template: new item_value filter

this filter is used with XMLUI to specify filters before using a generate method.

src/tools/common/template.py

@@ -203,6 +203,7 @@ class Renderer(object):
         self.env.filters['date_days'] = self._date_days
         self.env.filters['xmlui_class'] = self._xmlui_class
         self.env.filters['attr_escape'] = self.attr_escape
+        self.env.filters['item_filter'] = self._item_filter
         self.env.filters['adv_format'] = self._adv_format
 
     def installTranslations(self):
@@ -365,6 +366,34 @@ class Renderer(object):
                 continue
         return u' '.join(classes) or None
 
+    def _item_filter(self, item, filters):
+        """return item's value, filtered if suitable
+
+        @param item(object): item to filter
+            value must have name and value attributes,
+            mostly used for XMLUI items
+        @param filters(dict[unicode, (callable, dict, None)]): map of name => filter
+            if filter is None, return the value unchanged
+            if filter is a callable, apply it
+            if filter is a dict, it can have following keys:
+                - filters: iterable of filters to apply
+                - filters_args: kwargs of filters in the same order as filters (use empty dict if needed)
+                - template: template to format where {value} is the filtered value
+        """
+        value = item.value
+        filter_ = filters.get(item.name, None)
+        if filter_ is None:
+            return value
+        elif isinstance(filter_, dict):
+            filter_args = filter_.get(u'filter_args')
+            for idx, f_name in enumerate(filter_.get(u'filters', [])):
+                kwargs = filter_args[idx] if filter_args is not None else {}
+                value = self.env.filters[f_name](value, **kwargs)
+            template = filter_.get(u'template', u'{value}')
+            return template.format(value=value)
+        else:
+            return filter_(item.value)
+
     def _adv_format(self, value, template, **kwargs):
         """Advancer formatter