kotlin.collections.Iterators.kt Maven / Gradle / Ivy
@file:kotlin.jvm.JvmMultifileClass
@file:kotlin.jvm.JvmName("CollectionsKt")
package kotlin
import java.util.Enumeration
/**
* Creates an [Iterator] for an [Enumeration], allowing to use it in `for` loops.
*/
public operator fun Enumeration.iterator(): Iterator = object : Iterator {
override fun hasNext(): Boolean = hasMoreElements()
public override fun next(): T = nextElement()
}
/**
* Returns the given iterator itself. This allows to use an instance of iterator in a `for` loop.
*/
public operator fun Iterator.iterator(): Iterator = this
/**
* Performs the given [operation] on each element of this [Iterator].
*/
public inline fun Iterator.forEach(operation: (T) -> Unit) : Unit {
for (element in this) operation(element)
}
/**
* Data class representing a value from a collection or sequence, along with its index in that collection or sequence.
*
* @property value the underlying value.
* @property index the index of the value in the collection or sequence.
*/
public data class IndexedValue(public val index: Int, public val value: T)
/**
* A wrapper over another [Iterable] (or any other object that can produce an [Iterator]) that returns
* an indexing iterator.
*/
public class IndexingIterable(private val iteratorFactory: () -> Iterator) : Iterable> {
override fun iterator(): Iterator> = IndexingIterator(iteratorFactory())
}
/**
* Iterator transforming original `iterator` into iterator of [IndexedValue], counting index from zero.
*/
public class IndexingIterator(private val iterator: Iterator) : Iterator> {
private var index = 0
final override fun hasNext(): Boolean = iterator.hasNext()
final override fun next(): IndexedValue = IndexedValue(index++, iterator.next())
}