Sfoglia il codice sorgente

Merge pull request #2 from ckeditor/t/1

First implementation of GitHub markdown DataProcessor.
Piotrek Koszuliński 9 anni fa
parent
commit
79cab134e6
19 ha cambiato i file con 4560 aggiunte e 0 eliminazioni
  1. 54 0
      packages/ckeditor5-markdown-gfm/src/gfmdataprocessor.js
  2. 1286 0
      packages/ckeditor5-markdown-gfm/src/lib/marked/marked.js
  3. 175 0
      packages/ckeditor5-markdown-gfm/src/lib/marked/renderer.js
  4. 68 0
      packages/ckeditor5-markdown-gfm/src/lib/to-markdown/converters.js
  5. 785 0
      packages/ckeditor5-markdown-gfm/src/lib/to-markdown/to-markdown.js
  6. 23 0
      packages/ckeditor5-markdown-gfm/tests/_utils/utils.js
  7. 175 0
      packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/blockquotes.js
  8. 280 0
      packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/code.js
  9. 71 0
      packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/escaping.js
  10. 93 0
      packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/headers.js
  11. 204 0
      packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/horizontal-rules.js
  12. 72 0
      packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/images.js
  13. 428 0
      packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/links.js
  14. 343 0
      packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/lists.js
  15. 126 0
      packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/paragraphs.js
  16. 26 0
      packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/strikethrough.js
  17. 107 0
      packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/strong-emphasis.js
  18. 158 0
      packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/tables.js
  19. 86 0
      packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/tabs.js

+ 54 - 0
packages/ckeditor5-markdown-gfm/src/gfmdataprocessor.js

@@ -0,0 +1,54 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import marked from './lib/marked/marked.js';
+import toMarkdown from './lib/to-markdown/to-markdown.js';
+import HtmlDataProcessor from '../engine/dataprocessor/htmldataprocessor.js';
+import GFMRenderer from './lib/marked/renderer.js';
+import converters from './lib/to-markdown/converters.js';
+
+/**
+ * GFMDataProcessor class.
+ * This data processor implementation uses GitHub flavored markdown as input/output data.
+ *
+ * @memberOf markdown-gfm
+ * @implements engine.dataProcessor.DataProcessor
+ */
+export default class GFMDataProcessor {
+	constructor() {
+		this._htmlDP = new HtmlDataProcessor();
+	}
+
+	/**
+	 * Converts provided markdown string to view tree.
+	 *
+	 * @param {String} data Markdown string.
+	 * @returns {engine.view.DocumentFragment} Converted view element.
+	 */
+	toView( data ) {
+		const html = marked.parse( data, {
+			gfm: true,
+			breaks: true,
+			tables: true,
+			xhtml: true,
+			renderer: new GFMRenderer()
+		} );
+
+		return this._htmlDP.toView( html );
+	}
+
+	/**
+	 * Converts provided {@link engine.view.DocumentFragment DocumentFragment} to data format - in this case markdown string.
+	 *
+	 * @param {engine.view.DocumentFragment} viewFragment
+	 * @returns {String} Markdown string.
+	 */
+	toData( viewFragment ) {
+		const html = this._htmlDP.toData( viewFragment );
+
+		return toMarkdown( html, { gfm: true, converters } );
+	}
+}
+

