markdown-it/lib/index.js

// Main perser class

'use strict';


var utils        = require('./common/utils');
var helpers      = require('./helpers');
var Renderer     = require('./renderer');
var ParserCore   = require('./parser_core');
var ParserBlock  = require('./parser_block');
var ParserInline = require('./parser_inline');
var LinkifyIt    = require('linkify-it');
var mdurl        = require('mdurl');
var punycode     = require('punycode');


var config = {
  'default': require('./presets/default'),
  zero: require('./presets/zero'),
  commonmark: require('./presets/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.
//

var BAD_PROTO_RE = /^(vbscript|javascript|file|data):/;
var GOOD_DATA_RE = /^data:image\/(gif|png|jpeg|webp);/;

function validateLink(url) {
  // url should be normalized at this point, and existing entities are decoded
  var str = url.trim().toLowerCase();

  return BAD_PROTO_RE.test(str) ? (GOOD_DATA_RE.test(str) ? true : false) : true;
}

////////////////////////////////////////////////////////////////////////////////


var RECODE_HOSTNAME_FOR = [ 'http:', 'https:', 'mailto:' ];

function normalizeLink(url) {
  var parsed = mdurl.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.encode(mdurl.format(parsed));
}

function normalizeLinkText(url) {
  var parsed = mdurl.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) {}
    }
  }

  return mdurl.decode(mdurl.format(parsed));
}


/**
 * 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.js) -
 *   configures parser to strict [CommonMark](http://commonmark.org/) mode.
 * - [default](https://github.com/markdown-it/markdown-it/blob/master/lib/presets/default.js) -
 *   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.js) -
 *   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.js) +
 *   quotes beautification (smartquotes).
 * - __quotes__ - `“”‘’`, string. Double + single quotes replacement pairs, when
 *   typographer enabled and smartquotes on. Set doubles to '«»' for Russian,
 *   '„“' for German.
 * - __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.
 *
 * ##### 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(lang, str).value;
 *       } catch (__) {}
 *     }
 *
 *     try {
 *       return hljs.highlightAuto(str).value;
 *     } catch (__) {}
 *
 *     return ''; // use external default escaping
 *   }
 * });
 * ```
 **/
function MarkdownIt(presetName, options) {
  if (!(this instanceof MarkdownIt)) {
    return new MarkdownIt(presetName, options);
  }

  if (!options) {
    if (!utils.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 ParserCore();

  /**
   * 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.js).
   **/
  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.js)
   * rule.
   **/
  this.linkify = new LinkifyIt();

  /**
   * MarkdownIt#validateLink(url) -> Boolean
   *
   * Link validation function. CommonMark allows too much in links. By default
   * we disable `javascript:` and `vbscript:` schemas. 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.js).
   **/
  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 = 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) {
  utils.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 with - 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) {
  var self = this, presetName;

  if (utils.isString(presets)) {
    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);
      }
    });
  }
  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) {
  var result = [];

  if (!Array.isArray(list)) { list = [ list ]; }

  [ 'core', 'block', 'inline' ].forEach(function (chain) {
    result = result.concat(this[chain].ruler.enable(list, true));
  }, this);

  var 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) {
  var result = [];

  if (!Array.isArray(list)) { list = [ list ]; }

  [ 'core', 'block', 'inline' ].forEach(function (chain) {
    result = result.concat(this[chain].ruler.disable(list, true));
  }, this);

  var 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, ... */) {
  var 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 returns 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 for 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) {
  var 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) {
  var 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;