forked from eldersantos/community
/
ExtractBuilder.scala
55 lines (48 loc) · 2.11 KB
/
ExtractBuilder.scala
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/**
* Copyright (c) 2002-2012 "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.executionplan.builders
import org.neo4j.cypher.internal.pipes.{ExtractPipe, Pipe}
import org.neo4j.cypher.internal.executionplan.{PartiallySolvedQuery, PlanBuilder}
import org.neo4j.cypher.internal.commands.{CachedExpression, Expression}
class ExtractBuilder extends PlanBuilder {
def apply(v1: (Pipe, PartiallySolvedQuery)): (Pipe, PartiallySolvedQuery) = v1 match {
case (p, q) => ExtractBuilder.extractIfNecessary(q, p, q.returns.map(_.token.expression))
}
def isDefinedAt(x: (Pipe, PartiallySolvedQuery)): Boolean = x match {
case (p, q) => !q.extracted && q.readyToAggregate && q.aggregateQuery.solved
}
def priority: Int = PlanBuilder.Extraction
}
object ExtractBuilder {
def extractIfNecessary(psq: PartiallySolvedQuery, p: Pipe, expressions: Seq[Expression]): (Pipe, PartiallySolvedQuery) = {
val missing = p.symbols.missingExpressions(expressions)
if (missing.nonEmpty) {
val newPsq = expressions.foldLeft(psq)((psq, exp) => psq.rewrite(fromQueryExpression =>
if (exp == fromQueryExpression)
CachedExpression(fromQueryExpression.identifier.name, fromQueryExpression.identifier)
else
fromQueryExpression
))
(new ExtractPipe(p, expressions), newPsq.copy(extracted = true))
} else {
(p, psq.copy(extracted = true))
}
}
}