          token_c.markup = 'linkify';
          token_c.info = 'auto';
          nodes.push(token_c);
          lastPos = links[ln].lastIndex;
        }
        if (lastPos < text.length) {
          const token = new state.Token('text', '', 0);
          token.content = text.slice(lastPos);
          token.level = level;
          nodes.push(token);
        }

        // replace current node
        blockTokens[j].children = tokens = arrayReplaceAt(tokens, i, nodes);
      }
    }
  }
}

// Simple typographic replacements
//
// (c) (C) → ©
// (tm) (TM) → ™
// (r) (R) → ®
// +- → ±
// ... → … (also ?.... → ?.., !.... → !..)
// ???????? → ???, !!!!! → !!!, `,,` → `,`
// -- → &ndash;, --- → &mdash;
//

// TODO:
// - fractionals 1/2, 1/4, 3/4 -> ½, ¼, ¾
// - multiplications 2 x 4 -> 2 × 4

const RARE_RE = /\+-|\.\.|\?\?\?\?|!!!!|,,|--/;

// Workaround for phantomjs - need regex without /g flag,
// or root check will fail every second time
const SCOPED_ABBR_TEST_RE = /\((c|tm|r)\)/i;
const SCOPED_ABBR_RE = /\((c|tm|r)\)/ig;
const SCOPED_ABBR = {
  c: '©',
  r: '®',
  tm: '™'
};
function replaceFn(match, name) {
  return SCOPED_ABBR[name.toLowerCase()];
}
function replace_scoped(inlineTokens) {
  let inside_autolink = 0;
  for (let i = inlineTokens.length - 1; i >= 0; i--) {
    const token = inlineTokens[i];
    if (token.type === 'text' && !inside_autolink) {
      token.content = token.content.replace(SCOPED_ABBR_RE, replaceFn);
    }
    if (token.type === 'link_open' && token.info === 'auto') {
      inside_autolink--;
    }
    if (token.type === 'link_close' && token.info === 'auto') {
      inside_autolink++;
    }
  }
}
function replace_rare(inlineTokens) {
  let inside_autolink = 0;
  for (let i = inlineTokens.length - 1; i >= 0; i--) {
    const token = inlineTokens[i];
    if (token.type === 'text' && !inside_autolink) {
      if (RARE_RE.test(token.content)) {
        token.content = token.content.replace(/\+-/g, '±')
        // .., ..., ....... -> …
        // but ?..... & !..... -> ?.. & !..
        .replace(/\.{2,}/g, '…').replace(/([?!])…/g, '$1..').replace(/([?!]){4,}/g, '$1$1$1').replace(/,{2,}/g, ',')
        // em-dash
        .replace(/(^|[^-])---(?=[^-]|$)/mg, '$1\u2014')
        // en-dash
        .replace(/(^|\s)--(?=\s|$)/mg, '$1\u2013').replace(/(^|[^-\s])--(?=[^-\s]|$)/mg, '$1\u2013');
      }
    }
    if (token.type === 'link_open' && token.info === 'auto') {
      inside_autolink--;
    }
    if (token.type === 'link_close' && token.info === 'auto') {
      inside_autolink++;
    }
  }
}
function replace(state) {
  let blkIdx;
  if (!state.md.options.typographer) {
    return;
  }
  for (blkIdx = state.tokens.length - 1; blkIdx >= 0; blkIdx--) {
    if (state.tokens[blkIdx].type !== 'inline') {
      continue;
    }
    if (SCOPED_ABBR_TEST_RE.test(state.tokens[blkIdx].content)) {
      replace_scoped(state.tokens[blkIdx].children);
    }
    if (RARE_RE.test(state.tokens[blkIdx].content)) {
      replace_rare(state.tokens[blkIdx].children);
    }
  }
}

// Convert straight quotation marks to typographic ones
//

const QUOTE_TEST_RE = /['"]/;
const QUOTE_RE = /['"]/g;
const APOSTROPHE = '\u2019'; /* ’ */

function replaceAt(str, index, ch) {
  return str.slice(0, index) + ch + str.slice(index + 1);
}
function process_inlines(tokens, state) {
  let j;
  const stack = [];
  for (let i = 0; i < tokens.length; i++) {
    const token = tokens[i];
    const thisLevel = tokens[i].level;
    for (j = stack.length - 1; j >= 0; j--) {
      if (stack[j].level <= thisLevel) {
        break;
      }
    }
    stack.length = j + 1;
    if (token.type !== 'text') {
      continue;
    }
    let text = token.content;
    let pos = 0;
    let max = text.length;

    /* eslint no-labels:0,block-scoped-var:0 */
    OUTER: while (pos < max) {
      QUOTE_RE.lastIndex = pos;
      const t = QUOTE_RE.exec(text);
      if (!t) {
        break;
      }
      let canOpen = true;
      let canClose = true;
      pos = t.index + 1;
      const isSingle = t[0] === "'";

      // Find previous character,
      // default to space if it's the beginning of the line
      //
      let lastChar = 0x20;
      if (t.index - 1 >= 0) {
        lastChar = text.charCodeAt(t.index - 1);
      } else {
        for (j = i - 1; j >= 0; j--) {
          if (tokens[j].type === 'softbreak' || tokens[j].type === 'hardbreak') break; // lastChar defaults to 0x20
          if (!tokens[j].content) continue; // should skip all tokens except 'text', 'html_inline' or 'code_inline'

          lastChar = tokens[j].content.charCodeAt(tokens[j].content.length - 1);
          break;
        }
      }

      // Find next character,
      // default to space if it's the end of the line
      //
      let nextChar = 0x20;
      if (pos < max) {
        nextChar = text.charCodeAt(pos);
      } else {
        for (j = i + 1; j < tokens.length; j++) {
          if (tokens[j].type === 'softbreak' || tokens[j].type === 'hardbreak') break; // nextChar defaults to 0x20
          if (!tokens[j].content) continue; // should skip all tokens except 'text', 'html_inline' or 'code_inline'

          nextChar = tokens[j].content.charCodeAt(0);
          break;
        }
      }
      const isLastPunctChar = isMdAsciiPunct(lastChar) || isPunctChar(String.fromCharCode(lastChar));
      const isNextPunctChar = isMdAsciiPunct(nextChar) || isPunctChar(String.fromCharCode(nextChar));
      const isLastWhiteSpace = isWhiteSpace(lastChar);
      const isNextWhiteSpace = isWhiteSpace(nextChar);
      if (isNextWhiteSpace) {
        canOpen = false;
      } else if (isNextPunctChar) {
        if (!(isLastWhiteSpace || isLastPunctChar)) {
          canOpen = false;
        }
      }
      if (isLastWhiteSpace) {
        canClose = false;
      } else if (isLastPunctChar) {
        if (!(isNextWhiteSpace || isNextPunctChar)) {
          canClose = false;
        }
      }
      if (nextChar === 0x22 /* " */ && t[0] === '"') {
        if (lastChar >= 0x30 /* 0 */ && lastChar <= 0x39 /* 9 */) {
          // special case: 1"" - count first quote as an inch
          canClose = canOpen = false;
        }
      }
      if (canOpen && canClose) {
        // Replace quotes in the middle of punctuation sequence, but not
        // in the middle of the words, i.e.:
        //
        // 1. foo " bar " baz - not replaced
        // 2. foo-"-bar-"-baz - replaced
        // 3. foo"bar"baz     - not replaced
        //
        canOpen = isLastPunctChar;
        canClose = isNextPunctChar;
      }
      if (!canOpen && !canClose) {
        // middle of word
        if (isSingle) {
          token.content = replaceAt(token.content, t.index, APOSTROPHE);
        }
        continue;
      }
      if (canClose) {
        // this could be a closing quote, rewind the stack to get a match
        for (j = stack.length - 1; j >= 0; j--) {
          let item = stack[j];
          if (stack[j].level < thisLevel) {
            break;
          }
          if (item.single === isSingle && stack[j].level === thisLevel) {
            item = stack[j];
            let openQuote;
            let closeQuote;
            if (isSingle) {
              openQuote = state.md.options.quotes[2];
              closeQuote = state.md.options.quotes[3];
            } else {
              openQuote = state.md.options.quotes[0];
              closeQuote = state.md.options.quotes[1];
            }

            // replace token.content *before* tokens[item.token].content,
            // because, if they are pointing at the same token, replaceAt
            // could mess up indices when quote length != 1
            token.content = replaceAt(token.content, t.index, closeQuote);
            tokens[item.token].content = replaceAt(tokens[item.token].content, item.pos, openQuote);
            pos += closeQuote.length - 1;
            if (item.token === i) {
              pos += openQuote.length - 1;
            }
            text = token.content;
            max = text.length;
            stack.length = j;
            continue OUTER;
          }
        }
      }
      if (canOpen) {
        stack.push({
          token: i,
          pos: t.index,
          single: isSingle,
          level: thisLevel
        });
      } else if (canClose && isSingle) {
        token.content = replaceAt(token.content, t.index, APOSTROPHE);
      }
    }
  }
}
function smartquotes(state) {
  /* eslint max-depth:0 */
  if (!state.md.options.typographer) {
    return;
  }
  for (let blkIdx = state.tokens.length - 1; blkIdx >= 0; blkIdx--) {
    if (state.tokens[blkIdx].type !== 'inline' || !QUOTE_TEST_RE.test(state.tokens[blkIdx].content)) {
      continue;
    }
    process_inlines(state.tokens[blkIdx].children, state);
  }
}

// Join raw text tokens with the rest of the text
//
// This is set as a separate rule to provide an opportunity for plugins
// to run text replacements after text join, but before escape join.
//
// For example, `\:)` shouldn't be replaced with an emoji.
//

function text_join(state) {
  let curr, last;
  const blockTokens = state.tokens;
  const l = blockTokens.length;
  for (let j = 0; j < l; j++) {
    if (blockTokens[j].type !== 'inline') continue;
    const tokens = blockTokens[j].children;
    const max = tokens.length;
    for (curr = 0; curr < max; curr++) {
      if (tokens[curr].type === 'text_special') {
        tokens[curr].type = 'text';
      }
    }
    for (curr = last = 0; curr < max; curr++) {
      if (tokens[curr].type === 'text' && curr + 1 < max && tokens[curr + 1].type === 'text') {
        // collapse two adjacent text nodes
        tokens[curr + 1].content = tokens[curr].content + tokens[curr + 1].content;
      } else {
        if (curr !== last) {
          tokens[last] = tokens[curr];
        }
        last++;
      }
    }
    if (curr !== last) {
      tokens.length = last;
    }
  }
}

/** internal
 * class Core
 *
 * Top-level rules executor. Glues block/inline parsers and does intermediate
 * transformations.
 **/

const _rules$2 = [['normalize', normalize], ['block', block], ['inline', inline], ['linkify', linkify$1], ['replacements', replace], ['smartquotes', smartquotes],
// `text_join` finds `text_special` tokens (for escape sequences)
// and joins them with the rest of the text
['text_join', text_join]];

/**
 * new Core()
 **/
function Core() {
  /**
   * Core#ruler -> Ruler
   *
   * [[Ruler]] instance. Keep configuration of core rules.
   **/
  this.ruler = new Ruler();
  for (let i = 0; i < _rules$2.length; i++) {
    this.ruler.push(_rules$2[i][0], _rules$2[i][1]);
  }
}

/**
 * Core.process(state)
 *
 * Executes core chain rules.
 **/
Core.prototype.process = function (state) {
  const rules = this.ruler.getRules('');
  for (let i = 0, l = rules.length; i < l; i++) {
    rules[i](state);
  }
};
Core.prototype.State = StateCore;

// Parser state class

function StateBlock(src, md, env, tokens) {
  this.src = src;

  // link to parser instance
  this.md = md;
  this.env = env;

  //
  // Internal state vartiables
  //

  this.tokens = tokens;
  this.bMarks = []; // line begin offsets for fast jumps
  this.eMarks = []; // line end offsets for fast jumps
  this.tShift = []; // offsets of the first non-space characters (tabs not expanded)
  this.sCount = []; // indents for each line (tabs expanded)

  // An amount of virtual spaces (tabs expanded) between beginning
  // of each line (bMarks) and real beginning of that line.
  //
  // It exists only as a hack because blockquotes override bMarks
  // losing information in the process.
  //
  // It's used only when expanding tabs, you can think about it as
  // an initial tab length, e.g. bsCount=21 applied to string `\t123`
  // means first tab should be expanded to 4-21%4 === 3 spaces.
  //
  this.bsCount = [];

  // block parser variables

  // required block content indent (for example, if we are
  // inside a list, it would be positioned after list marker)
  this.blkIndent = 0;
  this.line = 0; // line index in src
  this.lineMax = 0; // lines count
  this.tight = false; // loose/tight mode for lists
  this.ddIndent = -1; // indent of the current dd block (-1 if there isn't any)
  this.listIndent = -1; // indent of the current list block (-1 if there isn't any)

  // can be 'blockquote', 'list', 'root', 'paragraph' or 'reference'
  // used in lists to determine if they interrupt a paragraph
  this.parentType = 'root';
  this.level = 0;

  // Create caches
  // Generate markers.
  const s = this.src;
  for (let start = 0, pos = 0, indent = 0, offset = 0, len = s.length, indent_found = false; pos < len; pos++) {
    const ch = s.charCodeAt(pos);
    if (!indent_found) {
      if (isSpace(ch)) {
        indent++;
        if (ch === 0x09) {
          offset += 4 - offset % 4;
        } else {
          offset++;
        }
        continue;
      } else {
        indent_found = true;
      }
    }
    if (ch === 0x0A || pos === len - 1) {
      if (ch !== 0x0A) {
        pos++;
      }
      this.bMarks.push(start);
      this.eMarks.push(pos);
      this.tShift.push(indent);
      this.sCount.push(offset);
      this.bsCount.push(0);
      indent_found = false;
      indent = 0;
      offset = 0;
      start = pos + 1;
    }
  }

  // Push fake entry to simplify cache bounds checks
  this.bMarks.push(s.length);
  this.eMarks.push(s.length);
  this.tShift.push(0);
  this.sCount.push(0);
  this.bsCount.push(0);
  this.lineMax = this.bMarks.length - 1; // don't count last fake line
}

// Push new token to "stream".
//
StateBlock.prototype.push = function (type, tag, nesting) {
  const token = new Token(type, tag, nesting);
  token.block = true;
  if (nesting < 0) this.level--; // closing tag
  token.level = this.level;
  if (nesting > 0) this.level++; // opening tag

  this.tokens.push(token);
  return token;
};
StateBlock.prototype.isEmpty = function isEmpty(line) {
  return this.bMarks[line] + this.tShift[line] >= this.eMarks[line];
};
StateBlock.prototype.skipEmptyLines = function skipEmptyLines(from) {
  for (let max = this.lineMax; from < max; from++) {
    if (this.bMarks[from] + this.tShift[from] < this.eMarks[from]) {
      break;
    }
  }
  return from;
};

// Skip spaces from given position.
StateBlock.prototype.skipSpaces = function skipSpaces(pos) {
  for (let max = this.src.length; pos < max; pos++) {
    const ch = this.src.charCodeAt(pos);
    if (!isSpace(ch)) {
      break;
    }
  }
  return pos;
};

// Skip spaces from given position in reverse.
StateBlock.prototype.skipSpacesBack = function skipSpacesBack(pos, min) {
  if (pos <= min) {
    return pos;
  }
  while (pos > min) {
    if (!isSpace(this.src.charCodeAt(--pos))) {
      return pos + 1;
    }
  }
  return pos;
};

// Skip char codes from given position
StateBlock.prototype.skipChars = function skipChars(pos, code) {
  for (let max = this.src.length; pos < max; pos++) {
    if (this.src.charCodeAt(pos) !== code) {
      break;
    }
  }
  return pos;
};

// Skip char codes reverse from given position - 1
StateBlock.prototype.skipCharsBack = function skipCharsBack(pos, code, min) {
  if (pos <= min) {
    return pos;
  }
  while (pos > min) {
    if (code !== this.src.charCodeAt(--pos)) {
      return pos + 1;
    }
  }
  return pos;
};

