Implement Spark-compliant regexp_extract function

datafusion/spark/Cargo.toml

@@ -45,6 +45,7 @@ datafusion-expr = { workspace = true }
 datafusion-functions = { workspace = true, features = ["crypto_expressions"] }
 datafusion-macros = { workspace = true }
 log = { workspace = true }
+regex = { workspace = true }
 
 [dev-dependencies]
 criterion = { workspace = true }

datafusion/spark/src/function/mod.rs

@@ -32,6 +32,7 @@ pub mod map;
 pub mod math;
 pub mod misc;
 pub mod predicate;
+pub mod regexp;
 pub mod string;
 pub mod r#struct;
 pub mod table;

datafusion/spark/src/function/regexp/mod.rs

@@ -0,0 +1,40 @@
+// 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.
+
+use datafusion_expr::ScalarUDF;
+use datafusion_functions::make_udf_function;
+use std::sync::Arc;
+
+pub mod regexp_extract;
+
+make_udf_function!(regexp_extract::SparkRegexpExtract, regexp_extract);
+
+pub mod expr_fn {
+    use datafusion_functions::export_functions;
+
+    export_functions!((
+        regexp_extract,
+        "Extract a specific group matched by the Java regex, from the specified string column.\
+         If the regex did not match, or the specified group did not match, \
+         an empty string is returned.",
+        str regexp idx
+    ));
+}
+
+pub fn functions() -> Vec<Arc<ScalarUDF>> {
+    vec![regexp_extract()]
+}