Draft: Logical signature

datafusion/common/src/lib.rs

@@ -44,6 +44,7 @@ pub mod scalar;
 pub mod stats;
 pub mod test_util;
 pub mod tree_node;
+pub mod types;
 pub mod utils;
 
 /// Reexport arrow crate

datafusion/common/src/types/field.rs

@@ -0,0 +1,114 @@
+// 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_schema::{Field, Fields, UnionFields};
+use std::hash::{Hash, Hasher};
+use std::{ops::Deref, sync::Arc};
+
+use super::{LogicalTypeRef, NativeType};
+
+/// A record of a logical type, its name and its nullability.
+#[derive(Debug, Clone, Eq, PartialOrd, Ord)]
+pub struct LogicalField {
+    pub name: String,
+    pub logical_type: LogicalTypeRef,
+    pub nullable: bool,
+}
+
+impl PartialEq for LogicalField {
+    fn eq(&self, other: &Self) -> bool {
+        self.name == other.name
+            && self.logical_type.eq(&other.logical_type)
+            && self.nullable == other.nullable
+    }
+}
+
+impl Hash for LogicalField {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.name.hash(state);
+        self.logical_type.hash(state);
+        self.nullable.hash(state);
+    }
+}
+
+impl From<&Field> for LogicalField {
+    fn from(value: &Field) -> Self {
+        Self {
+            name: value.name().clone(),
+            logical_type: Arc::new(NativeType::from(value.data_type().clone())),
+            nullable: value.is_nullable(),
+        }
+    }
+}
+
+/// A reference counted [`LogicalField`].
+pub type LogicalFieldRef = Arc<LogicalField>;
+
+/// A cheaply cloneable, owned collection of [`LogicalFieldRef`].
+#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct LogicalFields(Arc<[LogicalFieldRef]>);
+
+impl Deref for LogicalFields {
+    type Target = [LogicalFieldRef];
+
+    fn deref(&self) -> &Self::Target {
+        self.0.as_ref()
+    }
+}
+
+impl From<&Fields> for LogicalFields {
+    fn from(value: &Fields) -> Self {
+        value
+            .iter()
+            .map(|field| Arc::new(LogicalField::from(field.as_ref())))
+            .collect()
+    }
+}
+
+impl FromIterator<LogicalFieldRef> for LogicalFields {
+    fn from_iter<T: IntoIterator<Item = LogicalFieldRef>>(iter: T) -> Self {
+        Self(iter.into_iter().collect())
+    }
+}
+
+/// A cheaply cloneable, owned collection of [`LogicalFieldRef`] and their
+/// corresponding type ids.
+#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct LogicalUnionFields(Arc<[(i8, LogicalFieldRef)]>);
+
+impl Deref for LogicalUnionFields {
+    type Target = [(i8, LogicalFieldRef)];
+
+    fn deref(&self) -> &Self::Target {
+        self.0.as_ref()
+    }
+}
+
+impl From<&UnionFields> for LogicalUnionFields {
+    fn from(value: &UnionFields) -> Self {
+        value
+            .iter()
+            .map(|(i, field)| (i, Arc::new(LogicalField::from(field.as_ref()))))
+            .collect()
+    }
+}
+
+impl FromIterator<(i8, LogicalFieldRef)> for LogicalUnionFields {
+    fn from_iter<T: IntoIterator<Item = (i8, LogicalFieldRef)>>(iter: T) -> Self {
+        Self(iter.into_iter().collect())
+    }
+}

datafusion/common/src/types/logical.rs

@@ -0,0 +1,118 @@
+// 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 core::fmt;
+use std::{cmp::Ordering, hash::Hash, sync::Arc};
+
+use super::NativeType;
+
+/// Signature that uniquely identifies a type among other types.
+#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub enum TypeSignature<'a> {
+    /// Represents a built-in native type.
+    Native(&'a NativeType),
+    /// Represents an arrow-compatible extension type.
+    /// (<https://arrow.apache.org/docs/format/Columnar.html#extension-types>)
+    ///
+    /// The `name` should contain the same value as 'ARROW:extension:name'.
+    Extension {
+        name: &'a str,
+        parameters: &'a [TypeParameter<'a>],
+    },
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub enum TypeParameter<'a> {
+    Type(TypeSignature<'a>),
+    Number(i128),
+}
+
+/// A reference counted [`LogicalType`].
+pub type LogicalTypeRef = Arc<dyn LogicalType>;
+
+/// Representation of a logical type with its signature and its native backing
+/// type.
+///
+/// The logical type is meant to be used during the DataFusion logical planning
+/// phase in order to reason about logical types without worrying about their
+/// underlying physical implementation.
+///
+/// ### Extension types
+///
+/// [`LogicalType`] is a trait in order to allow the possibility of declaring
+/// extension types:
+///
+/// ```
+/// use datafusion_common::types::{LogicalType, NativeType, TypeSignature};
+///
+/// struct JSON {}
+///
+/// impl LogicalType for JSON {
+///     fn native(&self) -> &NativeType {
+///         &NativeType::Utf8
+///     }
+///
+///    fn signature(&self) -> TypeSignature<'_> {
+///        TypeSignature::Extension {
+///            name: "JSON",
+///            parameters: &[],
+///        }
+///    }
+/// }
+/// ```
+pub trait LogicalType: Sync + Send {
+    fn native(&self) -> &NativeType;
+    fn signature(&self) -> TypeSignature<'_>;
+}
+
+impl fmt::Debug for dyn LogicalType {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple("LogicalType")
+            .field(&self.signature())
+            .field(&self.native())
+            .finish()
+    }
+}
+
+impl PartialEq for dyn LogicalType {
+    fn eq(&self, other: &Self) -> bool {
+        self.native().eq(other.native()) && self.signature().eq(&other.signature())
+    }
+}
+
+impl Eq for dyn LogicalType {}
+
+impl PartialOrd for dyn LogicalType {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for dyn LogicalType {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.signature()
+            .cmp(&other.signature())
+            .then(self.native().cmp(other.native()))
+    }
+}
+
+impl Hash for dyn LogicalType {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        self.signature().hash(state);
+        self.native().hash(state);
+    }
+}

datafusion/common/src/types/mod.rs

@@ -0,0 +1,24 @@
+// 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.
+
+mod field;
+mod logical;
+mod native;
+
+pub use field::*;
+pub use logical::*;
+pub use native::*;