// cut lines range from source.
StateBlock.prototype.getLines = function getLines(begin, end, indent, keepLastLF) {
  if (begin >= end) {
    return '';
  }
  const queue = new Array(end - begin);
  for (let i = 0, line = begin; line < end; line++, i++) {
    let lineIndent = 0;
    const lineStart = this.bMarks[line];
    let first = lineStart;
    let last;
    if (line + 1 < end || keepLastLF) {
      // No need for bounds check because we have fake entry on tail.
      last = this.eMarks[line] + 1;
    } else {
      last = this.eMarks[line];
    }
    while (first < last && lineIndent < indent) {
      const ch = this.src.charCodeAt(first);
      if (isSpace(ch)) {
        if (ch === 0x09) {
          lineIndent += 4 - (lineIndent + this.bsCount[line]) % 4;
        } else {
          lineIndent++;
        }
      } else if (first - lineStart < this.tShift[line]) {
        // patched tShift masked characters to look like spaces (blockquotes, list markers)
        lineIndent++;
      } else {
        break;
      }
      first++;
    }
    if (lineIndent > indent) {
      // partially expanding tabs in code blocks, e.g '\t\tfoobar'
      // with indent=2 becomes '  \tfoobar'
      queue[i] = new Array(lineIndent - indent + 1).join(' ') + this.src.slice(first, last);
    } else {
      queue[i] = this.src.slice(first, last);
    }
  }
  return queue.join('');
};

// re-export Token class to use in block rules
StateBlock.prototype.Token = Token;

// GFM table, https://github.github.com/gfm/#tables-extension-


// Limit the amount of empty autocompleted cells in a table,
// see https://github.com/markdown-it/markdown-it/issues/1000,
//
// Both pulldown-cmark and commonmark-hs limit the number of cells this way to ~200k.
// We set it to 65k, which can expand user input by a factor of x370
// (256x256 square is 1.8kB expanded into 650kB).
const MAX_AUTOCOMPLETED_CELLS = 0x10000;
function getLine(state, line) {
  const pos = state.bMarks[line] + state.tShift[line];
  const max = state.eMarks[line];
  return state.src.slice(pos, max);
}
function escapedSplit(str) {
  const result = [];
  const max = str.length;
  let pos = 0;
  let ch = str.charCodeAt(pos);
  let isEscaped = false;
  let lastPos = 0;
  let current = '';
  while (pos < max) {
    if (ch === 0x7c /* | */) {
      if (!isEscaped) {
        // pipe separating cells, '|'
        result.push(current + str.substring(lastPos, pos));
        current = '';
        lastPos = pos + 1;
      } else {
        // escaped pipe, '\|'
        current += str.substring(lastPos, pos - 1);
        lastPos = pos;
      }
    }
    isEscaped = ch === 0x5c /* \ */;
    pos++;
    ch = str.charCodeAt(pos);
  }
  result.push(current + str.substring(lastPos));
  return result;
}
function table(state, startLine, endLine, silent) {
  // should have at least two lines
  if (startLine + 2 > endLine) {
    return false;
  }
  let nextLine = startLine + 1;
  if (state.sCount[nextLine] < state.blkIndent) {
    return false;
  }

  // if it's indented more than 3 spaces, it should be a code block
  if (state.sCount[nextLine] - state.blkIndent >= 4) {
    return false;
  }

  // first character of the second line should be '|', '-', ':',
  // and no other characters are allowed but spaces;
  // basically, this is the equivalent of /^[-:|][-:|\s]*$/ regexp

  let pos = state.bMarks[nextLine] + state.tShift[nextLine];
  if (pos >= state.eMarks[nextLine]) {
    return false;
  }
  const firstCh = state.src.charCodeAt(pos++);
  if (firstCh !== 0x7C /* | */ && firstCh !== 0x2D /* - */ && firstCh !== 0x3A /* : */) {
    return false;
  }
  if (pos >= state.eMarks[nextLine]) {
    return false;
  }
  const secondCh = state.src.charCodeAt(pos++);
  if (secondCh !== 0x7C /* | */ && secondCh !== 0x2D /* - */ && secondCh !== 0x3A /* : */ && !isSpace(secondCh)) {
    return false;
  }

  // if first character is '-', then second character must not be a space
  // (due to parsing ambiguity with list)
  if (firstCh === 0x2D /* - */ && isSpace(secondCh)) {
    return false;
  }
  while (pos < state.eMarks[nextLine]) {
    const ch = state.src.charCodeAt(pos);
    if (ch !== 0x7C /* | */ && ch !== 0x2D /* - */ && ch !== 0x3A /* : */ && !isSpace(ch)) {
      return false;
    }
    pos++;
  }
  let lineText = getLine(state, startLine + 1);
  let columns = lineText.split('|');
  const aligns = [];
  for (let i = 0; i < columns.length; i++) {
    const t = columns[i].trim();
    if (!t) {
      // allow empty columns before and after table, but not in between columns;
      // e.g. allow ` |---| `, disallow ` ---||--- `
      if (i === 0 || i === columns.length - 1) {
        continue;
      } else {
        return false;
      }
    }
    if (!/^:?-+:?$/.test(t)) {
      return false;
    }
    if (t.charCodeAt(t.length - 1) === 0x3A /* : */) {
      aligns.push(t.charCodeAt(0) === 0x3A /* : */ ? 'center' : 'right');
    } else if (t.charCodeAt(0) === 0x3A /* : */) {
      aligns.push('left');
    } else {
      aligns.push('');
    }
  }
  lineText = getLine(state, startLine).trim();
  if (lineText.indexOf('|') === -1) {
    return false;
  }
  if (state.sCount[startLine] - state.blkIndent >= 4) {
    return false;
  }
  columns = escapedSplit(lineText);
  if (columns.length && columns[0] === '') columns.shift();
  if (columns.length && columns[columns.length - 1] === '') columns.pop();

  // header row will define an amount of columns in the entire table,
  // and align row should be exactly the same (the rest of the rows can differ)
  const columnCount = columns.length;
  if (columnCount === 0 || columnCount !== aligns.length) {
    return false;
  }
  if (silent) {
    return true;
  }
  const oldParentType = state.parentType;
  state.parentType = 'table';

  // use 'blockquote' lists for termination because it's
  // the most similar to tables
  const terminatorRules = state.md.block.ruler.getRules('blockquote');
  const token_to = state.push('table_open', 'table', 1);
  const tableLines = [startLine, 0];
  token_to.map = tableLines;
  const token_tho = state.push('thead_open', 'thead', 1);
  token_tho.map = [startLine, startLine + 1];
  const token_htro = state.push('tr_open', 'tr', 1);
  token_htro.map = [startLine, startLine + 1];
  for (let i = 0; i < columns.length; i++) {
    const token_ho = state.push('th_open', 'th', 1);
    if (aligns[i]) {
      token_ho.attrs = [['style', 'text-align:' + aligns[i]]];
    }
    const token_il = state.push('inline', '', 0);
    token_il.content = columns[i].trim();
    token_il.children = [];
    state.push('th_close', 'th', -1);
  }
  state.push('tr_close', 'tr', -1);
  state.push('thead_close', 'thead', -1);
  let tbodyLines;
  let autocompletedCells = 0;
  for (nextLine = startLine + 2; nextLine < endLine; nextLine++) {
    if (state.sCount[nextLine] < state.blkIndent) {
      break;
    }
    let terminate = false;
    for (let i = 0, l = terminatorRules.length; i < l; i++) {
      if (terminatorRules[i](state, nextLine, endLine, true)) {
        terminate = true;
        break;
      }
    }
    if (terminate) {
      break;
    }
    lineText = getLine(state, nextLine).trim();
    if (!lineText) {
      break;
    }
    if (state.sCount[nextLine] - state.blkIndent >= 4) {
      break;
    }
    columns = escapedSplit(lineText);
    if (columns.length && columns[0] === '') columns.shift();
    if (columns.length && columns[columns.length - 1] === '') columns.pop();

    // note: autocomplete count can be negative if user specifies more columns than header,
    // but that does not affect intended use (which is limiting expansion)
    autocompletedCells += columnCount - columns.length;
    if (autocompletedCells > MAX_AUTOCOMPLETED_CELLS) {
      break;
    }
    if (nextLine === startLine + 2) {
      const token_tbo = state.push('tbody_open', 'tbody', 1);
      token_tbo.map = tbodyLines = [startLine + 2, 0];
    }
    const token_tro = state.push('tr_open', 'tr', 1);
    token_tro.map = [nextLine, nextLine + 1];
    for (let i = 0; i < columnCount; i++) {
      const token_tdo = state.push('td_open', 'td', 1);
      if (aligns[i]) {
        token_tdo.attrs = [['style', 'text-align:' + aligns[i]]];
      }
      const token_il = state.push('inline', '', 0);
      token_il.content = columns[i] ? columns[i].trim() : '';
      token_il.children = [];
      state.push('td_close', 'td', -1);
    }
    state.push('tr_close', 'tr', -1);
  }
  if (tbodyLines) {
    state.push('tbody_close', 'tbody', -1);
    tbodyLines[1] = nextLine;
  }
  state.push('table_close', 'table', -1);
  tableLines[1] = nextLine;
  state.parentType = oldParentType;
  state.line = nextLine;
  return true;
}

// Code block (4 spaces padded)

function code(state, startLine, endLine /*, silent */) {
  if (state.sCount[startLine] - state.blkIndent < 4) {
    return false;
  }
  let nextLine = startLine + 1;
  let last = nextLine;
  while (nextLine < endLine) {
    if (state.isEmpty(nextLine)) {
      nextLine++;
      continue;
    }
    if (state.sCount[nextLine] - state.blkIndent >= 4) {
      nextLine++;
      last = nextLine;
      continue;
    }
    break;
  }
  state.line = last;
  const token = state.push('code_block', 'code', 0);
  token.content = state.getLines(startLine, last, 4 + state.blkIndent, false) + '\n';
  token.map = [startLine, state.line];
  return true;
}

// fences (``` lang, ~~~ lang)

function fence(state, startLine, endLine, silent) {
  let pos = state.bMarks[startLine] + state.tShift[startLine];
  let max = state.eMarks[startLine];

  // if it's indented more than 3 spaces, it should be a code block
  if (state.sCount[startLine] - state.blkIndent >= 4) {
    return false;
  }
  if (pos + 3 > max) {
    return false;
  }
  const marker = state.src.charCodeAt(pos);
  if (marker !== 0x7E /* ~ */ && marker !== 0x60 /* ` */) {
    return false;
  }

  // scan marker length
  let mem = pos;
  pos = state.skipChars(pos, marker);
  let len = pos - mem;
  if (len < 3) {
    return false;
  }
  const markup = state.src.slice(mem, pos);
  const params = state.src.slice(pos, max);
  if (marker === 0x60 /* ` */) {
    if (params.indexOf(String.fromCharCode(marker)) >= 0) {
      return false;
    }
  }

  // Since start is found, we can report success here in validation mode
  if (silent) {
    return true;
  }

  // search end of block
  let nextLine = startLine;
  let haveEndMarker = false;
  for (;;) {
    nextLine++;
    if (nextLine >= endLine) {
      // unclosed block should be autoclosed by end of document.
      // also block seems to be autoclosed by end of parent
      break;
    }
    pos = mem = state.bMarks[nextLine] + state.tShift[nextLine];
    max = state.eMarks[nextLine];
    if (pos < max && state.sCount[nextLine] < state.blkIndent) {
      // non-empty line with negative indent should stop the list:
      // - ```
      //  test
      break;
    }
    if (state.src.charCodeAt(pos) !== marker) {
      continue;
    }
    if (state.sCount[nextLine] - state.blkIndent >= 4) {
      // closing fence should be indented less than 4 spaces
      continue;
    }
    pos = state.skipChars(pos, marker);

    // closing code fence must be at least as long as the opening one
    if (pos - mem < len) {
      continue;
    }

    // make sure tail has spaces only
    pos = state.skipSpaces(pos);
    if (pos < max) {
      continue;
    }
    haveEndMarker = true;
    // found!
    break;
  }

  // If a fence has heading spaces, they should be removed from its inner block
  len = state.sCount[startLine];
  state.line = nextLine + (haveEndMarker ? 1 : 0);
  const token = state.push('fence', 'code', 0);
  token.info = params;
  token.content = state.getLines(startLine + 1, nextLine, len, true);
  token.markup = markup;
  token.map = [startLine, state.line];
  return true;
}

// Block quotes

function blockquote(state, startLine, endLine, silent) {
  let pos = state.bMarks[startLine] + state.tShift[startLine];
  let max = state.eMarks[startLine];
  const oldLineMax = state.lineMax;

  // if it's indented more than 3 spaces, it should be a code block
  if (state.sCount[startLine] - state.blkIndent >= 4) {
    return false;
  }

  // check the block quote marker
  if (state.src.charCodeAt(pos) !== 0x3E /* > */) {
    return false;
  }

  // we know that it's going to be a valid blockquote,
  // so no point trying to find the end of it in silent mode
  if (silent) {
    return true;
  }
  const oldBMarks = [];
  const oldBSCount = [];
  const oldSCount = [];
  const oldTShift = [];
  const terminatorRules = state.md.block.ruler.getRules('blockquote');
  const oldParentType = state.parentType;
  state.parentType = 'blockquote';
  let lastLineEmpty = false;
  let nextLine;

  // Search the end of the block
  //
  // Block ends with either:
  //  1. an empty line outside:
  //     ```
  //     > test
  //
  //     ```
  //  2. an empty line inside:
  //     ```
  //     >
  //     test
  //     ```
  //  3. another tag:
  //     ```
  //     > test
  //      - - -
  //     ```
  for (nextLine = startLine; nextLine < endLine; nextLine++) {
    // check if it's outdented, i.e. it's inside list item and indented
    // less than said list item:
    //
    // ```
    // 1. anything
    //    > current blockquote
    // 2. checking this line
    // ```
    const isOutdented = state.sCount[nextLine] < state.blkIndent;
    pos = state.bMarks[nextLine] + state.tShift[nextLine];
    max = state.eMarks[nextLine];
    if (pos >= max) {
      // Case 1: line is not inside the blockquote, and this line is empty.
      break;
    }
    if (state.src.charCodeAt(pos++) === 0x3E /* > */ && !isOutdented) {
      // This line is inside the blockquote.

