Add bool8

Author: tschwarzinger

datafusion/common/src/types/canonical_extensions/bool8.rs

@@ -0,0 +1,96 @@
+// 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 crate::error::_internal_err;
+use crate::types::extension::DFExtensionType;
+use arrow::array::{Array, Int8Array};
+use arrow::datatypes::DataType;
+use arrow::util::display::{ArrayFormatter, DisplayIndex, FormatOptions, FormatResult};
+use std::fmt::Write;
+
+/// Defines the extension type logic for the canonical `arrow.uuid` extension type.
+///
+/// See [`DFExtensionType`] for information on DataFusion's extension type mechanism.
+impl DFExtensionType for arrow_schema::extension::Bool8 {
+    fn storage_type(&self) -> DataType {
+        DataType::Int8
+    }
+
+    fn serialize_metadata(&self) -> Option<String> {
+        None
+    }
+
+    fn create_array_formatter<'fmt>(
+        &self,
+        array: &'fmt dyn Array,
+        options: &FormatOptions<'fmt>,
+    ) -> crate::Result<Option<ArrayFormatter<'fmt>>> {
+        if array.data_type() != &DataType::Int8 {
+            return _internal_err!("Wrong array type for Bool8");
+        }
+
+        let display_index = Bool8ValueDisplayIndex {
+            array: array.as_any().downcast_ref().unwrap(),
+            null_str: options.null(),
+        };
+        Ok(Some(ArrayFormatter::new(
+            Box::new(display_index),
+            options.safe(),
+        )))
+    }
+}
+
+/// Pretty printer for binary UUID values.
+#[derive(Debug, Clone, Copy)]
+struct Bool8ValueDisplayIndex<'a> {
+    array: &'a Int8Array,
+    null_str: &'a str,
+}
+
+impl DisplayIndex for Bool8ValueDisplayIndex<'_> {
+    fn write(&self, idx: usize, f: &mut dyn Write) -> FormatResult {
+        if self.array.is_null(idx) {
+            write!(f, "{}", self.null_str)?;
+            return Ok(());
+        }
+
+        let bytes = self.array.value(idx);
+        write!(f, "{}", bytes != 0)?;
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    pub fn test_pretty_bool8() {
+        let values = Int8Array::from_iter([Some(0), Some(1), Some(-20), None]);
+
+        let extension_type = arrow_schema::extension::Bool8 {};
+        let formatter = extension_type
+            .create_array_formatter(&values, &FormatOptions::default().with_null("NULL"))
+            .unwrap()
+            .unwrap();
+
+        assert_eq!(formatter.value(0).to_string(), "false");
+        assert_eq!(formatter.value(1).to_string(), "true");
+        assert_eq!(formatter.value(2).to_string(), "true");
+        assert_eq!(formatter.value(3).to_string(), "NULL");
+    }
+}

datafusion/common/src/types/canonical_extensions/mod.rs

@@ -15,4 +15,5 @@
 // specific language governing permissions and limitations
 // under the License.
 
+mod bool8;
 mod uuid;