lib/grammar.tt in parse_a_changelog-1.0.1 vs lib/grammar.tt in parse_a_changelog-1.0.2

@@ -43,13 +43,21 @@
   rule release_header
     '## ' '['? release_version ']'? ' - ' release_date "\n"
   end
 
   rule release_version
-    [0-9]+ '.' [0-9]+ '.' [0-9]+
+    [0-9]+ '.' [0-9]+ '.' [0-9]+ pre_release_version
   end
 
+  rule pre_release_version
+    ( '-' [0-9A-Za-z-]+ pre_release_group* ) / ''
+  end
+
+  rule pre_release_group
+    '.' [0-9A-Za-z-]+
+  end
+
   rule release_date
     [0-9] [0-9] [0-9] [0-9] '-' [0-9] [0-9] '-' [0-9] [0-9]
   end
 
   rule diff_section
@@ -71,8 +79,8 @@
   rule release_url
     'https://github.com/' (!'/' .)+ '/' (!'/' .)+ '/compare/' diff_version '...' diff_version
   end
 
   rule diff_version
-    ('HEAD' / 'v' release_version)
+    'HEAD' / ( 'v' release_version )
   end
 end