      // set offset past spaces and ">"
      let initial = state.sCount[nextLine] + 1;
      let spaceAfterMarker;
      let adjustTab;

      // skip one optional space after '>'
      if (state.src.charCodeAt(pos) === 0x20 /* space */) {
        // ' >   test '
        //     ^ -- position start of line here:
        pos++;
        initial++;
        adjustTab = false;
        spaceAfterMarker = true;
      } else if (state.src.charCodeAt(pos) === 0x09 /* tab */) {
        spaceAfterMarker = true;
        if ((state.bsCount[nextLine] + initial) % 4 === 3) {
          // '  >\t  test '
          //       ^ -- position start of line here (tab has width===1)
          pos++;
          initial++;
          adjustTab = false;
        } else {
          // ' >\t  test '
          //    ^ -- position start of line here + shift bsCount slightly
          //         to make extra space appear
          adjustTab = true;
        }
      } else {
        spaceAfterMarker = false;
      }
      let offset = initial;
      oldBMarks.push(state.bMarks[nextLine]);
      state.bMarks[nextLine] = pos;
      while (pos < max) {
        const ch = state.src.charCodeAt(pos);
        if (isSpace(ch)) {
          if (ch === 0x09) {
            offset += 4 - (offset + state.bsCount[nextLine] + (adjustTab ? 1 : 0)) % 4;
          } else {
            offset++;
          }
        } else {
          break;
        }
        pos++;
      }
      lastLineEmpty = pos >= max;
      oldBSCount.push(state.bsCount[nextLine]);
      state.bsCount[nextLine] = state.sCount[nextLine] + 1 + (spaceAfterMarker ? 1 : 0);
      oldSCount.push(state.sCount[nextLine]);
      state.sCount[nextLine] = offset - initial;
      oldTShift.push(state.tShift[nextLine]);
      state.tShift[nextLine] = pos - state.bMarks[nextLine];
      continue;
    }

    // Case 2: line is not inside the blockquote, and the last line was empty.
    if (lastLineEmpty) {
      break;
    }

    // Case 3: another tag found.
    let terminate = false;
    for (let i = 0, l = terminatorRules.length; i < l; i++) {
      if (terminatorRules[i](state, nextLine, endLine, true)) {
        terminate = true;
        break;
      }
    }
    if (terminate) {
      // Quirk to enforce "hard termination mode" for paragraphs;
      // normally if you call `tokenize(state, startLine, nextLine)`,
      // paragraphs will look below nextLine for paragraph continuation,
      // but if blockquote is terminated by another tag, they shouldn't
      state.lineMax = nextLine;
      if (state.blkIndent !== 0) {
        // state.blkIndent was non-zero, we now set it to zero,
        // so we need to re-calculate all offsets to appear as
        // if indent wasn't changed
        oldBMarks.push(state.bMarks[nextLine]);
        oldBSCount.push(state.bsCount[nextLine]);
        oldTShift.push(state.tShift[nextLine]);
        oldSCount.push(state.sCount[nextLine]);
        state.sCount[nextLine] -= state.blkIndent;
      }
      break;
    }
    oldBMarks.push(state.bMarks[nextLine]);
    oldBSCount.push(state.bsCount[nextLine]);
    oldTShift.push(state.tShift[nextLine]);
    oldSCount.push(state.sCount[nextLine]);

    // A negative indentation means that this is a paragraph continuation
    //
    state.sCount[nextLine] = -1;
  }
  const oldIndent = state.blkIndent;
  state.blkIndent = 0;
  const token_o = state.push('blockquote_open', 'blockquote', 1);
  token_o.markup = '>';
  const lines = [startLine, 0];
  token_o.map = lines;
  state.md.block.tokenize(state, startLine, nextLine);
  const token_c = state.push('blockquote_close', 'blockquote', -1);
  token_c.markup = '>';
  state.lineMax = oldLineMax;
  state.parentType = oldParentType;
  lines[1] = state.line;

  // Restore original tShift; this might not be necessary since the parser
  // has already been here, but just to make sure we can do that.
  for (let i = 0; i < oldTShift.length; i++) {
    state.bMarks[i + startLine] = oldBMarks[i];
    state.tShift[i + startLine] = oldTShift[i];
    state.sCount[i + startLine] = oldSCount[i];
    state.bsCount[i + startLine] = oldBSCount[i];
  }
  state.blkIndent = oldIndent;
  return true;
}

// Horizontal rule

function hr(state, startLine, endLine, silent) {
  const max = state.eMarks[startLine];
  // if it's indented more than 3 spaces, it should be a code block
  if (state.sCount[startLine] - state.blkIndent >= 4) {
    return false;
  }
  let pos = state.bMarks[startLine] + state.tShift[startLine];
  const marker = state.src.charCodeAt(pos++);

  // Check hr marker
  if (marker !== 0x2A /* * */ && marker !== 0x2D /* - */ && marker !== 0x5F /* _ */) {
    return false;
  }

  // markers can be mixed with spaces, but there should be at least 3 of them

  let cnt = 1;
  while (pos < max) {
    const ch = state.src.charCodeAt(pos++);
    if (ch !== marker && !isSpace(ch)) {
      return false;
    }
    if (ch === marker) {
      cnt++;
    }
  }
  if (cnt < 3) {
    return false;
  }
  if (silent) {
    return true;
  }
  state.line = startLine + 1;
  const token = state.push('hr', 'hr', 0);
  token.map = [startLine, state.line];
  token.markup = Array(cnt + 1).join(String.fromCharCode(marker));
  return true;
}

// Lists


// Search `[-+*][\n ]`, returns next pos after marker on success
// or -1 on fail.
function skipBulletListMarker(state, startLine) {
  const max = state.eMarks[startLine];
  let pos = state.bMarks[startLine] + state.tShift[startLine];
  const marker = state.src.charCodeAt(pos++);
  // Check bullet
  if (marker !== 0x2A /* * */ && marker !== 0x2D /* - */ && marker !== 0x2B /* + */) {
    return -1;
  }
  if (pos < max) {
    const ch = state.src.charCodeAt(pos);
    if (!isSpace(ch)) {
      // " -test " - is not a list item
      return -1;
    }
  }
  return pos;
}

// Search `\d+[.)][\n ]`, returns next pos after marker on success
// or -1 on fail.
function skipOrderedListMarker(state, startLine) {
  const start = state.bMarks[startLine] + state.tShift[startLine];
  const max = state.eMarks[startLine];
  let pos = start;

  // List marker should have at least 2 chars (digit + dot)
  if (pos + 1 >= max) {
    return -1;
  }
  let ch = state.src.charCodeAt(pos++);
  if (ch < 0x30 /* 0 */ || ch > 0x39 /* 9 */) {
    return -1;
  }
  for (;;) {
    // EOL -> fail
    if (pos >= max) {
      return -1;
    }
    ch = state.src.charCodeAt(pos++);
    if (ch >= 0x30 /* 0 */ && ch <= 0x39 /* 9 */) {
      // List marker should have no more than 9 digits
      // (prevents integer overflow in browsers)
      if (pos - start >= 10) {
        return -1;
      }
      continue;
    }

    // found valid marker
    if (ch === 0x29 /* ) */ || ch === 0x2e /* . */) {
      break;
    }
    return -1;
  }
  if (pos < max) {
    ch = state.src.charCodeAt(pos);
    if (!isSpace(ch)) {
      // " 1.test " - is not a list item
      return -1;
    }
  }
  return pos;
}
function markTightParagraphs(state, idx) {
  const level = state.level + 2;
  for (let i = idx + 2, l = state.tokens.length - 2; i < l; i++) {
    if (state.tokens[i].level === level && state.tokens[i].type === 'paragraph_open') {
      state.tokens[i + 2].hidden = true;
      state.tokens[i].hidden = true;
      i += 2;
    }
  }
}
function list(state, startLine, endLine, silent) {
  let max, pos, start, token;
  let nextLine = startLine;
  let tight = true;

  // if it's indented more than 3 spaces, it should be a code block
  if (state.sCount[nextLine] - state.blkIndent >= 4) {
    return false;
  }

  // Special case:
  //  - item 1
  //   - item 2
  //    - item 3
  //     - item 4
  //      - this one is a paragraph continuation
  if (state.listIndent >= 0 && state.sCount[nextLine] - state.listIndent >= 4 && state.sCount[nextLine] < state.blkIndent) {
    return false;
  }
  let isTerminatingParagraph = false;

  // limit conditions when list can interrupt
  // a paragraph (validation mode only)
  if (silent && state.parentType === 'paragraph') {
    // Next list item should still terminate previous list item;
    //
    // This code can fail if plugins use blkIndent as well as lists,
    // but I hope the spec gets fixed long before that happens.
    //
    if (state.sCount[nextLine] >= state.blkIndent) {
      isTerminatingParagraph = true;
    }
  }

  // Detect list type and position after marker
  let isOrdered;
  let markerValue;
  let posAfterMarker;
  if ((posAfterMarker = skipOrderedListMarker(state, nextLine)) >= 0) {
    isOrdered = true;
    start = state.bMarks[nextLine] + state.tShift[nextLine];
    markerValue = Number(state.src.slice(start, posAfterMarker - 1));

    // If we're starting a new ordered list right after
    // a paragraph, it should start with 1.
    if (isTerminatingParagraph && markerValue !== 1) return false;
  } else if ((posAfterMarker = skipBulletListMarker(state, nextLine)) >= 0) {
    isOrdered = false;
  } else {
    return false;
  }

  // If we're starting a new unordered list right after
  // a paragraph, first line should not be empty.
  if (isTerminatingParagraph) {
    if (state.skipSpaces(posAfterMarker) >= state.eMarks[nextLine]) return false;
  }

  // For validation mode we can terminate immediately
  if (silent) {
    return true;
  }

  // We should terminate list on style change. Remember first one to compare.
  const markerCharCode = state.src.charCodeAt(posAfterMarker - 1);

  // Start list
  const listTokIdx = state.tokens.length;
  if (isOrdered) {
    token = state.push('ordered_list_open', 'ol', 1);
    if (markerValue !== 1) {
      token.attrs = [['start', markerValue]];
    }
  } else {
    token = state.push('bullet_list_open', 'ul', 1);
  }
  const listLines = [nextLine, 0];
  token.map = listLines;
  token.markup = String.fromCharCode(markerCharCode);

  //
  // Iterate list items
  //

  let prevEmptyEnd = false;
  const terminatorRules = state.md.block.ruler.getRules('list');
  const oldParentType = state.parentType;
  state.parentType = 'list';
  while (nextLine < endLine) {
    pos = posAfterMarker;
    max = state.eMarks[nextLine];
    const initial = state.sCount[nextLine] + posAfterMarker - (state.bMarks[nextLine] + state.tShift[nextLine]);
    let offset = initial;
    while (pos < max) {
      const ch = state.src.charCodeAt(pos);
      if (ch === 0x09) {
        offset += 4 - (offset + state.bsCount[nextLine]) % 4;
      } else if (ch === 0x20) {
        offset++;
      } else {
        break;
      }
      pos++;
    }
    const contentStart = pos;
    let indentAfterMarker;
    if (contentStart >= max) {
      // trimming space in "-    \n  3" case, indent is 1 here
      indentAfterMarker = 1;
    } else {
      indentAfterMarker = offset - initial;
    }

    // If we have more than 4 spaces, the indent is 1
    // (the rest is just indented code block)
    if (indentAfterMarker > 4) {
      indentAfterMarker = 1;
    }

    // "  -  test"
    //  ^^^^^ - calculating total length of this thing
    const indent = initial + indentAfterMarker;

    // Run subparser & write tokens
    token = state.push('list_item_open', 'li', 1);
    token.markup = String.fromCharCode(markerCharCode);
    const itemLines = [nextLine, 0];
    token.map = itemLines;
    if (isOrdered) {
      token.info = state.src.slice(start, posAfterMarker - 1);
    }

    // change current state, then restore it after parser subcall
    const oldTight = state.tight;
    const oldTShift = state.tShift[nextLine];
    const oldSCount = state.sCount[nextLine];

    //  - example list
    // ^ listIndent position will be here
    //   ^ blkIndent position will be here
    //
    const oldListIndent = state.listIndent;
    state.listIndent = state.blkIndent;
    state.blkIndent = indent;
    state.tight = true;
    state.tShift[nextLine] = contentStart - state.bMarks[nextLine];
    state.sCount[nextLine] = offset;
    if (contentStart >= max && state.isEmpty(nextLine + 1)) {
      // workaround for this case
      // (list item is empty, list terminates before "foo"):
      // ~~~~~~~~
      //   -
      //
      //     foo
      // ~~~~~~~~
      state.line = Math.min(state.line + 2, endLine);
    } else {
      state.md.block.tokenize(state, nextLine, endLine, true);
    }

    // If any of list item is tight, mark list as tight
    if (!state.tight || prevEmptyEnd) {
      tight = false;
    }
    // Item become loose if finish with empty line,
    // but we should filter last element, because it means list finish
    prevEmptyEnd = state.line - nextLine > 1 && state.isEmpty(state.line - 1);
    state.blkIndent = state.listIndent;
    state.listIndent = oldListIndent;
    state.tShift[nextLine] = oldTShift;
    state.sCount[nextLine] = oldSCount;
    state.tight = oldTight;
    token = state.push('list_item_close', 'li', -1);
    token.markup = String.fromCharCode(markerCharCode);
    nextLine = state.line;
    itemLines[1] = nextLine;
    if (nextLine >= endLine) {
      break;
    }

    //
    // Try to check if list is terminated or continued.
    //
    if (state.sCount[nextLine] < state.blkIndent) {
      break;
    }

    // if it's indented more than 3 spaces, it should be a code block
    if (state.sCount[nextLine] - state.blkIndent >= 4) {
      break;
    }

    // fail if terminating block found
    let terminate = false;
    for (let i = 0, l = terminatorRules.length; i < l; i++) {
      if (terminatorRules[i](state, nextLine, endLine, true)) {
        terminate = true;
        break;
      }
    }
    if (terminate) {
      break;
    }

    // fail if list has another type
    if (isOrdered) {
      posAfterMarker = skipOrderedListMarker(state, nextLine);
      if (posAfterMarker < 0) {
        break;
      }
      start = state.bMarks[nextLine] + state.tShift[nextLine];
    } else {
      posAfterMarker = skipBulletListMarker(state, nextLine);
      if (posAfterMarker < 0) {
        break;
      }
    }
    if (markerCharCode !== state.src.charCodeAt(posAfterMarker - 1)) {
      break;
    }
  }

  // Finalize list
  if (isOrdered) {
    token = state.push('ordered_list_close', 'ol', -1);
  } else {
    token = state.push('bullet_list_close', 'ul', -1);
  }
  token.markup = String.fromCharCode(markerCharCode);
  listLines[1] = nextLine;
  state.line = nextLine;
  state.parentType = oldParentType;

  // mark paragraphs tight if needed
  if (tight) {
    markTightParagraphs(state, listTokIdx);
  }
  return true;
}

function reference(state, startLine, _endLine, silent) {
  let pos = state.bMarks[startLine] + state.tShift[startLine];
  let max = state.eMarks[startLine];
  let nextLine = startLine + 1;

  // if it's indented more than 3 spaces, it should be a code block
  if (state.sCount[startLine] - state.blkIndent >= 4) {
    return false;
  }
  if (state.src.charCodeAt(pos) !== 0x5B /* [ */) {
    return false;
  }
  function getNextLine(nextLine) {
    const endLine = state.lineMax;
    if (nextLine >= endLine || state.isEmpty(nextLine)) {
      // empty line or end of input
      return null;
    }
    let isContinuation = false;

    // this would be a code block normally, but after paragraph
    // it's considered a lazy continuation regardless of what's there
    if (state.sCount[nextLine] - state.blkIndent > 3) {
      isContinuation = true;
    }

    // quirk for blockquotes, this line should already be checked by that rule
    if (state.sCount[nextLine] < 0) {
      isContinuation = true;
    }
    if (!isContinuation) {
      const terminatorRules = state.md.block.ruler.getRules('reference');
      const oldParentType = state.parentType;
      state.parentType = 'reference';

      // Some tags can terminate paragraph without empty line.
      let terminate = false;
      for (let i = 0, l = terminatorRules.length; i < l; i++) {
        if (terminatorRules[i](state, nextLine, endLine, true)) {
          terminate = true;
          break;
        }
      }
      state.parentType = oldParentType;
      if (terminate) {
        // terminated by another block
        return null;
      }
    }
    const pos = state.bMarks[nextLine] + state.tShift[nextLine];
    const max = state.eMarks[nextLine];

    // max + 1 explicitly includes the newline
    return state.src.slice(pos, max + 1);
  }
  let str = state.src.slice(pos, max + 1);
  max = str.length;
  let labelEnd = -1;
  for (pos = 1; pos < max; pos++) {
    const ch = str.charCodeAt(pos);
    if (ch === 0x5B /* [ */) {
      return false;
    } else if (ch === 0x5D /* ] */) {
      labelEnd = pos;
      break;
    } else if (ch === 0x0A /* \n */) {
      const lineContent = getNextLine(nextLine);
      if (lineContent !== null) {
        str += lineContent;
        max = str.length;
        nextLine++;
      }
    } else if (ch === 0x5C /* \ */) {
      pos++;
      if (pos < max && str.charCodeAt(pos) === 0x0A) {
        const lineContent = getNextLine(nextLine);
        if (lineContent !== null) {
          str += lineContent;
          max = str.length;
          nextLine++;
        }
      }
    }
  }
  if (labelEnd < 0 || str.charCodeAt(labelEnd + 1) !== 0x3A /* : */) {
    return false;
  }