+ 1286 - 0
packages/ckeditor5-markdown-gfm/src/lib/marked/marked.js

@@ -0,0 +1,1286 @@
+/**
+ * marked - a markdown parser
+ * Copyright (c) 2011-2014, Christopher Jeffrey. (MIT Licensed)
+ * https://github.com/chjj/marked
+ */
+
+;(function() {
+
+/**
+ * Block-Level Grammar
+ */
+
+var block = {
+  newline: /^\n+/,
+  code: /^( {4}[^\n]+\n*)+/,
+  fences: noop,
+  hr: /^( *[-*_]){3,} *(?:\n+|$)/,
+  heading: /^ *(#{1,6}) *([^\n]+?) *#* *(?:\n+|$)/,
+  nptable: noop,
+  lheading: /^([^\n]+)\n *(=|-){2,} *(?:\n+|$)/,
+  blockquote: /^( *>[^\n]+(\n(?!def)[^\n]+)*\n*)+/,
+  list: /^( *)(bull) [\s\S]+?(?:hr|def|\n{2,}(?! )(?!\1bull )\n*|\s*$)/,
+  html: /^ *(?:comment *(?:\n|\s*$)|closed *(?:\n{2,}|\s*$)|closing *(?:\n{2,}|\s*$))/,
+  def: /^ *\[([^\]]+)\]: *<?([^\s>]+)>?(?: +["(]([^\n]+)[")])? *(?:\n+|$)/,
+  table: noop,
+  paragraph: /^((?:[^\n]+\n?(?!hr|heading|lheading|blockquote|tag|def))+)\n*/,
+  text: /^[^\n]+/
+};
+
+block.bullet = /(?:[*+-]|\d+\.)/;
+block.item = /^( *)(bull) [^\n]*(?:\n(?!\1bull )[^\n]*)*/;
+block.item = replace(block.item, 'gm')
+  (/bull/g, block.bullet)
+  ();
+
+block.list = replace(block.list)
+  (/bull/g, block.bullet)
+  ('hr', '\\n+(?=\\1?(?:[-*_] *){3,}(?:\\n+|$))')
+  ('def', '\\n+(?=' + block.def.source + ')')
+  ();
+
+block.blockquote = replace(block.blockquote)
+  ('def', block.def)
+  ();
+
+block._tag = '(?!(?:'
+  + 'a|em|strong|small|s|cite|q|dfn|abbr|data|time|code'
+  + '|var|samp|kbd|sub|sup|i|b|u|mark|ruby|rt|rp|bdi|bdo'
+  + '|span|br|wbr|ins|del|img)\\b)\\w+(?!:/|[^\\w\\s@]*@)\\b';
+
+block.html = replace(block.html)
+  ('comment', /<!--[\s\S]*?-->/)
+  ('closed', /<(tag)[\s\S]+?<\/\1>/)
+  ('closing', /<tag(?:"[^"]*"|'[^']*'|[^'">])*?>/)
+  (/tag/g, block._tag)
+  ();
+
+block.paragraph = replace(block.paragraph)
+  ('hr', block.hr)
+  ('heading', block.heading)
+  ('lheading', block.lheading)
+  ('blockquote', block.blockquote)
+  ('tag', '<' + block._tag)
+  ('def', block.def)
+  ();
+
+/**
+ * Normal Block Grammar
+ */
+
+block.normal = merge({}, block);
+
+/**
+ * GFM Block Grammar
+ */
+
+block.gfm = merge({}, block.normal, {
+  fences: /^ *(`{3,}|~{3,})[ \.]*(\S+)? *\n([\s\S]*?)\s*\1 *(?:\n+|$)/,
+  paragraph: /^/,
+  heading: /^ *(#{1,6}) +([^\n]+?) *#* *(?:\n+|$)/
+});
+
+block.gfm.paragraph = replace(block.paragraph)
+  ('(?!', '(?!'
+    + block.gfm.fences.source.replace('\\1', '\\2') + '|'
+    + block.list.source.replace('\\1', '\\3') + '|')
+  ();
+
+/**
+ * GFM + Tables Block Grammar
+ */
+
+block.tables = merge({}, block.gfm, {
+  nptable: /^ *(\S.*\|.*)\n *([-:]+ *\|[-| :]*)\n((?:.*\|.*(?:\n|$))*)\n*/,
+  table: /^ *\|(.+)\n *\|( *[-:]+[-| :]*)\n((?: *\|.*(?:\n|$))*)\n*/
+});
+
+/**
+ * Block Lexer
+ */
+
+function Lexer(options) {
+  this.tokens = [];
+  this.tokens.links = {};
+  this.options = options || marked.defaults;
+  this.rules = block.normal;
+
+  if (this.options.gfm) {
+    if (this.options.tables) {
+      this.rules = block.tables;
+    } else {
+      this.rules = block.gfm;
+    }
+  }
+}
+
+/**
+ * Expose Block Rules
+ */
+
+Lexer.rules = block;
+
+/**
+ * Static Lex Method
+ */
+
+Lexer.lex = function(src, options) {
+  var lexer = new Lexer(options);
+  return lexer.lex(src);
+};
+
+/**
+ * Preprocessing
+ */
+
+Lexer.prototype.lex = function(src) {
+  src = src
+    .replace(/\r\n|\r/g, '\n')
+    .replace(/\t/g, '    ')
+    .replace(/\u00a0/g, ' ')
+    .replace(/\u2424/g, '\n');
+
+  return this.token(src, true);
+};
+
+/**
+ * Lexing
+ */
+
+Lexer.prototype.token = function(src, top, bq) {
+  var src = src.replace(/^ +$/gm, '')
+    , next
+    , loose
+    , cap
+    , bull
+    , b
+    , item
+    , space
+    , i
+    , l;
+
+  while (src) {
+    // newline
+    if (cap = this.rules.newline.exec(src)) {
+      src = src.substring(cap[0].length);
+      if (cap[0].length > 1) {
+        this.tokens.push({
+          type: 'space'
+        });
+      }
+    }
+
+    // code
+    if (cap = this.rules.code.exec(src)) {
+      src = src.substring(cap[0].length);
+      cap = cap[0].replace(/^ {4}/gm, '');
+      this.tokens.push({
+        type: 'code',
+        text: !this.options.pedantic
+          ? cap.replace(/\n+$/, '')
+          : cap
+      });
+      continue;
+    }
+
+    // fences (gfm)
+    if (cap = this.rules.fences.exec(src)) {
+      src = src.substring(cap[0].length);
+      this.tokens.push({
+        type: 'code',
+        lang: cap[2],
+        text: cap[3] || ''
+      });
+      continue;
+    }
+
+    // heading
+    if (cap = this.rules.heading.exec(src)) {
+      src = src.substring(cap[0].length);
+      this.tokens.push({
+        type: 'heading',
+        depth: cap[1].length,
+        text: cap[2]
+      });
+      continue;
+    }
+
+    // table no leading pipe (gfm)
+    if (top && (cap = this.rules.nptable.exec(src))) {
+      src = src.substring(cap[0].length);
+
+      item = {
+        type: 'table',
+        header: cap[1].replace(/^ *| *\| *$/g, '').split(/ *\| */),
+        align: cap[2].replace(/^ *|\| *$/g, '').split(/ *\| */),
+        cells: cap[3].replace(/\n$/, '').split('\n')
+      };
+
+      for (i = 0; i < item.align.length; i++) {
+        if (/^ *-+: *$/.test(item.align[i])) {
+          item.align[i] = 'right';
+        } else if (/^ *:-+: *$/.test(item.align[i])) {
+          item.align[i] = 'center';
+        } else if (/^ *:-+ *$/.test(item.align[i])) {
+          item.align[i] = 'left';
+        } else {
+          item.align[i] = null;
+        }
+      }
+
+      for (i = 0; i < item.cells.length; i++) {
+        item.cells[i] = item.cells[i].split(/ *\| */);
+      }
+
+      this.tokens.push(item);
+
+      continue;
+    }
+
+    // lheading
+    if (cap = this.rules.lheading.exec(src)) {
+      src = src.substring(cap[0].length);
+      this.tokens.push({
+        type: 'heading',
+        depth: cap[2] === '=' ? 1 : 2,
+        text: cap[1]
+      });
+      continue;
+    }
+
+    // hr
+    if (cap = this.rules.hr.exec(src)) {
+      src = src.substring(cap[0].length);
+      this.tokens.push({
+        type: 'hr'
+      });
+      continue;
+    }
+
+    // blockquote
+    if (cap = this.rules.blockquote.exec(src)) {
+      src = src.substring(cap[0].length);
+
+      this.tokens.push({
+        type: 'blockquote_start'
+      });
+
+      cap = cap[0].replace(/^ *> ?/gm, '');
+
+      // Pass `top` to keep the current
+      // "toplevel" state. This is exactly
+      // how markdown.pl works.
+      this.token(cap, top, true);
+
+      this.tokens.push({
+        type: 'blockquote_end'
+      });
+
+      continue;
+    }
+
+    // list
+    if (cap = this.rules.list.exec(src)) {
+      src = src.substring(cap[0].length);
+      bull = cap[2];
+
+      this.tokens.push({
+        type: 'list_start',
+        ordered: bull.length > 1
+      });
+
+      // Get each top-level item.
+      cap = cap[0].match(this.rules.item);
+
+      next = false;
+      l = cap.length;
+      i = 0;
+
+      for (; i < l; i++) {
+        item = cap[i];
+
+        // Remove the list item's bullet
+        // so it is seen as the next token.
+        space = item.length;
+        item = item.replace(/^ *([*+-]|\d+\.) +/, '');
+
+        // Outdent whatever the
+        // list item contains. Hacky.
+        if (~item.indexOf('\n ')) {
+          space -= item.length;
+          item = !this.options.pedantic
+            ? item.replace(new RegExp('^ {1,' + space + '}', 'gm'), '')
+            : item.replace(/^ {1,4}/gm, '');
+        }
+
+        // Determine whether the next list item belongs here.
+        // Backpedal if it does not belong in this list.
+        if (this.options.smartLists && i !== l - 1) {
+          b = block.bullet.exec(cap[i + 1])[0];
+          if (bull !== b && !(bull.length > 1 && b.length > 1)) {
+            src = cap.slice(i + 1).join('\n') + src;
+            i = l - 1;
+          }
+        }
+
+        // Determine whether item is loose or not.
+        // Use: /(^|\n)(?! )[^\n]+\n\n(?!\s*$)/
+        // for discount behavior.
+        loose = next || /\n\n(?!\s*$)/.test(item);
+        if (i !== l - 1) {
+          next = item.charAt(item.length - 1) === '\n';
+          if (!loose) loose = next;
+        }
+
+        this.tokens.push({
+          type: loose
+            ? 'loose_item_start'
+            : 'list_item_start'
+        });
+
+        // Recurse.
+        this.token(item, false, bq);
+
+        this.tokens.push({
+          type: 'list_item_end'
+        });
+      }
+
+      this.tokens.push({
+        type: 'list_end'
+      });
+
+      continue;
+    }
+
+    // html
+    if (cap = this.rules.html.exec(src)) {
+      src = src.substring(cap[0].length);
+      this.tokens.push({
+        type: this.options.sanitize
+          ? 'paragraph'
+          : 'html',
+        pre: !this.options.sanitizer
+          && (cap[1] === 'pre' || cap[1] === 'script' || cap[1] === 'style'),
+        text: cap[0]
+      });
+      continue;
+    }
+
+    // def
+    if ((!bq && top) && (cap = this.rules.def.exec(src))) {
+      src = src.substring(cap[0].length);
+      this.tokens.links[cap[1].toLowerCase()] = {
+        href: cap[2],
+        title: cap[3]
+      };
+      continue;
+    }
+
+    // table (gfm)
+    if (top && (cap = this.rules.table.exec(src))) {
+      src = src.substring(cap[0].length);
+
+      item = {
+        type: 'table',
+        header: cap[1].replace(/^ *| *\| *$/g, '').split(/ *\| */),
+        align: cap[2].replace(/^ *|\| *$/g, '').split(/ *\| */),
+        cells: cap[3].replace(/(?: *\| *)?\n$/, '').split('\n')
+      };
+
+      for (i = 0; i < item.align.length; i++) {
+        if (/^ *-+: *$/.test(item.align[i])) {
+          item.align[i] = 'right';
+        } else if (/^ *:-+: *$/.test(item.align[i])) {
+          item.align[i] = 'center';
+        } else if (/^ *:-+ *$/.test(item.align[i])) {
+          item.align[i] = 'left';
+        } else {
+          item.align[i] = null;
+        }
+      }
+
+      for (i = 0; i < item.cells.length; i++) {
+        item.cells[i] = item.cells[i]
+          .replace(/^ *\| *| *\| *$/g, '')
+          .split(/ *\| */);
+      }
+
+      this.tokens.push(item);
+
+      continue;
+    }
+
+    // top-level paragraph
+    if (top && (cap = this.rules.paragraph.exec(src))) {
+      src = src.substring(cap[0].length);
+      this.tokens.push({
+        type: 'paragraph',
+        text: cap[1].charAt(cap[1].length - 1) === '\n'
+          ? cap[1].slice(0, -1)
+          : cap[1]
+      });
+      continue;
+    }
+
+    // text
+    if (cap = this.rules.text.exec(src)) {
+      // Top-level should never reach here.
+      src = src.substring(cap[0].length);
+      this.tokens.push({
+        type: 'text',
+        text: cap[0]
+      });
+      continue;
+    }
+
+    if (src) {
+      throw new
+        Error('Infinite loop on byte: ' + src.charCodeAt(0));
+    }
+  }
+
+  return this.tokens;
+};
+
+/**
+ * Inline-Level Grammar
+ */
+
+var inline = {
+  escape: /^\\([\\`*{}\[\]()#+\-.!_>])/,
+  autolink: /^<([^ >]+(@|:\/)[^ >]+)>/,
+  url: noop,
+  tag: /^<!--[\s\S]*?-->|^<\/?\w+(?:"[^"]*"|'[^']*'|[^'">])*?>/,
+  link: /^!?\[(inside)\]\(href\)/,
+  reflink: /^!?\[(inside)\]\s*\[([^\]]*)\]/,
+  nolink: /^!?\[((?:\[[^\]]*\]|[^\[\]])*)\]/,
+  strong: /^__([\s\S]+?)__(?!_)|^\*\*([\s\S]+?)\*\*(?!\*)/,
+  em: /^\b_((?:[^_]|__)+?)_\b|^\*((?:\*\*|[\s\S])+?)\*(?!\*)/,
+  code: /^(`+)\s*([\s\S]*?[^`])\s*\1(?!`)/,
+  br: /^ {2,}\n(?!\s*$)/,
+  del: noop,
+  text: /^[\s\S]+?(?=[\\<!\[_*`]| {2,}\n|$)/
+};
+
+inline._inside = /(?:\[[^\]]*\]|[^\[\]]|\](?=[^\[]*\]))*/;
+inline._href = /\s*<?([\s\S]*?)>?(?:\s+['"]([\s\S]*?)['"])?\s*/;
+
+inline.link = replace(inline.link)
+  ('inside', inline._inside)
+  ('href', inline._href)
+  ();
+
+inline.reflink = replace(inline.reflink)
+  ('inside', inline._inside)
+  ();
+
+/**
+ * Normal Inline Grammar
+ */
+
+inline.normal = merge({}, inline);
+
+/**
+ * Pedantic Inline Grammar
+ */
+
+inline.pedantic = merge({}, inline.normal, {
+  strong: /^__(?=\S)([\s\S]*?\S)__(?!_)|^\*\*(?=\S)([\s\S]*?\S)\*\*(?!\*)/,
+  em: /^_(?=\S)([\s\S]*?\S)_(?!_)|^\*(?=\S)([\s\S]*?\S)\*(?!\*)/
+});
+
+/**
+ * GFM Inline Grammar
+ */
+
+inline.gfm = merge({}, inline.normal, {
+  escape: replace(inline.escape)('])', '~|])')(),
+  url: /^(https?:\/\/[^\s<]+[^<.,:;"')\]\s])/,
+  del: /^~~(?=\S)([\s\S]*?\S)~~/,
+  text: replace(inline.text)
+    (']|', '~]|')
+    ('|', '|https?://|')
+    ()
+});
+
+/**
+ * GFM + Line Breaks Inline Grammar
+ */
+
+inline.breaks = merge({}, inline.gfm, {
+  br: replace(inline.br)('{2,}', '*')(),
+  text: replace(inline.gfm.text)('{2,}', '*')()
+});
+
+/**
+ * Inline Lexer & Compiler
+ */
+
+function InlineLexer(links, options) {
+  this.options = options || marked.defaults;
+  this.links = links;
+  this.rules = inline.normal;
+  this.renderer = this.options.renderer || new Renderer;
+  this.renderer.options = this.options;
+
+  if (!this.links) {
+    throw new
+      Error('Tokens array requires a `links` property.');
+  }
+
+  if (this.options.gfm) {
+    if (this.options.breaks) {
+      this.rules = inline.breaks;
+    } else {
+      this.rules = inline.gfm;
+    }
+  } else if (this.options.pedantic) {
+    this.rules = inline.pedantic;
+  }
+}
+
+/**
+ * Expose Inline Rules
+ */
+
+InlineLexer.rules = inline;
+
+/**
+ * Static Lexing/Compiling Method
+ */
+
+InlineLexer.output = function(src, links, options) {
+  var inline = new InlineLexer(links, options);
+  return inline.output(src);
+};
+
+/**
+ * Lexing/Compiling
+ */
+
+InlineLexer.prototype.output = function(src) {
+  var out = ''
+    , link
+    , text
+    , href
+    , cap;
+
+  while (src) {
+    // escape
+    if (cap = this.rules.escape.exec(src)) {
+      src = src.substring(cap[0].length);
+      out += cap[1];
+      continue;
+    }
+
+    // autolink
+    if (cap = this.rules.autolink.exec(src)) {
+      src = src.substring(cap[0].length);
+      if (cap[2] === '@') {
+        text = cap[1].charAt(6) === ':'
+          ? this.mangle(cap[1].substring(7))
+          : this.mangle(cap[1]);
+        href = this.mangle('mailto:') + text;
+      } else {
+        text = escape(cap[1]);
+        href = text;
+      }
+      out += this.renderer.link(href, null, text);
+      continue;
+    }
+
+    // url (gfm)
+    if (!this.inLink && (cap = this.rules.url.exec(src))) {
+      src = src.substring(cap[0].length);
+      text = escape(cap[1]);
+      href = text;
+      out += this.renderer.link(href, null, text);
+      continue;
+    }
+
+    // tag
+    if (cap = this.rules.tag.exec(src)) {
+      if (!this.inLink && /^<a /i.test(cap[0])) {
+        this.inLink = true;
+      } else if (this.inLink && /^<\/a>/i.test(cap[0])) {
+        this.inLink = false;
+      }
+      src = src.substring(cap[0].length);
+      out += this.options.sanitize
+        ? this.options.sanitizer
+          ? this.options.sanitizer(cap[0])
+          : escape(cap[0])
+        : cap[0]
+      continue;
+    }
+
+    // link
+    if (cap = this.rules.link.exec(src)) {
+      src = src.substring(cap[0].length);
+      this.inLink = true;
+      out += this.outputLink(cap, {
+        href: cap[2],
+        title: cap[3]
+      });
+      this.inLink = false;
+      continue;
+    }
+
+    // reflink, nolink
+    if ((cap = this.rules.reflink.exec(src))
+        || (cap = this.rules.nolink.exec(src))) {
+      src = src.substring(cap[0].length);
+      link = (cap[2] || cap[1]).replace(/\s+/g, ' ');
+      link = this.links[link.toLowerCase()];
+      if (!link || !link.href) {
+        out += cap[0].charAt(0);
+        src = cap[0].substring(1) + src;
+        continue;
+      }
+      this.inLink = true;
+      out += this.outputLink(cap, link);
+      this.inLink = false;
+      continue;
+    }
+
+    // strong
+    if (cap = this.rules.strong.exec(src)) {
+      src = src.substring(cap[0].length);
+      out += this.renderer.strong(this.output(cap[2] || cap[1]));
+      continue;
+    }
+
+    // em
+    if (cap = this.rules.em.exec(src)) {
+      src = src.substring(cap[0].length);
+      out += this.renderer.em(this.output(cap[2] || cap[1]));
+      continue;
+    }
+
+    // code
+    if (cap = this.rules.code.exec(src)) {
+      src = src.substring(cap[0].length);
+      out += this.renderer.codespan(escape(cap[2], true));
+      continue;
+    }
+
+    // br
+    if (cap = this.rules.br.exec(src)) {
+      src = src.substring(cap[0].length);
+      out += this.renderer.br();
+      continue;
+    }
+
+    // del (gfm)
+    if (cap = this.rules.del.exec(src)) {
+      src = src.substring(cap[0].length);
+      out += this.renderer.del(this.output(cap[1]));
+      continue;
+    }
+
+    // text
+    if (cap = this.rules.text.exec(src)) {
+      src = src.substring(cap[0].length);
+      out += this.renderer.text(escape(this.smartypants(cap[0])));
+      continue;
+    }
+
+    if (src) {
+      throw new
+        Error('Infinite loop on byte: ' + src.charCodeAt(0));
+    }
+  }
+
+  return out;
+};
+
+/**
+ * Compile Link
+ */
+
+InlineLexer.prototype.outputLink = function(cap, link) {
+  var href = escape(link.href)
+    , title = link.title ? escape(link.title) : null;
+
+  return cap[0].charAt(0) !== '!'
+    ? this.renderer.link(href, title, this.output(cap[1]))
+    : this.renderer.image(href, title, escape(cap[1]));
+};
+
+/**
+ * Smartypants Transformations
+ */
+
+InlineLexer.prototype.smartypants = function(text) {
+  if (!this.options.smartypants) return text;
+  return text
+    // em-dashes
+    .replace(/---/g, '\u2014')
+    // en-dashes
+    .replace(/--/g, '\u2013')
+    // opening singles
+    .replace(/(^|[-\u2014/(\[{"\s])'/g, '$1\u2018')
+    // closing singles & apostrophes
+    .replace(/'/g, '\u2019')
+    // opening doubles
+    .replace(/(^|[-\u2014/(\[{\u2018\s])"/g, '$1\u201c')
+    // closing doubles
+    .replace(/"/g, '\u201d')
+    // ellipses
+    .replace(/\.{3}/g, '\u2026');
+};
+
+/**
+ * Mangle Links
+ */
+
+InlineLexer.prototype.mangle = function(text) {
+  if (!this.options.mangle) return text;
+  var out = ''
+    , l = text.length
+    , i = 0
+    , ch;
+
+  for (; i < l; i++) {
+    ch = text.charCodeAt(i);
+    if (Math.random() > 0.5) {
+      ch = 'x' + ch.toString(16);
+    }
+    out += '&#' + ch + ';';
+  }
+
+  return out;
+};
+
+/**
+ * Renderer
+ */
+
+function Renderer(options) {
+  this.options = options || { };
+}
+
+Renderer.prototype.code = function(code, lang, escaped) {
+  if (this.options.highlight) {
+    var out = this.options.highlight(code, lang);
+    if (out != null && out !== code) {
+      escaped = true;
+      code = out;
+    }
+  }
+
+  if (!lang) {
+    return '<pre><code>'
+      + (escaped ? code : escape(code, true))
+      + '\n</code></pre>';
+  }
+
+  return '<pre><code class="'
+    + this.options.langPrefix
+    + escape(lang, true)
+    + '">'
+    + (escaped ? code : escape(code, true))
+    + '\n</code></pre>\n';
+};
+
+Renderer.prototype.blockquote = function(quote) {
+  return '<blockquote>\n' + quote + '</blockquote>\n';
+};
+
+Renderer.prototype.html = function(html) {
+  return html;
+};
+
+Renderer.prototype.heading = function(text, level, raw) {
+  return '<h'
+    + level
+    + ' id="'
+    + this.options.headerPrefix
+    + raw.toLowerCase().replace(/[^\w]+/g, '-')
+    + '">'
+    + text
+    + '</h'
+    + level
+    + '>\n';
+};
+
+Renderer.prototype.hr = function() {
+  return this.options.xhtml ? '<hr/>\n' : '<hr>\n';
+};
+
+Renderer.prototype.list = function(body, ordered) {
+  var type = ordered ? 'ol' : 'ul';
+  return '<' + type + '>\n' + body + '</' + type + '>\n';
+};
+
+Renderer.prototype.listitem = function(text) {
+  return '<li>' + text + '</li>\n';
+};
+
+Renderer.prototype.paragraph = function(text) {
+  return '<p>' + text + '</p>\n';
+};
+
+Renderer.prototype.table = function(header, body) {
+  return '<table>\n'
+    + '<thead>\n'
+    + header
+    + '</thead>\n'
+    + '<tbody>\n'
+    + body
+    + '</tbody>\n'
+    + '</table>\n';
+};
+
+Renderer.prototype.tablerow = function(content) {
+  return '<tr>\n' + content + '</tr>\n';
+};
+
+Renderer.prototype.tablecell = function(content, flags) {
+  var type = flags.header ? 'th' : 'td';
+  var tag = flags.align
+    ? '<' + type + ' style="text-align:' + flags.align + '">'
+    : '<' + type + '>';
+  return tag + content + '</' + type + '>\n';
+};
+
+// span level renderer
+Renderer.prototype.strong = function(text) {
+  return '<strong>' + text + '</strong>';
+};
+
+Renderer.prototype.em = function(text) {
+  return '<em>' + text + '</em>';
+};
+
+Renderer.prototype.codespan = function(text) {
+  return '<code>' + text + '</code>';
+};
+
+Renderer.prototype.br = function() {
+  return this.options.xhtml ? '<br/>' : '<br>';
+};
+
+Renderer.prototype.del = function(text) {
+  return '<del>' + text + '</del>';
+};
+
+Renderer.prototype.link = function(href, title, text) {
+  if (this.options.sanitize) {
+    try {
+      var prot = decodeURIComponent(unescape(href))
+        .replace(/[^\w:]/g, '')
+        .toLowerCase();
+    } catch (e) {
+      return '';
+    }
+    if (prot.indexOf('javascript:') === 0 || prot.indexOf('vbscript:') === 0) {
+      return '';
+    }
+  }
+  var out = '<a href="' + href + '"';
+  if (title) {
+    out += ' title="' + title + '"';
+  }
+  out += '>' + text + '</a>';
+  return out;
+};
+
+Renderer.prototype.image = function(href, title, text) {
+  var out = '<img src="' + href + '" alt="' + text + '"';
+  if (title) {
+    out += ' title="' + title + '"';
+  }
+  out += this.options.xhtml ? '/>' : '>';
+  return out;
+};
+
+Renderer.prototype.text = function(text) {
+  return text;
+};
+
+/**
+ * Parsing & Compiling
+ */
+
+function Parser(options) {
+  this.tokens = [];
+  this.token = null;
+  this.options = options || marked.defaults;
+  this.options.renderer = this.options.renderer || new Renderer;
+  this.renderer = this.options.renderer;
+  this.renderer.options = this.options;
+}
+
+/**
+ * Static Parse Method
+ */
+
+Parser.parse = function(src, options, renderer) {
+  var parser = new Parser(options, renderer);
+  return parser.parse(src);
+};
+
+/**
+ * Parse Loop
+ */
+
+Parser.prototype.parse = function(src) {
+  this.inline = new InlineLexer(src.links, this.options, this.renderer);
+  this.tokens = src.reverse();
+
+  var out = '';
+  while (this.next()) {
+    out += this.tok();
+  }
+
+  return out;
+};
+
+/**
+ * Next Token
+ */
+
+Parser.prototype.next = function() {
+  return this.token = this.tokens.pop();
+};
+
+/**
+ * Preview Next Token
+ */
+
+Parser.prototype.peek = function() {
+  return this.tokens[this.tokens.length - 1] || 0;
+};
+
+/**
+ * Parse Text Tokens
+ */
+
+Parser.prototype.parseText = function() {
+  var body = this.token.text;
+
+  while (this.peek().type === 'text') {
+    body += '\n' + this.next().text;
+  }
+
+  return this.inline.output(body);
+};
+
+/**
+ * Parse Current Token
+ */
+
+Parser.prototype.tok = function() {
+  switch (this.token.type) {
+    case 'space': {
+      return '';
+    }
+    case 'hr': {
+      return this.renderer.hr();
+    }
+    case 'heading': {
+      return this.renderer.heading(
+        this.inline.output(this.token.text),
+        this.token.depth,
+        this.token.text);
+    }
+    case 'code': {
+      return this.renderer.code(this.token.text,
+        this.token.lang,
+        this.token.escaped);
+    }
+    case 'table': {
+      var header = ''
+        , body = ''
+        , i
+        , row
+        , cell
+        , flags
+        , j;
+
+      // header
+      cell = '';
+      for (i = 0; i < this.token.header.length; i++) {
+        flags = { header: true, align: this.token.align[i] };
+        cell += this.renderer.tablecell(
+          this.inline.output(this.token.header[i]),
+          { header: true, align: this.token.align[i] }
+        );
+      }
+      header += this.renderer.tablerow(cell);
+
+      for (i = 0; i < this.token.cells.length; i++) {
+        row = this.token.cells[i];
+
+        cell = '';
+        for (j = 0; j < row.length; j++) {
+          cell += this.renderer.tablecell(
+            this.inline.output(row[j]),
+            { header: false, align: this.token.align[j] }
+          );
+        }
+
+        body += this.renderer.tablerow(cell);
+      }
+      return this.renderer.table(header, body);
+    }
+    case 'blockquote_start': {
+      var body = '';
+
+      while (this.next().type !== 'blockquote_end') {
+        body += this.tok();
+      }
+
+      return this.renderer.blockquote(body);
+    }
+    case 'list_start': {
+      var body = ''
+        , ordered = this.token.ordered;
+
+      while (this.next().type !== 'list_end') {
+        body += this.tok();
+      }
+
+      return this.renderer.list(body, ordered);
+    }
+    case 'list_item_start': {
+      var body = '';
+
+      while (this.next().type !== 'list_item_end') {
+        body += this.token.type === 'text'
+          ? this.parseText()
+          : this.tok();
+      }
+
+      return this.renderer.listitem(body);
+    }
+    case 'loose_item_start': {
+      var body = '';
+
+      while (this.next().type !== 'list_item_end') {
+        body += this.tok();
+      }
+
+      return this.renderer.listitem(body);
+    }
+    case 'html': {
+      var html = !this.token.pre && !this.options.pedantic
+        ? this.inline.output(this.token.text)
+        : this.token.text;
+      return this.renderer.html(html);
+    }
+    case 'paragraph': {
+      return this.renderer.paragraph(this.inline.output(this.token.text));
+    }
+    case 'text': {
+      return this.renderer.paragraph(this.parseText());
+    }
+  }
+};
+
+/**
+ * Helpers
+ */
+
+function escape(html, encode) {
+  return html
+    .replace(!encode ? /&(?!#?\w+;)/g : /&/g, '&amp;')
+    .replace(/</g, '&lt;')
+    .replace(/>/g, '&gt;')
+    .replace(/"/g, '&quot;')
+    .replace(/'/g, '&#39;');
+}
+
+function unescape(html) {
+	// explicitly match decimal, hex, and named HTML entities
+  return html.replace(/&(#(?:\d+)|(?:#x[0-9A-Fa-f]+)|(?:\w+));?/g, function(_, n) {
+    n = n.toLowerCase();
+    if (n === 'colon') return ':';
+    if (n.charAt(0) === '#') {
+      return n.charAt(1) === 'x'
+        ? String.fromCharCode(parseInt(n.substring(2), 16))
+        : String.fromCharCode(+n.substring(1));
+    }
+    return '';
+  });
+}
+
+function replace(regex, opt) {
+  regex = regex.source;
+  opt = opt || '';
+  return function self(name, val) {
+    if (!name) return new RegExp(regex, opt);
+    val = val.source || val;
+    val = val.replace(/(^|[^\[])\^/g, '$1');
+    regex = regex.replace(name, val);
+    return self;
+  };
+}
+
+function noop() {}
+noop.exec = noop;
+
+function merge(obj) {
+  var i = 1
+    , target
+    , key;
+
+  for (; i < arguments.length; i++) {
+    target = arguments[i];
+    for (key in target) {
+      if (Object.prototype.hasOwnProperty.call(target, key)) {
+        obj[key] = target[key];
+      }
+    }
+  }
+
+  return obj;
+}
+
+
+/**
+ * Marked
+ */
+
+function marked(src, opt, callback) {
+  if (callback || typeof opt === 'function') {
+    if (!callback) {
+      callback = opt;
+      opt = null;
+    }
+
+    opt = merge({}, marked.defaults, opt || {});
+
+    var highlight = opt.highlight
+      , tokens
+      , pending
+      , i = 0;
+
+    try {
+      tokens = Lexer.lex(src, opt)
+    } catch (e) {
+      return callback(e);
+    }
+
+    pending = tokens.length;
+
+    var done = function(err) {
+      if (err) {
+        opt.highlight = highlight;
+        return callback(err);
+      }
+
+      var out;
+
+      try {
+        out = Parser.parse(tokens, opt);
+      } catch (e) {
+        err = e;
+      }
+
+      opt.highlight = highlight;
+
+      return err
+        ? callback(err)
+        : callback(null, out);
+    };
+
+    if (!highlight || highlight.length < 3) {
+      return done();
+    }
+
+    delete opt.highlight;
+
+    if (!pending) return done();
+
+    for (; i < tokens.length; i++) {
+      (function(token) {
+        if (token.type !== 'code') {
+          return --pending || done();
+        }
+        return highlight(token.text, token.lang, function(err, code) {
+          if (err) return done(err);
+          if (code == null || code === token.text) {
+            return --pending || done();
+          }
+          token.text = code;
+          token.escaped = true;
+          --pending || done();
+        });
+      })(tokens[i]);
+    }
+
+    return;
+  }
+  try {
+    if (opt) opt = merge({}, marked.defaults, opt);
+    return Parser.parse(Lexer.lex(src, opt), opt);
+  } catch (e) {
+    e.message += '\nPlease report this to https://github.com/chjj/marked.';
+    if ((opt || marked.defaults).silent) {
+      return '<p>An error occured:</p><pre>'
+        + escape(e.message + '', true)
+        + '</pre>';
+    }
+    throw e;
+  }
+}
+
+/**
+ * Options
+ */
+
+marked.options =
+marked.setOptions = function(opt) {
+  merge(marked.defaults, opt);
+  return marked;
+};
+
+marked.defaults = {
+  gfm: true,
+  tables: true,
+  breaks: false,
+  pedantic: false,
+  sanitize: false,
+  sanitizer: null,
+  mangle: true,
+  smartLists: false,
+  silent: false,
+  highlight: null,
+  langPrefix: 'lang-',
+  smartypants: false,
+  headerPrefix: '',
+  renderer: new Renderer,
+  xhtml: false
+};
+
+/**
+ * Expose
+ */
+
+marked.Parser = Parser;
+marked.parser = Parser.parse;
+
+marked.Renderer = Renderer;
+
+marked.Lexer = Lexer;
+marked.lexer = Lexer.lex;
+
+marked.InlineLexer = InlineLexer;
+marked.inlineLexer = InlineLexer.output;
+
+marked.parse = marked;
+
+if (typeof module !== 'undefined' && typeof exports === 'object') {
+  module.exports = marked;
+} else if (typeof define === 'function' && define.amd) {
+  define(function() { return marked; });
+} else {
+  this.marked = marked;
+}
+
+}).call(function() {
+  return this || (typeof window !== 'undefined' ? window : global);
+}());

