Refactor image tag parser so that it only has two cases to handle

wagtail/wagtailimages/models.py

@@ -68,8 +68,8 @@ class AbstractImage(models.Model, TagSearchable):
         except ObjectDoesNotExist:
             file_field = self.file
 
-			# If we have a backend attribute then pass it to process
-			# image - else pass 'default'
+            # If we have a backend attribute then pass it to process
+            # image - else pass 'default'
             backend_name = getattr(self, 'backend', 'default')
             generated_image_file = filter.process_image(file_field.file, backend_name=backend_name)
 

wagtail/wagtailimages/templatetags/image_tags.py

@@ -15,31 +15,22 @@ def image(parser, token):
     filter_spec = bits[1]
     bits = bits[2:]
 
-    if len(bits) == 0:
-        # token is of the form {% image self.photo max-320x200 %}
-        return ImageNode(image_var, filter_spec)
-
-    elif len(bits) == 2:
+    if len(bits) == 2 and bits[0] == 'as':
         # token is of the form {% image self.photo max-320x200 as img %}
-
-        if bits[0] == 'as':
-            return ImageNode(image_var, filter_spec, output_var_name=bits[1])
-
-    if len(bits) > 0:
-        # customized <img> attrs
+        return ImageNode(image_var, filter_spec, output_var_name=bits[1])
+    else:
+        # token is of the form {% image self.photo max-320x200 %} - all additional tokens
+        # should be kwargs, which become attributes
         attrs = {}
         for bit in bits:
             try:
-                name,value = bit.split('=')
-            except:
-                raise template.TemplateSyntaxError("'image' tag should be of the form {%% image self.photo max-320x200 [ custom-attr=\"value\" [ ... ] ] %%} or {%% image self.photo max-320x200 as img %%}")
+                name, value = bit.split('=')
+            except ValueError:
+                raise template.TemplateSyntaxError("'image' tag should be of the form {% image self.photo max-320x200 [ custom-attr=\"value\" ... ] %} or {% image self.photo max-320x200 as img %}")
             attrs[name] = parser.compile_filter(value) # setup to resolve context variables as value
 
         return ImageNode(image_var, filter_spec, attrs=attrs)
 
-    # something is wrong if we made it this far
-    raise template.TemplateSyntaxError("'image' tag should be of the form {%% image self.photo max-320x200 [ custom-attr=\"value\" [ ... ] ] %%} or {%% image self.photo max-320x200 as img %%}")
-
 
 class ImageNode(template.Node):
     def __init__(self, image_var_name, filter_spec, output_var_name=None, attrs={}):