  // [label]:   destination   'title'
  //         ^^^ skip optional whitespace here
  for (pos = labelEnd + 2; pos < max; pos++) {
    const ch = str.charCodeAt(pos);
    if (ch === 0x0A) {
      const lineContent = getNextLine(nextLine);
      if (lineContent !== null) {
        str += lineContent;
        max = str.length;
        nextLine++;
      }
    } else if (isSpace(ch)) ; else {
      break;
    }
  }

  // [label]:   destination   'title'
  //            ^^^^^^^^^^^ parse this
  const destRes = state.md.helpers.parseLinkDestination(str, pos, max);
  if (!destRes.ok) {
    return false;
  }
  const href = state.md.normalizeLink(destRes.str);
  if (!state.md.validateLink(href)) {
    return false;
  }
  pos = destRes.pos;

  // save cursor state, we could require to rollback later
  const destEndPos = pos;
  const destEndLineNo = nextLine;

  // [label]:   destination   'title'
  //                       ^^^ skipping those spaces
  const start = pos;
  for (; pos < max; pos++) {
    const ch = str.charCodeAt(pos);
    if (ch === 0x0A) {
      const lineContent = getNextLine(nextLine);
      if (lineContent !== null) {
        str += lineContent;
        max = str.length;
        nextLine++;
      }
    } else if (isSpace(ch)) ; else {
      break;
    }
  }

  // [label]:   destination   'title'
  //                          ^^^^^^^ parse this
  let titleRes = state.md.helpers.parseLinkTitle(str, pos, max);
  while (titleRes.can_continue) {
    const lineContent = getNextLine(nextLine);
    if (lineContent === null) break;
    str += lineContent;
    pos = max;
    max = str.length;
    nextLine++;
    titleRes = state.md.helpers.parseLinkTitle(str, pos, max, titleRes);
  }
  let title;
  if (pos < max && start !== pos && titleRes.ok) {
    title = titleRes.str;
    pos = titleRes.pos;
  } else {
    title = '';
    pos = destEndPos;
    nextLine = destEndLineNo;
  }

  // skip trailing spaces until the rest of the line
  while (pos < max) {
    const ch = str.charCodeAt(pos);
    if (!isSpace(ch)) {
      break;
    }
    pos++;
  }
  if (pos < max && str.charCodeAt(pos) !== 0x0A) {
    if (title) {
      // garbage at the end of the line after title,
      // but it could still be a valid reference if we roll back
      title = '';
      pos = destEndPos;
      nextLine = destEndLineNo;
      while (pos < max) {
        const ch = str.charCodeAt(pos);
        if (!isSpace(ch)) {
          break;
        }
        pos++;
      }
    }
  }
  if (pos < max && str.charCodeAt(pos) !== 0x0A) {
    // garbage at the end of the line
    return false;
  }
  const label = normalizeReference(str.slice(1, labelEnd));
  if (!label) {
    // CommonMark 0.20 disallows empty labels
    return false;
  }

  // Reference can not terminate anything. This check is for safety only.
  /* istanbul ignore if */
  if (silent) {
    return true;
  }
  if (typeof state.env.references === 'undefined') {
    state.env.references = {};
  }
  if (typeof state.env.references[label] === 'undefined') {
    state.env.references[label] = {
      title,
      href
    };
  }
  state.line = nextLine;
  return true;
}

// List of valid html blocks names, according to commonmark spec
// https://spec.commonmark.org/0.30/#html-blocks

var block_names = ['address', 'article', 'aside', 'base', 'basefont', 'blockquote', 'body', 'caption', 'center', 'col', 'colgroup', 'dd', 'details', 'dialog', 'dir', 'div', 'dl', 'dt', 'fieldset', 'figcaption', 'figure', 'footer', 'form', 'frame', 'frameset', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'head', 'header', 'hr', 'html', 'iframe', 'legend', 'li', 'link', 'main', 'menu', 'menuitem', 'nav', 'noframes', 'ol', 'optgroup', 'option', 'p', 'param', 'search', 'section', 'summary', 'table', 'tbody', 'td', 'tfoot', 'th', 'thead', 'title', 'tr', 'track', 'ul'];

// Regexps to match html elements

const attr_name = '[a-zA-Z_:][a-zA-Z0-9:._-]*';
const unquoted = '[^"\'=<>`\\x00-\\x20]+';
const single_quoted = "'[^']*'";
const double_quoted = '"[^"]*"';
const attr_value = '(?:' + unquoted + '|' + single_quoted + '|' + double_quoted + ')';
const attribute = '(?:\\s+' + attr_name + '(?:\\s*=\\s*' + attr_value + ')?)';
const open_tag = '<[A-Za-z][A-Za-z0-9\\-]*' + attribute + '*\\s*\\/?>';
const close_tag = '<\\/[A-Za-z][A-Za-z0-9\\-]*\\s*>';
const comment = '<!---?>|<!--(?:[^-]|-[^-]|--[^>])*-->';
const processing = '<[?][\\s\\S]*?[?]>';
const declaration = '<![A-Za-z][^>]*>';
const cdata = '<!\\[CDATA\\[[\\s\\S]*?\\]\\]>';
const HTML_TAG_RE = new RegExp('^(?:' + open_tag + '|' + close_tag + '|' + comment + '|' + processing + '|' + declaration + '|' + cdata + ')');
const HTML_OPEN_CLOSE_TAG_RE = new RegExp('^(?:' + open_tag + '|' + close_tag + ')');

// HTML block


// An array of opening and corresponding closing sequences for html tags,
// last argument defines whether it can terminate a paragraph or not
//
const HTML_SEQUENCES = [[/^<(script|pre|style|textarea)(?=(\s|>|$))/i, /<\/(script|pre|style|textarea)>/i, true], [/^<!--/, /-->/, true], [/^<\?/, /\?>/, true], [/^<![A-Z]/, />/, true], [/^<!\[CDATA\[/, /\]\]>/, true], [new RegExp('^</?(' + block_names.join('|') + ')(?=(\\s|/?>|$))', 'i'), /^$/, true], [new RegExp(HTML_OPEN_CLOSE_TAG_RE.source + '\\s*$'), /^$/, false]];
function html_block(state, startLine, endLine, silent) {
  let pos = state.bMarks[startLine] + state.tShift[startLine];
  let max = state.eMarks[startLine];

  // if it's indented more than 3 spaces, it should be a code block
  if (state.sCount[startLine] - state.blkIndent >= 4) {
    return false;
  }
  if (!state.md.options.html) {
    return false;
  }
  if (state.src.charCodeAt(pos) !== 0x3C /* < */) {
    return false;
  }
  let lineText = state.src.slice(pos, max);
  let i = 0;
  for (; i < HTML_SEQUENCES.length; i++) {
    if (HTML_SEQUENCES[i][0].test(lineText)) {
      break;
    }
  }
  if (i === HTML_SEQUENCES.length) {
    return false;
  }
  if (silent) {
    // true if this sequence can be a terminator, false otherwise
    return HTML_SEQUENCES[i][2];
  }
  let nextLine = startLine + 1;

  // If we are here - we detected HTML block.
  // Let's roll down till block end.
  if (!HTML_SEQUENCES[i][1].test(lineText)) {
    for (; nextLine < endLine; nextLine++) {
      if (state.sCount[nextLine] < state.blkIndent) {
        break;
      }
      pos = state.bMarks[nextLine] + state.tShift[nextLine];
      max = state.eMarks[nextLine];
      lineText = state.src.slice(pos, max);
      if (HTML_SEQUENCES[i][1].test(lineText)) {
        if (lineText.length !== 0) {
          nextLine++;
        }
        break;
      }
    }
  }
  state.line = nextLine;
  const token = state.push('html_block', '', 0);
  token.map = [startLine, nextLine];
  token.content = state.getLines(startLine, nextLine, state.blkIndent, true);
  return true;
}

// heading (#, ##, ...)

function heading(state, startLine, endLine, silent) {
  let pos = state.bMarks[startLine] + state.tShift[startLine];
  let max = state.eMarks[startLine];

  // if it's indented more than 3 spaces, it should be a code block
  if (state.sCount[startLine] - state.blkIndent >= 4) {
    return false;
  }
  let ch = state.src.charCodeAt(pos);
  if (ch !== 0x23 /* # */ || pos >= max) {
    return false;
  }

  // count heading level
  let level = 1;
  ch = state.src.charCodeAt(++pos);
  while (ch === 0x23 /* # */ && pos < max && level <= 6) {
    level++;
    ch = state.src.charCodeAt(++pos);
  }
  if (level > 6 || pos < max && !isSpace(ch)) {
    return false;
  }
  if (silent) {
    return true;
  }

  // Let's cut tails like '    ###  ' from the end of string

  max = state.skipSpacesBack(max, pos);
  const tmp = state.skipCharsBack(max, 0x23, pos); // #
  if (tmp > pos && isSpace(state.src.charCodeAt(tmp - 1))) {
    max = tmp;
  }
  state.line = startLine + 1;
  const token_o = state.push('heading_open', 'h' + String(level), 1);
  token_o.markup = '########'.slice(0, level);
  token_o.map = [startLine, state.line];
  const token_i = state.push('inline', '', 0);
  token_i.content = state.src.slice(pos, max).trim();
  token_i.map = [startLine, state.line];
  token_i.children = [];
  const token_c = state.push('heading_close', 'h' + String(level), -1);
  token_c.markup = '########'.slice(0, level);
  return true;
}

// lheading (---, ===)

function lheading(state, startLine, endLine /*, silent */) {
  const terminatorRules = state.md.block.ruler.getRules('paragraph');

  // if it's indented more than 3 spaces, it should be a code block
  if (state.sCount[startLine] - state.blkIndent >= 4) {
    return false;
  }
  const oldParentType = state.parentType;
  state.parentType = 'paragraph'; // use paragraph to match terminatorRules

  // jump line-by-line until empty one or EOF
  let level = 0;
  let marker;
  let nextLine = startLine + 1;
  for (; nextLine < endLine && !state.isEmpty(nextLine); nextLine++) {
    // this would be a code block normally, but after paragraph
    // it's considered a lazy continuation regardless of what's there
    if (state.sCount[nextLine] - state.blkIndent > 3) {
      continue;
    }

    //
    // Check for underline in setext header
    //
    if (state.sCount[nextLine] >= state.blkIndent) {
      let pos = state.bMarks[nextLine] + state.tShift[nextLine];
      const max = state.eMarks[nextLine];
      if (pos < max) {
        marker = state.src.charCodeAt(pos);
        if (marker === 0x2D /* - */ || marker === 0x3D /* = */) {
          pos = state.skipChars(pos, marker);
          pos = state.skipSpaces(pos);
          if (pos >= max) {
            level = marker === 0x3D /* = */ ? 1 : 2;
            break;
          }
        }
      }
    }

    // quirk for blockquotes, this line should already be checked by that rule
    if (state.sCount[nextLine] < 0) {
      continue;
    }

    // Some tags can terminate paragraph without empty line.
    let terminate = false;
    for (let i = 0, l = terminatorRules.length; i < l; i++) {
      if (terminatorRules[i](state, nextLine, endLine, true)) {
        terminate = true;
        break;
      }
    }
    if (terminate) {
      break;
    }
  }
  if (!level) {
    // Didn't find valid underline
    return false;
  }
  const content = state.getLines(startLine, nextLine, state.blkIndent, false).trim();
  state.line = nextLine + 1;
  const token_o = state.push('heading_open', 'h' + String(level), 1);
  token_o.markup = String.fromCharCode(marker);
  token_o.map = [startLine, state.line];
  const token_i = state.push('inline', '', 0);
  token_i.content = content;
  token_i.map = [startLine, state.line - 1];
  token_i.children = [];
  const token_c = state.push('heading_close', 'h' + String(level), -1);
  token_c.markup = String.fromCharCode(marker);
  state.parentType = oldParentType;
  return true;
}

// Paragraph

function paragraph(state, startLine, endLine) {
  const terminatorRules = state.md.block.ruler.getRules('paragraph');
  const oldParentType = state.parentType;
  let nextLine = startLine + 1;
  state.parentType = 'paragraph';

  // jump line-by-line until empty one or EOF
  for (; nextLine < endLine && !state.isEmpty(nextLine); nextLine++) {
    // this would be a code block normally, but after paragraph
    // it's considered a lazy continuation regardless of what's there
    if (state.sCount[nextLine] - state.blkIndent > 3) {
      continue;
    }

    // quirk for blockquotes, this line should already be checked by that rule
    if (state.sCount[nextLine] < 0) {
      continue;
    }

    // Some tags can terminate paragraph without empty line.
    let terminate = false;
    for (let i = 0, l = terminatorRules.length; i < l; i++) {
      if (terminatorRules[i](state, nextLine, endLine, true)) {
        terminate = true;
        break;
      }
    }
    if (terminate) {
      break;
    }
  }
  const content = state.getLines(startLine, nextLine, state.blkIndent, false).trim();
  state.line = nextLine;
  const token_o = state.push('paragraph_open', 'p', 1);
  token_o.map = [startLine, state.line];
  const token_i = state.push('inline', '', 0);
  token_i.content = content;
  token_i.map = [startLine, state.line];
  token_i.children = [];
  state.push('paragraph_close', 'p', -1);
  state.parentType = oldParentType;
  return true;
}

/** internal
 * class ParserBlock
 *
 * Block-level tokenizer.
 **/

const _rules$1 = [
// First 2 params - rule name & source. Secondary array - list of rules,
// which can be terminated by this one.
['table', table, ['paragraph', 'reference']], ['code', code], ['fence', fence, ['paragraph', 'reference', 'blockquote', 'list']], ['blockquote', blockquote, ['paragraph', 'reference', 'blockquote', 'list']], ['hr', hr, ['paragraph', 'reference', 'blockquote', 'list']], ['list', list, ['paragraph', 'reference', 'blockquote']], ['reference', reference], ['html_block', html_block, ['paragraph', 'reference', 'blockquote']], ['heading', heading, ['paragraph', 'reference', 'blockquote']], ['lheading', lheading], ['paragraph', paragraph]];

/**
 * new ParserBlock()
 **/
function ParserBlock() {
  /**
   * ParserBlock#ruler -> Ruler
   *
   * [[Ruler]] instance. Keep configuration of block rules.
   **/
  this.ruler = new Ruler();
  for (let i = 0; i < _rules$1.length; i++) {
    this.ruler.push(_rules$1[i][0], _rules$1[i][1], {
      alt: (_rules$1[i][2] || []).slice()
    });
  }
}

// Generate tokens for input range
//
ParserBlock.prototype.tokenize = function (state, startLine, endLine) {
  const rules = this.ruler.getRules('');
  const len = rules.length;
  const maxNesting = state.md.options.maxNesting;
  let line = startLine;
  let hasEmptyLines = false;
  while (line < endLine) {
    state.line = line = state.skipEmptyLines(line);
    if (line >= endLine) {
      break;
    }

    // Termination condition for nested calls.
    // Nested calls currently used for blockquotes & lists
    if (state.sCount[line] < state.blkIndent) {
      break;
    }

    // If nesting level exceeded - skip tail to the end. That's not ordinary
    // situation and we should not care about content.
    if (state.level >= maxNesting) {
      state.line = endLine;
      break;
    }

    // Try all possible rules.
    // On success, rule should:
    //
    // - update `state.line`
    // - update `state.tokens`
    // - return true
    const prevLine = state.line;
    let ok = false;
    for (let i = 0; i < len; i++) {
      ok = rules[i](state, line, endLine, false);
      if (ok) {
        if (prevLine >= state.line) {
          throw new Error("block rule didn't increment state.line");
        }
        break;
      }
    }

    // this can only happen if user disables paragraph rule
    if (!ok) throw new Error('none of the block rules matched');

    // set state.tight if we had an empty line before current tag
    // i.e. latest empty line should not count
    state.tight = !hasEmptyLines;

    // paragraph might "eat" one newline after it in nested lists
    if (state.isEmpty(state.line - 1)) {
      hasEmptyLines = true;
    }
    line = state.line;
    if (line < endLine && state.isEmpty(line)) {
      hasEmptyLines = true;
      line++;
      state.line = line;
    }
  }
};