+ 175 - 0
packages/ckeditor5-markdown-gfm/src/lib/marked/renderer.js

@@ -0,0 +1,175 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+/**
+ * Original marked.js library renderer with fixes:
+ * - no formatting for output HTML string - all newlines between tags are removed to create clean output,
+ * - changed long string concatenations to ES5 template strings,
+ * - changed code style.
+ *
+ * @see {@link https://github.com/chjj/marked#renderer} Methods description.
+ * @param options
+ * @constructor
+ */
+function Renderer( options ) {
+	this.options = options || {};
+}
+
+Renderer.prototype.code = function( code, lang, escaped ) {
+	if ( this.options.highlight ) {
+		const out = this.options.highlight( code, lang );
+
+		if ( out !== null && out !== code ) {
+			escaped = true;
+			code = out;
+		}
+	}
+
+	if ( !lang ) {
+		return `<pre><code>${ escaped ? code : escape( code, true ) }</code></pre>`;
+	}
+
+	const cssClass = this.options.langPrefix + escape( lang, true );
+
+	return `<pre><code class="${ cssClass }">${ escaped ? code : escape( code, true ) }</code></pre>`;
+};
+
+Renderer.prototype.blockquote = function( quote ) {
+	return `<blockquote>${ quote }</blockquote>`;
+};
+
+Renderer.prototype.html = function( html ) {
+	return html;
+};
+
+Renderer.prototype.heading = function( text, level, raw ) {
+	return `<h${ level }>${ text }</h${ level }>`;
+};
+
+Renderer.prototype.hr = function() {
+	return this.options.xhtml ? '<hr/>' : '<hr>';
+};
+
+Renderer.prototype.list = function( body, ordered ) {
+	const type = ordered ? 'ol' : 'ul';
+
+	return `<${ type }>${ body }</${ type }>`;
+};
+
+Renderer.prototype.listitem = function( text ) {
+	return `<li>${ text }</li>`;
+};
+
+Renderer.prototype.paragraph = function( text ) {
+	return `<p>${ text }</p>`;
+};
+
+Renderer.prototype.table = function( header, body ) {
+	return `<table><thead>${ header }</thead><tbody>${ body }</tbody></table>`;
+};
+
+Renderer.prototype.tablerow = function( content ) {
+	return '<tr>' + content + '</tr>';
+};
+
+Renderer.prototype.tablecell = function( content, flags ) {
+	const type = flags.header ? 'th' : 'td';
+	const tag = flags.align ? `<${ type } align="${ flags.align }">` : `<${ type }>`;
+
+	return tag + content + `</${ type }>`;
+};
+
+// span level renderer
+Renderer.prototype.strong = function( text ) {
+	return `<strong>${ text }</strong>`;
+};
+
+Renderer.prototype.em = function( text ) {
+	return `<em>${ text }</em>`;
+};
+
+Renderer.prototype.codespan = function( text ) {
+	return `<code>${ text.trim() }</code>`;
+};
+
+Renderer.prototype.br = function() {
+	return this.options.xhtml ? '<br/>' : '<br>';
+};
+
+Renderer.prototype.del = function( text ) {
+	return `<del>${ text }</del>`;
+};
+
+Renderer.prototype.link = function( href, title, text ) {
+	if ( this.options.sanitize ) {
+		let prot;
+
+		try {
+			prot = decodeURIComponent( unescape( href ) )
+				.replace( /[^\w:]/g, '' )
+				.toLowerCase();
+		} catch ( e ) {
+			return '';
+		}
+
+		if ( prot.indexOf( 'javascript:' ) === 0 || prot.indexOf( 'vbscript:' ) === 0 ) { // jshint ignore:line
+			return '';
+		}
+	}
+
+	let out = '<a href="' + href + '"';
+
+	if ( title ) {
+		out += ' title="' + title + '"';
+	}
+	out += '>' + text + '</a>';
+
+	return out;
+};
+
+Renderer.prototype.image = function( href, title, text ) {
+	let out = '<img src="' + href + '" alt="' + text + '"';
+
+	if ( title ) {
+		out += ' title="' + title + '"';
+	}
+	out += this.options.xhtml ? '/>' : '>';
+
+	return out;
+};
+
+Renderer.prototype.text = function( text ) {
+	return text;
+};
+
+export default Renderer;
+
+function escape( html, encode ) {
+	return html
+		.replace( !encode ? /&(?!#?\w+;)/g : /&/g, '&amp;' )
+		.replace( /</g, '&lt;' )
+		.replace( />/g, '&gt;' )
+		.replace( /"/g, '&quot;' )
+		.replace( /'/g, '&#39;' );
+}
+
+function unescape( html ) {
+	// explicitly match decimal, hex, and named HTML entities
+	return html.replace( /&(#(?:\d+)|(?:#x[0-9A-Fa-f]+)|(?:\w+));?/g, function( _, n ) {
+		n = n.toLowerCase();
+
+		if ( n === 'colon' ) {
+			return ':';
+		}
+
+		if ( n.charAt( 0 ) === '#' ) {
+			return n.charAt( 1 ) === 'x' ?
+				String.fromCharCode( parseInt( n.substring( 2 ), 16 ) ) :
+				String.fromCharCode( +n.substring( 1 ) ); // jscs:ignore
+		}
+
+		return '';
+	} );
+}

+ 68 - 0
packages/ckeditor5-markdown-gfm/src/lib/to-markdown/converters.js

@@ -0,0 +1,68 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+// Exports an array with custom converters used by to-markdown library.
+export default [
+	// Converting code blocks with class name matching output from marked library.
+	{
+		filter: ( node ) =>  {
+			const regexp = /lang-(.+)/;
+
+			return node.nodeName === 'PRE' &&
+				node.firstChild &&
+				node.firstChild.nodeName === 'CODE' &&
+				regexp.test( node.firstChild.className );
+		},
+		replacement: ( content, node ) => {
+			const regexp = /lang-(.+)/;
+			const lang = regexp.exec( node.firstChild.className )[ 1 ];
+
+			return '\n\n``` ' + lang + '\n' + node.firstChild.textContent + '\n```\n\n';
+		}
+	},
+	// Converting empty links.
+	{
+		filter: ( node ) => {
+			return node.nodeName === 'A' && !node.getAttribute( 'href' );
+		},
+
+		replacement: ( content, node ) => {
+			const title = node.title ? `"${node.title}"` : '';
+
+			return `[${ content }](${ title })`;
+		}
+	},
+	// Headers - fixing newline at the beginning.
+	{
+		filter: [ 'h1', 'h2', 'h3', 'h4', 'h5', 'h6' ],
+		replacement: ( content, node ) => {
+			const hLevel = node.nodeName.charAt( 1 );
+			let hPrefix = '';
+
+			for ( let i = 0; i < hLevel; i++ ) {
+				hPrefix += '#';
+			}
+
+			return hPrefix + ' ' + content;
+		}
+	},
+	// Inline code - fixing backticks inside code blocks.
+	{
+		filter: ( node ) => {
+			const hasSiblings = node.previousSibling || node.nextSibling;
+			const isCodeBlock = node.parentNode.nodeName === 'PRE' && !hasSiblings;
+
+			return node.nodeName === 'CODE' && !isCodeBlock;
+		},
+		replacement: ( content ) => {
+			// If content starts or ends with backtick - use double backtick.
+			if ( content.indexOf( '`' ) > -1 ) {
+				return '`` ' + content + ' ``';
+			}
+
+			return '`' + content + '`';
+		}
+	}
+];

