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org.neo4j.cypher.internal.util.Rewritable.scala Maven / Gradle / Ivy
/*
* Copyright (c) "Neo4j"
* Neo4j Sweden AB [http://neo4j.com]
*
* 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
*
* http://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.neo4j.cypher.internal.util
import org.neo4j.cypher.internal.util.Foldable.TreeAny
import org.neo4j.cypher.internal.util.Rewritable.RewritableAny
import java.lang.reflect.Method
import scala.annotation.tailrec
import scala.collection.mutable
object Rewriter {
def lift(f: PartialFunction[AnyRef, AnyRef]): Rewriter =
f.orElse({ case x => x })
val noop: Rewriter = Rewriter.lift(PartialFunction.empty)
}
object RewriterWithParent {
def lift(f: PartialFunction[(AnyRef, Option[AnyRef]), AnyRef]): RewriterWithParent =
f.orElse({ case (x, _) => x })
}
object Rewritable {
implicit class IteratorEq[A <: AnyRef](val iterator: Iterator[A]) {
def eqElements[B <: AnyRef](that: Iterator[B]): Boolean = {
while (iterator.hasNext && that.hasNext) {
if (!(iterator.next eq that.next))
return false
}
!iterator.hasNext && !that.hasNext
}
}
private val productCopyConstructors = new ThreadLocal[mutable.HashMap[Class[_], Method]]() {
override def initialValue: mutable.HashMap[Class[_], Method] =
new mutable.HashMap[Class[_], Method]
}
def copyConstructor(product: Product): Method = {
def getCopyMethod(productClass: Class[_ <: Product]): Method = {
try {
productClass.getMethods.find(_.getName == "copy").get
} catch {
case _: NoSuchElementException =>
throw new IllegalStateException(
s"Failed trying to rewrite $productClass - this class does not have a `copy` method"
)
}
}
val productClass = product.getClass
productCopyConstructors.get.getOrElseUpdate(productClass, getCopyMethod(productClass))
}
def dupAny(that: AnyRef, children: Seq[AnyRef]): AnyRef =
try {
if (children.iterator eqElements that.treeChildren) {
that
} else {
that match {
case a: Rewritable =>
a.dup(children)
case _: IndexedSeq[_] =>
children.toIndexedSeq
case _: List[_] =>
children.toList
case _: Seq[_] =>
children
case _: Set[_] =>
children.toSet
case _: Map[_, _] =>
children.map(value => value.asInstanceOf[(String, AnyRef)]).toMap
case p: Product =>
copyConstructor(p).invoke(p, children: _*)
case t =>
t
}
}
} catch {
case e: IllegalArgumentException =>
throw new IllegalStateException(s"Failed rewriting $that\nTried using children: ${children.mkString(",")}", e)
}
def dupProduct(product: Product, children: Seq[AnyRef]): Product = product match {
case a: Rewritable =>
a.dup(children)
case _ =>
if (children.iterator eqElements product.treeChildren)
product
else
copyConstructor(product).invoke(product, children: _*).asInstanceOf[Product]
}
implicit class RewritableAny[T <: AnyRef](val that: T) extends AnyVal {
def rewrite(rewriter: Rewriter): AnyRef = {
val result = rewriter.apply(that)
result
}
def rewrite(rewriter: RewriterWithParent, parent: Option[AnyRef]): AnyRef = {
val result = rewriter.apply((that, parent))
result
}
def endoRewrite(rewriter: Rewriter): T = rewrite(rewriter).asInstanceOf[T]
}
}
case class TypedRewriter[T <: Rewritable](rewriter: Rewriter) extends (T => T) {
def apply(that: T) = rewriter.apply(that).asInstanceOf[T]
def narrowed[S <: T] = TypedRewriter[S](rewriter)
}
trait Rewritable {
