refactor: provide infrastructure for SQLGlot aggregations compiler (#1926)

Fixes internal issue 431277229

Author: chelsea-lin

bigframes/core/compile/sqlglot/aggregate_compiler.py

@@ -13,16 +13,17 @@
 # limitations under the License.
 from __future__ import annotations
 
-import functools
-import typing
-
 import sqlglot.expressions as sge
 
-from bigframes.core import expression, window_spec
+from bigframes.core import expression
+from bigframes.core.compile.sqlglot.aggregations import (
+    binary_compiler,
+    nullary_compiler,
+    ordered_unary_compiler,
+    unary_compiler,
+)
 from bigframes.core.compile.sqlglot.expressions import typed_expr
 import bigframes.core.compile.sqlglot.scalar_compiler as scalar_compiler
-import bigframes.core.compile.sqlglot.sqlglot_ir as ir
-import bigframes.operations as ops
 
 
 def compile_aggregate(
@@ -31,16 +32,18 @@ def compile_aggregate(
 ) -> sge.Expression:
     """Compiles BigFrames aggregation expression into SQLGlot expression."""
     if isinstance(aggregate, expression.NullaryAggregation):
-        return compile_nullary_agg(aggregate.op)
+        return nullary_compiler.compile(aggregate.op)
     if isinstance(aggregate, expression.UnaryAggregation):
         column = typed_expr.TypedExpr(
             scalar_compiler.compile_scalar_expression(aggregate.arg),
             aggregate.arg.output_type,
         )
         if not aggregate.op.order_independent:
-            return compile_ordered_unary_agg(aggregate.op, column, order_by=order_by)
+            return ordered_unary_compiler.compile(
+                aggregate.op, column, order_by=order_by
+            )
         else:
-            return compile_unary_agg(aggregate.op, column)
+            return unary_compiler.compile(aggregate.op, column)
     elif isinstance(aggregate, expression.BinaryAggregation):
         left = typed_expr.TypedExpr(
             scalar_compiler.compile_scalar_expression(aggregate.left),
@@ -50,63 +53,6 @@ def compile_aggregate(
             scalar_compiler.compile_scalar_expression(aggregate.right),
             aggregate.right.output_type,
         )
-        return compile_binary_agg(aggregate.op, left, right)
+        return binary_compiler.compile(aggregate.op, left, right)
     else:
         raise ValueError(f"Unexpected aggregation: {aggregate}")
-
-
-@functools.singledispatch
-def compile_nullary_agg(
-    op: ops.aggregations.WindowOp,
-    window: typing.Optional[window_spec.WindowSpec] = None,
-) -> sge.Expression:
-    raise ValueError(f"Can't compile unrecognized operation: {op}")
-
-
-@functools.singledispatch
-def compile_binary_agg(
-    op: ops.aggregations.WindowOp,
-    left: typed_expr.TypedExpr,
-    right: typed_expr.TypedExpr,
-    window: typing.Optional[window_spec.WindowSpec] = None,
-) -> sge.Expression:
-    raise ValueError(f"Can't compile unrecognized operation: {op}")
-
-
-@functools.singledispatch
-def compile_unary_agg(
-    op: ops.aggregations.WindowOp,
-    column: typed_expr.TypedExpr,
-    window: typing.Optional[window_spec.WindowSpec] = None,
-) -> sge.Expression:
-    raise ValueError(f"Can't compile unrecognized operation: {op}")
-
-
-@functools.singledispatch
-def compile_ordered_unary_agg(
-    op: ops.aggregations.WindowOp,
-    column: typed_expr.TypedExpr,
-    window: typing.Optional[window_spec.WindowSpec] = None,
-    order_by: typing.Sequence[sge.Expression] = [],
-) -> sge.Expression:
-    raise ValueError(f"Can't compile unrecognized operation: {op}")
-
-
-@compile_unary_agg.register
-def _(
-    op: ops.aggregations.SumOp,
-    column: typed_expr.TypedExpr,
-    window: typing.Optional[window_spec.WindowSpec] = None,
-) -> sge.Expression:
-    # Will be null if all inputs are null. Pandas defaults to zero sum though.
-    expr = _apply_window_if_present(sge.func("SUM", column.expr), window)
-    return sge.func("IFNULL", expr, ir._literal(0, column.dtype))
-
-
-def _apply_window_if_present(
-    value: sge.Expression,
-    window: typing.Optional[window_spec.WindowSpec] = None,
-) -> sge.Expression:
-    if window is not None:
-        raise NotImplementedError("Can't apply window to the expression.")
-    return value