+ 785 - 0
packages/ckeditor5-markdown-gfm/src/lib/to-markdown/to-markdown.js

@@ -0,0 +1,785 @@
+(function(f){if(typeof exports==="object"&&typeof module!=="undefined"){module.exports=f()}else if(typeof define==="function"&&define.amd){define([],f)}else{var g;if(typeof window!=="undefined"){g=window}else if(typeof global!=="undefined"){g=global}else if(typeof self!=="undefined"){g=self}else{g=this}g.toMarkdown = f()}})(function(){var define,module,exports;return (function e(t,n,r){function s(o,u){if(!n[o]){if(!t[o]){var a=typeof require=="function"&&require;if(!u&&a)return a(o,!0);if(i)return i(o,!0);var f=new Error("Cannot find module '"+o+"'");throw f.code="MODULE_NOT_FOUND",f}var l=n[o]={exports:{}};t[o][0].call(l.exports,function(e){var n=t[o][1][e];return s(n?n:e)},l,l.exports,e,t,n,r)}return n[o].exports}var i=typeof require=="function"&&require;for(var o=0;o<r.length;o++)s(r[o]);return s})({1:[function(require,module,exports){
+	/*
+	 * to-markdown - an HTML to Markdown converter
+	 *
+	 * Copyright 2011+, Dom Christie
+	 * Licenced under the MIT licence
+	 *
+	 */
+
+	'use strict'
+
+	var toMarkdown
+	var converters
+	var mdConverters = require('./lib/md-converters')
+	var gfmConverters = require('./lib/gfm-converters')
+	var HtmlParser = require('./lib/html-parser')
+	var collapse = require('collapse-whitespace')
+
+	/*
+	 * Utilities
+	 */
+
+	var blocks = ['address', 'article', 'aside', 'audio', 'blockquote', 'body',
+		'canvas', 'center', 'dd', 'dir', 'div', 'dl', 'dt', 'fieldset', 'figcaption',
+		'figure', 'footer', 'form', 'frameset', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6',
+		'header', 'hgroup', 'hr', 'html', 'isindex', 'li', 'main', 'menu', 'nav',
+		'noframes', 'noscript', 'ol', 'output', 'p', 'pre', 'section', 'table',
+		'tbody', 'td', 'tfoot', 'th', 'thead', 'tr', 'ul'
+	]
+
+	function isBlock (node) {
+		return blocks.indexOf(node.nodeName.toLowerCase()) !== -1
+	}
+
+	var voids = [
+		'area', 'base', 'br', 'col', 'command', 'embed', 'hr', 'img', 'input',
+		'keygen', 'link', 'meta', 'param', 'source', 'track', 'wbr'
+	]
+
+	function isVoid (node) {
+		return voids.indexOf(node.nodeName.toLowerCase()) !== -1
+	}
+
+	function htmlToDom (string) {
+		var tree = new HtmlParser().parseFromString(string, 'text/html')
+		collapse(tree.documentElement, isBlock)
+		return tree
+	}
+
+	/*
+	 * Flattens DOM tree into single array
+	 */
+
+	function bfsOrder (node) {
+		var inqueue = [node]
+		var outqueue = []
+		var elem
+		var children
+		var i
+
+		while (inqueue.length > 0) {
+			elem = inqueue.shift()
+			outqueue.push(elem)
+			children = elem.childNodes
+			for (i = 0; i < children.length; i++) {
+				if (children[i].nodeType === 1) inqueue.push(children[i])
+			}
+		}
+		outqueue.shift()
+		return outqueue
+	}
+
+	/*
+	 * Contructs a Markdown string of replacement text for a given node
+	 */
+
+	function getContent (node) {
+		var text = ''
+		for (var i = 0; i < node.childNodes.length; i++) {
+			if (node.childNodes[i].nodeType === 1) {
+				text += node.childNodes[i]._replacement
+			} else if (node.childNodes[i].nodeType === 3) {
+				text += node.childNodes[i].data
+			} else continue
+		}
+		return text
+	}
+
+	/*
+	 * Returns the HTML string of an element with its contents converted
+	 */
+
+	function outer (node, content) {
+		return node.cloneNode(false).outerHTML.replace('><', '>' + content + '<')
+	}
+
+	function canConvert (node, filter) {
+		if (typeof filter === 'string') {
+			return filter === node.nodeName.toLowerCase()
+		}
+		if (Array.isArray(filter)) {
+			return filter.indexOf(node.nodeName.toLowerCase()) !== -1
+		} else if (typeof filter === 'function') {
+			return filter.call(toMarkdown, node)
+		} else {
+			throw new TypeError('`filter` needs to be a string, array, or function')
+		}
+	}
+
+	function isFlankedByWhitespace (side, node) {
+		var sibling
+		var regExp
+		var isFlanked
+
+		if (side === 'left') {
+			sibling = node.previousSibling
+			regExp = / $/
+		} else {
+			sibling = node.nextSibling
+			regExp = /^ /
+		}
+
+		if (sibling) {
+			if (sibling.nodeType === 3) {
+				isFlanked = regExp.test(sibling.nodeValue)
+			} else if (sibling.nodeType === 1 && !isBlock(sibling)) {
+				isFlanked = regExp.test(sibling.textContent)
+			}
+		}
+		return isFlanked
+	}
+
+	function flankingWhitespace (node) {
+		var leading = ''
+		var trailing = ''
+
+		if (!isBlock(node)) {
+			var hasLeading = /^[ \r\n\t]/.test(node.innerHTML)
+			var hasTrailing = /[ \r\n\t]$/.test(node.innerHTML)
+
+			if (hasLeading && !isFlankedByWhitespace('left', node)) {
+				leading = ' '
+			}
+			if (hasTrailing && !isFlankedByWhitespace('right', node)) {
+				trailing = ' '
+			}
+		}
+
+		return { leading: leading, trailing: trailing }
+	}
+
+	/*
+	 * Finds a Markdown converter, gets the replacement, and sets it on
+	 * `_replacement`
+	 */
+
+	function process (node) {
+		var replacement
+		var content = getContent(node)
+
+		// Remove blank nodes
+		if (!isVoid(node) && !/A|TH|TD/.test(node.nodeName) && /^\s*$/i.test(content)) {
+			node._replacement = ''
+			return
+		}
+
+		for (var i = 0; i < converters.length; i++) {
+			var converter = converters[i]
+
+			if (canConvert(node, converter.filter)) {
+				if (typeof converter.replacement !== 'function') {
+					throw new TypeError(
+						'`replacement` needs to be a function that returns a string'
+					)
+				}
+
+				var whitespace = flankingWhitespace(node)
+
+				if (whitespace.leading || whitespace.trailing) {
+					content = content.trim()
+				}
+				replacement = whitespace.leading +
+					converter.replacement.call(toMarkdown, content, node) +
+					whitespace.trailing
+				break
+			}
+		}
+
+		node._replacement = replacement
+	}
+
+	toMarkdown = function (input, options) {
+		options = options || {}
+
+		if (typeof input !== 'string') {
+			throw new TypeError(input + ' is not a string')
+		}
+
+		// Escape potential ol triggers
+		input = input.replace(/(\d+)\. /g, '$1\\. ')
+
+		var clone = htmlToDom(input).body
+		var nodes = bfsOrder(clone)
+		var output
+
+		converters = mdConverters.slice(0)
+		if (options.gfm) {
+			converters = gfmConverters.concat(converters)
+		}
+
+		if (options.converters) {
+			converters = options.converters.concat(converters)
+		}
+
+		// Process through nodes in reverse (so deepest child elements are first).
+		for (var i = nodes.length - 1; i >= 0; i--) {
+			process(nodes[i])
+		}
+		output = getContent(clone)
+
+		return output.replace(/^[\t\r\n]+|[\t\r\n\s]+$/g, '')
+			.replace(/\n\s+\n/g, '\n\n')
+			.replace(/\n{3,}/g, '\n\n')
+	}
+
+	toMarkdown.isBlock = isBlock
+	toMarkdown.isVoid = isVoid
+	toMarkdown.outer = outer
+
+	module.exports = toMarkdown
+
+},{"./lib/gfm-converters":2,"./lib/html-parser":3,"./lib/md-converters":4,"collapse-whitespace":7}],2:[function(require,module,exports){
+	'use strict'
+
+	function cell (content, node) {
+		var index = Array.prototype.indexOf.call(node.parentNode.childNodes, node)
+		var prefix = ' '
+		if (index === 0) prefix = '| '
+		return prefix + content + ' |'
+	}
+
+	var highlightRegEx = /highlight highlight-(\S+)/
+
+	module.exports = [
+		{
+			filter: 'br',
+			replacement: function () {
+				return '\n'
+			}
+		},
+		{
+			filter: ['del', 's', 'strike'],
+			replacement: function (content) {
+				return '~~' + content + '~~'
+			}
+		},
+
+		{
+			filter: function (node) {
+				return node.type === 'checkbox' && node.parentNode.nodeName === 'LI'
+			},
+			replacement: function (content, node) {
+				return (node.checked ? '[x]' : '[ ]') + ' '
+			}
+		},
+
+		{
+			filter: ['th', 'td'],
+			replacement: function (content, node) {
+				return cell(content, node)
+			}
+		},
+
+		{
+			filter: 'tr',
+			replacement: function (content, node) {
+				var borderCells = ''
+				var alignMap = { left: ':--', right: '--:', center: ':-:' }
+
+				if (node.parentNode.nodeName === 'THEAD') {
+					for (var i = 0; i < node.childNodes.length; i++) {
+						var align = node.childNodes[i].attributes.align
+						var border = '---'
+
+						if (align) border = alignMap[align.value] || border
+
+						borderCells += cell(border, node.childNodes[i])
+					}
+				}
+				return '\n' + content + (borderCells ? '\n' + borderCells : '')
+			}
+		},
+
+		{
+			filter: 'table',
+			replacement: function (content) {
+				return '\n\n' + content + '\n\n'
+			}
+		},
+
+		{
+			filter: ['thead', 'tbody', 'tfoot'],
+			replacement: function (content) {
+				return content
+			}
+		},
+
+		// Fenced code blocks
+		{
+			filter: function (node) {
+				return node.nodeName === 'PRE' &&
+					node.firstChild &&
+					node.firstChild.nodeName === 'CODE'
+			},
+			replacement: function (content, node) {
+				return '\n\n```\n' + node.firstChild.textContent + '\n```\n\n'
+			}
+		},
+
+		// Syntax-highlighted code blocks
+		{
+			filter: function (node) {
+				return node.nodeName === 'PRE' &&
+					node.parentNode.nodeName === 'DIV' &&
+					highlightRegEx.test(node.parentNode.className)
+			},
+			replacement: function (content, node) {
+				var language = node.parentNode.className.match(highlightRegEx)[1]
+				return '\n\n```' + language + '\n' + node.textContent + '\n```\n\n'
+			}
+		},
+
+		{
+			filter: function (node) {
+				return node.nodeName === 'DIV' &&
+					highlightRegEx.test(node.className)
+			},
+			replacement: function (content) {
+				return '\n\n' + content + '\n\n'
+			}
+		}
+	]
+
+},{}],3:[function(require,module,exports){
+	/*
+	 * Set up window for Node.js
+	 */
+
+	var _window = (typeof window !== 'undefined' ? window : this)
+
+	/*
+	 * Parsing HTML strings
+	 */
+
+	function canParseHtmlNatively () {
+		var Parser = _window.DOMParser
+		var canParse = false
+
+		// Adapted from https://gist.github.com/1129031
+		// Firefox/Opera/IE throw errors on unsupported types
+		try {
+			// WebKit returns null on unsupported types
+			if (new Parser().parseFromString('', 'text/html')) {
+				canParse = true
+			}
+		} catch (e) {}
+
+		return canParse
+	}
+
+	function createHtmlParser () {
+		var Parser = function () {}
+
+		// For Node.js environments
+		if (typeof document === 'undefined') {
+			var jsdom = require('jsdom')
+			Parser.prototype.parseFromString = function (string) {
+				return jsdom.jsdom(string, {
+					features: {
+						FetchExternalResources: [],
+						ProcessExternalResources: false
+					}
+				})
+			}
+		} else {
+			if (!shouldUseActiveX()) {
+				Parser.prototype.parseFromString = function (string) {
+					var doc = document.implementation.createHTMLDocument('')
+					doc.open()
+					doc.write(string)
+					doc.close()
+					return doc
+				}
+			} else {
+				Parser.prototype.parseFromString = function (string) {
+					var doc = new window.ActiveXObject('htmlfile')
+					doc.designMode = 'on' // disable on-page scripts
+					doc.open()
+					doc.write(string)
+					doc.close()
+					return doc
+				}
+			}
+		}
+		return Parser
+	}
+
+	function shouldUseActiveX () {
+		var useActiveX = false
+
+		try {
+			document.implementation.createHTMLDocument('').open()
+		} catch (e) {
+			if (window.ActiveXObject) useActiveX = true
+		}
+
+		return useActiveX
+	}
+
+	module.exports = canParseHtmlNatively() ? _window.DOMParser : createHtmlParser()
+
+},{"jsdom":6}],4:[function(require,module,exports){
+	'use strict'
+
+	module.exports = [
+		{
+			filter: 'p',
+			replacement: function (content) {
+				return '\n\n' + content + '\n\n'
+			}
+		},
+
+		{
+			filter: 'br',
+			replacement: function () {
+				return '  \n'
+			}
+		},
+
+		{
+			filter: ['h1', 'h2', 'h3', 'h4', 'h5', 'h6'],
+			replacement: function (content, node) {
+				var hLevel = node.nodeName.charAt(1)
+				var hPrefix = ''
+				for (var i = 0; i < hLevel; i++) {
+					hPrefix += '#'
+				}
+				return '\n\n' + hPrefix + ' ' + content + '\n\n'
+			}
+		},
+
+		{
+			filter: 'hr',
+			replacement: function () {
+				return '\n\n* * *\n\n'
+			}
+		},
+
+		{
+			filter: ['em', 'i'],
+			replacement: function (content) {
+				return '_' + content + '_'
+			}
+		},
+
+		{
+			filter: ['strong', 'b'],
+			replacement: function (content) {
+				return '**' + content + '**'
+			}
+		},
+
+		// Inline code
+		{
+			filter: function (node) {
+				var hasSiblings = node.previousSibling || node.nextSibling
+				var isCodeBlock = node.parentNode.nodeName === 'PRE' && !hasSiblings
+
+				return node.nodeName === 'CODE' && !isCodeBlock
+			},
+			replacement: function (content) {
+				return '`' + content + '`'
+			}
+		},
+
+		{
+			filter: function (node) {
+				return node.nodeName === 'A' && node.getAttribute('href')
+			},
+			replacement: function (content, node) {
+				var titlePart = node.title ? ' "' + node.title + '"' : ''
+				return '[' + content + '](' + node.getAttribute('href') + titlePart + ')'
+			}
+		},
+
+		{
+			filter: 'img',
+			replacement: function (content, node) {
+				var alt = node.alt || ''
+				var src = node.getAttribute('src') || ''
+				var title = node.title || ''
+				var titlePart = title ? ' "' + title + '"' : ''
+				return src ? '![' + alt + ']' + '(' + src + titlePart + ')' : ''
+			}
+		},
+
+		// Code blocks
+		{
+			filter: function (node) {
+				return node.nodeName === 'PRE' && node.firstChild.nodeName === 'CODE'
+			},
+			replacement: function (content, node) {
+				return '\n\n    ' + node.firstChild.textContent.replace(/\n/g, '\n    ') + '\n\n'
+			}
+		},
+
+		{
+			filter: 'blockquote',
+			replacement: function (content) {
+				content = content.trim()
+				content = content.replace(/\n{3,}/g, '\n\n')
+				content = content.replace(/^/gm, '> ')
+				return '\n\n' + content + '\n\n'
+			}
+		},
+
+		{
+			filter: 'li',
+			replacement: function (content, node) {
+				content = content.replace(/^\s+/, '').replace(/\n/gm, '\n    ')
+				var prefix = '*   '
+				var parent = node.parentNode
+				var index = Array.prototype.indexOf.call(parent.children, node) + 1
+
+				prefix = /ol/i.test(parent.nodeName) ? index + '.  ' : '*   '
+				return prefix + content
+			}
+		},
+
+		{
+			filter: ['ul', 'ol'],
+			replacement: function (content, node) {
+				var strings = []
+				for (var i = 0; i < node.childNodes.length; i++) {
+					strings.push(node.childNodes[i]._replacement)
+				}
+
+				if (/li/i.test(node.parentNode.nodeName)) {
+					return '\n' + strings.join('\n')
+				}
+				return '\n\n' + strings.join('\n') + '\n\n'
+			}
+		},
+
+		{
+			filter: function (node) {
+				return this.isBlock(node)
+			},
+			replacement: function (content, node) {
+				return '\n\n' + this.outer(node, content) + '\n\n'
+			}
+		},
+
+		// Anything else!
+		{
+			filter: function () {
+				return true
+			},
+			replacement: function (content, node) {
+				return this.outer(node, content)
+			}
+		}
+	]
+
+},{}],5:[function(require,module,exports){
+	/**
+	 * This file automatically generated from `build.js`.
+	 * Do not manually edit.
+	 */
+
+	module.exports = [
+		"address",
+		"article",
+		"aside",
+		"audio",
+		"blockquote",
+		"canvas",
+		"dd",
+		"div",
+		"dl",
+		"fieldset",
+		"figcaption",
+		"figure",
+		"footer",
+		"form",
+		"h1",
+		"h2",
+		"h3",
+		"h4",
+		"h5",
+		"h6",
+		"header",
+		"hgroup",
+		"hr",
+		"main",
+		"nav",
+		"noscript",
+		"ol",
+		"output",
+		"p",
+		"pre",
+		"section",
+		"table",
+		"tfoot",
+		"ul",
+		"video"
+	];
+
+},{}],6:[function(require,module,exports){
+
+},{}],7:[function(require,module,exports){
+	'use strict';
+
+	var voidElements = require('void-elements');
+	Object.keys(voidElements).forEach(function (name) {
+		voidElements[name.toUpperCase()] = 1;
+	});
+
+	var blockElements = {};
+	require('block-elements').forEach(function (name) {
+		blockElements[name.toUpperCase()] = 1;
+	});
+
+	/**
+	 * isBlockElem(node) determines if the given node is a block element.
+	 *
+	 * @param {Node} node
+	 * @return {Boolean}
+	 */
+	function isBlockElem(node) {
+		return !!(node && blockElements[node.nodeName]);
+	}
+
+	/**
+	 * isVoid(node) determines if the given node is a void element.
+	 *
+	 * @param {Node} node
+	 * @return {Boolean}
+	 */
+	function isVoid(node) {
+		return !!(node && voidElements[node.nodeName]);
+	}
+
+	/**
+	 * whitespace(elem [, isBlock]) removes extraneous whitespace from an
+	 * the given element. The function isBlock may optionally be passed in
+	 * to determine whether or not an element is a block element; if none
+	 * is provided, defaults to using the list of block elements provided
+	 * by the `block-elements` module.
+	 *
+	 * @param {Node} elem
+	 * @param {Function} blockTest
+	 */
+	function collapseWhitespace(elem, isBlock) {
+		if (!elem.firstChild || elem.nodeName === 'PRE') return;
+
+		if (typeof isBlock !== 'function') {
+			isBlock = isBlockElem;
+		}
+
+		var prevText = null;
+		var prevVoid = false;
+
+		var prev = null;
+		var node = next(prev, elem);
+
+		while (node !== elem) {
+			if (node.nodeType === 3) {
+				// Node.TEXT_NODE
+				var text = node.data.replace(/[ \r\n\t]+/g, ' ');
+
+				if ((!prevText || / $/.test(prevText.data)) && !prevVoid && text[0] === ' ') {
+					text = text.substr(1);
+				}
+
+				// `text` might be empty at this point.
+				if (!text) {
+					node = remove(node);
+					continue;
+				}
+
+				node.data = text;
+				prevText = node;
+			} else if (node.nodeType === 1) {
+				// Node.ELEMENT_NODE
+				if (isBlock(node) || node.nodeName === 'BR') {
+					if (prevText) {
+						prevText.data = prevText.data.replace(/ $/, '');
+					}
+
+					prevText = null;
+					prevVoid = false;
+				} else if (isVoid(node)) {
+					// Avoid trimming space around non-block, non-BR void elements.
+					prevText = null;
+					prevVoid = true;
+				}
+			} else {
+				node = remove(node);
+				continue;
+			}
+
+			var nextNode = next(prev, node);
+			prev = node;
+			node = nextNode;
+		}
+
+		if (prevText) {
+			prevText.data = prevText.data.replace(/ $/, '');
+			if (!prevText.data) {
+				remove(prevText);
+			}
+		}
+	}
+
+	/**
+	 * remove(node) removes the given node from the DOM and returns the
+	 * next node in the sequence.
+	 *
+	 * @param {Node} node
+	 * @return {Node} node
+	 */
+	function remove(node) {
+		var next = node.nextSibling || node.parentNode;
+
+		node.parentNode.removeChild(node);
+
+		return next;
+	}
+
+	/**
+	 * next(prev, current) returns the next node in the sequence, given the
+	 * current and previous nodes.
+	 *
+	 * @param {Node} prev
+	 * @param {Node} current
+	 * @return {Node}
+	 */
+	function next(prev, current) {
+		if (prev && prev.parentNode === current || current.nodeName === 'PRE') {
+			return current.nextSibling || current.parentNode;
+		}
+
+		return current.firstChild || current.nextSibling || current.parentNode;
+	}
+
+	module.exports = collapseWhitespace;
+
+},{"block-elements":5,"void-elements":8}],8:[function(require,module,exports){
+	/**
+	 * This file automatically generated from `pre-publish.js`.
+	 * Do not manually edit.
+	 */
+
+	module.exports = {
+		"area": true,
+		"base": true,
+		"br": true,
+		"col": true,
+		"embed": true,
+		"hr": true,
+		"img": true,
+		"input": true,
+		"keygen": true,
+		"link": true,
+		"menuitem": true,
+		"meta": true,
+		"param": true,
+		"source": true,
+		"track": true,
+		"wbr": true
+	};
+
+},{}]},{},[1])(1)
+});

