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Cassandra support for Spring Data
/*
* Copyright 2013-2019 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.cassandra.core.mapping;
import java.util.Comparator;
import org.springframework.data.cassandra.core.cql.CqlIdentifier;
/**
* {@link Comparator} implementation that orders {@link CassandraPersistentProperty} instances.
*
* Composite primary key properties and primary key properties sort before non-primary key properties. Ordering rules:
*
* - Composite primary keys first (equal if both {@link CassandraPersistentProperty} are a composite primary key)
* - Primary key columns (see {@link CassandraPrimaryKeyColumnAnnotationComparator}, compare by ordinal/name/ordering)
*
* - Regular columns, compared by column name (see {@link CqlIdentifier#compareTo(CqlIdentifier)})
*
*
* @author Alex Shvid
* @author Matthew T. Adams
* @author Mark Paluch
* @author John Blum
* @see java.util.Comparator
* @see org.springframework.data.cassandra.core.mapping.CassandraPersistentProperty
*/
public enum CassandraPersistentPropertyComparator implements Comparator {
/**
* Comparator instance.
*/
INSTANCE;
/* (non-Javadoc)
* @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
*/
@Override
public int compare(CassandraPersistentProperty left, CassandraPersistentProperty right) {
if (left == null && right == null) {
return 0;
} else if (left != null && right == null) {
return 1;
} else if (left == null) {
return -1;
} else if (left.equals(right)) {
return 0;
}
boolean leftIsCompositePrimaryKey = left.isCompositePrimaryKey();
boolean rightIsCompositePrimaryKey = right.isCompositePrimaryKey();
if (leftIsCompositePrimaryKey && rightIsCompositePrimaryKey) {
return 0;
}
boolean leftIsPrimaryKey = left.isPrimaryKeyColumn();
boolean rightIsPrimaryKey = right.isPrimaryKeyColumn();
if (leftIsPrimaryKey && rightIsPrimaryKey) {
PrimaryKeyColumn leftAnnotation = left.findAnnotation(PrimaryKeyColumn.class);
PrimaryKeyColumn rightAnnotation = right.findAnnotation(PrimaryKeyColumn.class);
if (leftAnnotation == null || rightAnnotation == null) {
return 0;
}
return CassandraPrimaryKeyColumnAnnotationComparator.INSTANCE.compare(leftAnnotation, rightAnnotation);
}
boolean leftIsKey = leftIsCompositePrimaryKey || leftIsPrimaryKey;
boolean rightIsKey = rightIsCompositePrimaryKey || rightIsPrimaryKey;
if (leftIsKey && !rightIsKey) {
return -1;
} else if (!leftIsKey && rightIsKey) {
return 1;
}
// else, neither property is a composite primary key nor a primary key; compare @Column annotations
return left.getRequiredColumnName().compareTo(right.getRequiredColumnName());
}
}