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Reimplemented the iterator concatenator.
No longer accesses an iterator unless all previously added ones have been exhausted. No recurses on a tree (could trigger a stack overflow exception).
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59
src/main/scala/com/signalcollect/util/IteratorConcatenator.scala
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,59 @@ | ||
| /* | ||
| * @author Philip Stutz | ||
| * | ||
| * Copyright 2014 University of Zurich | ||
| * | ||
| * 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. | ||
| * | ||
| */ | ||
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| package com.signalcollect.util | ||
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| import scala.annotation.tailrec | ||
| import scala.collection.mutable.Queue | ||
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| /** | ||
| * To avoid https://issues.scala-lang.org/browse/SI-8428, which is not really fixed. | ||
| * | ||
| * Unfortunately I could not reproduce the problem outside of a large and complex TripleRush evaluation. | ||
| */ | ||
| final class IteratorConcatenator[U] extends Iterator[U] { | ||
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| val iterators = new Queue[Iterator[U]]() | ||
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| def clear { | ||
| iterators.clear | ||
| } | ||
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| def appendIterator(i: Iterator[U]) { | ||
| iterators.enqueue(i) | ||
| } | ||
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| def next: U = { | ||
| iterators.head.next | ||
| } | ||
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| @tailrec def hasNext: Boolean = { | ||
| if (iterators.isEmpty) { | ||
| false | ||
| } else { | ||
| val headHasNext = iterators.head.hasNext | ||
| if (!headHasNext) { | ||
| iterators.dequeue | ||
| hasNext | ||
| } else { | ||
| true | ||
| } | ||
| } | ||
| } | ||
| } |
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54
src/test/scala/com/signalcollect/util/IteratorConcatenatorSpec.scala
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,54 @@ | ||
| /* | ||
| * @author Philip Stutz | ||
| * | ||
| * Copyright 2014 University of Zurich | ||
| * | ||
| * 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. | ||
| */ | ||
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| package com.signalcollect.util | ||
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| import org.scalacheck.Gen | ||
| import org.scalacheck.Gen._ | ||
| import org.scalacheck.Arbitrary._ | ||
| import org.scalatest.FlatSpec | ||
| import org.scalatest.ShouldMatchers | ||
| import org.scalatest.prop.Checkers | ||
| import java.io.DataOutputStream | ||
| import java.io.ByteArrayOutputStream | ||
| import org.scalacheck.Arbitrary | ||
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| class IteratorConcatenatorSpec extends FlatSpec with ShouldMatchers with Checkers with TestAnnouncements { | ||
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| "IteratorConcatenator" should "correctly concatenate multiple iterators" in { | ||
| val c = new IteratorConcatenator[Int] | ||
| for (i <- 1 to 1000 by 10) { | ||
| c.appendIterator((i until i + 10).iterator) | ||
| } | ||
| c.appendIterator(Seq(1001, 1002, 1003).iterator) | ||
| c.appendIterator(Set(1004).iterator) | ||
| assert(c.toList == (1 to 1004).toList) | ||
| } | ||
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| it should "should work with random appends" in { | ||
| check( | ||
| (is: List[List[Int]]) => { | ||
| val c = new IteratorConcatenator[Int] | ||
| is.foreach { list => c.appendIterator(list.iterator) } | ||
| assert(c.toList == is.flatMap(_.iterator).toList) | ||
| true | ||
| }, | ||
| minSuccessful(100)) | ||
| } | ||
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| } |