Merge pull request #1803 from jakevdp/schema-inheritance

Internal: add inheritance structure to core classes

altair/utils/schemapi.py

@@ -40,6 +40,17 @@ def debug_mode(arg):
         DEBUG_MODE = original
 
 
+def _subclasses(cls):
+    """Breadth-first sequence of all classes which inherit from cls."""
+    seen = set()
+    current_set = {cls}
+    while current_set:
+        seen |= current_set
+        current_set = set.union(*(set(cls.__subclasses__()) for cls in current_set))
+        for cls in current_set - seen:
+            yield cls
+
+
 def _todict(obj, validate, context):
     """Convert an object to a dict representation."""
     if isinstance(obj, SchemaBase):
@@ -337,7 +348,7 @@ def to_json(self, validate=True, ignore=[], context={},
     @classmethod
     def _default_wrapper_classes(cls):
         """Return the set of classes used within cls.from_dict()"""
-        return SchemaBase.__subclasses__()
+        return _subclasses(SchemaBase)
 
     @classmethod
     def from_dict(cls, dct, validate=True, _wrapper_classes=None):
@@ -487,7 +498,9 @@ def _passthrough(*args, **kwds):
             return args[0] if args else kwds
 
         if cls is None:
-            # TODO: do something more than simply selecting the last match?
+            # If there are multiple matches, we use the last one in the dict.
+            # Our class dict is constructed breadth-first from top to bottom,
+            # so the last class that matches is the most specific.
             matches = self.class_dict[self.hash_schema(schema)]
             cls = matches[-1] if matches else _passthrough
         schema = _resolve_references(schema, rootschema)

altair/vega/v4/schema/core.py

@@ -3,7 +3,7 @@
 # The contents of this file are automatically written by
 # tools/generate_schema_wrapper.py. Do not modify directly.
 
-from altair.utils.schemapi import SchemaBase, Undefined
+from altair.utils.schemapi import SchemaBase, Undefined, _subclasses
 
 import pkgutil
 import json
@@ -16,7 +16,7 @@ def load_schema():
 class VegaSchema(SchemaBase):
     @classmethod
     def _default_wrapper_classes(cls):
-        return VegaSchema.__subclasses__()
+        return _subclasses(VegaSchema)
 
 
 class Root(VegaSchema):

altair/vega/v5/schema/core.py

@@ -3,7 +3,7 @@
 # The contents of this file are automatically written by
 # tools/generate_schema_wrapper.py. Do not modify directly.
 
-from altair.utils.schemapi import SchemaBase, Undefined
+from altair.utils.schemapi import SchemaBase, Undefined, _subclasses
 
 import pkgutil
 import json
@@ -16,7 +16,7 @@ def load_schema():
 class VegaSchema(SchemaBase):
     @classmethod
     def _default_wrapper_classes(cls):
-        return VegaSchema.__subclasses__()
+        return _subclasses(VegaSchema)
 
 
 class Root(VegaSchema):

altair/vegalite/v2/api.py

@@ -92,8 +92,7 @@ def _prepare_data(data, context):
         data = _consolidate_data(data, context)
 
     # if data is still not a recognized type, then return
-    if not isinstance(data, (dict, core.Data, core.UrlData,
-                             core.InlineData, core.NamedData)):
+    if not isinstance(data, (dict, core.Data)):
         warnings.warn("data of type {} not recognized".format(type(data)))
 
     return data
@@ -329,19 +328,12 @@ def condition(predicate, if_true, if_false, **kwargs):
     spec: dict or VegaLiteSchema
         the spec that describes the condition
     """
-    selection_predicates = (core.SelectionNot, core.SelectionOr,
-                            core.SelectionAnd, core.SelectionOperand)
-    test_predicates = (six.string_types, expr.Expression, core.Predicate,
-                       core.LogicalOperandPredicate, core.LogicalNotPredicate,
-                       core.LogicalOrPredicate, core.LogicalAndPredicate,
-                       core.FieldEqualPredicate, core.FieldOneOfPredicate,
-                       core.FieldRangePredicate, core.FieldLTPredicate,
-                       core.FieldGTPredicate, core.FieldLTEPredicate,
-                       core.FieldGTEPredicate, core.SelectionPredicate)
+    test_predicates = (six.string_types, expr.Expression, 
+                       core.LogicalOperandPredicate)
 
     if isinstance(predicate, NamedSelection):
         condition = {'selection': predicate._get_name()}
-    elif isinstance(predicate, selection_predicates):
+    elif isinstance(predicate, core.SelectionOperand):
         condition = {'selection': predicate}
     elif isinstance(predicate, test_predicates):
         condition = {'test': predicate}
@@ -872,11 +864,9 @@ def transform_filter(self, filter, **kwargs):
         alt.FilterTransform : underlying transform object
 
         """
-        selection_predicates = (core.SelectionNot, core.SelectionOr,
-                                core.SelectionAnd, core.SelectionOperand)
         if isinstance(filter, NamedSelection):
             filter = {'selection': filter._get_name()}
-        elif isinstance(filter, selection_predicates):
+        elif isinstance(filter, core.SelectionOperand):
             filter = {'selection': filter}
         return self._add_transform(core.FilterTransform(filter=filter, **kwargs))