/**
 * ParserBlock.parse(str, md, env, outTokens)
 *
 * Process input string and push block tokens into `outTokens`
 **/
ParserBlock.prototype.parse = function (src, md, env, outTokens) {
  if (!src) {
    return;
  }
  const state = new this.State(src, md, env, outTokens);
  this.tokenize(state, state.line, state.lineMax);
};
ParserBlock.prototype.State = StateBlock;

// Inline parser state

function StateInline(src, md, env, outTokens) {
  this.src = src;
  this.env = env;
  this.md = md;
  this.tokens = outTokens;
  this.tokens_meta = Array(outTokens.length);
  this.pos = 0;
  this.posMax = this.src.length;
  this.level = 0;
  this.pending = '';
  this.pendingLevel = 0;

  // Stores { start: end } pairs. Useful for backtrack
  // optimization of pairs parse (emphasis, strikes).
  this.cache = {};

  // List of emphasis-like delimiters for current tag
  this.delimiters = [];

  // Stack of delimiter lists for upper level tags
  this._prev_delimiters = [];

  // backtick length => last seen position
  this.backticks = {};
  this.backticksScanned = false;

  // Counter used to disable inline linkify-it execution
  // inside <a> and markdown links
  this.linkLevel = 0;
}

// Flush pending text
//
StateInline.prototype.pushPending = function () {
  const token = new Token('text', '', 0);
  token.content = this.pending;
  token.level = this.pendingLevel;
  this.tokens.push(token);
  this.pending = '';
  return token;
};

// Push new token to "stream".
// If pending text exists - flush it as text token
//
StateInline.prototype.push = function (type, tag, nesting) {
  if (this.pending) {
    this.pushPending();
  }
  const token = new Token(type, tag, nesting);
  let token_meta = null;
  if (nesting < 0) {
    // closing tag
    this.level--;
    this.delimiters = this._prev_delimiters.pop();
  }
  token.level = this.level;
  if (nesting > 0) {
    // opening tag
    this.level++;
    this._prev_delimiters.push(this.delimiters);
    this.delimiters = [];
    token_meta = {
      delimiters: this.delimiters
    };
  }
  this.pendingLevel = this.level;
  this.tokens.push(token);
  this.tokens_meta.push(token_meta);
  return token;
};

// Scan a sequence of emphasis-like markers, and determine whether
// it can start an emphasis sequence or end an emphasis sequence.
//
//  - start - position to scan from (it should point at a valid marker);
//  - canSplitWord - determine if these markers can be found inside a word
//
StateInline.prototype.scanDelims = function (start, canSplitWord) {
  const max = this.posMax;
  const marker = this.src.charCodeAt(start);

  // treat beginning of the line as a whitespace
  const lastChar = start > 0 ? this.src.charCodeAt(start - 1) : 0x20;
  let pos = start;
  while (pos < max && this.src.charCodeAt(pos) === marker) {
    pos++;
  }
  const count = pos - start;

  // treat end of the line as a whitespace
  const nextChar = pos < max ? this.src.charCodeAt(pos) : 0x20;
  const isLastPunctChar = isMdAsciiPunct(lastChar) || isPunctChar(String.fromCharCode(lastChar));
  const isNextPunctChar = isMdAsciiPunct(nextChar) || isPunctChar(String.fromCharCode(nextChar));
  const isLastWhiteSpace = isWhiteSpace(lastChar);
  const isNextWhiteSpace = isWhiteSpace(nextChar);
  const left_flanking = !isNextWhiteSpace && (!isNextPunctChar || isLastWhiteSpace || isLastPunctChar);
  const right_flanking = !isLastWhiteSpace && (!isLastPunctChar || isNextWhiteSpace || isNextPunctChar);
  const can_open = left_flanking && (canSplitWord || !right_flanking || isLastPunctChar);
  const can_close = right_flanking && (canSplitWord || !left_flanking || isNextPunctChar);
  return {
    can_open,
    can_close,
    length: count
  };
};

// re-export Token class to use in block rules
StateInline.prototype.Token = Token;

// Skip text characters for text token, place those to pending buffer
// and increment current pos

// Rule to skip pure text
// '{}$%@~+=:' reserved for extentions

// !, ", #, $, %, &, ', (, ), *, +, ,, -, ., /, :, ;, <, =, >, ?, @, [, \, ], ^, _, `, {, |, }, or ~

// !!!! Don't confuse with "Markdown ASCII Punctuation" chars
// http://spec.commonmark.org/0.15/#ascii-punctuation-character
function isTerminatorChar(ch) {
  switch (ch) {
    case 0x0A /* \n */:
    case 0x21 /* ! */:
    case 0x23 /* # */:
    case 0x24 /* $ */:
    case 0x25 /* % */:
    case 0x26 /* & */:
    case 0x2A /* * */:
    case 0x2B /* + */:
    case 0x2D /* - */:
    case 0x3A /* : */:
    case 0x3C /* < */:
    case 0x3D /* = */:
    case 0x3E /* > */:
    case 0x40 /* @ */:
    case 0x5B /* [ */:
    case 0x5C /* \ */:
    case 0x5D /* ] */:
    case 0x5E /* ^ */:
    case 0x5F /* _ */:
    case 0x60 /* ` */:
    case 0x7B /* { */:
    case 0x7D /* } */:
    case 0x7E /* ~ */:
      return true;
    default:
      return false;
  }
}
function text(state, silent) {
  let pos = state.pos;
  while (pos < state.posMax && !isTerminatorChar(state.src.charCodeAt(pos))) {
    pos++;
  }
  if (pos === state.pos) {
    return false;
  }
  if (!silent) {
    state.pending += state.src.slice(state.pos, pos);
  }
  state.pos = pos;
  return true;
}

// Alternative implementation, for memory.
//
// It costs 10% of performance, but allows extend terminators list, if place it
// to `ParserInline` property. Probably, will switch to it sometime, such
// flexibility required.

/*
var TERMINATOR_RE = /[\n!#$%&*+\-:<=>@[\\\]^_`{}~]/;

module.exports = function text(state, silent) {
  var pos = state.pos,
      idx = state.src.slice(pos).search(TERMINATOR_RE);

  // first char is terminator -> empty text
  if (idx === 0) { return false; }

  // no terminator -> text till end of string
  if (idx < 0) {
    if (!silent) { state.pending += state.src.slice(pos); }
    state.pos = state.src.length;
    return true;
  }

  if (!silent) { state.pending += state.src.slice(pos, pos + idx); }

  state.pos += idx;

  return true;
}; */

// Process links like https://example.org/

// RFC3986: scheme = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
const SCHEME_RE = /(?:^|[^a-z0-9.+-])([a-z][a-z0-9.+-]*)$/i;
function linkify(state, silent) {
  if (!state.md.options.linkify) return false;
  if (state.linkLevel > 0) return false;
  const pos = state.pos;
  const max = state.posMax;
  if (pos + 3 > max) return false;
  if (state.src.charCodeAt(pos) !== 0x3A /* : */) return false;
  if (state.src.charCodeAt(pos + 1) !== 0x2F /* / */) return false;
  if (state.src.charCodeAt(pos + 2) !== 0x2F /* / */) return false;
  const match = state.pending.match(SCHEME_RE);
  if (!match) return false;
  const proto = match[1];
  const link = state.md.linkify.matchAtStart(state.src.slice(pos - proto.length));
  if (!link) return false;
  let url = link.url;

  // invalid link, but still detected by linkify somehow;
  // need to check to prevent infinite loop below
  if (url.length <= proto.length) return false;

  // disallow '*' at the end of the link (conflicts with emphasis)
  // do manual backsearch to avoid perf issues with regex /\*+$/ on "****...****a".
  let urlEnd = url.length;
  while (urlEnd > 0 && url.charCodeAt(urlEnd - 1) === 0x2A /* * */) {
    urlEnd--;
  }
  if (urlEnd !== url.length) {
    url = url.slice(0, urlEnd);
  }
  const fullUrl = state.md.normalizeLink(url);
  if (!state.md.validateLink(fullUrl)) return false;
  if (!silent) {
    state.pending = state.pending.slice(0, -proto.length);
    const token_o = state.push('link_open', 'a', 1);
    token_o.attrs = [['href', fullUrl]];
    token_o.markup = 'linkify';
    token_o.info = 'auto';
    const token_t = state.push('text', '', 0);
    token_t.content = state.md.normalizeLinkText(url);
    const token_c = state.push('link_close', 'a', -1);
    token_c.markup = 'linkify';
    token_c.info = 'auto';
  }
  state.pos += url.length - proto.length;
  return true;
}

// Proceess '\n'

function newline(state, silent) {
  let pos = state.pos;
  if (state.src.charCodeAt(pos) !== 0x0A /* \n */) {
    return false;
  }
  const pmax = state.pending.length - 1;
  const max = state.posMax;

  // '  \n' -> hardbreak
  // Lookup in pending chars is bad practice! Don't copy to other rules!
  // Pending string is stored in concat mode, indexed lookups will cause
  // convertion to flat mode.
  if (!silent) {
    if (pmax >= 0 && state.pending.charCodeAt(pmax) === 0x20) {
      if (pmax >= 1 && state.pending.charCodeAt(pmax - 1) === 0x20) {
        // Find whitespaces tail of pending chars.
        let ws = pmax - 1;
        while (ws >= 1 && state.pending.charCodeAt(ws - 1) === 0x20) ws--;
        state.pending = state.pending.slice(0, ws);
        state.push('hardbreak', 'br', 0);
      } else {
        state.pending = state.pending.slice(0, -1);
        state.push('softbreak', 'br', 0);
      }
    } else {
      state.push('softbreak', 'br', 0);
    }
  }
  pos++;

  // skip heading spaces for next line
  while (pos < max && isSpace(state.src.charCodeAt(pos))) {
    pos++;
  }
  state.pos = pos;
  return true;
}

// Process escaped chars and hardbreaks

const ESCAPED = [];
for (let i = 0; i < 256; i++) {
  ESCAPED.push(0);
}
'\\!"#$%&\'()*+,./:;<=>?@[]^_`{|}~-'.split('').forEach(function (ch) {
  ESCAPED[ch.charCodeAt(0)] = 1;
});
function escape(state, silent) {
  let pos = state.pos;
  const max = state.posMax;
  if (state.src.charCodeAt(pos) !== 0x5C /* \ */) return false;
  pos++;

  // '\' at the end of the inline block
  if (pos >= max) return false;
  let ch1 = state.src.charCodeAt(pos);
  if (ch1 === 0x0A) {
    if (!silent) {
      state.push('hardbreak', 'br', 0);
    }
    pos++;
    // skip leading whitespaces from next line
    while (pos < max) {
      ch1 = state.src.charCodeAt(pos);
      if (!isSpace(ch1)) break;
      pos++;
    }
    state.pos = pos;
    return true;
  }
  let escapedStr = state.src[pos];
  if (ch1 >= 0xD800 && ch1 <= 0xDBFF && pos + 1 < max) {
    const ch2 = state.src.charCodeAt(pos + 1);
    if (ch2 >= 0xDC00 && ch2 <= 0xDFFF) {
      escapedStr += state.src[pos + 1];
      pos++;
    }
  }
  const origStr = '\\' + escapedStr;
  if (!silent) {
    const token = state.push('text_special', '', 0);
    if (ch1 < 256 && ESCAPED[ch1] !== 0) {
      token.content = escapedStr;
    } else {
      token.content = origStr;
    }
    token.markup = origStr;
    token.info = 'escape';
  }
  state.pos = pos + 1;
  return true;
}

// Parse backticks

function backtick(state, silent) {
  let pos = state.pos;
  const ch = state.src.charCodeAt(pos);
  if (ch !== 0x60 /* ` */) {
    return false;
  }
  const start = pos;
  pos++;
  const max = state.posMax;

  // scan marker length
  while (pos < max && state.src.charCodeAt(pos) === 0x60 /* ` */) {
    pos++;
  }
  const marker = state.src.slice(start, pos);
  const openerLength = marker.length;
  if (state.backticksScanned && (state.backticks[openerLength] || 0) <= start) {
    if (!silent) state.pending += marker;
    state.pos += openerLength;
    return true;
  }
  let matchEnd = pos;
  let matchStart;

  // Nothing found in the cache, scan until the end of the line (or until marker is found)
  while ((matchStart = state.src.indexOf('`', matchEnd)) !== -1) {
    matchEnd = matchStart + 1;

    // scan marker length
    while (matchEnd < max && state.src.charCodeAt(matchEnd) === 0x60 /* ` */) {
      matchEnd++;
    }
    const closerLength = matchEnd - matchStart;
    if (closerLength === openerLength) {
      // Found matching closer length.
      if (!silent) {
        const token = state.push('code_inline', 'code', 0);
        token.markup = marker;
        token.content = state.src.slice(pos, matchStart).replace(/\n/g, ' ').replace(/^ (.+) $/, '$1');
      }
      state.pos = matchEnd;
      return true;
    }

    // Some different length found, put it in cache as upper limit of where closer can be found
    state.backticks[closerLength] = matchStart;
  }

  // Scanned through the end, didn't find anything
  state.backticksScanned = true;
  if (!silent) state.pending += marker;
  state.pos += openerLength;
  return true;
}

// ~~strike through~~
//

// Insert each marker as a separate text token, and add it to delimiter list
//
function strikethrough_tokenize(state, silent) {
  const start = state.pos;
  const marker = state.src.charCodeAt(start);
  if (silent) {
    return false;
  }
  if (marker !== 0x7E /* ~ */) {
    return false;
  }
  const scanned = state.scanDelims(state.pos, true);
  let len = scanned.length;
  const ch = String.fromCharCode(marker);
  if (len < 2) {
    return false;
  }
  let token;
  if (len % 2) {
    token = state.push('text', '', 0);
    token.content = ch;
    len--;
  }
  for (let i = 0; i < len; i += 2) {
    token = state.push('text', '', 0);
    token.content = ch + ch;
    state.delimiters.push({
      marker,
      length: 0,
      // disable "rule of 3" length checks meant for emphasis
      token: state.tokens.length - 1,
      end: -1,
      open: scanned.can_open,
      close: scanned.can_close
    });
  }
  state.pos += scanned.length;
  return true;
}
function postProcess$1(state, delimiters) {
  let token;
  const loneMarkers = [];
  const max = delimiters.length;
  for (let i = 0; i < max; i++) {
    const startDelim = delimiters[i];
    if (startDelim.marker !== 0x7E /* ~ */) {
      continue;
    }
    if (startDelim.end === -1) {
      continue;
    }
    const endDelim = delimiters[startDelim.end];
    token = state.tokens[startDelim.token];
    token.type = 's_open';
    token.tag = 's';
    token.nesting = 1;
    token.markup = '~~';
    token.content = '';
    token = state.tokens[endDelim.token];
    token.type = 's_close';
    token.tag = 's';
    token.nesting = -1;
    token.markup = '~~';
    token.content = '';
    if (state.tokens[endDelim.token - 1].type === 'text' && state.tokens[endDelim.token - 1].content === '~') {
      loneMarkers.push(endDelim.token - 1);
    }
  }

  // If a marker sequence has an odd number of characters, it's splitted
  // like this: `~~~~~` -> `~` + `~~` + `~~`, leaving one marker at the
  // start of the sequence.
  //
  // So, we have to move all those markers after subsequent s_close tags.
  //
  while (loneMarkers.length) {
    const i = loneMarkers.pop();
    let j = i + 1;
    while (j < state.tokens.length && state.tokens[j].type === 's_close') {
      j++;
    }
    j--;
    if (i !== j) {
      token = state.tokens[j];
      state.tokens[j] = state.tokens[i];
      state.tokens[i] = token;
    }
  }
}

// Walk through delimiter list and replace text tokens with tags
//
function strikethrough_postProcess(state) {
  const tokens_meta = state.tokens_meta;
  const max = state.tokens_meta.length;
  postProcess$1(state, state.delimiters);
  for (let curr = 0; curr < max; curr++) {
    if (tokens_meta[curr] && tokens_meta[curr].delimiters) {
      postProcess$1(state, tokens_meta[curr].delimiters);
    }
  }
}
var r_strikethrough = {
  tokenize: strikethrough_tokenize,
  postProcess: strikethrough_postProcess
};

