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CypherOrdering.scala
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CypherOrdering.scala
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/*
* Copyright (c) 2002-2017 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.cypher.internal.compiler.v3_3
import java.util.Comparator
import org.neo4j.cypher.internal.compiler.v3_3.MinMaxOrdering._
import org.neo4j.kernel.impl.api.PropertyValueComparison
object CypherOrdering {
val DEFAULT = Ordering.comparatorToOrdering(PropertyValueComparison.COMPARE_VALUES.asInstanceOf[Comparator[Any]]).withNullsLast
}
case class MinMaxOrdering[T](ordering: Ordering[T]) {
val forMin = ordering.withNullsFirst
val forMax = ordering.withNullsLast
}
object MinMaxOrdering {
val BY_VALUE = MinMaxOrdering(Ordering.comparatorToOrdering(PropertyValueComparison.COMPARE_VALUES.asInstanceOf[Comparator[Any]]))
val BY_NUMBER = MinMaxOrdering(Ordering.comparatorToOrdering(PropertyValueComparison.COMPARE_NUMBERS))
val BY_STRING = MinMaxOrdering(Ordering.comparatorToOrdering(PropertyValueComparison.COMPARE_STRINGS))
implicit class NullOrdering[T](ordering: Ordering[T]) {
def withNullsFirst = new Ordering[T] {
override def compare(x: T, y: T): Int = {
if (x == null) {
if (y == null) 0 else -1
} else if (y == null) {
+1
} else {
ordering.compare(x, y)
}
}
}
def withNullsLast = new Ordering[T] {
override def compare(x: T, y: T): Int = {
if (x == null) {
if (y == null) 0 else +1
} else if (y == null) {
-1
} else {
ordering.compare(x, y)
}
}
}
}
}