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Spring Data Relational support
/*
* Copyright 2021-2023 the original author or authors.
*
* Licensed 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
*
* https://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.
*/
package org.springframework.data.relational.core.sql;
import java.util.Arrays;
/**
* Represents an analytic function, also known as windowing function
*
* @author Jens Schauder
* @since 2.7
*/
public class AnalyticFunction extends AbstractSegment implements Expression {
private final SimpleFunction function;
private final Partition partition;
private final OrderBy orderBy;
public static AnalyticFunction create(String function, Expression... arguments) {
return new AnalyticFunction(SimpleFunction.create(function, Arrays.asList(arguments)), new Partition(),
new OrderBy());
}
private AnalyticFunction(SimpleFunction function, Partition partition, OrderBy orderBy) {
super(function, partition, orderBy);
this.function = function;
this.partition = partition;
this.orderBy = orderBy;
}
public AnalyticFunction partitionBy(Expression... partitionBy) {
return new AnalyticFunction(function, new Partition(partitionBy), orderBy);
}
public AnalyticFunction orderBy(OrderByField... orderBy) {
return new AnalyticFunction(function, partition, new OrderBy(orderBy));
}
public AnalyticFunction orderBy(Expression... orderByExpression) {
final OrderByField[] orderByFields = Arrays.stream(orderByExpression) //
.map(OrderByField::from) //
.toArray(OrderByField[]::new);
return new AnalyticFunction(function, partition, new OrderBy(orderByFields));
}
public AliasedAnalyticFunction as(String alias) {
return new AliasedAnalyticFunction(this, SqlIdentifier.unquoted(alias));
}
public AliasedAnalyticFunction as(SqlIdentifier alias) {
return new AliasedAnalyticFunction(this, alias);
}
public static class Partition extends SegmentList {
Partition(Expression... expressions) {
super(expressions);
}
}
private static class AliasedAnalyticFunction extends AnalyticFunction implements Aliased {
private final SqlIdentifier alias;
AliasedAnalyticFunction(AnalyticFunction analyticFunction, SqlIdentifier alias) {
super(analyticFunction.function, analyticFunction.partition, analyticFunction.orderBy);
this.alias = alias;
}
@Override
public SqlIdentifier getAlias() {
return alias;
}
}
}