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udaf.rs
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udaf.rs
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// 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.
//! Udaf module contains functions and structs supporting user-defined aggregate functions.
use crate::Expr;
use crate::{
AccumulatorFunctionImplementation, ReturnTypeFunction, Signature, StateTypeFunction,
};
use std::fmt::{self, Debug, Formatter};
use std::sync::Arc;
/// Logical representation of a user-defined aggregate function (UDAF)
/// A UDAF is different from a UDF in that it is stateful across batches.
#[derive(Clone)]
pub struct AggregateUDF {
/// name
pub name: String,
/// signature
pub signature: Signature,
/// Return type
pub return_type: ReturnTypeFunction,
/// actual implementation
pub accumulator: AccumulatorFunctionImplementation,
/// the accumulator's state's description as a function of the return type
pub state_type: StateTypeFunction,
}
impl Debug for AggregateUDF {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
f.debug_struct("AggregateUDF")
.field("name", &self.name)
.field("signature", &self.signature)
.field("fun", &"<FUNC>")
.finish()
}
}
impl PartialEq for AggregateUDF {
fn eq(&self, other: &Self) -> bool {
self.name == other.name && self.signature == other.signature
}
}
impl Eq for AggregateUDF {}
impl std::hash::Hash for AggregateUDF {
fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
self.name.hash(state);
self.signature.hash(state);
}
}
impl AggregateUDF {
/// Create a new AggregateUDF
pub fn new(
name: &str,
signature: &Signature,
return_type: &ReturnTypeFunction,
accumulator: &AccumulatorFunctionImplementation,
state_type: &StateTypeFunction,
) -> Self {
Self {
name: name.to_owned(),
signature: signature.clone(),
return_type: return_type.clone(),
accumulator: accumulator.clone(),
state_type: state_type.clone(),
}
}
/// creates a logical expression with a call of the UDAF
/// This utility allows using the UDAF without requiring access to the registry.
pub fn call(&self, args: Vec<Expr>) -> Expr {
Expr::AggregateUDF(crate::expr::AggregateUDF {
fun: Arc::new(self.clone()),
args,
filter: None,
order_by: None,
})
}
}