fix(core): make aggregate functions and window functions support zero…

… argument (#943)

wren-core/core/src/mdl/function.rs

@@ -117,7 +117,13 @@ impl ByPassAggregateUDF {
         Self {
             name: name.to_string(),
             return_type,
-            signature: Signature::variadic_any(Volatility::Immutable),
+            signature: Signature::one_of(
+                vec![
+                    TypeSignature::VariadicAny,
+                    TypeSignature::Uniform(0, vec![]),
+                ],
+                Volatility::Volatile,
+            ),
         }
     }
 }
@@ -158,7 +164,13 @@ impl ByPassWindowFunction {
         Self {
             name: name.to_string(),
             return_type,
-            signature: Signature::variadic_any(Volatility::Immutable),
+            signature: Signature::one_of(
+                vec![
+                    TypeSignature::VariadicAny,
+                    TypeSignature::Uniform(0, vec![]),
+                ],
+                Volatility::Volatile,
+            ),
         }
     }
 }
@@ -214,6 +226,14 @@ mod test {
             .into_unoptimized_plan();
         let expected = "Projection: date_diff(Int64(1), Int64(2))\n  EmptyRelation";
         assert_eq!(format!("{plan}"), expected);
+
+        ctx.register_udf(ScalarUDF::new_from_impl(ByPassScalarUDF::new(
+            "today",
+            DataType::Utf8,
+        )));
+        let plan_2 = ctx.sql("SELECT today()").await?.into_unoptimized_plan();
+        assert_eq!(format!("{plan_2}"), "Projection: today()\n  EmptyRelation");
+
         Ok(())
     }
 
@@ -230,6 +250,23 @@ mod test {
         \n      Projection: column1 AS c1, column2 AS c2\
         \n        Values: (Int64(1), Int64(2)), (Int64(2), Int64(3)), (Int64(3), Int64(4))";
         assert_eq!(format!("{plan}"), expected);
+
+        ctx.register_udaf(AggregateUDF::new_from_impl(ByPassAggregateUDF::new(
+            "total_count",
+            DataType::Int64,
+        )));
+        let plan_2 = ctx
+            .sql("SELECT total_count() AS total_count FROM (VALUES (1), (2), (3)) AS val(x)")
+            .await?
+            .into_unoptimized_plan();
+        assert_eq!(
+            format!("{plan_2}"),
+            "Projection: total_count() AS total_count\
+        \n  Aggregate: groupBy=[[]], aggr=[[total_count()]]\
+        \n    SubqueryAlias: val\n      Projection: column1 AS x\
+        \n        Values: (Int64(1)), (Int64(2)), (Int64(3))"
+        );
+
         Ok(())
     }
 
@@ -247,6 +284,19 @@ mod test {
         \n  WindowAggr: windowExpr=[[custom_window(Int64(1), Int64(2)) ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING]]\
         \n    EmptyRelation";
         assert_eq!(format!("{plan}"), expected);
+
+        ctx.register_udwf(WindowUDF::new_from_impl(ByPassWindowFunction::new(
+            "cume_dist",
+            DataType::Int64,
+        )));
+        let plan_2 = ctx
+            .sql("SELECT cume_dist() OVER ()")
+            .await?
+            .into_unoptimized_plan();
+        assert_eq!(format!("{plan_2}"), "Projection: cume_dist() ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING\
+        \n  WindowAggr: windowExpr=[[cume_dist() ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING]]\
+        \n    EmptyRelation");
+
         Ok(())
     }
 }