Fix emphasis followed by a punctuation (fixes markedjs#1378)

lib/marked.js

@@ -541,13 +541,18 @@ var inline = {
   reflink: /^!?\[(label)\]\[(?!\s*\])((?:\\[\[\]]?|[^\[\]\\])+)\]/,
   nolink: /^!?\[(?!\s*\])((?:\[[^\[\]]*\]|\\[\[\]]|[^\[\]])*)\](?:\[\])?/,
   strong: /^__([^\s])__(?!_)|^\*\*([^\s])\*\*(?!\*)|^__([^\s][\s\S]*?[^\s])__(?!_)|^\*\*([^\s][\s\S]*?[^\s])\*\*(?!\*)/,
-  em: /^_([^\s_])_(?!_)|^\*([^\s*"<\[])\*(?!\*)|^_([^\s][\s\S]*?[^\s_])_(?!_|[^\s.])|^_([^\s_][\s\S]*?[^\s])_(?!_|[^\s.])|^\*([^\s"<\[][\s\S]*?[^\s*])\*(?!\*)|^\*([^\s*"<\[][\s\S]*?[^\s])\*(?!\*)/,
+  em: /^_([^\s_])_(?!_)|^\*([^\s*"<\[])\*(?!\*)|^_([^\s][\s\S]*?[^\s_])_(?!_|[^\spunctuation])|^_([^\s_][\s\S]*?[^\s])_(?!_|[^\spunctuation])|^\*([^\s"<\[][\s\S]*?[^\s*])\*(?!\*)|^\*([^\s*"<\[][\s\S]*?[^\s])\*(?!\*)/,
   code: /^(`+)([^`]|[^`][\s\S]*?[^`])\1(?!`)/,
   br: /^( {2,}|\\)\n(?!\s*$)/,
   del: noop,
   text: /^(`+|[^`])[\s\S]*?(?=[\\<!\[`*]|\b_| {2,}\n|$)/
 };
 
+// list of punctuation marks from common mark spec 
+// without ` and ] to workaround Rule 17 (inline code blocks/links)
+inline._punctuation = '!"#$%&\'()*+,\\-./:;<=>?@\\[^_{|}~';
+inline.em = edit(inline.em).replace(/punctuation/g, inline._punctuation).getRegex();
+
 inline._escapes = /\\([!"#$%&'()*+,\-./:;<=>?@\[\]\\^_`{|}~])/g;
 
 inline._scheme = /[a-zA-Z][a-zA-Z0-9+.-]{1,31}/;