final cleanup

Author: chelsea-lin

bigframes/core/expression.py

@@ -433,35 +433,24 @@ class ResolvedDerefOp(DerefOp):
     """An expression that refers to a column by ID and resolved with schema bound."""
 
     dtype: dtypes.Dtype
-    nullable: bool = True
+    is_nullable: bool
 
     @classmethod
     def from_field(cls, f: field.Field):
-        return cls(f.id, f.dtype, f.nullable)
+        return cls(id=f.id, dtype=f.dtype, is_nullable=f.nullable)
 
     @property
     def is_resolved(self) -> bool:
         return True
 
+    @property
+    def nullable(self) -> bool:
+        return self.is_nullable
+
     @property
     def output_type(self) -> dtypes.ExpressionType:
         return self.dtype
 
-    def bind_variables(
-        self, bindings: Mapping[str, Expression], allow_partial_bindings: bool = False
-    ) -> Expression:
-        return self
-
-    def bind_refs(
-        self,
-        bindings: Mapping[ids.ColumnId, Expression],
-        allow_partial_bindings: bool = False,
-    ) -> Expression:
-        # TODO: Check if we can remove.
-        if self.id in bindings.keys():
-            return bindings[self.id]
-        return self
-
 
 @dataclasses.dataclass(frozen=True)
 class OpExpression(Expression):

bigframes/core/rewrite/schema_binding.py

@@ -13,7 +13,6 @@
 # limitations under the License.
 
 import dataclasses
-import typing
 
 from bigframes.core import bigframe_node
 from bigframes.core import expression as ex
@@ -56,14 +55,8 @@ def bind_schema_to_node(
     if isinstance(node, nodes.JoinNode):
         conditions = tuple(
             (
-                typing.cast(
-                    ex.ResolvedDerefOp,
-                    ex.bind_schema_fields(left, node.left_child.field_by_id),
-                ),
-                typing.cast(
-                    ex.ResolvedDerefOp,
-                    ex.bind_schema_fields(right, node.right_child.field_by_id),
-                ),
+                ex.ResolvedDerefOp.from_field(node.left_child.field_by_id[left.id]),
+                ex.ResolvedDerefOp.from_field(node.right_child.field_by_id[right.id]),
             )
             for left, right in node.conditions
         )

tests/unit/core/test_expression.py

@@ -77,7 +77,9 @@ def test_deref_op_dtype_resolution():
 
 
 def test_field_ref_expr_dtype_resolution_short_circuit():
-    expression = ex.ResolvedDerefOp(id=ids.ColumnId("mycol"), dtype=dtypes.INT_DTYPE)
+    expression = ex.ResolvedDerefOp(
+        id=ids.ColumnId("mycol"), dtype=dtypes.INT_DTYPE, is_nullable=True
+    )
     field_bindings = _create_field_bindings({"anotherCol": dtypes.STRING_DTYPE})
 
     result = ex.bind_schema_fields(expression, field_bindings)