+ 23 - 0
packages/ckeditor5-markdown-gfm/tests/_utils/utils.js

@@ -0,0 +1,23 @@
+import { stringify } from '/ckeditor5/engine/dev-utils/view.js';
+import MarkdownDataProcessor from '/ckeditor5/markdown-gfm/gfmdataprocessor.js';
+
+/**
+ * Tests MarkdownDataProcessor.
+ *
+ * @param {String} markdown Markdown to be processed to view.
+ * @param {String} viewString Expected view structure.
+ * @param {String} [normalizedMarkdown] When converting back to the markdown it might be different than provided input
+ * markdown string (which will be used if this parameter is not provided).
+ */
+export function testDataProcessor( markdown, viewString, normalizedMarkdown ) {
+	const dataProcessor = new MarkdownDataProcessor();
+	const viewFragment = dataProcessor.toView( markdown );
+
+	// Check if view has correct data.
+	expect( stringify( viewFragment ) ).to.equal( viewString );
+
+	// Check if converting back gives the same result.
+	const normalized = typeof normalizedMarkdown !== 'undefined' ? normalizedMarkdown : markdown;
+
+	expect( dataProcessor.toData( viewFragment ) ).to.equal( normalized );
+}

+ 175 - 0
packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/blockquotes.js

@@ -0,0 +1,175 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import { testDataProcessor as test } from '/tests/markdown-gfm/_utils/utils.js';
+
+describe( 'GFMDataProcessor', () => {
+	describe( 'blockquotes', () => {
+		it( 'should process single blockquotes', () => {
+			test(
+				'> foo bar',
+
+				// GitHub is rendering as:
+				//
+				// <blockquote>
+				// <p>foo bar</p>
+				// </blockquote>
+				'<blockquote><p>foo bar</p></blockquote>'
+			);
+		} );
+
+		it( 'should process nested blockquotes', () => {
+			test(
+				'> foo\n' +
+				'> \n' +
+				'> > bar\n' +
+				'> \n' +
+				'> foo',
+
+				// GitHub is rendering as:
+				// <blockquote>
+				// <p>foo</p>
+				//
+				// <blockquote>
+				// <p>bar</p>
+				// </blockquote>
+				//
+				// <p>foo</p>
+				// </blockquote>
+				'<blockquote>' +
+					'<p>foo</p>' +
+					'<blockquote>' +
+						'<p>bar</p>' +
+					'</blockquote>' +
+					'<p>foo</p>' +
+				'</blockquote>'
+			);
+		} );
+
+		it( 'should process list within a blockquote', () => {
+			test(
+				'> A list within a blockquote:\n' +
+				'> \n' +
+				'> *   asterisk 1\n' +
+				'> *   asterisk 2\n' +
+				'> *   asterisk 3',
+
+				// GitHub is rendering as:
+				// <blockquote>
+				// <p>A list within a blockquote:</p>
+				//
+				// <ul>
+				// <li>asterisk 1</li>
+				// <li>asterisk 2</li>
+				// <li>asterisk 3</li>
+				// </ul>
+				// </blockquote>
+				'<blockquote>' +
+					'<p>A list within a blockquote:</p>' +
+					'<ul>' +
+						'<li>asterisk 1</li>' +
+						'<li>asterisk 2</li>' +
+						'<li>asterisk 3</li>' +
+					'</ul>' +
+				'</blockquote>'
+			);
+		} );
+
+		it( 'should process blockquotes with code inside with ```', () => {
+			test(
+				'> Example 1:\n' +
+				'> \n' +
+				'> ```\n' +
+				'> code 1\n' +
+				'> ```\n' +
+				'> \n' +
+				'> Example 2:\n' +
+				'> \n' +
+				'> ```\n' +
+				'> code 2\n' +
+				'> ```',
+
+				// GitHub is rendering as:
+				// <blockquote>
+				// <p>Example 1:</p>
+				//
+				// <pre><code>code 1
+				// </code></pre>
+				//
+				// <p>Example 2:</p>
+				//
+				// <pre><code>code 2
+				// </code></pre>
+				// </blockquote>
+				'<blockquote>' +
+					'<p>Example 1:</p>' +
+					'<pre>' +
+						'<code>' +
+							'code 1' +
+						'</code>' +
+					'</pre>' +
+					'<p>Example 2:</p>' +
+					'<pre>' +
+						'<code>' +
+							'code 2' +
+						'</code>' +
+					'</pre>' +
+				'</blockquote>'
+			);
+		} );
+
+		it( 'should process blockquotes with code inside with tabs', () => {
+			test(
+				'> Example 1:\n' +
+				'>\n' +
+				'>     code 1\n' +
+				'>\n' +
+				'> Example 2:\n' +
+				'>\n' +
+				'>     code 2\n',
+
+				// GitHub is rendering as:
+				// <blockquote>
+				// <p>Example 1:</p>
+				//
+				// <pre><code>code 1
+				// </code></pre>
+				//
+				// <p>Example 2:</p>
+				//
+				// <pre><code>code 2
+				// </code></pre>
+				// </blockquote>
+				'<blockquote>' +
+					'<p>Example 1:</p>' +
+					'<pre>' +
+						'<code>' +
+							'code 1' +
+						'</code>' +
+					'</pre>' +
+					'<p>Example 2:</p>' +
+					'<pre>' +
+						'<code>' +
+							'code 2' +
+						'</code>' +
+					'</pre>' +
+				'</blockquote>',
+
+				// When converting back to data, DataProcessor will normalize tabs to ```.
+				'> Example 1:\n' +
+				'> \n' +
+				'> ```\n' +
+				'> code 1\n' +
+				'> ```\n' +
+				'> \n' +
+				'> Example 2:\n' +
+				'> \n' +
+				'> ```\n' +
+				'> code 2\n' +
+				'> ```'
+			);
+		} );
+	} );
+} );

+ 280 - 0
packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/code.js

@@ -0,0 +1,280 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import { testDataProcessor as test } from '/tests/markdown-gfm/_utils/utils.js';
+
+describe( 'GFMDataProcessor', () => {
+	describe( 'code', () => {
+		it( 'should process inline code', () => {
+			test(
+				'regular text and `inline code`',
+
+				'<p>regular text and <code>inline code</code></p>'
+			);
+		} );
+
+		it( 'should properly process multiple code', () => {
+			test(
+				'`this is code` and this is `too`',
+
+				'<p><code>this is code</code> and this is <code>too</code></p>'
+			);
+		} );
+
+		it( 'should process spaces inside inline code', () => {
+			test(
+				'regular text and` inline code`',
+
+				'<p>regular text and<code>inline code</code></p>',
+
+				// When converting back it will be normalized and spaces
+				// at the beginning of inline code will be removed.
+				'regular text and`inline code`'
+			);
+		} );
+
+		it( 'should properly process backticks inside code spans #1', () => {
+			test(
+				'`` `backticks` ``',
+
+				'<p><code>`backticks`</code></p>'
+			);
+		} );
+
+		it( 'should properly process backticks inside code spans #2', () => {
+			test(
+				'`` some `backticks` inside ``',
+
+				'<p><code>some `backticks` inside</code></p>'
+			);
+		} );
+
+		it( 'should process code blocks indented with tabs', () => {
+			test(
+				'	code block',
+
+				// GitHub is rendering as:
+				// <pre><code>code block
+				// </code></pre>
+				'<pre><code>code block</code></pre>',
+
+				// When converting back tabs are normalized to ```.
+				'```\n' +
+				'code block\n' +
+				'```'
+			);
+		} );
+
+		it( 'should process code blocks indented with spaces', () => {
+			test(
+				'    code block',
+
+				// GitHub is rendering as:
+				// <pre><code>code block
+				// </code></pre>
+
+				'<pre><code>code block</code></pre>',
+
+				// When converting back tabs are normalized to ```.
+
+				'```\n' +
+				'code block\n' +
+				'```'
+			);
+		} );
+
+		it( 'should process multi line code blocks indented with tabs', () => {
+			test(
+				'	first line\n' +
+				'	second line',
+
+				// GitHub is rendering as:
+				// <pre><code>first line
+				// second line
+				// </code></pre>
+
+				'<pre><code>first line\n' +
+				'second line</code></pre>',
+
+				// When converting back tabs are normalized to ```.
+
+				'```\n' +
+				'first line\n' +
+				'second line\n' +
+				'```'
+			);
+		} );
+
+		it( 'should process multi line code blocks indented with spaces', () => {
+			test(
+				'    first line\n' +
+				'    second line',
+
+				// GitHub is rendering as:
+				// <pre><code>first line
+				// second line
+				// </code></pre>
+
+				'<pre><code>first line\n' +
+				'second line</code></pre>',
+
+				// When converting back spaces are normalized to ```.
+
+				'```\n' +
+				'first line\n' +
+				'second line\n' +
+				'```'
+			);
+		} );
+
+		it( 'should process multi line code blocks with trailing spaces', () => {
+			test(
+				'	the lines in this block  \n' +
+				'	all contain trailing spaces  ',
+
+				// GitHub is rendering as:
+				// <pre><code>the lines in this block
+				// all contain trailing spaces
+				// </code></pre>
+
+				'<pre><code>the lines in this block  \n' +
+				'all contain trailing spaces  </code></pre>',
+
+				// When converting back tabs are normalized to ```.
+				'```\n' +
+				'the lines in this block  \n' +
+				'all contain trailing spaces  \n' +
+				'```'
+			);
+		} );
+
+		it( 'should process code block with language name', () => {
+			test(
+				'``` js\n' +
+				'var a = \'hello\';\n' +
+				'console.log(a + \' world\');\n' +
+				'```',
+
+				// GitHub is rendering as special html with syntax highlighting.
+				// We will need to handle this separately by some feature.
+
+				'<pre><code class="lang-js">var a = \'hello\';\n' +
+				'console.log(a + \' world\');</code></pre>'
+			);
+		} );
+
+		it( 'should process code block with language name and using ~~~ as delimiter', () => {
+			test(
+				'~~~ bash\n' +
+				'#!/bin/bash\n' +
+				'~~~',
+
+				// GitHub is rendering as special html with syntax highlighting.
+				// We will need to handle this separately by some feature.
+
+				'<pre><code class="lang-bash">#!/bin/bash</code></pre>',
+
+				// When converting back ~~~ are normalized to ```.
+
+				'``` bash\n' +
+				'#!/bin/bash\n' +
+				'```'
+			);
+		} );
+
+		it( 'should process code block with language name and using ``````` as delimiter', () => {
+			test(
+				'``````` js\n' +
+				'var a = \'hello\';\n' +
+				'console.log(a + \' world\');\n' +
+				'```````',
+
+				// GitHub is rendering as special html with syntax highlighting.
+				// We will need to handle this separately by some feature.
+
+				'<pre><code class="lang-js">var a = \'hello\';\n' +
+				'console.log(a + \' world\');</code></pre>',
+
+				// When converting back ``````` are normalized to ```.
+
+				'``` js\n' +
+				'var a = \'hello\';\n' +
+				'console.log(a + \' world\');\n' +
+				'```'
+			);
+		} );
+
+		it( 'should process code block with language name and using ~~~~~~~~~~ as delimiter', () => {
+			test(
+				'~~~~~~~~~~ js\n' +
+				'var a = \'hello\';\n' +
+				'console.log(a + \' world\');\n' +
+				'~~~~~~~~~~',
+
+				// GitHub is rendering as special html with syntax highlighting.
+				// We will need to handle this separately by some feature.
+
+				'<pre><code class="lang-js">var a = \'hello\';\n' +
+				'console.log(a + \' world\');</code></pre>',
+
+				// When converting back ~~~~~~~~~~ are normalized to ```.
+
+				'``` js\n' +
+				'var a = \'hello\';\n' +
+				'console.log(a + \' world\');\n' +
+				'```'
+			);
+		} );
+
+		it( 'should process empty code block', () => {
+			test(
+				'``` js\n' +
+				'```',
+
+				// GitHub is rendering as special html with syntax highlighting.
+				// We will need to handle this separately by some feature.
+
+				'<pre><code class="lang-js"></code></pre>',
+
+				// When converting back, empty code blocks will be removed.
+				// This might be an issue when switching from source to editor
+				// but changing this cannot be done in to-markdown converters.
+				''
+			);
+		} );
+
+		it( 'should process code block with empty line', () => {
+			test(
+				'``` js\n' +
+				'\n' +
+				'```',
+
+				// GitHub is rendering as special html with syntax highlighting.
+				// We will need to handle this separately by some feature.
+
+				'<pre><code class="lang-js"></code></pre>',
+
+				// When converting back, empty code blocks will be removed.
+				// This might be an issue when switching from source to editor
+				// but changing this cannot be done in to-markdown converters.
+				''
+			);
+		} );
+
+		it( 'should process nested code', () => {
+			test(
+				'````` code `` code ``` `````',
+
+				// GitHub is rendering as:
+				// <p><code>code `` code ```</code></p>
+
+				'<p><code>code `` code ```</code></p>',
+
+				// When converting back ````` will be normalized to ``.
+				'`` code `` code ``` ``'
+			);
+		} );
+	} );
+} );

