[task apache#9539] Move starts_with, to_hex, trim, upper to datafusio…

…n-functions

Signed-off-by: tangruilin <tang.ruilin@foxmail.com>

datafusion/functions/Cargo.toml

@@ -29,12 +29,21 @@ authors = { workspace = true }
 rust-version = { workspace = true }
 
 [features]
+# enable string functions
+string_expressions = []
 # enable core functions
 core_expressions = []
 # enable datetime functions
 datetime_expressions = []
 # Enable encoding by default so the doctests work. In general don't automatically enable all packages.
-default = ["core_expressions", "datetime_expressions", "encoding_expressions", "math_expressions", "regex_expressions"]
+default = [
+    "core_expressions",
+    "datetime_expressions",
+    "encoding_expressions",
+    "math_expressions",
+    "regex_expressions",
+    "string_expressions",
+]
 # enable encode/decode functions
 encoding_expressions = ["base64", "hex"]
 # enable math functions

datafusion/functions/src/lib.rs

@@ -84,6 +84,10 @@ use log::debug;
 #[macro_use]
 pub mod macros;
 
+#[cfg(feature = "string_expressions")]
+pub mod string;
+make_stub_package!(string, "string_expressions");
+
 /// Core datafusion expressions
 /// Enabled via feature flag `core_expressions`
 #[cfg(feature = "core_expressions")]
@@ -137,7 +141,8 @@ pub fn register_all(registry: &mut dyn FunctionRegistry) -> Result<()> {
         .chain(datetime::functions())
         .chain(encoding::functions())
         .chain(math::functions())
-        .chain(regex::functions());
+        .chain(regex::functions())
+        .chain(string::functions());
 
     all_functions.try_for_each(|udf| {
         let existing_udf = registry.register_udf(udf)?;

datafusion/functions/src/string/mod.rs

@@ -0,0 +1,22 @@
+// 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.
+
+//! "regx" DataFusion functions
+
+pub mod starts_with;
+// create UDFs
+export_functions!();

datafusion/functions/src/string/starts_with.rs

@@ -0,0 +1,79 @@
+// 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 arrow::array::{Array, ArrayRef, OffsetSizeTrait};
+use arrow::compute::kernels::regexp;
+use arrow::datatypes::DataType;
+use datafusion_common::exec_err;
+use datafusion_common::ScalarValue;
+use datafusion_common::{arrow_datafusion_err, plan_err};
+use datafusion_common::{
+    cast::as_generic_string_array, internal_err, DataFusionError, Result,
+};
+use datafusion_expr::ColumnarValue;
+use datafusion_expr::TypeSignature::*;
+use datafusion_expr::{ScalarUDFImpl, Signature, Volatility};
+use std::any::Any;
+use std::sync::Arc;
+
+#[derive(Debug)]
+pub(super) struct StartsWithFunc {
+    signature: Signature,
+}
+impl StartsWithFunc {
+    pub fn new() -> Self {
+        use DataType::*;
+        Self {
+            signature: Signature::one_of(
+                vec![
+                    Exact(vec![Utf8, Utf8]),
+                    Exact(vec![LargeUtf8, Utf8]),
+                    Exact(vec![Utf8, Utf8, Utf8]),
+                    Exact(vec![LargeUtf8, Utf8, Utf8]),
+                ],
+                Volatility::Immutable,
+            ),
+        }
+    }
+}
+
+impl ScalarUDFImpl for StartsWithFunc {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    fn name(&self) -> &str {
+        "starts_with"
+    }
+
+    fn signature(&self) -> &Signature {
+        &self.signature
+    }
+
+    fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
+        use DataType::*;
+
+        Ok(Boolean)
+    }
+
+    fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> {
+        unimplemented!("starts_with")
+    }
+}
+
+#[cfg(test)]
+mod tests {}