// Process *this* and _that_
//

// Insert each marker as a separate text token, and add it to delimiter list
//
function emphasis_tokenize(state, silent) {
  const start = state.pos;
  const marker = state.src.charCodeAt(start);
  if (silent) {
    return false;
  }
  if (marker !== 0x5F /* _ */ && marker !== 0x2A /* * */) {
    return false;
  }
  const scanned = state.scanDelims(state.pos, marker === 0x2A);
  for (let i = 0; i < scanned.length; i++) {
    const token = state.push('text', '', 0);
    token.content = String.fromCharCode(marker);
    state.delimiters.push({
      // Char code of the starting marker (number).
      //
      marker,
      // Total length of these series of delimiters.
      //
      length: scanned.length,
      // A position of the token this delimiter corresponds to.
      //
      token: state.tokens.length - 1,
      // If this delimiter is matched as a valid opener, `end` will be
      // equal to its position, otherwise it's `-1`.
      //
      end: -1,
      // Boolean flags that determine if this delimiter could open or close
      // an emphasis.
      //
      open: scanned.can_open,
      close: scanned.can_close
    });
  }
  state.pos += scanned.length;
  return true;
}
function postProcess(state, delimiters) {
  const max = delimiters.length;
  for (let i = max - 1; i >= 0; i--) {
    const startDelim = delimiters[i];
    if (startDelim.marker !== 0x5F /* _ */ && startDelim.marker !== 0x2A /* * */) {
      continue;
    }

    // Process only opening markers
    if (startDelim.end === -1) {
      continue;
    }
    const endDelim = delimiters[startDelim.end];

    // If the previous delimiter has the same marker and is adjacent to this one,
    // merge those into one strong delimiter.
    //
    // `<em><em>whatever</em></em>` -> `<strong>whatever</strong>`
    //
    const isStrong = i > 0 && delimiters[i - 1].end === startDelim.end + 1 &&
    // check that first two markers match and adjacent
    delimiters[i - 1].marker === startDelim.marker && delimiters[i - 1].token === startDelim.token - 1 &&
    // check that last two markers are adjacent (we can safely assume they match)
    delimiters[startDelim.end + 1].token === endDelim.token + 1;
    const ch = String.fromCharCode(startDelim.marker);
    const token_o = state.tokens[startDelim.token];
    token_o.type = isStrong ? 'strong_open' : 'em_open';
    token_o.tag = isStrong ? 'strong' : 'em';
    token_o.nesting = 1;
    token_o.markup = isStrong ? ch + ch : ch;
    token_o.content = '';
    const token_c = state.tokens[endDelim.token];
    token_c.type = isStrong ? 'strong_close' : 'em_close';
    token_c.tag = isStrong ? 'strong' : 'em';
    token_c.nesting = -1;
    token_c.markup = isStrong ? ch + ch : ch;
    token_c.content = '';
    if (isStrong) {
      state.tokens[delimiters[i - 1].token].content = '';
      state.tokens[delimiters[startDelim.end + 1].token].content = '';
      i--;
    }
  }
}

// Walk through delimiter list and replace text tokens with tags
//
function emphasis_post_process(state) {
  const tokens_meta = state.tokens_meta;
  const max = state.tokens_meta.length;
  postProcess(state, state.delimiters);
  for (let curr = 0; curr < max; curr++) {
    if (tokens_meta[curr] && tokens_meta[curr].delimiters) {
      postProcess(state, tokens_meta[curr].delimiters);
    }
  }
}
var r_emphasis = {
  tokenize: emphasis_tokenize,
  postProcess: emphasis_post_process
};

// Process [link](<to> "stuff")

function link(state, silent) {
  let code, label, res, ref;
  let href = '';
  let title = '';
  let start = state.pos;
  let parseReference = true;
  if (state.src.charCodeAt(state.pos) !== 0x5B /* [ */) {
    return false;
  }
  const oldPos = state.pos;
  const max = state.posMax;
  const labelStart = state.pos + 1;
  const labelEnd = state.md.helpers.parseLinkLabel(state, state.pos, true);

  // parser failed to find ']', so it's not a valid link
  if (labelEnd < 0) {
    return false;
  }
  let pos = labelEnd + 1;
  if (pos < max && state.src.charCodeAt(pos) === 0x28 /* ( */) {
    //
    // Inline link
    //

    // might have found a valid shortcut link, disable reference parsing
    parseReference = false;

    // [link](  <href>  "title"  )
    //        ^^ skipping these spaces
    pos++;
    for (; pos < max; pos++) {
      code = state.src.charCodeAt(pos);
      if (!isSpace(code) && code !== 0x0A) {
        break;
      }
    }
    if (pos >= max) {
      return false;
    }

    // [link](  <href>  "title"  )
    //          ^^^^^^ parsing link destination
    start = pos;
    res = state.md.helpers.parseLinkDestination(state.src, pos, state.posMax);
    if (res.ok) {
      href = state.md.normalizeLink(res.str);
      if (state.md.validateLink(href)) {
        pos = res.pos;
      } else {
        href = '';
      }

      // [link](  <href>  "title"  )
      //                ^^ skipping these spaces
      start = pos;
      for (; pos < max; pos++) {
        code = state.src.charCodeAt(pos);
        if (!isSpace(code) && code !== 0x0A) {
          break;
        }
      }

      // [link](  <href>  "title"  )
      //                  ^^^^^^^ parsing link title
      res = state.md.helpers.parseLinkTitle(state.src, pos, state.posMax);
      if (pos < max && start !== pos && res.ok) {
        title = res.str;
        pos = res.pos;

        // [link](  <href>  "title"  )
        //                         ^^ skipping these spaces
        for (; pos < max; pos++) {
          code = state.src.charCodeAt(pos);
          if (!isSpace(code) && code !== 0x0A) {
            break;
          }
        }
      }
    }
    if (pos >= max || state.src.charCodeAt(pos) !== 0x29 /* ) */) {
      // parsing a valid shortcut link failed, fallback to reference
      parseReference = true;
    }
    pos++;
  }
  if (parseReference) {
    //
    // Link reference
    //
    if (typeof state.env.references === 'undefined') {
      return false;
    }
    if (pos < max && state.src.charCodeAt(pos) === 0x5B /* [ */) {
      start = pos + 1;
      pos = state.md.helpers.parseLinkLabel(state, pos);
      if (pos >= 0) {
        label = state.src.slice(start, pos++);
      } else {
        pos = labelEnd + 1;
      }
    } else {
      pos = labelEnd + 1;
    }

    // covers label === '' and label === undefined
    // (collapsed reference link and shortcut reference link respectively)
    if (!label) {
      label = state.src.slice(labelStart, labelEnd);
    }
    ref = state.env.references[normalizeReference(label)];
    if (!ref) {
      state.pos = oldPos;
      return false;
    }
    href = ref.href;
    title = ref.title;
  }

  //
  // We found the end of the link, and know for a fact it's a valid link;
  // so all that's left to do is to call tokenizer.
  //
  if (!silent) {
    state.pos = labelStart;
    state.posMax = labelEnd;
    const token_o = state.push('link_open', 'a', 1);
    const attrs = [['href', href]];
    token_o.attrs = attrs;
    if (title) {
      attrs.push(['title', title]);
    }
    state.linkLevel++;
    state.md.inline.tokenize(state);
    state.linkLevel--;
    state.push('link_close', 'a', -1);
  }
  state.pos = pos;
  state.posMax = max;
  return true;
}

// Process ![image](<src> "title")

function image(state, silent) {
  let code, content, label, pos, ref, res, title, start;
  let href = '';
  const oldPos = state.pos;
  const max = state.posMax;
  if (state.src.charCodeAt(state.pos) !== 0x21 /* ! */) {
    return false;
  }
  if (state.src.charCodeAt(state.pos + 1) !== 0x5B /* [ */) {
    return false;
  }
  const labelStart = state.pos + 2;
  const labelEnd = state.md.helpers.parseLinkLabel(state, state.pos + 1, false);

  // parser failed to find ']', so it's not a valid link
  if (labelEnd < 0) {
    return false;
  }
  pos = labelEnd + 1;
  if (pos < max && state.src.charCodeAt(pos) === 0x28 /* ( */) {
    //
    // Inline link
    //

    // [link](  <href>  "title"  )
    //        ^^ skipping these spaces
    pos++;
    for (; pos < max; pos++) {
      code = state.src.charCodeAt(pos);
      if (!isSpace(code) && code !== 0x0A) {
        break;
      }
    }
    if (pos >= max) {
      return false;
    }

    // [link](  <href>  "title"  )
    //          ^^^^^^ parsing link destination
    start = pos;
    res = state.md.helpers.parseLinkDestination(state.src, pos, state.posMax);
    if (res.ok) {
      href = state.md.normalizeLink(res.str);
      if (state.md.validateLink(href)) {
        pos = res.pos;
      } else {
        href = '';
      }
    }

    // [link](  <href>  "title"  )
    //                ^^ skipping these spaces
    start = pos;
    for (; pos < max; pos++) {
      code = state.src.charCodeAt(pos);
      if (!isSpace(code) && code !== 0x0A) {
        break;
      }
    }

    // [link](  <href>  "title"  )
    //                  ^^^^^^^ parsing link title
    res = state.md.helpers.parseLinkTitle(state.src, pos, state.posMax);
    if (pos < max && start !== pos && res.ok) {
      title = res.str;
      pos = res.pos;

      // [link](  <href>  "title"  )
      //                         ^^ skipping these spaces
      for (; pos < max; pos++) {
        code = state.src.charCodeAt(pos);
        if (!isSpace(code) && code !== 0x0A) {
          break;
        }
      }
    } else {
      title = '';
    }
    if (pos >= max || state.src.charCodeAt(pos) !== 0x29 /* ) */) {
      state.pos = oldPos;
      return false;
    }
    pos++;
  } else {
    //
    // Link reference
    //
    if (typeof state.env.references === 'undefined') {
      return false;
    }
    if (pos < max && state.src.charCodeAt(pos) === 0x5B /* [ */) {
      start = pos + 1;
      pos = state.md.helpers.parseLinkLabel(state, pos);
      if (pos >= 0) {
        label = state.src.slice(start, pos++);
      } else {
        pos = labelEnd + 1;
      }
    } else {
      pos = labelEnd + 1;
    }

    // covers label === '' and label === undefined
    // (collapsed reference link and shortcut reference link respectively)
    if (!label) {
      label = state.src.slice(labelStart, labelEnd);
    }
    ref = state.env.references[normalizeReference(label)];
    if (!ref) {
      state.pos = oldPos;
      return false;
    }
    href = ref.href;
    title = ref.title;
  }

  //
  // We found the end of the link, and know for a fact it's a valid link;
  // so all that's left to do is to call tokenizer.
  //
  if (!silent) {
    content = state.src.slice(labelStart, labelEnd);
    const tokens = [];
    state.md.inline.parse(content, state.md, state.env, tokens);
    const token = state.push('image', 'img', 0);
    const attrs = [['src', href], ['alt', '']];
    token.attrs = attrs;
    token.children = tokens;
    token.content = content;
    if (title) {
      attrs.push(['title', title]);
    }
  }
  state.pos = pos;
  state.posMax = max;
  return true;
}

// Process autolinks '<protocol:...>'

/* eslint max-len:0 */
const EMAIL_RE = /^([a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*)$/;
/* eslint-disable-next-line no-control-regex */
const AUTOLINK_RE = /^([a-zA-Z][a-zA-Z0-9+.-]{1,31}):([^<>\x00-\x20]*)$/;
function autolink(state, silent) {
  let pos = state.pos;
  if (state.src.charCodeAt(pos) !== 0x3C /* < */) {
    return false;
  }
  const start = state.pos;
  const max = state.posMax;
  for (;;) {
    if (++pos >= max) return false;
    const ch = state.src.charCodeAt(pos);
    if (ch === 0x3C /* < */) return false;
    if (ch === 0x3E /* > */) break;
  }
  const url = state.src.slice(start + 1, pos);
  if (AUTOLINK_RE.test(url)) {
    const fullUrl = state.md.normalizeLink(url);
    if (!state.md.validateLink(fullUrl)) {
      return false;
    }
    if (!silent) {
      const token_o = state.push('link_open', 'a', 1);
      token_o.attrs = [['href', fullUrl]];
      token_o.markup = 'autolink';
      token_o.info = 'auto';
      const token_t = state.push('text', '', 0);
      token_t.content = state.md.normalizeLinkText(url);
      const token_c = state.push('link_close', 'a', -1);
      token_c.markup = 'autolink';
      token_c.info = 'auto';
    }
    state.pos += url.length + 2;
    return true;
  }
  if (EMAIL_RE.test(url)) {
    const fullUrl = state.md.normalizeLink('mailto:' + url);
    if (!state.md.validateLink(fullUrl)) {
      return false;
    }
    if (!silent) {
      const token_o = state.push('link_open', 'a', 1);
      token_o.attrs = [['href', fullUrl]];
      token_o.markup = 'autolink';
      token_o.info = 'auto';
      const token_t = state.push('text', '', 0);
      token_t.content = state.md.normalizeLinkText(url);
      const token_c = state.push('link_close', 'a', -1);
      token_c.markup = 'autolink';
      token_c.info = 'auto';
    }
    state.pos += url.length + 2;
    return true;
  }
  return false;
}

// Process html tags

function isLinkOpen(str) {
  return /^<a[>\s]/i.test(str);
}
function isLinkClose(str) {
  return /^<\/a\s*>/i.test(str);
}
function isLetter(ch) {
  /* eslint no-bitwise:0 */
  const lc = ch | 0x20; // to lower case
  return lc >= 0x61 /* a */ && lc <= 0x7a /* z */;
}
function html_inline(state, silent) {
  if (!state.md.options.html) {
    return false;
  }

  // Check start
  const max = state.posMax;
  const pos = state.pos;
  if (state.src.charCodeAt(pos) !== 0x3C /* < */ || pos + 2 >= max) {
    return false;
  }

  // Quick fail on second char
  const ch = state.src.charCodeAt(pos + 1);
  if (ch !== 0x21 /* ! */ && ch !== 0x3F /* ? */ && ch !== 0x2F /* / */ && !isLetter(ch)) {
    return false;
  }
  const match = state.src.slice(pos).match(HTML_TAG_RE);
  if (!match) {
    return false;
  }
  if (!silent) {
    const token = state.push('html_inline', '', 0);
    token.content = match[0];
    if (isLinkOpen(token.content)) state.linkLevel++;
    if (isLinkClose(token.content)) state.linkLevel--;
  }
  state.pos += match[0].length;
  return true;
}

// Process html entity - &#123;, &#xAF;, &quot;, ...

const DIGITAL_RE = /^&#((?:x[a-f0-9]{1,6}|[0-9]{1,7}));/i;
const NAMED_RE = /^&([a-z][a-z0-9]{1,31});/i;
function entity(state, silent) {
  const pos = state.pos;
  const max = state.posMax;
  if (state.src.charCodeAt(pos) !== 0x26 /* & */) return false;
  if (pos + 1 >= max) return false;
  const ch = state.src.charCodeAt(pos + 1);
  if (ch === 0x23 /* # */) {
    const match = state.src.slice(pos).match(DIGITAL_RE);
    if (match) {
      if (!silent) {
        const code = match[1][0].toLowerCase() === 'x' ? parseInt(match[1].slice(1), 16) : parseInt(match[1], 10);
        const token = state.push('text_special', '', 0);
        token.content = isValidEntityCode(code) ? fromCodePoint(code) : fromCodePoint(0xFFFD);
        token.markup = match[0];
        token.info = 'entity';
      }
      state.pos += match[0].length;
      return true;
    }
  } else {
    const match = state.src.slice(pos).match(NAMED_RE);
    if (match) {
      const decoded = entities.decodeHTML(match[0]);
      if (decoded !== match[0]) {
        if (!silent) {
          const token = state.push('text_special', '', 0);
          token.content = decoded;
          token.markup = match[0];
          token.info = 'entity';
        }
        state.pos += match[0].length;
        return true;
      }
    }
  }
  return false;
}