+ 71 - 0
packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/escaping.js

@@ -0,0 +1,71 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import MarkdownDataProcessor from '/ckeditor5/markdown-gfm/gfmdataprocessor.js';
+import { stringify } from '/ckeditor5/engine/dev-utils/view.js';
+
+const testCases = {
+	'backslash': { test: '\\\\', result: '\\' },
+	'underscore': { test: '\\_', result: '_' },
+	'left brace': { test: '\\{', result: '{' },
+	'right brace': { test: '\\}', result: '}' },
+	'left bracket': { test: '\\[', result: '[' },
+	'right bracket': { test: '\\]', result: ']' },
+	'left paren': { test: '\\(', result: '(' },
+	'right paren': { test: '\\)', result: ')' },
+	'greater than': { test: '\\>', result: '>' },
+	'hash': { test: '\\#', result: '#' },
+	'peroid': { test: '\\.', result: '.' },
+	'exclamation mark': { test: '\\!', result: '!' },
+	'plus': { test: '\\+', result: '+' },
+	'minus': { test: '\\-', result: '-' },
+};
+
+describe( 'GFMDataProcessor', () => {
+	let dataProcessor;
+
+	beforeEach( () => {
+		dataProcessor = new MarkdownDataProcessor();
+	} );
+
+	describe( 'escaping', () => {
+		describe( 'toView', () => {
+			for ( let key in testCases ) {
+				const test = testCases[ key ].test;
+				const result = testCases[ key ].result;
+
+				it( `should escape ${key}`, () => {
+					const documentFragment = dataProcessor.toView( test );
+
+					expect( stringify( documentFragment ) ).to.equal( `<p>${ result }</p>` );
+				} );
+
+				it( `should not escape ${key} in code blocks`, () => {
+					const documentFragment = dataProcessor.toView( `	${ test }` );
+
+					expect( stringify( documentFragment ) ).to.equal( `<pre><code>${ test }</code></pre>` );
+				} );
+
+				it( `should not escape ${key} in code spans`, () => {
+					const documentFragment = dataProcessor.toView( '`' + test + '`' );
+
+					expect( stringify( documentFragment ) ).to.equal( `<p><code>${ test }</code></p>` );
+				} );
+			}
+
+			it( 'should escape backtick', () => {
+				const documentFragment = dataProcessor.toView( '\\`' );
+
+				expect( stringify( documentFragment ) ).to.equal( '<p>`</p>' );
+			} );
+
+			it( 'should not escape backtick in code blocks', () => {
+				const documentFragment = dataProcessor.toView( '	\\`' );
+
+				expect( stringify( documentFragment ) ).to.equal( '<pre><code>\\`</code></pre>' );
+			} );
+		} );
+	} );
+} );

+ 93 - 0
packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/headers.js

@@ -0,0 +1,93 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import { testDataProcessor as test } from '/tests/markdown-gfm/_utils/utils.js';
+
+describe( 'GFMDataProcessor', () => {
+	describe( 'headers', () => {
+		it( 'should process level 1 header #1', () => {
+			test(
+				'# Level 1',
+
+				'<h1>Level 1</h1>'
+			);
+		} );
+
+		it( 'should process level 1 header #2', () => {
+			test(
+				'Level 1\n' +
+				'===',
+
+				'<h1>Level 1</h1>',
+
+				// When converting back it will be normalized to # representation.
+				'# Level 1'
+			);
+		} );
+
+		it( 'should process level 2 header #1', () => {
+			test(
+				'## Level 2',
+
+				'<h2>Level 2</h2>'
+			);
+		} );
+
+		it( 'should process level 2 header #2', () => {
+			test(
+				'Level 2\n' +
+				'---',
+
+				'<h2>Level 2</h2>',
+
+				// When converting back it will be normalized to ## representation.
+				'## Level 2'
+			);
+		} );
+
+		it( 'should process level 3 header', () => {
+			test(
+				'### Level 3',
+
+				'<h3>Level 3</h3>'
+			);
+		} );
+
+		it( 'should process level 4 header', () => {
+			test(
+				'#### Level 4',
+
+				'<h4>Level 4</h4>'
+			);
+		} );
+
+		it( 'should process level 5 header', () => {
+			test(
+				'##### Level 5',
+
+				'<h5>Level 5</h5>'
+			);
+		} );
+
+		it( 'should process level 6 header', () => {
+			test(
+				'###### Level 6',
+
+				'<h6>Level 6</h6>'
+			);
+		} );
+
+		it( 'should create header when more spaces before text', () => {
+			test(
+				'#      Level 1',
+
+				'<h1>Level 1</h1>',
+
+				// When converting back it will be normalized to # Level 1.
+				'# Level 1'
+			);
+		} );
+	} );
+} );

+ 204 - 0
packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/horizontal-rules.js

@@ -0,0 +1,204 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import { testDataProcessor as test } from '/tests/markdown-gfm/_utils/utils.js';
+
+describe( 'GFMDataProcessor', () => {
+	// Horizontal rules are are always rendered by GitHub as <hr> and normalized when converting
+	// back to * * *.
+	describe( 'horizontal rules', () => {
+		describe( 'dashes', () => {
+			it( '#1', () => {
+				test( '---', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#2', () => {
+				test( ' ---', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#3', () => {
+				test( '  ---', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#4', () => {
+				test( '   ---', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#5 - code', () => {
+				test(
+					'    ---',
+
+					// Four spaces are interpreted as code block.
+					'<pre><code>---</code></pre>',
+
+					// Code block will be normalized to ``` representation.
+					'```\n' +
+					'---\n' +
+					'```'
+				);
+			} );
+		} );
+
+		describe( 'dashes with spaces', () => {
+			it( '#1', () => {
+				test( '- - -', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#2', () => {
+				test( ' - - -', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#3', () => {
+				test( '  - - -', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#4', () => {
+				test( '   - - -', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#5 - code', () => {
+				test(
+					'    - - -',
+
+					// Four spaces are interpreted as code block.
+					'<pre><code>- - -</code></pre>',
+
+					// Code block will be normalized to ``` representation.
+					'```\n' +
+					'- - -\n' +
+					'```'
+				);
+			} );
+		} );
+
+		describe( 'asterisks', () => {
+			it( '#1', () => {
+				test( '***', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#2', () => {
+				test( ' ***', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#3', () => {
+				test( '  ***', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#4', () => {
+				test( '   ***', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#5 - code', () => {
+				test(
+					'    ***',
+
+					// Four spaces are interpreted as code block.
+					'<pre><code>***</code></pre>',
+
+					// Code block will be normalized to ``` representation.
+					'```\n' +
+					'***\n' +
+					'```'
+				);
+			} );
+		} );
+
+		describe( 'asterisks with spaces', () => {
+			it( '#1', () => {
+				test( '* * *', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#2', () => {
+				test( ' * * *', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#3', () => {
+				test( '  * * *', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#4', () => {
+				test( '   * * *', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#5 - code', () => {
+				test(
+					'    * * *',
+
+					// Four spaces are interpreted as code block.
+					'<pre><code>* * *</code></pre>',
+
+					// Code block will be normalized to ``` representation.
+					'```\n' +
+					'* * *\n' +
+					'```'
+				);
+			} );
+		} );
+
+		describe( 'underscores', () => {
+			it( '#1', () => {
+				test( '___', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#2', () => {
+				test( ' ___', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#3', () => {
+				test( '  ___', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#4', () => {
+				test( '   ___', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#5 - code', () => {
+				test(
+					'    ___',
+
+					// Four spaces are interpreted as code block.
+					'<pre><code>___</code></pre>',
+
+					// Code block will be normalized to ``` representation.
+					'```\n' +
+					'___\n' +
+					'```'
+				);
+			} );
+		} );
+
+		describe( 'underscores with spaces', () => {
+			it( '#1', () => {
+				test( '_ _ _', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#2', () => {
+				test( ' _ _ _', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#3', () => {
+				test( '  _ _ _', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#4', () => {
+				test( '   _ _ _', '<hr></hr>', '* * *' );
+			} );
+
+			it( '#5 - code', () => {
+				test(
+					'    _ _ _',
+
+					// Four spaces are interpreted as code block.
+					'<pre><code>_ _ _</code></pre>',
+
+					// Code block will be normalized to ``` representation.
+					'```\n' +
+					'_ _ _\n' +
+					'```'
+				);
+			} );
+		} );
+	} );
+} );

+ 72 - 0
packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/images.js

@@ -0,0 +1,72 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import { testDataProcessor as test } from '/tests/markdown-gfm/_utils/utils.js';
+
+describe( 'GFMDataProcessor', () => {
+	describe( 'images', () => {
+		it( 'should process images', () => {
+			test(
+				'![alt text](http://example.com/image.png "title text")',
+
+				// GitHub is rendering as:
+				// <p><a href="..." target="_blank"><img src="..." alt="..." title="..." data-canonical-src="..."></a></p>
+				// We will handle images separately by features.
+				'<p><img alt="alt text" src="http://example.com/image.png" title="title text"></img></p>'
+
+			);
+		} );
+
+		it( 'should process images without title', () => {
+			test(
+				'![alt text](http://example.com/image.png)',
+				'<p><img alt="alt text" src="http://example.com/image.png"></img></p>'
+			);
+		} );
+
+		it( 'should process images without alt text', () => {
+			test(
+				'![](http://example.com/image.png "title text")',
+				'<p><img alt="" src="http://example.com/image.png" title="title text"></img></p>'
+			);
+		} );
+
+		it( 'should process referenced images', () => {
+			test(
+				'![alt text][logo]\n' +
+				'[logo]: http://example.com/image.png "title text"',
+
+				'<p><img alt="alt text" src="http://example.com/image.png" title="title text"></img></p>',
+
+				// Referenced images when converting back are converted to direct links.
+				'![alt text](http://example.com/image.png "title text")'
+			);
+		} );
+
+		it( 'should process referenced images without title', () => {
+			test(
+				'![alt text][logo]\n' +
+				'[logo]: http://example.com/image.png',
+
+				'<p><img alt="alt text" src="http://example.com/image.png"></img></p>',
+
+				// Referenced images when converting back are converted to direct links.
+				'![alt text](http://example.com/image.png)'
+			);
+		} );
+
+		it( 'should process referenced images without alt text', () => {
+			test(
+				'![][logo]\n' +
+				'[logo]: http://example.com/image.png "title text"',
+
+				'<p><img alt="" src="http://example.com/image.png" title="title text"></img></p>',
+
+				// Referenced images when converting back are converted to direct links.
+				'![](http://example.com/image.png "title text")'
+			);
+		} );
+	} );
+} );

