arrow-schema 58.1.0

// Licensed to the Apache Software Foundation (ASF) under one
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// 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.

//! 8-bit Boolean
//!
//! <https://arrow.apache.org/docs/format/CanonicalExtensions.html#bit-boolean>

use crate::{ArrowError, DataType, extension::ExtensionType};

/// The extension type for `8-bit Boolean`.
///
/// Extension name: `arrow.bool8`.
///
/// The storage type of the extension is `Int8` where:
/// - false is denoted by the value 0.
/// - true can be specified using any non-zero value. Preferably 1.
///
/// <https://arrow.apache.org/docs/format/CanonicalExtensions.html#bit-boolean>
#[derive(Debug, Default, Clone, Copy, PartialEq)]
pub struct Bool8;

impl ExtensionType for Bool8 {
    const NAME: &'static str = "arrow.bool8";

    type Metadata = &'static str;

    fn metadata(&self) -> &Self::Metadata {
        &""
    }

    fn serialize_metadata(&self) -> Option<String> {
        Some(String::default())
    }

    fn deserialize_metadata(metadata: Option<&str>) -> Result<Self::Metadata, ArrowError> {
        if metadata.is_some_and(str::is_empty) {
            Ok("")
        } else {
            Err(ArrowError::InvalidArgumentError(
                "Bool8 extension type expects an empty string as metadata".to_owned(),
            ))
        }
    }

    fn supports_data_type(&self, data_type: &DataType) -> Result<(), ArrowError> {
        match data_type {
            DataType::Int8 => Ok(()),
            data_type => Err(ArrowError::InvalidArgumentError(format!(
                "Bool8 data type mismatch, expected Int8, found {data_type}"
            ))),
        }
    }

    fn try_new(data_type: &DataType, _metadata: Self::Metadata) -> Result<Self, ArrowError> {
        Self.supports_data_type(data_type).map(|_| Self)
    }
}

#[cfg(test)]
mod tests {
    #[cfg(feature = "canonical_extension_types")]
    use crate::extension::CanonicalExtensionType;
    use crate::{
        Field,
        extension::{EXTENSION_TYPE_METADATA_KEY, EXTENSION_TYPE_NAME_KEY},
    };

    use super::*;

    #[test]
    fn valid() -> Result<(), ArrowError> {
        let mut field = Field::new("", DataType::Int8, false);
        field.try_with_extension_type(Bool8)?;
        field.try_extension_type::<Bool8>()?;
        #[cfg(feature = "canonical_extension_types")]
        assert_eq!(
            field.try_canonical_extension_type()?,
            CanonicalExtensionType::Bool8(Bool8)
        );

        Ok(())
    }

    #[test]
    #[should_panic(expected = "Extension type name missing")]
    fn missing_name() {
        let field = Field::new("", DataType::Int8, false).with_metadata(
            [(EXTENSION_TYPE_METADATA_KEY.to_owned(), "".to_owned())]
                .into_iter()
                .collect(),
        );
        field.extension_type::<Bool8>();
    }

    #[test]
    #[should_panic(expected = "expected Int8, found Boolean")]
    fn invalid_type() {
        Field::new("", DataType::Boolean, false).with_extension_type(Bool8);
    }

    #[test]
    #[should_panic(expected = "Bool8 extension type expects an empty string as metadata")]
    fn missing_metadata() {
        let field = Field::new("", DataType::Int8, false).with_metadata(
            [(EXTENSION_TYPE_NAME_KEY.to_owned(), Bool8::NAME.to_owned())]
                .into_iter()
                .collect(),
        );
        field.extension_type::<Bool8>();
    }

    #[test]
    #[should_panic(expected = "Bool8 extension type expects an empty string as metadata")]
    fn invalid_metadata() {
        let field = Field::new("", DataType::Int8, false).with_metadata(
            [
                (EXTENSION_TYPE_NAME_KEY.to_owned(), Bool8::NAME.to_owned()),
                (
                    EXTENSION_TYPE_METADATA_KEY.to_owned(),
                    "non-empty".to_owned(),
                ),
            ]
            .into_iter()
            .collect(),
        );
        field.extension_type::<Bool8>();
    }
}