def dup(children: Seq[AnyRef]): this.type
}
object inSequence {
private class InSequenceRewriter(rewriters: Seq[Rewriter]) extends Rewriter {
override def apply(that: AnyRef): AnyRef = {
val it = rewriters.iterator
//this piece of code is used a lot and has been through profiling
//please don't just remove it because it is ugly looking
var result = that
while (it.hasNext) {
result = result.rewrite(it.next())
}
result
}
}
private class InSequenceRewriterWithCancel(rewriters: Seq[Rewriter], cancellation: CancellationChecker) extends Rewriter {
override def apply(that: AnyRef): AnyRef = {
val it = rewriters.iterator
var result = that
while (it.hasNext) {
cancellation.throwIfCancelled()
result = result.rewrite(it.next())
}
result
}
}
def apply(rewriters: Rewriter*): Rewriter =
new InSequenceRewriter(rewriters)
def apply(cancellation: CancellationChecker)(rewriters: Rewriter*): Rewriter =
new InSequenceRewriterWithCancel(rewriters, cancellation)
}
object topDown {
private class TopDownRewriter(rewriter: Rewriter,
stopper: AnyRef => Boolean,
cancellation: CancellationChecker) extends Rewriter {
override def apply(that: AnyRef): AnyRef = {
val initialStack = mutable.ArrayStack((List(that), new mutable.MutableList[AnyRef]()))
val result = rec(initialStack)
assert(result.size == 1)
result.head
}
@tailrec
private def rec(stack: mutable.ArrayStack[(List[AnyRef], mutable.MutableList[AnyRef])]): mutable.MutableList[AnyRef] = {
cancellation.throwIfCancelled()
val (currentJobs, _) = stack.top
if (currentJobs.isEmpty) {
val (_, newChildren) = stack.pop()
if (stack.isEmpty) {
newChildren
} else {
val (job :: jobs, doneJobs) = stack.pop()
val doneJob = Rewritable.dupAny(job, newChildren)
stack.push((jobs, doneJobs += doneJob))
rec(stack)
}
} else {
val (newJob :: jobs, doneJobs) = stack.pop()
if (stopper(newJob)) {
stack.push((jobs, doneJobs += newJob))
} else {
val rewrittenJob = newJob.rewrite(rewriter)
stack.push((rewrittenJob :: jobs, doneJobs))
stack.push((rewrittenJob.treeChildren.toList, new mutable.MutableList()))
}
rec(stack)
}
}
}
def apply(rewriter: Rewriter,
stopper: AnyRef => Boolean = _ => false,
cancellation: CancellationChecker = CancellationChecker.NeverCancelled): Rewriter =
new TopDownRewriter(rewriter, stopper, cancellation)
}
/**
* Top-down rewriter that also lets the rules see the parent of each node as additional context
*/
object topDownWithParent {
private class TopDownWithParentRewriter(rewriter: RewriterWithParent,
stopper: AnyRef => Boolean,
cancellation: CancellationChecker) extends Rewriter {
override def apply(that: AnyRef): AnyRef = {
val initialStack = mutable.ArrayStack((List(that), new mutable.MutableList[AnyRef]()))
val result = rec(initialStack)
assert(result.size == 1)
result.head
}
@tailrec
private def rec(stack: mutable.ArrayStack[(List[AnyRef], mutable.MutableList[AnyRef])]): mutable.MutableList[AnyRef] = {
cancellation.throwIfCancelled()
val (currentJobs, _) = stack.top
if (currentJobs.isEmpty) {
val (_, newChildren) = stack.pop()
if (stack.isEmpty) {
newChildren
} else {
val (job :: jobs, doneJobs) = stack.pop()
val doneJob = Rewritable.dupAny(job, newChildren)
stack.push((jobs, doneJobs += doneJob))
rec(stack)
}
} else {
val (newJob :: jobs, doneJobs) = stack.pop()
if (stopper(newJob)) {
stack.push((jobs, doneJobs += newJob))
} else {
