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useTop.scala
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useTop.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_4.planner.logical.plans.rewriter
import org.neo4j.cypher.internal.frontend.v3_4.{Rewriter, bottomUp}
import org.neo4j.cypher.internal.v3_4.logical.plans.{DoNotIncludeTies, Limit, Sort, Top}
/**
* When doing ORDER BY c1,c2,...,cn LIMIT e, we don't have to sort the full result in one go
*/
case object useTop extends Rewriter {
private val instance: Rewriter = bottomUp(Rewriter.lift {
case o @ Limit(Sort(src, sortDescriptions), limit, DoNotIncludeTies) =>
Top(src, sortDescriptions, limit)(o.solved)
})
override def apply(input: AnyRef): AnyRef = instance.apply(input)
}