Compression methods now alter their argument instead of making a copy

compress.py

+from color import color_shortcut
+
+
 def combine_blocks(blocks):
     # Map of property stringification to list of containing blocks
     #property_locations = {}
@@ -5,13 +8,31 @@ def combine_blocks(blocks):
     return blocks
 
 
+def _filter_property(basename, properties):
+    prefix = basename + '-'
+    filtered = []
+
+    for prop in list(properties):
+        name, value = prop
+
+        if name == basename or name[:len(prefix)] == prefix:
+            filtered.append(properties.remove(prop))
+
+    return filtered
+
+
 def compress_color(properties):
-    return properties
+    for i, (name, value) in enumerate(properties):
+        if name in ('color', 'background-color', 'border-color'):
+            properties[i] = (name, color_shortcut(value))
 
 
 def compress_font(properties):
-    return properties
+    #fonts = _filter_property('font', properties)
+    pass
 
 
 def compress_dimension(properties):
-    return properties
+    #margins = _filter_property('margin', properties)
+    #paddings = _filter_property('padding', properties)
+    pass

generate.py

@@ -70,13 +70,13 @@ def generate_group(selectors, blocks, combine_blocks=True,
 
     for block_selectors, properties in blocks:
         if compress_color:
-            properties = compress.compress_color(properties)
+            compress.compress_color(properties)
 
         if compress_font:
-            properties = compress.compress_font(properties)
+            compress.compress_font(properties)
 
         if compress_dimension:
-            properties = compress.compress_dimension(properties)
+            compress.compress_dimension(properties)
 
         compressed_blocks.append(generate_block(block_selectors, properties,
             compress_whitespace=compress_whitespace,