kotlin.collections.ReversedViews.kt Maven / Gradle / Ivy
The newest version!
/*
* Copyright 2010-2018 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.
*/
@file:kotlin.jvm.JvmMultifileClass
@file:kotlin.jvm.JvmName("CollectionsKt")
package kotlin.collections
private open class ReversedListReadOnly(private val delegate: List) : AbstractList() {
override val size: Int get() = delegate.size
override fun get(index: Int): T = delegate[reverseElementIndex(index)]
}
private class ReversedList(private val delegate: MutableList) : AbstractMutableList() {
override val size: Int get() = delegate.size
override fun get(index: Int): T = delegate[reverseElementIndex(index)]
override fun clear() = delegate.clear()
override fun removeAt(index: Int): T = delegate.removeAt(reverseElementIndex(index))
override fun set(index: Int, element: T): T = delegate.set(reverseElementIndex(index), element)
override fun add(index: Int, element: T) {
delegate.add(reversePositionIndex(index), element)
}
}
private fun List<*>.reverseElementIndex(index: Int) =
if (index in 0..lastIndex) lastIndex - index else throw IndexOutOfBoundsException("Element index $index must be in range [${0..lastIndex}].")
private fun List<*>.reversePositionIndex(index: Int) =
if (index in 0..size) size - index else throw IndexOutOfBoundsException("Position index $index must be in range [${0..size}].")
/**
* Returns a reversed read-only view of the original List.
* All changes made in the original list will be reflected in the reversed one.
* @sample samples.collections.ReversedViews.asReversedList
*/
public fun List.asReversed(): List = ReversedListReadOnly(this)
/**
* Returns a reversed mutable view of the original mutable List.
* All changes made in the original list will be reflected in the reversed one and vice versa.
* @sample samples.collections.ReversedViews.asReversedMutableList
*/
@kotlin.jvm.JvmName("asReversedMutable")
public fun MutableList.asReversed(): MutableList = ReversedList(this)