+ 428 - 0
packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/links.js

@@ -0,0 +1,428 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import { testDataProcessor as test } from '/tests/markdown-gfm/_utils/utils.js';
+
+describe( 'GFMDataProcessor', () => {
+	describe( 'links', () => {
+		it( 'should autolink', () => {
+			test(
+				'Link: <http://example.com/>.',
+				'<p>Link: <a href="http://example.com/">http://example.com/</a>.</p>',
+
+				// When converting back it will be represented as standard markdown link.
+				'Link: [http://example.com/](http://example.com/).'
+			);
+		} );
+
+		it( 'should autolink #2', () => {
+			test(
+				'Link: http://example.com/.',
+				'<p>Link: <a href="http://example.com/">http://example.com/</a>.</p>',
+
+				// When converting back it will be represented as standard markdown link.
+				'Link: [http://example.com/](http://example.com/).'
+			);
+		} );
+
+		it( 'should autolink with params', () => {
+			test(
+				'Link: <http://example.com/?foo=1&bar=2>.',
+				'<p>Link: <a href="http://example.com/?foo=1&bar=2">http://example.com/?foo=1&bar=2</a>.</p>',
+
+				// When converting back it will be represented as standard markdown link.
+				'Link: [http://example.com/?foo=1&bar=2](http://example.com/?foo=1&bar=2).'
+			);
+		} );
+
+		it( 'should autolink inside list', () => {
+			test(
+				'* <http://example.com/>',
+
+				'<ul><li><a href="http://example.com/">http://example.com/</a></li></ul>',
+
+				// When converting back it will be represented as standard markdown link.
+				'*   [http://example.com/](http://example.com/)'
+			);
+		} );
+
+		it( 'should autolink inside blockquote', () => {
+			test(
+				'> Blockquoted: <http://example.com/>',
+
+				'<blockquote>' +
+				'<p>Blockquoted: <a href="http://example.com/">http://example.com/</a></p>' +
+				'</blockquote>',
+
+				// When converting back it will be represented as standard markdown link.
+				'> Blockquoted: [http://example.com/](http://example.com/)'
+			);
+		} );
+
+		it( 'should not autolink inside inline code', () => {
+			test(
+				'`<http://example.com/>`',
+				'<p><code><http://example.com/></code></p>'
+			);
+		} );
+
+		it( 'should not autolink inside code block', () => {
+			test(
+				'	<http://example.com/>',
+				'<pre><code><http://example.com/></code></pre>',
+
+				// When converting back, code block will be normalized to ```.
+				'```\n' +
+				'<http://example.com/>\n' +
+				'```'
+			);
+		} );
+
+		it( 'should not process already linked #1', () => {
+			test(
+				'Already linked: [http://example.com/](http://example.com/)',
+				'<p>Already linked: <a href="http://example.com/">http://example.com/</a></p>'
+			);
+		} );
+
+		it( 'should not process already linked #2', () => {
+			test(
+				'Already linked: [**http://example.com/**](http://example.com/)',
+				'<p>Already linked: <a href="http://example.com/"><strong>http://example.com/</strong></a></p>'
+			);
+		} );
+
+		it( 'should process inline links', () => {
+			test(
+				'[URL](/url/)',
+				'<p><a href="/url/">URL</a></p>'
+			);
+		} );
+
+		it( 'should process inline links with title', () => {
+			test(
+				'[URL and title](/url/ "title")',
+				'<p><a href="/url/" title="title">URL and title</a></p>'
+			);
+		} );
+
+		it( 'should process inline links with title preceded by two spaces', () => {
+			test(
+				'[URL and title](/url/  "title preceded by two spaces")',
+				'<p><a href="/url/" title="title preceded by two spaces">URL and title</a></p>',
+
+				// When converting back spaces will be normalized to one space.
+				'[URL and title](/url/ "title preceded by two spaces")'
+			);
+		} );
+
+		it( 'should process inline links with title preceded by tab', () => {
+			test(
+				'[URL and title](/url/	"title preceded by tab")',
+				'<p><a href="/url/" title="title preceded by tab">URL and title</a></p>',
+
+				// When converting back tab will be normalized to one space.
+				'[URL and title](/url/ "title preceded by tab")'
+			);
+		} );
+
+		it( 'should process inline links with title that has spaces afterwards', () => {
+			test(
+				'[URL and title](/url/ "title has spaces afterward"  )',
+				'<p><a href="/url/" title="title has spaces afterward">URL and title</a></p>',
+
+				// When converting back spaces will be removed.
+				'[URL and title](/url/ "title has spaces afterward")'
+			);
+		} );
+
+		it( 'should process inline links with spaces in URL', () => {
+			test(
+				'[URL and title]( /url/has space )',
+				'<p><a href="/url/has space">URL and title</a></p>',
+
+				// When converting back unneeded spaces will be removed.
+				'[URL and title](/url/has space)'
+			);
+		} );
+
+		it( 'should process inline links with titles and spaces in URL', () => {
+			test(
+				'[URL and title]( /url/has space/ "url has space and title")',
+				'<p><a href="/url/has space/" title="url has space and title">URL and title</a></p>',
+
+				// When converting back unneeded spaces will be removed.
+				'[URL and title](/url/has space/ "url has space and title")'
+			);
+		} );
+
+		it( 'should process empty link', () => {
+			test(
+				'[Empty]()',
+
+				'<p><a href="">Empty</a></p>'
+			);
+		} );
+
+		it( 'should process reference links', () => {
+			test(
+				'Foo [bar] [1].\n' +
+				'[1]: /url/  "Title"',
+
+				'<p>Foo <a href="/url/" title="Title">bar</a>.</p>',
+
+				// After converting back reference links will be converted to normal links.
+				// This might be a problem when switching between source and editor.
+				'Foo [bar](/url/ "Title").'
+			);
+		} );
+
+		it( 'should process reference links - without space', () => {
+			test(
+				'Foo [bar][1].\n' +
+				'[1]: /url/  "Title"',
+
+				'<p>Foo <a href="/url/" title="Title">bar</a>.</p>',
+
+				'Foo [bar](/url/ "Title").'
+			);
+		} );
+
+		it( 'should process reference links - with newline', () => {
+			test(
+				'Foo [bar]\n' +
+				'[1].\n' +
+				'[1]: /url/  "Title"',
+
+				'<p>Foo <a href="/url/" title="Title">bar</a>.</p>',
+
+				'Foo [bar](/url/ "Title").'
+			);
+		} );
+
+		it( 'should process reference links - with embedded brackets', () => {
+			test(
+				'With [embedded [brackets]] [b].\n' +
+				'[b]: /url/',
+
+				'<p>With <a href="/url/">embedded [brackets]</a>.</p>',
+
+				'With [embedded [brackets]](/url/).'
+			);
+		} );
+
+		it( 'should process reference links - with reference indented once', () => {
+			test(
+				'Indented [once][].\n' +
+				' [once]: /url',
+
+				'<p>Indented <a href="/url">once</a>.</p>',
+
+				'Indented [once](/url).'
+			);
+		} );
+
+		it( 'should process reference links - with reference indented twice', () => {
+			test(
+				'Indented [twice][].\n' +
+				'  [twice]: /url',
+
+				'<p>Indented <a href="/url">twice</a>.</p>',
+
+				'Indented [twice](/url).'
+			);
+		} );
+
+		it( 'should process reference links - with reference indented three times', () => {
+			test(
+				'Indented [trice][].\n' +
+				'   [trice]: /url',
+
+				'<p>Indented <a href="/url">trice</a>.</p>',
+
+				'Indented [trice](/url).'
+			);
+		} );
+
+		it( 'should NOT process reference links - with reference indented four times', () => {
+			test(
+				'Indented [four][].\n' +
+				'    [four]: /url',
+
+				// GitHub renders it as:
+				// <p>Indented [four][].<br>
+				// [four]: /url</p>
+				// Marked converts it to the code block.
+				'<p>Indented [four][].</p><pre><code>[four]: /url</code></pre>',
+
+				'Indented [four][].\n' +
+				'\n' +
+				'```\n' +
+				'[four]: /url\n' +
+				'```'
+			);
+		} );
+
+		it( 'should process reference links when title and reference are same #1', () => {
+			test(
+				'[this] [this]\n' +
+				'[this]: foo',
+
+				'<p><a href="foo">this</a></p>',
+
+				'[this](foo)'
+			);
+		} );
+
+		it( 'should process reference links when title and reference are same #2', () => {
+			test(
+				'[this][this]\n' +
+				'[this]: foo',
+
+				'<p><a href="foo">this</a></p>',
+
+				'[this](foo)'
+			);
+		} );
+
+		it( 'should process reference links when only title is provided and is same as reference #1', () => {
+			test(
+				'[this] []\n' +
+				'[this]: foo',
+
+				'<p><a href="foo">this</a></p>',
+
+				'[this](foo)'
+			);
+		} );
+
+		it( 'should process reference links when only title is provided and is same as reference #2', () => {
+			test(
+				'[this][]\n' +
+				'[this]: foo',
+
+				'<p><a href="foo">this</a></p>',
+
+				'[this](foo)'
+			);
+		} );
+
+		it( 'should process reference links when only title is provided and is same as reference #3', () => {
+			test(
+				'[this]\n' +
+				'[this]: foo',
+
+				'<p><a href="foo">this</a></p>',
+
+				'[this](foo)'
+			);
+		} );
+
+		it( 'should not process reference links when reference is not found #1', () => {
+			test(
+				'[this] []',
+
+				'<p>[this] []</p>'
+			);
+		} );
+
+		it( 'should not process reference links when reference is not found #2', () => {
+			test(
+				'[this][]',
+
+				'<p>[this][]</p>'
+			);
+		} );
+
+		it( 'should not process reference links when reference is not found #2', () => {
+			test(
+				'[this]',
+
+				'<p>[this]</p>'
+			);
+		} );
+
+		it( 'should process reference links nested in brackets #1', () => {
+			test(
+				'[a reference inside [this][]]\n' +
+				'[this]: foo',
+
+				'<p>[a reference inside <a href="foo">this</a>]</p>',
+
+				'[a reference inside [this](foo)]'
+			);
+		} );
+
+		it( 'should process reference links nested in brackets #2', () => {
+			test(
+				'[a reference inside [this]]\n' +
+				'[this]: foo',
+
+				'<p>[a reference inside <a href="foo">this</a>]</p>',
+
+				'[a reference inside [this](foo)]'
+			);
+		} );
+
+		it( 'should not process reference links when title is same as reference but reference is different', () => {
+			test(
+				'[this](/something/else/)\n' +
+				'[this]: foo',
+
+				'<p><a href="/something/else/">this</a></p>',
+
+				'[this](/something/else/)'
+			);
+		} );
+
+		it( 'should not process reference links suppressed by backslashes', () => {
+			test(
+				'Suppress \\[this] and [this\\].\n' +
+				'[this]: foo',
+
+				'<p>Suppress [this] and [this].</p>',
+
+				'Suppress [this] and [this].'
+			);
+		} );
+
+		it( 'should process reference links when used across multiple lines #1', () => {
+			test(
+				'This is [multiline\n' +
+				'reference]\n' +
+				'[multiline reference]: foo',
+
+				'<p>This is <a href="foo">multiline<br></br>reference</a></p>',
+
+				'This is [multiline\n' +
+				'reference](foo)'
+			);
+		} );
+
+		it( 'should process reference links when used across multiple lines #2', () => {
+			test(
+				'This is [multiline \n' +
+				'reference]\n' +
+				'[multiline reference]: foo',
+
+				'<p>This is <a href="foo">multiline<br></br>reference</a></p>',
+
+				'This is [multiline\n' +
+				'reference](foo)'
+			);
+		} );
+
+		it( 'should process reference links case-insensitive', () => {
+			test(
+				'[hi]\n' +
+				'[HI]: /url',
+
+				'<p><a href="/url">hi</a></p>',
+
+				'[hi](/url)'
+			);
+		} );
+	} );
+} );

+ 343 - 0
packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/lists.js

@@ -0,0 +1,343 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import { testDataProcessor as test } from '/tests/markdown-gfm/_utils/utils.js';
+
+describe( 'GFMDataProcessor', () => {
+	describe( 'lists', () => {
+		it( 'should process tight asterisks', () => {
+			test(
+				'*	item 1\n' +
+				'*	item 2\n' +
+				'*	item 3',
+
+				// GitHub renders it as (notice spaces before list items)
+				// <ul>
+				// <li>  item 1</li>
+				// <li>  item 2</li>
+				// <li>  item 3</li>
+				// </ul>
+				'<ul><li>item 1</li><li>item 2</li><li>item 3</li></ul>',
+
+				// List will be normalized to 3-space representation.
+				'*   item 1\n' +
+				'*   item 2\n' +
+				'*   item 3'
+			);
+		} );
+
+		it( 'should process loose asterisks', () => {
+			test(
+				'*	item 1\n' +
+				'\n' +
+				'*	item 2\n' +
+				'\n' +
+				'*	item 3',
+
+				// Loose lists are rendered with with paragraph inside.
+				'<ul>' +
+					'<li>' +
+						'<p>item 1</p>' +
+					'</li>' +
+					'<li>' +
+						'<p>item 2</p>' +
+					'</li>' +
+					'<li>' +
+						'<p>item 3</p>' +
+					'</li>' +
+				'</ul>',
+
+				// List will be normalized to 3-space representation.
+				'*   item 1\n' +
+				'\n' +
+				'*   item 2\n' +
+				'\n' +
+				'*   item 3'
+			);
+		} );
+
+		it( 'should process tight pluses', () => {
+			test(
+				'+	item 1\n' +
+				'+	item 2\n' +
+				'+	item 3',
+
+				'<ul>' +
+					'<li>item 1</li>' +
+					'<li>item 2</li>' +
+					'<li>item 3</li>' +
+				'</ul>',
+
+				// List will be normalized to asterisks, 3-space representation.
+				'*   item 1\n' +
+				'*   item 2\n' +
+				'*   item 3'
+			);
+		} );
+
+		it( 'should process loose pluses', () => {
+			test(
+				'+	item 1\n' +
+				'\n' +
+				'+	item 2\n' +
+				'\n' +
+				'+	item 3',
+
+				'<ul>' +
+					'<li>' +
+						'<p>item 1</p>' +
+					'</li>' +
+					'<li>' +
+						'<p>item 2</p>' +
+					'</li>' +
+					'<li>' +
+						'<p>item 3</p>' +
+					'</li>' +
+				'</ul>',
+
+				// List will be normalized to asterisks, 3-space representation.
+				'*   item 1\n' +
+				'\n' +
+				'*   item 2\n' +
+				'\n' +
+				'*   item 3'
+			);
+		} );
+
+		it( 'should process tight minuses', () => {
+			test(
+				'-	item 1\n' +
+				'-	item 2\n' +
+				'-	item 3',
+
+				'<ul>' +
+					'<li>item 1</li>' +
+					'<li>item 2</li>' +
+					'<li>item 3</li>' +
+				'</ul>',
+
+				// List will be normalized to asterisks, 3-space representation.
+				'*   item 1\n' +
+				'*   item 2\n' +
+				'*   item 3'
+			);
+		} );
+
+		it( 'should process loose minuses', () => {
+			test(
+				'-	item 1\n' +
+				'\n' +
+				'-	item 2\n' +
+				'\n' +
+				'-	item 3' ,
+
+				'<ul>' +
+					'<li>' +
+						'<p>item 1</p>' +
+					'</li>' +
+					'<li>' +
+						'<p>item 2</p>' +
+					'</li>' +
+					'<li>' +
+						'<p>item 3</p>' +
+					'</li>' +
+				'</ul>',
+
+				// List will be normalized to asterisks, 3-space representation.
+				'*   item 1\n' +
+				'\n' +
+				'*   item 2\n' +
+				'\n' +
+				'*   item 3'
+			);
+		} );
+
+		it( 'should process ordered list with tabs', () => {
+			test(
+				'1.	item 1\n' +
+				'2.	item 2\n' +
+				'3.	item 3',
+
+				'<ol>' +
+					'<li>item 1</li>' +
+					'<li>item 2</li>' +
+					'<li>item 3</li>' +
+				'</ol>',
+
+				// List will be normalized to 2-space representation.
+				'1.  item 1\n' +
+				'2.  item 2\n' +
+				'3.  item 3'
+			);
+		} );
+
+		it( 'should process ordered list with spaces', () => {
+			test(
+				'1. item 1\n' +
+				'2. item 2\n' +
+				'3. item 3',
+
+				'<ol>' +
+					'<li>item 1</li>' +
+					'<li>item 2</li>' +
+					'<li>item 3</li>' +
+				'</ol>',
+
+				// List will be normalized to 2-space representation.
+				'1.  item 1\n' +
+				'2.  item 2\n' +
+				'3.  item 3'
+			);
+		} );
+
+		it( 'should process loose ordered list with tabs', () => {
+			test(
+				'1.	item 1\n' +
+				'\n' +
+				'2.	item 2\n' +
+				'\n' +
+				'3.	item 3',
+
+				'<ol>' +
+					'<li>' +
+						'<p>item 1</p>' +
+					'</li>' +
+					'<li>' +
+						'<p>item 2</p>' +
+					'</li>' +
+					'<li>' +
+						'<p>item 3</p>' +
+					'</li>' +
+				'</ol>',
+
+				// List will be normalized to 2-space representation.
+				'1.  item 1\n' +
+				'\n' +
+				'2.  item 2\n' +
+				'\n' +
+				'3.  item 3'
+			);
+		} );
+
+		it( 'should process loose ordered list with spaces', () => {
+			test(
+				'1. item 1\n' +
+				'\n' +
+				'2. item 2\n' +
+				'\n' +
+				'3. item 3',
+
+				'<ol>' +
+					'<li>' +
+						'<p>item 1</p>' +
+					'</li>' +
+					'<li>' +
+						'<p>item 2</p>' +
+					'</li>' +
+					'<li>' +
+						'<p>item 3</p>' +
+					'</li>' +
+				'</ol>',
+
+				// List will be normalized to 2-space representation.
+				'1.  item 1\n' +
+				'\n' +
+				'2.  item 2\n' +
+				'\n' +
+				'3.  item 3'
+			);
+		} );
+
+		it( 'should process nested and mixed lists', () => {
+			test(
+				'1. First\n' +
+				'2. Second:\n' +
+				'	* Fee\n' +
+				'	* Fie\n' +
+				'	* Foe\n' +
+				'3. Third',
+
+				'<ol>' +
+					'<li>First</li>' +
+					'<li>Second:' +
+						'<ul>' +
+							'<li>Fee</li>' +
+							'<li>Fie</li>' +
+							'<li>Foe</li>' +
+						'</ul>' +
+					'</li>' +
+					'<li>Third</li>' +
+				'</ol>',
+
+				// All lists will be normalized after converting back.
+				'1.  First\n' +
+				'2.  Second:\n' +
+				'    *   Fee\n' +
+				'    *   Fie\n' +
+				'    *   Foe\n' +
+				'3.  Third'
+			);
+		} );
+
+		it( 'should process nested and mixed loose lists', () => {
+			test(
+				'1. First\n' +
+				'\n' +
+				'2. Second:\n' +
+				'	* Fee\n' +
+				'	* Fie\n' +
+				'	* Foe\n' +
+				'\n' +
+				'3. Third',
+
+				'<ol>' +
+					'<li>' +
+						'<p>First</p>' +
+					'</li>' +
+					'<li>' +
+						'<p>Second:</p>' +
+						'<ul>' +
+							'<li>Fee</li>' +
+							'<li>Fie</li>' +
+							'<li>Foe</li>' +
+						'</ul>' +
+					'</li>' +
+					'<li>' +
+						'<p>Third</p>' +
+					'</li>' +
+				'</ol>',
+
+				// All lists will be normalized after converting back.
+				'1.  First\n' +
+				'\n' +
+				'2.  Second:\n' +
+				'\n' +
+				'    *   Fee\n' +
+				'    *   Fie\n' +
+				'    *   Foe\n' +
+				'3.  Third'
+			);
+		} );
+
+		it( 'should create same bullet from different list indicators', () => {
+			test(
+				'* test\n' +
+				'+ test\n' +
+				'- test',
+
+				'<ul>' +
+					'<li>test</li>' +
+					'<li>test</li>' +
+					'<li>test</li>' +
+				'</ul>',
+
+				// After converting back list items will be unified.
+				'*   test\n' +
+				'*   test\n' +
+				'*   test'
+			);
+		} );
+	} );
+} );

