refactor: remove expr arguments in translate

This removes all usage of `expr` being passed explicitly to mapping
functions.  There are a few cases where Ibis 3.x will pass in
expressions still, but those should be handled by the `_expr` rule,
which forwards on the `op` (at a cost of an extra dispatch).

There are also a few bits where we do reductions on predicates that
operate on expressions.  Those should be converted to ops where
possible (without breaking support for older Ibis versions).

ibis_substrait/compiler/core.py

@@ -57,27 +57,21 @@ def __init__(self, udf_uri: str | None = None) -> None:
 
     def function_id(
         self,
-        *,
-        expr: ir.ValueExpr | None = None,
-        op: ops.Value | None = None,
+        op: ops.Value,
     ) -> int:
         """Create a function mapping for a given expression.
 
         Parameters
         ----------
-        expr
-            An ibis expression that produces a value.
         op
-            Passthrough op to directly specify desired substrait scalar function
+            Ibis operation to use to lookup desired substrait scalar function
 
         Returns
         -------
         ste.ExtensionsFunctionId
             This is a unique identifier for a given operation type, *argument
             types N-tuple.
         """
-        if op is None:
-            op = expr.op() if expr is not None else None
         op_type = type(op)
         op_name = IBIS_SUBSTRAIT_OP_MAPPING[op_type.__name__]
 
@@ -196,7 +190,7 @@ def compile(self, expr: ir.TableExpr, **kwargs: Any) -> stp.Plan:
         expr_schema = expr.schema()
         rel = stp.PlanRel(
             root=stalg.RelRoot(
-                input=translate(expr.op(), expr=expr, compiler=self, **kwargs),
+                input=translate(expr.op(), compiler=self, **kwargs),
                 names=translate(expr_schema).names,
             )
         )