Adds optional syntax to example blocks

This is helpful when you need to add a modifier call to template that
might not otherwise have a class. Instead of displaying class="" you
can wrap wrap the class []? which will strip it out of the section
example but leave it in the modifier examples.

<a href="#"[ class="$modifier_class]?>Link</a>

2 files changed, 7 insertions, 5 deletions

diff --git a/pykss/section.py b/pykss/section.py
index 8f3ed1a..edbfb45 100644
--- a/pykss/section.py
+++ b/pykss/section.py
@@ -9,7 +9,8 @@ MODIFIER_DESCRIPTION_SEPARATOR = ' - '
 EXAMPLE_START = 'Example:'
 REFERENCE_START = 'Styleguide'
 
-reference_re = re.compile('%s ([\d\.]+)' % REFERENCE_START)
+reference_re = re.compile(r'%s ([\d\.]+)' % REFERENCE_START)
+optional_re = re.compile(r'\[(.*)\]\?')
 
 
 class Section(object):
@@ -76,6 +77,6 @@ class Section(object):
         return self._reference
 
     def add_example(self, example):
-        self._example = example.replace('$modifier_class', '')
+        self._example = optional_re.sub('', example).replace('$modifier_class', '')
         for modifier in self._modifiers:
-            modifier.add_example(example)
+            modifier.add_example(optional_re.sub(r'\1', example))
diff --git a/tests/test_section.py b/tests/test_section.py
index 6ece110..200e65e 100644
--- a/tests/test_section.py
+++ b/tests/test_section.py
@@ -17,7 +17,7 @@ Your standard form button.
 .smaller  - A smaller button
 
 Example:
-    <a href="button$modifier_class">Button</a>
+    <a href="#" class="button$modifier_class">Button</a><a href="#"[ class="$modifier_class"]?>Button</a>
 
 Styleguide 2.1.1.
         """
@@ -36,7 +36,8 @@ Styleguide 2.1.1.
         self.assertEqual(self.section.modifiers[0].description, 'Highlights when hovering.')
 
     def test_parses_the_example(self):
-        self.assertEqual(self.section.example, '<a href="button">Button</a>')
+        expected = '<a href="#" class="button">Button</a><a href="#">Button</a>'
+        self.assertEqual(self.section.example, expected)
 
     def test_parses_the_styleguide_reference(self):
         self.assertEqual(self.section.section, '2.1.1')