+ 126 - 0
packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/paragraphs.js

@@ -0,0 +1,126 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import { testDataProcessor as test } from '/tests/markdown-gfm/_utils/utils.js';
+
+describe( 'GFMDataProcessor', () => {
+	describe( 'paragraphs', () => {
+		it( 'single line', () => {
+			test(
+				'single line paragraph',
+
+				'<p>single line paragraph</p>'
+			);
+		} );
+
+		it( 'multiline', () => {
+			test(
+				'first\n' +
+				'second\n' +
+				'third',
+
+				// GitHub is rendering as:
+				// <p>first<br>
+				// second<br>
+				// third</p>
+				'<p>first<br></br>second<br></br>third</p>'
+			);
+		} );
+
+		it( 'with header after #1', () => {
+			test(
+				'single line\n' +
+				'# header',
+
+				// GitHub is rendering as:
+				// <p>single line</p>
+				//
+				//<h1>header</h1>
+				'<p>single line</p><h1>header</h1>',
+
+				// To-markdown always put 2 empty lines after paragraph.
+				'single line\n\n' +
+				'# header'
+			);
+		} );
+
+		it( 'with header after #2', () => {
+			test(
+				'single line\n' +
+				'header\n' +
+				'===',
+
+				// GitHub is rendering as:
+				// <p>single line</p>
+				//
+				//<h1>header</h1>
+				'<p>single line</p><h1>header</h1>',
+
+				// To-markdown always put 2 empty lines after paragraph and normalize header to #.
+				'single line\n' +
+				'\n' +
+				'# header'
+			);
+		} );
+
+		it( 'with blockquote after', () => {
+			test(
+				'single line' +
+				'\n> quote',
+
+				// GitHub is rendereing as:
+				// <p>single line</p>
+				//
+				// <blockquote>
+				// <p>quote</p>
+				// </blockquote>
+				'<p>single line</p><blockquote><p>quote</p></blockquote>',
+
+				// To-markdown always put 2 empty lines after paragraph.
+				'single line\n' +
+				'\n' +
+				'> quote'
+			);
+		} );
+
+		it( 'with list after', () => {
+			test(
+				'single line\n' +
+				'* item',
+
+				// GitHub is rendering as:
+				// <p>single line</p>
+				//
+				// <ul>
+				// <li>item</li>
+				// </ul>
+				'<p>single line</p><ul><li>item</li></ul>',
+
+				// To-markdown always put 2 empty lines after paragraph.
+				'single line\n' +
+				'\n' +
+				'*   item'
+			);
+		} );
+
+		it( 'with div element after', () => {
+			test(
+				'single line\n' +
+				'<div>div element</div>',
+
+				// GitHub is rendering as:
+				// <p>single line</p>
+				//
+				// <div>div element</div>
+				'<p>single line</p><div>div element</div>',
+
+				// To-markdown always put 2 empty lines after paragraph.
+				'single line\n' +
+				'\n' +
+				'<div>div element</div>'
+			);
+		} );
+	} );
+} );

+ 26 - 0
packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/strikethrough.js

@@ -0,0 +1,26 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import { testDataProcessor as test } from '/tests/markdown-gfm/_utils/utils.js';
+
+describe( 'GFMDataProcessor', () => {
+	describe( 'Strikethrough', () => {
+		it( 'should process strikethrough text', () => {
+			test(
+				'~~deleted~~',
+
+				'<p><del>deleted</del></p>'
+			);
+		} );
+
+		it( 'should process strikethrough inside text', () => {
+			test(
+				'This is ~~deleted content~~.',
+
+				'<p>This is <del>deleted content</del>.</p>'
+			);
+		} );
+	} );
+} );

+ 107 - 0
packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/strong-emphasis.js

@@ -0,0 +1,107 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import { testDataProcessor as test } from '/tests/markdown-gfm/_utils/utils.js';
+
+describe( 'GFMDataProcessor', () => {
+	describe( 'strong and emphasis', () => {
+		it( 'should process strong', () => {
+			test(
+				'**this is strong** and __this too__',
+
+				'<p><strong>this is strong</strong> and <strong>this too</strong></p>',
+
+				// When converting back strong will always be represented by **.
+				'**this is strong** and **this too**'
+			);
+		} );
+
+		it( 'should process emphasis', () => {
+			test(
+				'*this is emphasis* and _this too_',
+
+				'<p><em>this is emphasis</em> and <em>this too</em></p>',
+
+				// When converting back emphasis will always be represented by __.
+				'_this is emphasis_ and _this too_'
+			);
+		} );
+
+		it( 'should process strong and emphasis together #1', () => {
+			test(
+				'***This is strong and em.***',
+
+				'<p><strong><em>This is strong and em.</em></strong></p>',
+
+				// Normalized after converting back.
+				'**_This is strong and em._**'
+			);
+		} );
+
+		it( 'should process strong and emphasis together #2', () => {
+			test(
+				'Single ***word*** is strong and em.',
+
+				'<p>Single <strong><em>word</em></strong> is strong and em.</p>',
+
+				// Normalized after converting back.
+				'Single **_word_** is strong and em.'
+			);
+		} );
+
+		it( 'should process strong and emphasis together #3', () => {
+			test(
+				'___This is strong and em.___',
+
+				'<p><strong><em>This is strong and em.</em></strong></p>',
+
+				// Normalized after converting back.
+				'**_This is strong and em._**'
+
+			);
+		} );
+
+		it( 'should process strong and emphasis together #4', () => {
+			test(
+				'Single ___word___ is strong and em.',
+
+				'<p>Single <strong><em>word</em></strong> is strong and em.</p>',
+
+				// Normalized after converting back.
+				'Single **_word_** is strong and em.'
+			);
+		} );
+
+		it( 'should not process emphasis inside words', () => {
+			test(
+				'This should_not_be_emp.',
+
+				'<p>This should_not_be_emp.</p>'
+			);
+		} );
+
+		// Below two tests are not working because marked library renders nested emphasis differently than
+		// it is done on GitHub.
+
+		// it( 'should process nested emphasis #1', () => {
+		// 	test(
+		// 		'*test **test** test*',
+		//
+		// 		// GitHub is rendering as:
+		// 		// <p><em>test *</em>test** test*</p>
+		//
+		// 		'<p><em>test *</em>test** test*</p>'
+		// 	);
+		// } );
+		// it( 'should process nested emphasis #2', () => {
+		// 	test(
+		// 		'_test __test__ test_',
+		//
+		// 		// GitHub is rendering as:
+		// 		'<p><em>test __test_</em> test_</p>'
+		// 	);
+		// } );
+	} );
+} );

+ 158 - 0
packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/tables.js

@@ -0,0 +1,158 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import { testDataProcessor as test } from '/tests/markdown-gfm/_utils/utils.js';
+
+describe( 'GFMDataProcessor', () => {
+	describe( 'tables', () => {
+		it( 'should process tables', () => {
+			test(
+				'| Heading 1 | Heading 2\n' +
+				'| --- | ---\n' +
+				'| Cell 1    | Cell 2\n' +
+				'| Cell 3    | Cell 4\n',
+
+				'<table>' +
+					'<thead>' +
+						'<tr>' +
+							'<th>Heading 1</th>' +
+							'<th>Heading 2</th>' +
+						'</tr>' +
+					'</thead>' +
+					'<tbody>' +
+						'<tr>' +
+							'<td>Cell 1</td>' +
+							'<td>Cell 2</td>' +
+						'</tr>' +
+						'<tr>' +
+							'<td>Cell 3</td>' +
+							'<td>Cell 4</td>' +
+						'</tr>' +
+					'</tbody>' +
+				'</table>',
+
+				// After converting back it will be normalized.
+				'| Heading 1 | Heading 2 |\n' +
+				'| --- | --- |\n' +
+				'| Cell 1 | Cell 2 |\n' +
+				'| Cell 3 | Cell 4 |'
+			);
+		} );
+
+		it( 'should process tables with aligned columns', () => {
+			test(
+				'| Header 1 | Header 2 | Header 3 | Header 4 |\n' +
+				'| :------: | -------: | :------- | -------- |\n' +
+				'| Cell 1   | Cell 2   | Cell 3   | Cell 4   |\n' +
+				'| Cell 5   | Cell 6   | Cell 7   | Cell 8   |',
+
+				'<table>' +
+					'<thead>' +
+						'<tr>' +
+							'<th align="center">Header 1</th>' +
+							'<th align="right">Header 2</th>' +
+							'<th align="left">Header 3</th>' +
+							'<th>Header 4</th>' +
+						'</tr>' +
+					'</thead>' +
+					'<tbody>' +
+						'<tr>' +
+							'<td align="center">Cell 1</td>' +
+							'<td align="right">Cell 2</td>' +
+							'<td align="left">Cell 3</td>' +
+							'<td>Cell 4</td>' +
+						'</tr>' +
+						'<tr>' +
+							'<td align="center">Cell 5</td>' +
+							'<td align="right">Cell 6</td>' +
+							'<td align="left">Cell 7</td>' +
+							'<td>Cell 8</td>' +
+						'</tr>' +
+					'</tbody>' +
+				'</table>',
+
+				// After converting back it will be normalized.
+				'| Header 1 | Header 2 | Header 3 | Header 4 |\n' +
+				'| :-: | --: | :-- | --- |\n' +
+				'| Cell 1 | Cell 2 | Cell 3 | Cell 4 |\n' +
+				'| Cell 5 | Cell 6 | Cell 7 | Cell 8 |'
+			);
+		} );
+
+		it( 'should process not table without borders', () => {
+			test(
+				'Header 1 | Header 2\n' +
+				'-------- | --------\n' +
+				'Cell 1   | Cell 2\n' +
+				'Cell 3   | Cell 4',
+
+				'<table>' +
+					'<thead>' +
+						'<tr>' +
+							'<th>Header 1</th>' +
+							'<th>Header 2</th>' +
+						'</tr>' +
+					'</thead>' +
+					'<tbody>' +
+						'<tr>' +
+							'<td>Cell 1</td>' +
+							'<td>Cell 2</td>' +
+						'</tr>' +
+						'<tr>' +
+							'<td>Cell 3</td>' +
+							'<td>Cell 4</td>' +
+						'</tr>' +
+					'</tbody>' +
+				'</table>',
+
+				// After converting back it will be normalized.
+				'| Header 1 | Header 2 |\n' +
+				'| --- | --- |\n' +
+				'| Cell 1 | Cell 2 |\n' +
+				'| Cell 3 | Cell 4 |'
+			);
+		} );
+
+		it( 'should process formatting inside cells', () => {
+			test(
+				'Header 1|Header 2|Header 3|Header 4\n' +
+				':-------|:------:|-------:|--------\n' +
+				'*Cell 1*  |**Cell 2**  |~~Cell 3~~  |Cell 4',
+
+				'<table>' +
+					'<thead>' +
+						'<tr>' +
+							'<th align="left">Header 1</th>' +
+							'<th align="center">Header 2</th>' +
+							'<th align="right">Header 3</th>' +
+							'<th>Header 4</th>' +
+						'</tr>' +
+					'</thead>' +
+					'<tbody>' +
+						'<tr>' +
+							'<td align="left">' +
+								'<em>Cell 1</em>' +
+							'</td>' +
+							'<td align="center">' +
+								'<strong>Cell 2</strong>' +
+							'</td>' +
+							'<td align="right">' +
+								'<del>Cell 3</del>' +
+							'</td>' +
+							'<td>' +
+								'Cell 4' +
+							'</td>' +
+						'</tr>' +
+					'</tbody>' +
+				'</table>',
+
+				// After converting back it will be normalized.
+				'| Header 1 | Header 2 | Header 3 | Header 4 |\n' +
+				'| :-- | :-: | --: | --- |\n' +
+				'| _Cell 1_ | **Cell 2** | ~~Cell 3~~ | Cell 4 |'
+			);
+		} );
+	} );
+} );

+ 86 - 0
packages/ckeditor5-markdown-gfm/tests/gfmdataprocessor/tabs.js

@@ -0,0 +1,86 @@
+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import { testDataProcessor as test } from '/tests/markdown-gfm/_utils/utils.js';
+
+describe( 'GFMDataProcessor', () => {
+	describe( 'tabs', () => {
+		it( 'should process list item with tabs', () => {
+			test(
+				'+	this is a list item indented with tabs',
+
+				// GitHub will render it as (notice two spaces at the beginning of the list item):
+				// <ul>
+				// <li>  this is a list item indented with tabs</li>
+				// </ul>
+				'<ul>' +
+				'<li>this is a list item indented with tabs</li>' +
+				'</ul>',
+
+				// After converting back list will be normalized to *.
+				'*   this is a list item indented with tabs'
+			);
+		} );
+
+		it( 'should process list item with spaces', () => {
+			test(
+				'+   this is a list item indented with spaces',
+
+				// GitHub will render it as (notice two spaces at the beginning of the list item):
+				// <ul>
+				// <li>  this is a list item indented with spaces</li>
+				// </ul>
+				'<ul>' +
+				'<li>this is a list item indented with spaces</li>' +
+				'</ul>',
+
+				// After converting back list will be normalized to *.
+				'*   this is a list item indented with spaces'
+			);
+		} );
+
+		it( 'should process code block indented by tab', () => {
+			test(
+				'	this code block is indented by one tab',
+
+				'<pre><code>this code block is indented by one tab</code></pre>',
+
+				// After converting back code block will be normalized to ``` representation.
+				'```\n' +
+				'this code block is indented by one tab\n' +
+				'```'
+			);
+		} );
+
+		it( 'should process code block indented by two tabs', () => {
+			test(
+				'		this code block is indented by two tabs',
+
+				'<pre><code>    this code block is indented by two tabs</code></pre>',
+
+				// After converting back code block will be normalized to ``` representation.
+				'```\n' +
+				'    this code block is indented by two tabs\n' +
+				'```'
+			);
+		} );
+
+		it( 'should process list items indented with tabs as code block', () => {
+			test(
+				'	+	list item\n' +
+				'	next line',
+
+				'<pre><code>+    list item\n' +
+				'next line</code></pre>',
+
+				// After converting back code block will be normalized to ``` representation.
+				'```\n' +
+				'+    list item\n' +
+				'next line\n' +
+				'```'
+			);
+		} );
+	} );
+} );