--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/taginthemiddle/model.py	Tue May 04 08:37:15 2010 -0700
@@ -0,0 +1,49 @@
+import os
+
+class Tags(object):
+  """file (e.g. .ini) based tagging scheme"""
+
+  def __init__(self, path):
+    """
+    - path: path to file
+    """
+    self.path = path
+    if not os.path.exists(path):
+      f = file(path, 'w')
+      f.close()
+    self.tags = {}
+    self.urls = {}
+    self.read(path)
+    
+
+  def read(self):
+    for line in file(path).readlines():
+      line = line.strip()
+      if not line:
+        continue
+      tag, urls = line.split('=', 1) # asserts '=' in line
+      tag = tag.strip()
+      urls = urls.strip()
+      self.tags[tag] = set([urls])
+      for url in urls:
+        self.urls.setdefault(url, set()).add(tag)
+
+  def write(self):
+    f = file(self.path, 'w')
+    for tag in sorted(self.tags.keys()):
+      print >> f, '%s = %s' % (tag, ' '.join(self.tags[tag]))
+    f.close()
+
+  def add(self, tag, url):
+    if url in self.tags[tag]:
+      return
+    self.tags[tag].add(url)
+    self.urls[url].add(tag)
+    self.write()
+
+  def remove(self, tag, url):
+    if url not in self.tags[tag]:
+      return
+    self.tags[tag].remove(url)
+    self.urls[url].remove(tag)
+    self.write()