added newitem.extractors based on old adaptors

--HG--
extra : convert_revision : svn%3Ab85faa78-f9eb-468e-a121-7cced6da292c%40886

scrapy/trunk/scrapy/contrib_exp/newitem/extractors.py

@@ -0,0 +1,71 @@
+import inspect
+
+
+class ItemExtractor(object):
+    def __init__(self, response=None, item=None):
+        if item:
+            self.item_instance = item
+        else:
+            self.item_instance = self.item_class()
+        
+        self._response = response
+        self._field_extractors = self._get_field_extractors()
+
+    def _get_field_extractors(self):
+        fe = {}
+        for field in self.item_instance._fields.keys():
+            if self.__class__.__dict__.has_key(field):
+                fe[field] = self.__class__.__dict__[field]
+        return fe
+
+    def __setattr__(self, name, value):
+        if not (name.startswith('_') or name == 'item_instance'):
+            if name in self._field_extractors.keys():
+                setattr(self.item_instance, name, 
+                        self._field_extractors[name](value, self._response))
+            else:
+                raise AttributeError(name)
+        else:
+            object.__setattr__(self, name, value)
+
+    def __getattribute__(self, name):
+        if not (name.startswith('_') or name.startswith('item_')):
+            return getattr(self.item_instance, name)
+        else:
+            return object.__getattribute__(self, name)
+
+
+class ExtractorField(object):
+    def __init__(self, funcs):
+        self._funcs = []
+
+        for func in funcs:
+            if inspect.isfunction(func):
+                func_args, _, _, _ = inspect.getargspec(func)
+            elif hasattr(func, '__call__'):
+                try:
+                    func_args, _, _, _ = inspect.getargspec(func.__call__)
+                except Exception:
+                    func_args = []
+
+            takes_args = True if 'adaptor_args' in func_args else False
+            self._funcs.append((func, takes_args))
+
+    def __call__(self, value, kwargs=None):
+        values = [value]
+
+        for func, takes_args in self._funcs:
+            next_round = []
+
+            for val in values:
+                val = func(val, kwargs) if takes_args else func(val)
+
+                if isinstance(val, tuple):
+                    next_round.extend(val)
+                elif val is not None:
+                    next_round.append(val)
+
+            values = next_round
+
+        return list(values)
+