// For each opening emphasis-like marker find a matching closing one
//

function processDelimiters(delimiters) {
  const openersBottom = {};
  const max = delimiters.length;
  if (!max) return;

  // headerIdx is the first delimiter of the current (where closer is) delimiter run
  let headerIdx = 0;
  let lastTokenIdx = -2; // needs any value lower than -1
  const jumps = [];
  for (let closerIdx = 0; closerIdx < max; closerIdx++) {
    const closer = delimiters[closerIdx];
    jumps.push(0);

    // markers belong to same delimiter run if:
    //  - they have adjacent tokens
    //  - AND markers are the same
    //
    if (delimiters[headerIdx].marker !== closer.marker || lastTokenIdx !== closer.token - 1) {
      headerIdx = closerIdx;
    }
    lastTokenIdx = closer.token;

    // Length is only used for emphasis-specific "rule of 3",
    // if it's not defined (in strikethrough or 3rd party plugins),
    // we can default it to 0 to disable those checks.
    //
    closer.length = closer.length || 0;
    if (!closer.close) continue;

    // Previously calculated lower bounds (previous fails)
    // for each marker, each delimiter length modulo 3,
    // and for whether this closer can be an opener;
    // https://github.com/commonmark/cmark/commit/34250e12ccebdc6372b8b49c44fab57c72443460
    /* eslint-disable-next-line no-prototype-builtins */
    if (!openersBottom.hasOwnProperty(closer.marker)) {
      openersBottom[closer.marker] = [-1, -1, -1, -1, -1, -1];
    }
    const minOpenerIdx = openersBottom[closer.marker][(closer.open ? 3 : 0) + closer.length % 3];
    let openerIdx = headerIdx - jumps[headerIdx] - 1;
    let newMinOpenerIdx = openerIdx;
    for (; openerIdx > minOpenerIdx; openerIdx -= jumps[openerIdx] + 1) {
      const opener = delimiters[openerIdx];
      if (opener.marker !== closer.marker) continue;
      if (opener.open && opener.end < 0) {
        let isOddMatch = false;

        // from spec:
        //
        // If one of the delimiters can both open and close emphasis, then the
        // sum of the lengths of the delimiter runs containing the opening and
        // closing delimiters must not be a multiple of 3 unless both lengths
        // are multiples of 3.
        //
        if (opener.close || closer.open) {
          if ((opener.length + closer.length) % 3 === 0) {
            if (opener.length % 3 !== 0 || closer.length % 3 !== 0) {
              isOddMatch = true;
            }
          }
        }
        if (!isOddMatch) {
          // If previous delimiter cannot be an opener, we can safely skip
          // the entire sequence in future checks. This is required to make
          // sure algorithm has linear complexity (see *_*_*_*_*_... case).
          //
          const lastJump = openerIdx > 0 && !delimiters[openerIdx - 1].open ? jumps[openerIdx - 1] + 1 : 0;
          jumps[closerIdx] = closerIdx - openerIdx + lastJump;
          jumps[openerIdx] = lastJump;
          closer.open = false;
          opener.end = closerIdx;
          opener.close = false;
          newMinOpenerIdx = -1;
          // treat next token as start of run,
          // it optimizes skips in **<...>**a**<...>** pathological case
          lastTokenIdx = -2;
          break;
        }
      }
    }
    if (newMinOpenerIdx !== -1) {
      // If match for this delimiter run failed, we want to set lower bound for
      // future lookups. This is required to make sure algorithm has linear
      // complexity.
      //
      // See details here:
      // https://github.com/commonmark/cmark/issues/178#issuecomment-270417442
      //
      openersBottom[closer.marker][(closer.open ? 3 : 0) + (closer.length || 0) % 3] = newMinOpenerIdx;
    }
  }
}
function link_pairs(state) {
  const tokens_meta = state.tokens_meta;
  const max = state.tokens_meta.length;
  processDelimiters(state.delimiters);
  for (let curr = 0; curr < max; curr++) {
    if (tokens_meta[curr] && tokens_meta[curr].delimiters) {
      processDelimiters(tokens_meta[curr].delimiters);
    }
  }
}

// Clean up tokens after emphasis and strikethrough postprocessing:
// merge adjacent text nodes into one and re-calculate all token levels
//
// This is necessary because initially emphasis delimiter markers (*, _, ~)
// are treated as their own separate text tokens. Then emphasis rule either
// leaves them as text (needed to merge with adjacent text) or turns them
// into opening/closing tags (which messes up levels inside).
//

function fragments_join(state) {
  let curr, last;
  let level = 0;
  const tokens = state.tokens;
  const max = state.tokens.length;
  for (curr = last = 0; curr < max; curr++) {
    // re-calculate levels after emphasis/strikethrough turns some text nodes
    // into opening/closing tags
    if (tokens[curr].nesting < 0) level--; // closing tag
    tokens[curr].level = level;
    if (tokens[curr].nesting > 0) level++; // opening tag

    if (tokens[curr].type === 'text' && curr + 1 < max && tokens[curr + 1].type === 'text') {
      // collapse two adjacent text nodes
      tokens[curr + 1].content = tokens[curr].content + tokens[curr + 1].content;
    } else {
      if (curr !== last) {
        tokens[last] = tokens[curr];
      }
      last++;
    }
  }
  if (curr !== last) {
    tokens.length = last;
  }
}

/** internal
 * class ParserInline
 *
 * Tokenizes paragraph content.
 **/


// Parser rules

const _rules = [['text', text], ['linkify', linkify], ['newline', newline], ['escape', escape], ['backticks', backtick], ['strikethrough', r_strikethrough.tokenize], ['emphasis', r_emphasis.tokenize], ['link', link], ['image', image], ['autolink', autolink], ['html_inline', html_inline], ['entity', entity]];

// `rule2` ruleset was created specifically for emphasis/strikethrough
// post-processing and may be changed in the future.
//
// Don't use this for anything except pairs (plugins working with `balance_pairs`).
//
const _rules2 = [['balance_pairs', link_pairs], ['strikethrough', r_strikethrough.postProcess], ['emphasis', r_emphasis.postProcess],
// rules for pairs separate '**' into its own text tokens, which may be left unused,
// rule below merges unused segments back with the rest of the text
['fragments_join', fragments_join]];

/**
 * new ParserInline()
 **/
function ParserInline() {
  /**
   * ParserInline#ruler -> Ruler
   *
   * [[Ruler]] instance. Keep configuration of inline rules.
   **/
  this.ruler = new Ruler();
  for (let i = 0; i < _rules.length; i++) {
    this.ruler.push(_rules[i][0], _rules[i][1]);
  }

  /**
   * ParserInline#ruler2 -> Ruler
   *
   * [[Ruler]] instance. Second ruler used for post-processing
   * (e.g. in emphasis-like rules).
   **/
  this.ruler2 = new Ruler();
  for (let i = 0; i < _rules2.length; i++) {
    this.ruler2.push(_rules2[i][0], _rules2[i][1]);
  }
}

// Skip single token by running all rules in validation mode;
// returns `true` if any rule reported success
//
ParserInline.prototype.skipToken = function (state) {
  const pos = state.pos;
  const rules = this.ruler.getRules('');
  const len = rules.length;
  const maxNesting = state.md.options.maxNesting;
  const cache = state.cache;
  if (typeof cache[pos] !== 'undefined') {
    state.pos = cache[pos];
    return;
  }
  let ok = false;
  if (state.level < maxNesting) {
    for (let i = 0; i < len; i++) {
      // Increment state.level and decrement it later to limit recursion.
      // It's harmless to do here, because no tokens are created. But ideally,
      // we'd need a separate private state variable for this purpose.
      //
      state.level++;
      ok = rules[i](state, true);
      state.level--;
      if (ok) {
        if (pos >= state.pos) {
          throw new Error("inline rule didn't increment state.pos");
        }
        break;
      }
    }
  } else {
    // Too much nesting, just skip until the end of the paragraph.
    //
    // NOTE: this will cause links to behave incorrectly in the following case,
    //       when an amount of `[` is exactly equal to `maxNesting + 1`:
    //
    //       [[[[[[[[[[[[[[[[[[[[[foo]()
    //
    // TODO: remove this workaround when CM standard will allow nested links
    //       (we can replace it by preventing links from being parsed in
    //       validation mode)
    //
    state.pos = state.posMax;
  }
  if (!ok) {
    state.pos++;
  }
  cache[pos] = state.pos;
};

// Generate tokens for input range
//
ParserInline.prototype.tokenize = function (state) {
  const rules = this.ruler.getRules('');
  const len = rules.length;
  const end = state.posMax;
  const maxNesting = state.md.options.maxNesting;
  while (state.pos < end) {
    // Try all possible rules.
    // On success, rule should:
    //
    // - update `state.pos`
    // - update `state.tokens`
    // - return true
    const prevPos = state.pos;
    let ok = false;
    if (state.level < maxNesting) {
      for (let i = 0; i < len; i++) {
        ok = rules[i](state, false);
        if (ok) {
          if (prevPos >= state.pos) {
            throw new Error("inline rule didn't increment state.pos");
          }
          break;
        }
      }
    }
    if (ok) {
      if (state.pos >= end) {
        break;
      }
      continue;
    }
    state.pending += state.src[state.pos++];
  }
  if (state.pending) {
    state.pushPending();
  }
};

/**
 * ParserInline.parse(str, md, env, outTokens)
 *
 * Process input string and push inline tokens into `outTokens`
 **/
ParserInline.prototype.parse = function (str, md, env, outTokens) {
  const state = new this.State(str, md, env, outTokens);
  this.tokenize(state);
  const rules = this.ruler2.getRules('');
  const len = rules.length;
  for (let i = 0; i < len; i++) {
    rules[i](state);
  }
};
ParserInline.prototype.State = StateInline;

// markdown-it default options

var cfg_default = {
  options: {
    // Enable HTML tags in source
    html: false,
    // Use '/' to close single tags (<br />)
    xhtmlOut: false,
    // Convert '\n' in paragraphs into <br>
    breaks: false,
    // CSS language prefix for fenced blocks
    langPrefix: 'language-',
    // autoconvert URL-like texts to links
    linkify: false,
    // Enable some language-neutral replacements + quotes beautification
    typographer: false,
    // Double + single quotes replacement pairs, when typographer enabled,
    // and smartquotes on. Could be either a String or an Array.
    //
    // For example, you can use '«»„“' for Russian, '„“‚‘' for German,
    // and ['«\xA0', '\xA0»', '‹\xA0', '\xA0›'] for French (including nbsp).
    quotes: '\u201c\u201d\u2018\u2019',
    /* “”‘’ */

    // Highlighter function. Should return escaped HTML,
    // or '' if the source string is not changed and should be escaped externaly.
    // If result starts with <pre... internal wrapper is skipped.
    //
    // function (/*str, lang*/) { return ''; }
    //
    highlight: null,
    // Internal protection, recursion limit
    maxNesting: 100
  },
  components: {
    core: {},
    block: {},
    inline: {}
  }
};

// "Zero" preset, with nothing enabled. Useful for manual configuring of simple
// modes. For example, to parse bold/italic only.

var cfg_zero = {
  options: {
    // Enable HTML tags in source
    html: false,
    // Use '/' to close single tags (<br />)
    xhtmlOut: false,
    // Convert '\n' in paragraphs into <br>
    breaks: false,
    // CSS language prefix for fenced blocks
    langPrefix: 'language-',
    // autoconvert URL-like texts to links
    linkify: false,
    // Enable some language-neutral replacements + quotes beautification
    typographer: false,
    // Double + single quotes replacement pairs, when typographer enabled,
    // and smartquotes on. Could be either a String or an Array.
    //
    // For example, you can use '«»„“' for Russian, '„“‚‘' for German,
    // and ['«\xA0', '\xA0»', '‹\xA0', '\xA0›'] for French (including nbsp).
    quotes: '\u201c\u201d\u2018\u2019',
    /* “”‘’ */

    // Highlighter function. Should return escaped HTML,
    // or '' if the source string is not changed and should be escaped externaly.
    // If result starts with <pre... internal wrapper is skipped.
    //
    // function (/*str, lang*/) { return ''; }
    //
    highlight: null,
    // Internal protection, recursion limit
    maxNesting: 20
  },
  components: {
    core: {
      rules: ['normalize', 'block', 'inline', 'text_join']
    },
    block: {
      rules: ['paragraph']
    },
    inline: {
      rules: ['text'],
      rules2: ['balance_pairs', 'fragments_join']
    }
  }
};

// Commonmark default options

var cfg_commonmark = {
  options: {
    // Enable HTML tags in source
    html: true,
    // Use '/' to close single tags (<br />)
    xhtmlOut: true,
    // Convert '\n' in paragraphs into <br>
    breaks: false,
    // CSS language prefix for fenced blocks
    langPrefix: 'language-',
    // autoconvert URL-like texts to links
    linkify: false,
    // Enable some language-neutral replacements + quotes beautification
    typographer: false,
    // Double + single quotes replacement pairs, when typographer enabled,
    // and smartquotes on. Could be either a String or an Array.
    //
    // For example, you can use '«»„“' for Russian, '„“‚‘' for German,
    // and ['«\xA0', '\xA0»', '‹\xA0', '\xA0›'] for French (including nbsp).
    quotes: '\u201c\u201d\u2018\u2019',
    /* “”‘’ */

    // Highlighter function. Should return escaped HTML,
    // or '' if the source string is not changed and should be escaped externaly.
    // If result starts with <pre... internal wrapper is skipped.
    //
    // function (/*str, lang*/) { return ''; }
    //
    highlight: null,
    // Internal protection, recursion limit
    maxNesting: 20
  },
  components: {
    core: {
      rules: ['normalize', 'block', 'inline', 'text_join']
    },
    block: {
      rules: ['blockquote', 'code', 'fence', 'heading', 'hr', 'html_block', 'lheading', 'list', 'reference', 'paragraph']
    },
    inline: {
      rules: ['autolink', 'backticks', 'emphasis', 'entity', 'escape', 'html_inline', 'image', 'link', 'newline', 'text'],
      rules2: ['balance_pairs', 'emphasis', 'fragments_join']
    }
  }
};

// Main parser class

const config = {
  default: cfg_default,
  zero: cfg_zero,
  commonmark: cfg_commonmark
};

//
// This validator can prohibit more than really needed to prevent XSS. It's a
// tradeoff to keep code simple and to be secure by default.
//
// If you need different setup - override validator method as you wish. Or
// replace it with dummy function and use external sanitizer.
//

const BAD_PROTO_RE = /^(vbscript|javascript|file|data):/;
const GOOD_DATA_RE = /^data:image\/(gif|png|jpeg|webp);/;
function validateLink(url) {
  // url should be normalized at this point, and existing entities are decoded
  const str = url.trim().toLowerCase();
  return BAD_PROTO_RE.test(str) ? GOOD_DATA_RE.test(str) : true;
}
const RECODE_HOSTNAME_FOR = ['http:', 'https:', 'mailto:'];
function normalizeLink(url) {
  const parsed = mdurl__namespace.parse(url, true);
  if (parsed.hostname) {
    // Encode hostnames in urls like:
    // `http://host/`, `https://host/`, `mailto:user@host`, `//host/`
    //
    // We don't encode unknown schemas, because it's likely that we encode
    // something we shouldn't (e.g. `skype:name` treated as `skype:host`)
    //
    if (!parsed.protocol || RECODE_HOSTNAME_FOR.indexOf(parsed.protocol) >= 0) {
      try {
        parsed.hostname = punycode.toASCII(parsed.hostname);
      } catch (er) {/**/}
    }
  }
  return mdurl__namespace.encode(mdurl__namespace.format(parsed));
}
function normalizeLinkText(url) {
  const parsed = mdurl__namespace.parse(url, true);
  if (parsed.hostname) {
    // Encode hostnames in urls like:
    // `http://host/`, `https://host/`, `mailto:user@host`, `//host/`
    //
    // We don't encode unknown schemas, because it's likely that we encode
    // something we shouldn't (e.g. `skype:name` treated as `skype:host`)
    //
    if (!parsed.protocol || RECODE_HOSTNAME_FOR.indexOf(parsed.protocol) >= 0) {
      try {
        parsed.hostname = punycode.toUnicode(parsed.hostname);
      } catch (er) {/**/}
    }
  }

