Slightly speed up unevaluatedProperties in the failing case.

When we decide a property isn't evaluated because it fails validation
of the unevaluated* schema (which we currently do in an entirely nonideal
way anyhow by doing the work *redundantly* in two places), there's no need
to build the full list of errors when a property fails validation, it's
enough to just know it fails validation.

This may change if/when we provide full context on unevaluatedProperties
failures, but for now we don't expose that information anyhow.

Author: Julian

jsonschema/_legacy_validators.py

@@ -276,8 +276,8 @@ def find_evaluated_item_indexes_by_schema(validator, instance, schema):
     for keyword in ["allOf", "oneOf", "anyOf"]:
         if keyword in schema:
             for subschema in schema[keyword]:
-                errs = list(validator.descend(instance, subschema))
-                if not errs:
+                errs = next(validator.descend(instance, subschema), None)
+                if errs is None:
                     evaluated_indexes += find_evaluated_item_indexes_by_schema(
                         validator, instance, subschema,
                     )

jsonschema/_utils.py

@@ -237,8 +237,8 @@ def find_evaluated_item_indexes_by_schema(validator, instance, schema):
     for keyword in ["allOf", "oneOf", "anyOf"]:
         if keyword in schema:
             for subschema in schema[keyword]:
-                errs = list(validator.descend(instance, subschema))
-                if not errs:
+                errs = next(validator.descend(instance, subschema), None)
+                if errs is None:
                     evaluated_indexes += find_evaluated_item_indexes_by_schema(
                         validator, instance, subschema,
                     )
@@ -301,8 +301,8 @@ def find_evaluated_property_keys_by_schema(validator, instance, schema):
     for keyword in ["allOf", "oneOf", "anyOf"]:
         if keyword in schema:
             for subschema in schema[keyword]:
-                errs = list(validator.descend(instance, subschema))
-                if not errs:
+                errs = next(validator.descend(instance, subschema), None)
+                if errs is None:
                     evaluated_keys += find_evaluated_property_keys_by_schema(
                         validator, instance, subschema,
                     )