com.hazelcast.org.apache.calcite.config.NullCollation Maven / Gradle / Ivy
/*
* 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 com.hazelcast.com.liance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.com.hazelcast.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 com.hazelcast.org.apache.calcite.config;
/** Strategy for how NULL values are to be sorted if NULLS FIRST or NULLS LAST
* are not specified in an item in the ORDER BY clause. */
public enum NullCollation {
/** Nulls first for DESC, nulls last for ASC. */
HIGH,
/** Nulls last for DESC, nulls first for ASC. */
LOW,
/** Nulls first for DESC and ASC. */
FIRST,
/** Nulls last for DESC and ASC. */
LAST;
/** Returns whether NULL values should appear last.
*
* @param desc Whether sort is descending
*/
public boolean last(boolean desc) {
switch (this) {
case FIRST:
return false;
case LAST:
return true;
case LOW:
return desc;
case HIGH:
default:
return !desc;
}
}
/** Returns whether a given com.hazelcast.com.ination of null direction and sort order is
* the default order of nulls returned in the ORDER BY clause. */
public boolean isDefaultOrder(boolean nullsFirst, boolean desc) {
final boolean asc = !desc;
final boolean nullsLast = !nullsFirst;
switch (this) {
case FIRST:
return nullsFirst;
case LAST:
return nullsLast;
case LOW:
return (asc && nullsFirst) || (desc && nullsLast);
case HIGH:
return (asc && nullsLast) || (desc && nullsFirst);
default:
throw new IllegalArgumentException("Unrecognized Null Collation");
}
}
}