org.jetbrains.kotlin.fir.util.ChainedIterator.kt Maven / Gradle / Ivy
/*
* Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
* Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
*/
package org.jetbrains.kotlin.fir.util
class ChainedIterator(delegates: Collection>) : Iterator {
private var metaIterator = delegates.iterator()
private var currentIterator: Iterator? = null
private fun promote() {
if (currentIterator?.hasNext() == true) return
while (metaIterator.hasNext()) {
currentIterator = metaIterator.next()
if (currentIterator!!.hasNext()) return
}
}
override fun hasNext(): Boolean {
promote()
return currentIterator?.hasNext() == true
}
override fun next(): T {
promote()
return currentIterator?.next() ?: throw NoSuchElementException()
}
}