core.sequence.kt Maven / Gradle / Ivy
/*
* Copyright 2010-2015 JetBrains s.r.o.
*
* 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 kotlin.sequences
internal class ConstrainedOnceSequence(sequence: Sequence) : Sequence {
@Volatile private var sequenceRef: Sequence? = sequence
//private val lock = Any()
//TODO: Synchronize with the synchonized() method
override fun iterator(): Iterator {
val sequence = sequenceRef ?: throw IllegalStateException("This sequence can be consumed only once.")
sequenceRef = null
return sequence.iterator()
}
}