feat: wire factorial and update wire skill

docs/source/contributor-guide/spark_expressions_support.md

@@ -385,7 +385,10 @@
 - [ ] e
 - [x] exp
 - [x] expm1
-- [ ] factorial
+- [x] factorial
+  - 3.4.3 (audited 2026-05-15): identical to v3.5.8.
+  - 3.5.8 (audited 2026-05-15): canonical reference; `extends UnaryExpression with ImplicitCastInputTypes with NullIntolerant`. Returns NULL for NULL input or values outside `[0, 20]`.
+  - 4.0.1 (audited 2026-05-15): `NullIntolerant` trait replaced by `nullIntolerant: Boolean` method override; behavior unchanged.
 - [x] floor
 - [x] greatest
 - [x] hex

docs/source/user-guide/latest/expressions.md

@@ -156,6 +156,7 @@ of expressions that be disabled.
 | Divide         | `/`            |
 | Exp            | `exp`          |
 | Expm1          | `expm1`        |
+| Factorial      | `factorial`    |
 | Floor          | `floor`        |
 | Hex            | `hex`          |
 | IntegralDivide | `div`          |

native/core/src/execution/jni_api.rs

@@ -58,6 +58,7 @@ use datafusion_spark::function::hash::sha2::SparkSha2;
 use datafusion_spark::function::map::map_from_entries::MapFromEntries;
 use datafusion_spark::function::map::str_to_map::SparkStrToMap;
 use datafusion_spark::function::math::expm1::SparkExpm1;
+use datafusion_spark::function::math::factorial::SparkFactorial;
 use datafusion_spark::function::math::hex::SparkHex;
 use datafusion_spark::function::math::trigonometry::SparkCsc;
 use datafusion_spark::function::math::width_bucket::SparkWidthBucket;
@@ -597,6 +598,7 @@ fn register_datafusion_spark_function(session_ctx: &SessionContext) {
     session_ctx.register_udf(ScalarUDF::new_from_impl(SparkUrlEncode::default()));
     session_ctx.register_udf(ScalarUDF::new_from_impl(SparkTryUrlDecode::default()));
     session_ctx.register_udf(ScalarUDF::new_from_impl(SparkCsc::default()));
+    session_ctx.register_udf(ScalarUDF::new_from_impl(SparkFactorial::default()));
 }
 
 /// Prepares arrow arrays for output.

spark/src/main/scala/org/apache/comet/serde/QueryPlanSerde.scala

@@ -108,6 +108,7 @@ object QueryPlanSerde extends Logging with CometExprShim with CometTypeShim {
     classOf[Divide] -> CometDivide,
     classOf[Exp] -> CometScalarFunction("exp"),
     classOf[Expm1] -> CometScalarFunction("expm1"),
+    classOf[Factorial] -> CometScalarFunction("factorial"),
     classOf[Floor] -> CometFloor,
     classOf[Greatest] -> CometScalarFunction("greatest"),
     classOf[Hex] -> CometHex,

spark/src/test/resources/sql-tests/expressions/math/factorial.sql

@@ -0,0 +1,39 @@
+-- Licensed to the Apache Software Foundation (ASF) under one
+-- or more contributor license agreements.  See the NOTICE file
+-- distributed with this work for additional information
+-- regarding copyright ownership.  The ASF licenses this file
+-- to you 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.
+
+-- ConfigMatrix: parquet.enable.dictionary=false,true
+
+statement
+CREATE TABLE test_factorial(i int) USING parquet
+
+statement
+INSERT INTO test_factorial VALUES
+  (0),
+  (1),
+  (5),
+  (12),
+  (20),
+  (21),
+  (-1),
+  (-5),
+  (100),
+  (NULL),
+  (2147483647),
+  (-2147483648)
+
+query
+SELECT i, factorial(i) FROM test_factorial