Swapnil Sankla
b93e385181
Ilya Gorbunov: Improve sample to illustrate stable iteration order and set equality.
88 lines
3.0 KiB
Kotlin
88 lines
3.0 KiB
Kotlin
@file:kotlin.jvm.JvmMultifileClass
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@file:kotlin.jvm.JvmName("SetsKt")
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package kotlin.collections
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internal object EmptySet : Set<Nothing>, Serializable {
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private const val serialVersionUID: Long = 3406603774387020532
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override fun equals(other: Any?): Boolean = other is Set<*> && other.isEmpty()
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override fun hashCode(): Int = 0
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override fun toString(): String = "[]"
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override val size: Int get() = 0
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override fun isEmpty(): Boolean = true
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override fun contains(element: Nothing): Boolean = false
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override fun containsAll(elements: Collection<Nothing>): Boolean = elements.isEmpty()
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override fun iterator(): Iterator<Nothing> = EmptyIterator
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private fun readResolve(): Any = EmptySet
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}
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/**
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* Returns an empty read-only set. The returned set is serializable (JVM).
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* @sample samples.collections.Collections.Sets.emptyReadOnlySet
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*/
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public fun <T> emptySet(): Set<T> = EmptySet
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/**
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* Returns a new read-only set with the given elements.
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* Elements of the set are iterated in the order they were specified.
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* The returned set is serializable (JVM).
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* @sample samples.collections.Collections.Sets.readOnlySet
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*/
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public fun <T> setOf(vararg elements: T): Set<T> = if (elements.size > 0) elements.toSet() else emptySet()
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/**
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* Returns an empty read-only set. The returned set is serializable (JVM).
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* @sample samples.collections.Collections.Sets.emptyReadOnlySet
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*/
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@kotlin.internal.InlineOnly
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public inline fun <T> setOf(): Set<T> = emptySet()
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/**
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* Returns an empty new [MutableSet].
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*
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* The returned set preserves the element iteration order.
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*/
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@SinceKotlin("1.1")
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@kotlin.internal.InlineOnly
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public inline fun <T> mutableSetOf(): MutableSet<T> = LinkedHashSet()
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/**
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* Returns a new [MutableSet] with the given elements.
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* Elements of the set are iterated in the order they were specified.
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*/
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public fun <T> mutableSetOf(vararg elements: T): MutableSet<T> = elements.toCollection(LinkedHashSet(mapCapacity(elements.size)))
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/** Returns an empty new [HashSet]. */
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@SinceKotlin("1.1")
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@kotlin.internal.InlineOnly
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public inline fun <T> hashSetOf(): HashSet<T> = HashSet()
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/** Returns a new [HashSet] with the given elements. */
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public fun <T> hashSetOf(vararg elements: T): HashSet<T> = elements.toCollection(HashSet(mapCapacity(elements.size)))
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/** Returns an empty new [LinkedHashSet]. */
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@SinceKotlin("1.1")
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@kotlin.internal.InlineOnly
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public inline fun <T> linkedSetOf(): LinkedHashSet<T> = LinkedHashSet()
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/**
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* Returns a new [LinkedHashSet] with the given elements.
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* Elements of the set are iterated in the order they were specified.
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*/
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public fun <T> linkedSetOf(vararg elements: T): LinkedHashSet<T> = elements.toCollection(LinkedHashSet(mapCapacity(elements.size)))
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/** Returns this Set if it's not `null` and the empty set otherwise. */
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@kotlin.internal.InlineOnly
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public inline fun <T> Set<T>?.orEmpty(): Set<T> = this ?: emptySet()
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internal fun <T> Set<T>.optimizeReadOnlySet() = when (size) {
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0 -> emptySet()
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1 -> setOf(iterator().next())
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else -> this
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}
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