bigframes/core/compile/sqlglot/aggregations/__init__.py

@@ -0,0 +1,13 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.

bigframes/core/compile/sqlglot/aggregations/binary_compiler.py

@@ -0,0 +1,35 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+import typing
+
+import sqlglot.expressions as sge
+
+from bigframes.core import window_spec
+import bigframes.core.compile.sqlglot.aggregations.op_registration as reg
+import bigframes.core.compile.sqlglot.expressions.typed_expr as typed_expr
+from bigframes.operations import aggregations as agg_ops
+
+BINARY_OP_REGISTRATION = reg.OpRegistration()
+
+
+def compile(
+    op: agg_ops.WindowOp,
+    left: typed_expr.TypedExpr,
+    right: typed_expr.TypedExpr,
+    window: typing.Optional[window_spec.WindowSpec] = None,
+) -> sge.Expression:
+    return BINARY_OP_REGISTRATION[op](op, left, right, window=window)

bigframes/core/compile/sqlglot/aggregations/nullary_compiler.py

@@ -0,0 +1,41 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+import typing
+
+import sqlglot.expressions as sge
+
+from bigframes.core import window_spec
+import bigframes.core.compile.sqlglot.aggregations.op_registration as reg
+from bigframes.core.compile.sqlglot.aggregations.utils import apply_window_if_present
+from bigframes.operations import aggregations as agg_ops
+
+NULLARY_OP_REGISTRATION = reg.OpRegistration()
+
+
+def compile(
+    op: agg_ops.WindowOp,
+    window: typing.Optional[window_spec.WindowSpec] = None,
+) -> sge.Expression:
+    return NULLARY_OP_REGISTRATION[op](op, window=window)
+
+
+@NULLARY_OP_REGISTRATION.register(agg_ops.SizeOp)
+def _(
+    op: agg_ops.SizeOp,
+    window: typing.Optional[window_spec.WindowSpec] = None,
+) -> sge.Expression:
+    return apply_window_if_present(sge.func("COUNT", sge.convert(1)), window)

bigframes/core/compile/sqlglot/aggregations/op_registration.py

@@ -0,0 +1,62 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+import typing
+
+from sqlglot import expressions as sge
+
+from bigframes.operations import aggregations as agg_ops
+
+# We should've been more specific about input types. Unfortunately,
+# MyPy doesn't support more rigorous checks.
+CompilationFunc = typing.Callable[..., sge.Expression]
+
+
+class OpRegistration:
+    def __init__(self) -> None:
+        self._registered_ops: dict[str, CompilationFunc] = {}
+
+    def register(
+        self, op: agg_ops.WindowOp | type[agg_ops.WindowOp]
+    ) -> typing.Callable[[CompilationFunc], CompilationFunc]:
+        def decorator(item: CompilationFunc):
+            def arg_checker(*args, **kwargs):
+                if not isinstance(args[0], agg_ops.WindowOp):
+                    raise ValueError(
+                        "The first parameter must be a window operator. "
+                        f"Got {type(args[0])}"
+                    )
+                return item(*args, **kwargs)
+
+            if hasattr(op, "name"):
+                key = typing.cast(str, op.name)
+                if key in self._registered_ops:
+                    raise ValueError(f"{key} is already registered")
+            else:
+                raise ValueError(f"The operator must have a 'name' attribute. Got {op}")
+            self._registered_ops[key] = item
+            return arg_checker
+
+        return decorator
+
+    def __getitem__(self, op: str | agg_ops.WindowOp) -> CompilationFunc:
+        if isinstance(op, agg_ops.WindowOp):
+            if not hasattr(op, "name"):
+                raise ValueError(f"The operator must have a 'name' attribute. Got {op}")
+            else:
+                key = typing.cast(str, op.name)
+                return self._registered_ops[key]
+        return self._registered_ops[op]

