implement URL auto-linking

Parsedown.php

@@ -733,10 +733,13 @@ class Parsedown
 			}
 		}
 
-		# automatic link
+		if (strpos($text, '://') !== FALSE)
-
-		if (strpos($text, '<') !== FALSE and preg_match_all('/<((https?|ftp|dict):[^\^\s]+?)>/i', $text, $matches, PREG_SET_ORDER))
 		{
+			switch (TRUE)
+			{
+				case preg_match_all('{<(https?:[/]{2}[^\s]+)>}i', $text, $matches, PREG_SET_ORDER):
+				case preg_match_all('{\b(https?:[/]{2}[^\s]+)\b}i', $text, $matches, PREG_SET_ORDER):
+
 					foreach ($matches as $matches)
 					{
 						$url = $matches[1];
@@ -757,6 +760,9 @@ class Parsedown
 
 						$index ++;
 					}
+
+					break;
+			}
 		}
 
 		# ~

tests/data/url_autolinking.html

@@ -0,0 +1 @@
+<p>Here's an autolink <a href="http://example.com">http://example.com</a>.</p>

tests/data/url_autolinking.md

@@ -0,0 +1 @@
+Here's an autolink http://example.com.