val maybeParent = {
if (stack.isEmpty) {
None
} else {
val (parentJobs, _) = stack.top
parentJobs.headOption
}
}
val rewrittenJob = newJob.rewrite(rewriter, maybeParent)
stack.push((rewrittenJob :: jobs, doneJobs))
stack.push((rewrittenJob.treeChildren.toList, new mutable.MutableList()))
}
rec(stack)
}
}
}
def apply(rewriter: RewriterWithParent,
stopper: AnyRef => Boolean = _ => false,
cancellation: CancellationChecker = CancellationChecker.NeverCancelled): Rewriter =
new TopDownWithParentRewriter(rewriter, stopper, cancellation)
}
object bottomUp {
private class BottomUpRewriter(rewriter: Rewriter,
stopper: AnyRef => Boolean,
cancellation: CancellationChecker) extends Rewriter {
override def apply(that: AnyRef): AnyRef = {
val initialStack = mutable.ArrayStack((List(that), new mutable.MutableList[AnyRef]()))
val result = rec(initialStack)
assert(result.size == 1)
result.head
}
@tailrec
private def rec(stack: mutable.ArrayStack[(List[AnyRef], mutable.MutableList[AnyRef])]): mutable.MutableList[AnyRef] = {
cancellation.throwIfCancelled()
val (currentJobs, _) = stack.top
if (currentJobs.isEmpty) {
val (_, newChildren) = stack.pop()
if (stack.isEmpty) {
newChildren
} else {
val (job :: jobs, doneJobs) = stack.pop()
val doneJob = Rewritable.dupAny(job, newChildren)
val rewrittenDoneJob = doneJob.rewrite(rewriter)
stack.push((jobs, doneJobs += rewrittenDoneJob))
rec(stack)
}
} else {
val next = currentJobs.head
if (stopper(next)) {
val (job :: jobs, doneJobs) = stack.pop()
stack.push((jobs, doneJobs += job))
} else {
stack.push((next.treeChildren.toList, new mutable.MutableList()))
}
rec(stack)
}
}
}
def apply(rewriter: Rewriter,
stopper: AnyRef => Boolean = _ => false,
cancellation: CancellationChecker = CancellationChecker.NeverCancelled): Rewriter =
new BottomUpRewriter(rewriter, stopper, cancellation)
}
object bottomUpWithRecorder {
private class BottomUpRewriter(rewriter: Rewriter,
stopper: AnyRef => Boolean,
recorder: (AnyRef, AnyRef) => Unit,
cancellation: CancellationChecker) extends Rewriter {
override def apply(that: AnyRef): AnyRef = {
val initialStack = mutable.ArrayStack((List(that), new mutable.MutableList[AnyRef]()))
val result = rec(initialStack)
assert(result.size == 1)
result.head
}
@tailrec
private def rec(stack: mutable.ArrayStack[(List[AnyRef], mutable.MutableList[AnyRef])]): mutable.MutableList[AnyRef] = {
cancellation.throwIfCancelled()
val (currentJobs, _) = stack.top
if (currentJobs.isEmpty) {
val (_, newChildren) = stack.pop()
if (stack.isEmpty) {
newChildren
} else {
val (job :: jobs, doneJobs) = stack.pop()
val doneJob = Rewritable.dupAny(job, newChildren)
val rewrittenDoneJob = doneJob.rewrite(rewriter)
if (!(doneJob eq rewrittenDoneJob))
recorder(doneJob, rewrittenDoneJob)
stack.push((jobs, doneJobs += rewrittenDoneJob))
rec(stack)
}
} else {
val next = currentJobs.head
if (stopper(next)) {
val (job :: jobs, doneJobs) = stack.pop()
stack.push((jobs, doneJobs += job))
} else {
stack.push((next.treeChildren.toList, new mutable.MutableList()))
}
rec(stack)
}
}
}
def apply(rewriter: Rewriter,
stopper: AnyRef => Boolean = _ => false,
recorder: (AnyRef, AnyRef) => Unit = (_, _) => (),
cancellation: CancellationChecker = CancellationChecker.NeverCancelled): Rewriter =
new BottomUpRewriter(rewriter, stopper, recorder, cancellation)
}
