Adds category support to mynt.

categories.diff

diff --git a/mynt/core.py b/mynt/core.py
index 0cab910..d7d6778 100644
--- a/mynt/core.py
+++ b/mynt/core.py
@@ -38,6 +38,8 @@ class Mynt(object):
         'archives_url': '/',
         'assets_url': '/assets/',
         'base_url': '/',
+        'category_layout': None,
+        'categories_url': '/',
         'date_format': '%A, %B %d, %Y',
         'domain': None,
         'include': [],
@@ -56,6 +58,7 @@ class Mynt(object):
     _renderer = None
     
     archives = OrderedDict()
+    categories = OrderedDict()
     config = {}
     pages = []
     posts = []
@@ -96,6 +99,11 @@ class Mynt(object):
         
         return format.format(self.config['archives_url'], year)
     
+    def _get_category_url(self, name):
+        format = self._get_url_format(self.config['categories_url'].endswith('/'))
+        
+        return format.format(self.config['categories_url'], self._slugify(name))
+    
     def _get_opts(self, args):
         opts = {}
         
@@ -264,10 +272,10 @@ class Mynt(object):
                 self.config['assets_url'] = absurl(self.config['assets_url'], '')
                 self.config['base_url'] = absurl(self.opts.get('base_url', self.config['base_url']), '')
                 
-                for setting in ('archives_url', 'posts_url', 'tags_url'):
+                for setting in ('archives_url', 'categories_url', 'posts_url', 'tags_url'):
                     self.config[setting] = absurl(self.config[setting])
                 
-                for setting in ('archives_url', 'assets_url', 'base_url', 'posts_url', 'tags_url'):
+                for setting in ('archives_url', 'assets_url', 'base_url', 'categories_url', 'posts_url', 'tags_url'):
                     if re.search(r'(?:^\.{2}/|/\.{2}$|/\.{2}/)', self.config[setting]):
                         raise ConfigException('Invalid config setting.', 'setting: {0}'.format(setting), 'path traversal is not allowed')
                 
@@ -295,6 +303,7 @@ class Mynt(object):
             
             try:
                 data = {
+                    'categories': [],
                     'content': content,
                     'date': post.date.strftime(self.config['date_format']).decode('utf-8'),
                     'excerpt': excerpt,
@@ -306,6 +315,7 @@ class Mynt(object):
                 raise PageException('Invalid post slug.', 'src: {0}'.format(post.path))
             
             data.update(post.frontmatter)
+            data['categories'].sort(key = unicode.lower)
             data['tags'].sort(key = unicode.lower)
             
             self.posts.append(data)
@@ -315,6 +325,12 @@ class Mynt(object):
                     self.tags[tag] = []
                 
                 self.tags[tag].append(data)
+                
+            for category in data['categories']:
+                if category not in self.categories:
+                    self.categories[category] = []
+                
+                self.categories[category].append(data)
     
     def _process(self):
         self._parse()
@@ -332,6 +348,7 @@ class Mynt(object):
             
             logger.debug('..  sorting tags')
             
+            categories = []
             tags = []
             
             for name, posts in self.tags:
@@ -360,6 +377,33 @@ class Mynt(object):
             
             for tag in tags:
                 self.tags[tag['name']] = tag
+            
+            for name, posts in self.categories:
+                posts.sort(key = lambda post: post['timestamp'], reverse = True)
+                
+                try:
+                    categories.append({
+                        'archives': self._archive(posts),
+                        'count': len(posts),
+                        'name': name,
+                        'posts': posts,
+                        'url': self._get_category_url(name)
+                    })
+                except PageException:
+                    message = ['category: {0}'.format(name)]
+                    
+                    for post in posts:
+                        message.append('post: {0}'.format(post.get('title', post['url'])))
+                    
+                    raise PageException('Invalid category slug.', *message)
+            
+            categories.sort(key = lambda category: category['name'].lower())
+            categories.sort(key = lambda category: category['count'], reverse = True)
+            
+            self.categories.clear()
+            
+            for category in categories:
+                self.categories[category['name']] = category
         else:
             logger.debug('..  no posts found')
     
@@ -370,6 +414,7 @@ class Mynt(object):
         
         self.renderer.register({
             'archives': self.archives,
+            'categories': self.categories,
             'posts': self.posts,
             'tags': self.tags
         })
@@ -407,6 +452,15 @@ class Mynt(object):
                     self._pygmentize(self.renderer.render(self.config['tag_layout'], {'tag': data}))
                 ))
         
+        if self.config['category_layout'] and self.categories:
+            logger.debug('..  categories')
+            
+            for name, data in self.categories:
+                self.pages.append(Page(
+                    self._get_path(data['url']),
+                    self._pygmentize(self.renderer.render(self.config['category_layout'], {'category': data}))
+                ))
+        
         if self.config['archive_layout'] and self.archives:
             logger.debug('..  archives')