bigframes/core/compile/sqlglot/aggregations/ordered_unary_compiler.py

@@ -0,0 +1,37 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+import typing
+
+import sqlglot.expressions as sge
+
+from bigframes.core import window_spec
+import bigframes.core.compile.sqlglot.aggregations.op_registration as reg
+import bigframes.core.compile.sqlglot.expressions.typed_expr as typed_expr
+from bigframes.operations import aggregations as agg_ops
+
+ORDERED_UNARY_OP_REGISTRATION = reg.OpRegistration()
+
+
+def compile(
+    op: agg_ops.WindowOp,
+    column: typed_expr.TypedExpr,
+    window: typing.Optional[window_spec.WindowSpec] = None,
+    order_by: typing.Sequence[sge.Expression] = [],
+) -> sge.Expression:
+    return ORDERED_UNARY_OP_REGISTRATION[op](
+        op, column, window=window, order_by=order_by
+    )

bigframes/core/compile/sqlglot/aggregations/unary_compiler.py

@@ -0,0 +1,56 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+import typing
+
+import sqlglot.expressions as sge
+
+from bigframes.core import window_spec
+import bigframes.core.compile.sqlglot.aggregations.op_registration as reg
+from bigframes.core.compile.sqlglot.aggregations.utils import apply_window_if_present
+import bigframes.core.compile.sqlglot.expressions.typed_expr as typed_expr
+import bigframes.core.compile.sqlglot.sqlglot_ir as ir
+from bigframes.operations import aggregations as agg_ops
+
+UNARY_OP_REGISTRATION = reg.OpRegistration()
+
+
+def compile(
+    op: agg_ops.WindowOp,
+    column: typed_expr.TypedExpr,
+    window: typing.Optional[window_spec.WindowSpec] = None,
+) -> sge.Expression:
+    return UNARY_OP_REGISTRATION[op](op, column, window=window)
+
+
+@UNARY_OP_REGISTRATION.register(agg_ops.SumOp)
+def _(
+    op: agg_ops.SumOp,
+    column: typed_expr.TypedExpr,
+    window: typing.Optional[window_spec.WindowSpec] = None,
+) -> sge.Expression:
+    # Will be null if all inputs are null. Pandas defaults to zero sum though.
+    expr = apply_window_if_present(sge.func("SUM", column.expr), window)
+    return sge.func("IFNULL", expr, ir._literal(0, column.dtype))
+
+
+@UNARY_OP_REGISTRATION.register(agg_ops.SizeUnaryOp)
+def _(
+    op: agg_ops.SizeUnaryOp,
+    _,
+    window: typing.Optional[window_spec.WindowSpec] = None,
+) -> sge.Expression:
+    return apply_window_if_present(sge.func("COUNT", sge.convert(1)), window)

bigframes/core/compile/sqlglot/aggregations/utils.py

@@ -0,0 +1,29 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from __future__ import annotations
+
+import typing
+
+import sqlglot.expressions as sge
+
+from bigframes.core import window_spec
+
+
+def apply_window_if_present(
+    value: sge.Expression,
+    window: typing.Optional[window_spec.WindowSpec] = None,
+) -> sge.Expression:
+    if window is not None:
+        raise NotImplementedError("Can't apply window to the expression.")
+    return value