chore(bigframes): Add simple Python bytcode translation

packages/bigframes/bigframes/core/bytecode.py

@@ -0,0 +1,263 @@
+# 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.
+
+import dis
+import operator
+import sys
+from types import ModuleType
+from typing import Callable
+
+import bigframes.core.py_expressions as py_exprs
+from bigframes.core import expression
+
+_BINARY_OP_MAP = {
+    "+": operator.add,
+    "-": operator.sub,
+    "*": operator.mul,
+    "/": operator.truediv,
+    "//": operator.floordiv,
+    "%": operator.mod,
+    "**": operator.pow,
+}
+
+_COMPARE_OP_MAP = {
+    "==": operator.eq,
+    "!=": operator.ne,
+    "<": operator.lt,
+    "<=": operator.le,
+    ">": operator.gt,
+    ">=": operator.ge,
+}
+
+_OLD_BINARY_OP_MAP = {
+    "BINARY_ADD": operator.add,
+    "INPLACE_ADD": operator.add,
+    "BINARY_SUBTRACT": operator.sub,
+    "INPLACE_SUBTRACT": operator.sub,
+    "BINARY_MULTIPLY": operator.mul,
+    "INPLACE_MULTIPLY": operator.mul,
+    "BINARY_TRUE_DIVIDE": operator.truediv,
+    "INPLACE_TRUE_DIVIDE": operator.truediv,
+    "BINARY_FLOOR_DIVIDE": operator.floordiv,
+    "INPLACE_FLOOR_DIVIDE": operator.floordiv,
+    "BINARY_MODULO": operator.mod,
+    "INPLACE_MODULO": operator.mod,
+    "BINARY_POWER": operator.pow,
+    "INPLACE_POWER": operator.pow,
+}
+
+
+_NULL = py_exprs.PyObject(None)
+
+
+def _compile_bytecode_to_py_expr(func: Callable) -> expression.Expression:
+    instructions = list(dis.get_instructions(func))
+
+    stack: list[expression.Expression] = []
+    globals_dict = func.__globals__
+    import builtins
+
+    builtins_dict = builtins.__dict__
+
+    closure_dict = {}
+    if func.__closure__:
+        free_vars = func.__code__.co_freevars
+        for var, cell in zip(free_vars, func.__closure__):
+            try:
+                closure_dict[var] = cell.cell_contents
+            except ValueError:
+                pass
+
+    for inst in instructions:
+        opname = inst.opname
+
+        if opname in ("RESUME", "PRECALL"):
+            continue
+
+        elif opname in ("LOAD_FAST_LOAD_FAST", "LOAD_FAST_BORROW_LOAD_FAST_BORROW"):
+            var1, var2 = inst.argval
+            stack.append(expression.UnboundVariableExpression(var1))
+            stack.append(expression.UnboundVariableExpression(var2))
+
+        elif opname.startswith("LOAD_FAST"):
+            stack.append(expression.UnboundVariableExpression(inst.argval))
+
+        elif opname in ("LOAD_CONST", "LOAD_SMALL_INT"):
+            stack.append(py_exprs.PyObject(inst.argval))
+
+        elif opname == "LOAD_GLOBAL":
+            # In Python 3.11+, the lowest bit of inst.arg indicates that a NULL
+            # should be pushed before the global variable.
