Ilya Gorbunov
26 lines
1.1 KiB
Kotlin
26 lines
1.1 KiB
Kotlin
package kotlin.collections
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/**
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* Data class representing a value from a collection or sequence, along with its index in that collection or sequence.
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*
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* @property value the underlying value.
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* @property index the index of the value in the collection or sequence.
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*/
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public data class IndexedValue<out T>(public val index: Int, public val value: T)
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/**
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* A wrapper over another [Iterable] (or any other object that can produce an [Iterator]) that returns
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* an indexing iterator.
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*/
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internal class IndexingIterable<out T>(private val iteratorFactory: () -> Iterator<T>) : Iterable<IndexedValue<T>> {
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override fun iterator(): Iterator<IndexedValue<T>> = IndexingIterator(iteratorFactory())
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}
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/**
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* Iterator transforming original `iterator` into iterator of [IndexedValue], counting index from zero.
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*/
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internal class IndexingIterator<out T>(private val iterator: Iterator<T>) : Iterator<IndexedValue<T>> {
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private var index = 0
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final override fun hasNext(): Boolean = iterator.hasNext()
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final override fun next(): IndexedValue<T> = IndexedValue(index++, iterator.next())
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} |