datafusion-functions 37.0.0

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// 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 std::any::Any;

use arrow::datatypes::DataType;

use datafusion_common::Result;
use datafusion_expr::ColumnarValue;
use datafusion_expr::{ScalarUDFImpl, Signature, Volatility};

use crate::string::common::handle;
use crate::utils::utf8_to_str_type;

#[derive(Debug)]
pub(super) struct LowerFunc {
    signature: Signature,
}

impl LowerFunc {
    pub fn new() -> Self {
        use DataType::*;
        Self {
            signature: Signature::uniform(
                1,
                vec![Utf8, LargeUtf8],
                Volatility::Immutable,
            ),
        }
    }
}

impl ScalarUDFImpl for LowerFunc {
    fn as_any(&self) -> &dyn Any {
        self
    }

    fn name(&self) -> &str {
        "lower"
    }

    fn signature(&self) -> &Signature {
        &self.signature
    }

    fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
        utf8_to_str_type(&arg_types[0], "lower")
    }

    fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> {
        handle(args, |string| string.to_lowercase(), "lower")
    }
}