+            if sys.version_info >= (3, 11) and inst.arg is not None and (inst.arg & 1):
+                stack.append(_NULL)
+            name = inst.argval
+            found = False
+            val = None
+            if name in closure_dict:
+                val = closure_dict[name]
+                found = True
+            elif name in globals_dict:
+                val = globals_dict[name]
+                found = True
+            elif name in builtins_dict:
+                val = builtins_dict[name]
+                found = True
+
+            if found:
+                if isinstance(val, ModuleType):
+                    stack.append(py_exprs.Module(val))
+                else:
+                    stack.append(py_exprs.PyObject(val))
+            else:
+                stack.append(expression.UnboundVariableExpression(name))
+
+        elif opname in ("LOAD_ATTR", "LOAD_METHOD"):
+            if not stack:
+                raise ValueError("Stack is empty")
+            target = stack.pop()
+            stack.append(py_exprs.GetAttr(target, inst.argval))
+            if opname == "LOAD_METHOD":
+                if isinstance(target, py_exprs.Module):
+                    stack.append(_NULL)
+                else:
+                    stack.append(target)
+
+        elif opname == "PUSH_NULL":
+            stack.append(_NULL)
+
+        elif opname == "BINARY_OP":
+            if len(stack) < 2:
+                raise ValueError("Stack is empty")
+            right = stack.pop()
+            left = stack.pop()
+            op_symbol = inst.argrepr
+            if not op_symbol and isinstance(inst.argval, str):
+                op_symbol = inst.argval
+            if op_symbol and op_symbol.endswith("="):
+                op_symbol = op_symbol[:-1]
+
+            if op_symbol not in _BINARY_OP_MAP:
+                raise ValueError(f"Unsupported binary operator: {op_symbol}")
+            stack.append(
+                py_exprs.Call(
+                    py_exprs.PyObject(_BINARY_OP_MAP[op_symbol]), (left, right)
+                )
+            )
+
+        # Support older Python versions compatibility
+        elif opname in _OLD_BINARY_OP_MAP:
+            if len(stack) < 2:
+                raise ValueError("Stack has < 2 elements")
+            right = stack.pop()
+            left = stack.pop()
+            stack.append(
+                py_exprs.Call(
+                    py_exprs.PyObject(_OLD_BINARY_OP_MAP[opname]), (left, right)
+                )
+            )
+
+        elif opname == "COMPARE_OP":
+            if len(stack) < 2:
+                raise ValueError("Stack has < 2 elements")
+            right = stack.pop()
+            left = stack.pop()
+            op_symbol = inst.argval
+            if op_symbol not in _COMPARE_OP_MAP:
+                raise ValueError(f"Unsupported compare operator: {op_symbol}")
+            stack.append(
+                py_exprs.Call(
+                    py_exprs.PyObject(_COMPARE_OP_MAP[op_symbol]), (left, right)
+                )
+            )
+
+        elif opname in ("UNARY_NEGATIVE", "UNARY_INVERT"):
+            if not stack:
+                raise ValueError("Stack is empty")
+            target = stack.pop()
+            stack.append(
+                py_exprs.Call(
+                    py_exprs.PyObject(
+                        operator.neg if opname == "UNARY_NEGATIVE" else operator.invert
+                    ),
+                    (target,),
+                )
+            )
+
+        elif opname == "UNARY_POSITIVE":
+            if not stack:
+                raise ValueError("Stack is empty")
+            target = stack.pop()
+            stack.append(py_exprs.Call(py_exprs.PyObject(operator.pos), (target,)))
+
+        elif opname == "CALL_INTRINSIC_1":
+            if inst.argrepr == "INTRINSIC_UNARY_POSITIVE":
+                if not stack:
+                    raise ValueError("Stack is empty")
+                target = stack.pop()
+                stack.append(py_exprs.Call(py_exprs.PyObject(operator.pos), (target,)))
+            else:
+                raise ValueError(f"Unsupported intrinsic: {inst.argrepr}")
+
+        elif opname in ("CALL", "CALL_FUNCTION", "CALL_METHOD"):
+            num_args = inst.arg
+            assert num_args is not None
+            if len(stack) < num_args:
+                raise ValueError("Stack has < 2 elements")
+            args = [stack.pop() for _ in range(num_args)][::-1]
+            # In Python 3.11, LOAD_GLOBAL with NULL push puts NULL below the global.
+            # If NULL is below the callable on the stack, swap them to match
+            # the expected layout [callable, NULL].
+            if len(stack) >= 2 and stack[-2] == _NULL:
+                stack[-1], stack[-2] = stack[-2], stack[-1]
+            if stack and stack[-1] == _NULL:
+                stack.pop()
+            elif (
+                stack
+                and stack[-1] != _NULL
+                and isinstance(stack[-1], expression.Expression)
+            ):
+                self_arg = stack.pop()
+                args = [self_arg] + args
+            if not stack:
+                raise ValueError("Stack is empty")
+            callable_expr = stack.pop()
+            stack.append(py_exprs.Call(callable_expr, tuple(args)))
+
+        elif opname == "RETURN_VALUE":
+            if not stack:
+                raise ValueError("Stack is empty")
+            return stack[-1]
+
+        elif opname in ("STORE_FAST", "POP_TOP"):
+            if stack:
+                stack.pop()
+
+        else:
+            raise ValueError(f"Unsupported opcode: {opname}")
+
+    raise ValueError("No return value found")
+
+
+def dis_to_expr(func: Callable, unpack_mode: bool = False) -> expression.Expression:
+    """
+    Try to convert a python function to a BigQuery expression.
+
+    Unpack mode is whether SQL columns are addressed as attributes of a single
+    python argument (e.g. row.col1), or as separate arguments (e.g. col1).
+
+    This is "best effort" - if the function contains operations that cannot
+    be converted to BigQuery expressions, it will raise an Exception.
+    """
+    py_expr = _compile_bytecode_to_py_expr(func)
+    return py_exprs.resolve_py_exprs(py_expr, unpack_mode=unpack_mode)