  // add '%' to exclude list because of https://github.com/markdown-it/markdown-it/issues/720
  return mdurl__namespace.decode(mdurl__namespace.format(parsed), mdurl__namespace.decode.defaultChars + '%');
}

/**
 * class MarkdownIt
 *
 * Main parser/renderer class.
 *
 * ##### Usage
 *
 * ```javascript
 * // node.js, "classic" way:
 * var MarkdownIt = require('markdown-it'),
 *     md = new MarkdownIt();
 * var result = md.render('# markdown-it rulezz!');
 *
 * // node.js, the same, but with sugar:
 * var md = require('markdown-it')();
 * var result = md.render('# markdown-it rulezz!');
 *
 * // browser without AMD, added to "window" on script load
 * // Note, there are no dash.
 * var md = window.markdownit();
 * var result = md.render('# markdown-it rulezz!');
 * ```
 *
 * Single line rendering, without paragraph wrap:
 *
 * ```javascript
 * var md = require('markdown-it')();
 * var result = md.renderInline('__markdown-it__ rulezz!');
 * ```
 **/

/**
 * new MarkdownIt([presetName, options])
 * - presetName (String): optional, `commonmark` / `zero`
 * - options (Object)
 *
 * Creates parser instanse with given config. Can be called without `new`.
 *
 * ##### presetName
 *
 * MarkdownIt provides named presets as a convenience to quickly
 * enable/disable active syntax rules and options for common use cases.
 *
 * - ["commonmark"](https://github.com/markdown-it/markdown-it/blob/master/lib/presets/commonmark.mjs) -
 *   configures parser to strict [CommonMark](http://commonmark.org/) mode.
 * - [default](https://github.com/markdown-it/markdown-it/blob/master/lib/presets/default.mjs) -
 *   similar to GFM, used when no preset name given. Enables all available rules,
 *   but still without html, typographer & autolinker.
 * - ["zero"](https://github.com/markdown-it/markdown-it/blob/master/lib/presets/zero.mjs) -
 *   all rules disabled. Useful to quickly setup your config via `.enable()`.
 *   For example, when you need only `bold` and `italic` markup and nothing else.
 *
 * ##### options:
 *
 * - __html__ - `false`. Set `true` to enable HTML tags in source. Be careful!
 *   That's not safe! You may need external sanitizer to protect output from XSS.
 *   It's better to extend features via plugins, instead of enabling HTML.
 * - __xhtmlOut__ - `false`. Set `true` to add '/' when closing single tags
 *   (`<br />`). This is needed only for full CommonMark compatibility. In real
 *   world you will need HTML output.
 * - __breaks__ - `false`. Set `true` to convert `\n` in paragraphs into `<br>`.
 * - __langPrefix__ - `language-`. CSS language class prefix for fenced blocks.
 *   Can be useful for external highlighters.
 * - __linkify__ - `false`. Set `true` to autoconvert URL-like text to links.
 * - __typographer__  - `false`. Set `true` to enable [some language-neutral
 *   replacement](https://github.com/markdown-it/markdown-it/blob/master/lib/rules_core/replacements.mjs) +
 *   quotes beautification (smartquotes).
 * - __quotes__ - `“”‘’`, String or Array. Double + single quotes replacement
 *   pairs, when typographer enabled and smartquotes on. For example, you can
 *   use `'«»„“'` for Russian, `'„“‚‘'` for German, and
 *   `['«\xA0', '\xA0»', '‹\xA0', '\xA0›']` for French (including nbsp).
 * - __highlight__ - `null`. Highlighter function for fenced code blocks.
 *   Highlighter `function (str, lang)` should return escaped HTML. It can also
 *   return empty string if the source was not changed and should be escaped
 *   externaly. If result starts with <pre... internal wrapper is skipped.
 *
 * ##### Example
 *
 * ```javascript
 * // commonmark mode
 * var md = require('markdown-it')('commonmark');
 *
 * // default mode
 * var md = require('markdown-it')();
 *
 * // enable everything
 * var md = require('markdown-it')({
 *   html: true,
 *   linkify: true,
 *   typographer: true
 * });
 * ```
 *
 * ##### Syntax highlighting
 *
 * ```js
 * var hljs = require('highlight.js') // https://highlightjs.org/
 *
 * var md = require('markdown-it')({
 *   highlight: function (str, lang) {
 *     if (lang && hljs.getLanguage(lang)) {
 *       try {
 *         return hljs.highlight(str, { language: lang, ignoreIllegals: true }).value;
 *       } catch (__) {}
 *     }
 *
 *     return ''; // use external default escaping
 *   }
 * });
 * ```
 *
 * Or with full wrapper override (if you need assign class to `<pre>` or `<code>`):
 *
 * ```javascript
 * var hljs = require('highlight.js') // https://highlightjs.org/
 *
 * // Actual default values
 * var md = require('markdown-it')({
 *   highlight: function (str, lang) {
 *     if (lang && hljs.getLanguage(lang)) {
 *       try {
 *         return '<pre><code class="hljs">' +
 *                hljs.highlight(str, { language: lang, ignoreIllegals: true }).value +
 *                '</code></pre>';
 *       } catch (__) {}
 *     }
 *
 *     return '<pre><code class="hljs">' + md.utils.escapeHtml(str) + '</code></pre>';
 *   }
 * });
 * ```
 *
 **/
function MarkdownIt(presetName, options) {
  if (!(this instanceof MarkdownIt)) {
    return new MarkdownIt(presetName, options);
  }
  if (!options) {
    if (!isString(presetName)) {
      options = presetName || {};
      presetName = 'default';
    }
  }

  /**
   * MarkdownIt#inline -> ParserInline
   *
   * Instance of [[ParserInline]]. You may need it to add new rules when
   * writing plugins. For simple rules control use [[MarkdownIt.disable]] and
   * [[MarkdownIt.enable]].
   **/
  this.inline = new ParserInline();

  /**
   * MarkdownIt#block -> ParserBlock
   *
   * Instance of [[ParserBlock]]. You may need it to add new rules when
   * writing plugins. For simple rules control use [[MarkdownIt.disable]] and
   * [[MarkdownIt.enable]].
   **/
  this.block = new ParserBlock();

  /**
   * MarkdownIt#core -> Core
   *
   * Instance of [[Core]] chain executor. You may need it to add new rules when
   * writing plugins. For simple rules control use [[MarkdownIt.disable]] and
   * [[MarkdownIt.enable]].
   **/
  this.core = new Core();

  /**
   * MarkdownIt#renderer -> Renderer
   *
   * Instance of [[Renderer]]. Use it to modify output look. Or to add rendering
   * rules for new token types, generated by plugins.
   *
   * ##### Example
   *
   * ```javascript
   * var md = require('markdown-it')();
   *
   * function myToken(tokens, idx, options, env, self) {
   *   //...
   *   return result;
   * };
   *
   * md.renderer.rules['my_token'] = myToken
   * ```
   *
   * See [[Renderer]] docs and [source code](https://github.com/markdown-it/markdown-it/blob/master/lib/renderer.mjs).
   **/
  this.renderer = new Renderer();

  /**
   * MarkdownIt#linkify -> LinkifyIt
   *
   * [linkify-it](https://github.com/markdown-it/linkify-it) instance.
   * Used by [linkify](https://github.com/markdown-it/markdown-it/blob/master/lib/rules_core/linkify.mjs)
   * rule.
   **/
  this.linkify = new LinkifyIt();

  /**
   * MarkdownIt#validateLink(url) -> Boolean
   *
   * Link validation function. CommonMark allows too much in links. By default
   * we disable `javascript:`, `vbscript:`, `file:` schemas, and almost all `data:...` schemas
   * except some embedded image types.
   *
   * You can change this behaviour:
   *
   * ```javascript
   * var md = require('markdown-it')();
   * // enable everything
   * md.validateLink = function () { return true; }
   * ```
   **/
  this.validateLink = validateLink;

  /**
   * MarkdownIt#normalizeLink(url) -> String
   *
   * Function used to encode link url to a machine-readable format,
   * which includes url-encoding, punycode, etc.
   **/
  this.normalizeLink = normalizeLink;

  /**
   * MarkdownIt#normalizeLinkText(url) -> String
   *
   * Function used to decode link url to a human-readable format`
   **/
  this.normalizeLinkText = normalizeLinkText;

  // Expose utils & helpers for easy acces from plugins

  /**
   * MarkdownIt#utils -> utils
   *
   * Assorted utility functions, useful to write plugins. See details
   * [here](https://github.com/markdown-it/markdown-it/blob/master/lib/common/utils.mjs).
   **/
  this.utils = utils;

  /**
   * MarkdownIt#helpers -> helpers
   *
   * Link components parser functions, useful to write plugins. See details
   * [here](https://github.com/markdown-it/markdown-it/blob/master/lib/helpers).
   **/
  this.helpers = assign({}, helpers);
  this.options = {};
  this.configure(presetName);
  if (options) {
    this.set(options);
  }
}

/** chainable
 * MarkdownIt.set(options)
 *
 * Set parser options (in the same format as in constructor). Probably, you
 * will never need it, but you can change options after constructor call.
 *
 * ##### Example
 *
 * ```javascript
 * var md = require('markdown-it')()
 *             .set({ html: true, breaks: true })
 *             .set({ typographer, true });
 * ```
 *
 * __Note:__ To achieve the best possible performance, don't modify a
 * `markdown-it` instance options on the fly. If you need multiple configurations
 * it's best to create multiple instances and initialize each with separate
 * config.
 **/
MarkdownIt.prototype.set = function (options) {
  assign(this.options, options);
  return this;
};

/** chainable, internal
 * MarkdownIt.configure(presets)
 *
 * Batch load of all options and compenent settings. This is internal method,
 * and you probably will not need it. But if you will - see available presets
 * and data structure [here](https://github.com/markdown-it/markdown-it/tree/master/lib/presets)
 *
 * We strongly recommend to use presets instead of direct config loads. That
 * will give better compatibility with next versions.
 **/
MarkdownIt.prototype.configure = function (presets) {
  const self = this;
  if (isString(presets)) {
    const presetName = presets;
    presets = config[presetName];
    if (!presets) {
      throw new Error('Wrong `markdown-it` preset "' + presetName + '", check name');
    }
  }
  if (!presets) {
    throw new Error('Wrong `markdown-it` preset, can\'t be empty');
  }
  if (presets.options) {
    self.set(presets.options);
  }
  if (presets.components) {
    Object.keys(presets.components).forEach(function (name) {
      if (presets.components[name].rules) {
        self[name].ruler.enableOnly(presets.components[name].rules);
      }
      if (presets.components[name].rules2) {
        self[name].ruler2.enableOnly(presets.components[name].rules2);
      }
    });
  }
  return this;
};

/** chainable
 * MarkdownIt.enable(list, ignoreInvalid)
 * - list (String|Array): rule name or list of rule names to enable
 * - ignoreInvalid (Boolean): set `true` to ignore errors when rule not found.
 *
 * Enable list or rules. It will automatically find appropriate components,
 * containing rules with given names. If rule not found, and `ignoreInvalid`
 * not set - throws exception.
 *
 * ##### Example
 *
 * ```javascript
 * var md = require('markdown-it')()
 *             .enable(['sub', 'sup'])
 *             .disable('smartquotes');
 * ```
 **/
MarkdownIt.prototype.enable = function (list, ignoreInvalid) {
  let result = [];
  if (!Array.isArray(list)) {
    list = [list];
  }
  ['core', 'block', 'inline'].forEach(function (chain) {
    result = result.concat(this[chain].ruler.enable(list, true));
  }, this);
  result = result.concat(this.inline.ruler2.enable(list, true));
  const missed = list.filter(function (name) {
    return result.indexOf(name) < 0;
  });
  if (missed.length && !ignoreInvalid) {
    throw new Error('MarkdownIt. Failed to enable unknown rule(s): ' + missed);
  }
  return this;
};

/** chainable
 * MarkdownIt.disable(list, ignoreInvalid)
 * - list (String|Array): rule name or list of rule names to disable.
 * - ignoreInvalid (Boolean): set `true` to ignore errors when rule not found.
 *
 * The same as [[MarkdownIt.enable]], but turn specified rules off.
 **/
MarkdownIt.prototype.disable = function (list, ignoreInvalid) {
  let result = [];
  if (!Array.isArray(list)) {
    list = [list];
  }
  ['core', 'block', 'inline'].forEach(function (chain) {
    result = result.concat(this[chain].ruler.disable(list, true));
  }, this);
  result = result.concat(this.inline.ruler2.disable(list, true));
  const missed = list.filter(function (name) {
    return result.indexOf(name) < 0;
  });
  if (missed.length && !ignoreInvalid) {
    throw new Error('MarkdownIt. Failed to disable unknown rule(s): ' + missed);
  }
  return this;
};

/** chainable
 * MarkdownIt.use(plugin, params)
 *
 * Load specified plugin with given params into current parser instance.
 * It's just a sugar to call `plugin(md, params)` with curring.
 *
 * ##### Example
 *
 * ```javascript
 * var iterator = require('markdown-it-for-inline');
 * var md = require('markdown-it')()
 *             .use(iterator, 'foo_replace', 'text', function (tokens, idx) {
 *               tokens[idx].content = tokens[idx].content.replace(/foo/g, 'bar');
 *             });
 * ```
 **/
MarkdownIt.prototype.use = function (plugin /*, params, ... */) {
  const args = [this].concat(Array.prototype.slice.call(arguments, 1));
  plugin.apply(plugin, args);
  return this;
};

/** internal
 * MarkdownIt.parse(src, env) -> Array
 * - src (String): source string
 * - env (Object): environment sandbox
 *
 * Parse input string and return list of block tokens (special token type
 * "inline" will contain list of inline tokens). You should not call this
 * method directly, until you write custom renderer (for example, to produce
 * AST).
 *
 * `env` is used to pass data between "distributed" rules and return additional
 * metadata like reference info, needed for the renderer. It also can be used to
 * inject data in specific cases. Usually, you will be ok to pass `{}`,
 * and then pass updated object to renderer.
 **/
MarkdownIt.prototype.parse = function (src, env) {
  if (typeof src !== 'string') {
    throw new Error('Input data should be a String');
  }
  const state = new this.core.State(src, this, env);
  this.core.process(state);
  return state.tokens;
};

/**
 * MarkdownIt.render(src [, env]) -> String
 * - src (String): source string
 * - env (Object): environment sandbox
 *
 * Render markdown string into html. It does all magic for you :).
 *
 * `env` can be used to inject additional metadata (`{}` by default).
 * But you will not need it with high probability. See also comment
 * in [[MarkdownIt.parse]].
 **/
MarkdownIt.prototype.render = function (src, env) {
  env = env || {};
  return this.renderer.render(this.parse(src, env), this.options, env);
};

/** internal
 * MarkdownIt.parseInline(src, env) -> Array
 * - src (String): source string
 * - env (Object): environment sandbox
 *
 * The same as [[MarkdownIt.parse]] but skip all block rules. It returns the
 * block tokens list with the single `inline` element, containing parsed inline
 * tokens in `children` property. Also updates `env` object.
 **/
MarkdownIt.prototype.parseInline = function (src, env) {
  const state = new this.core.State(src, this, env);
  state.inlineMode = true;
  this.core.process(state);
  return state.tokens;
};

/**
 * MarkdownIt.renderInline(src [, env]) -> String
 * - src (String): source string
 * - env (Object): environment sandbox
 *
 * Similar to [[MarkdownIt.render]] but for single paragraph content. Result
 * will NOT be wrapped into `<p>` tags.
 **/
MarkdownIt.prototype.renderInline = function (src, env) {
  env = env || {};
  return this.renderer.render(this.parseInline(src, env), this.options, env);
};

module.exports = MarkdownIt;
