resolve #105

Parsedown.php

@@ -87,7 +87,7 @@ class Parsedown
         '8' => array('List'),
         '9' => array('List'),
         ':' => array('Table'),
-        '<' => array('Markup'),
+        '<' => array('Comment', 'Markup'),
         '=' => array('Setext'),
         '>' => array('Quote'),
         '_' => array('Rule'),
@@ -346,6 +346,43 @@ class Parsedown
         return $Block;
     }
 
+    #
+    # Comment
+
+    protected function identifyComment($Line)
+    {
+        if (isset($Line['text'][3]) and $Line['text'][3] === '-' and $Line['text'][2] === '-' and $Line['text'][1] === '!')
+        {
+            $Block = array(
+                'element' => $Line['body'],
+            );
+
+            if (preg_match('/-->$/', $Line['text']))
+            {
+                $Block['closed'] = true;
+            }
+
+            return $Block;
+        }
+    }
+
+    protected function addToComment($Line, array $Block)
+    {
+        if (isset($Block['closed']))
+        {
+            return;
+        }
+
+        $Block['element'] .= "\n" . $Line['body'];
+
+        if (preg_match('/-->$/', $Line['text']))
+        {
+            $Block['closed'] = true;
+        }
+
+        return $Block;
+    }
+
     #
     # Fenced Code
 

test/data/HTML_Comment.html

@@ -0,0 +1,5 @@
+<!-- single line -->
+<p>paragraph</p>
+<!-- 
+  multiline -->
+<p>paragraph</p>

test/data/HTML_Comment.md

@@ -0,0 +1,8 @@
+<!-- single line -->
+
+paragraph
+
+<!-- 
+  multiline -->
+
+paragraph