resolve #92

Parsedown.php

@@ -1028,7 +1028,7 @@ class Parsedown
 
                 case '`':
 
-                    if (preg_match('/^(`+)[ ]*(.+?)[ ]*\1(?!`)/', $text, $matches))
+                    if (preg_match('/^(`+)[ ]*(.+?)[ ]*(?<!`)\1(?!`)/', $text, $matches))
                     {
                         $element_text = $matches[2];
                         $element_text = htmlspecialchars($element_text, ENT_NOQUOTES, 'UTF-8');

tests/data/code_span.html

@@ -2,4 +2,5 @@
 <p><code>this is also a codespan</code> trailing text</p>
 <p><code>and look at this one!</code></p>
 <p>single backtick in a code span: <code>`</code></p>
-<p>backtick-delimited string in a code span: <code>`foo`</code></p>
\ No newline at end of file
+<p>backtick-delimited string in a code span: <code>`foo`</code></p>
+<p><code>sth `` sth</code></p>
\ No newline at end of file

tests/data/code_span.md

@@ -6,4 +6,6 @@ a `code span`
 
 single backtick in a code span: `` ` ``
 
-backtick-delimited string in a code span: `` `foo` ``
\ No newline at end of file
+backtick-delimited string in a code span: `` `foo` ``
+
+`sth `` sth`
\ No newline at end of file