kotlin.collections.MapsJVM.kt Maven / Gradle / Ivy
/*
* Copyright 2010-2018 JetBrains s.r.o. 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("MapsKt")
package kotlin.collections
import java.util.Comparator
import java.util.LinkedHashMap
import java.util.Properties
import java.util.SortedMap
import java.util.TreeMap
import java.util.concurrent.ConcurrentMap
/**
* Returns an immutable map, mapping only the specified key to the
* specified value.
*
* The returned map is serializable.
*
* @sample samples.collections.Maps.Instantiation.mapFromPairs
*/
public fun mapOf(pair: Pair): Map = java.util.Collections.singletonMap(pair.first, pair.second)
/**
* Concurrent getOrPut, that is safe for concurrent maps.
*
* Returns the value for the given [key]. If the key is not found in the map, calls the [defaultValue] function,
* puts its result into the map under the given key and returns it.
*
* This method guarantees not to put the value into the map if the key is already there,
* but the [defaultValue] function may be invoked even if the key is already in the map.
*/
public inline fun ConcurrentMap.getOrPut(key: K, defaultValue: () -> V): V {
// Do not use computeIfAbsent on JVM8 as it would change locking behavior
return this.get(key)
?: defaultValue().let { default -> this.putIfAbsent(key, default) ?: default }
}
/**
* Converts this [Map] to a [SortedMap] so iteration order will be in key order.
*
* @sample samples.collections.Maps.Transformations.mapToSortedMap
*/
public fun , V> Map.toSortedMap(): SortedMap = TreeMap(this)
/**
* Converts this [Map] to a [SortedMap] using the given [comparator] so that iteration order will be in the order
* defined by the comparator.
*
* @sample samples.collections.Maps.Transformations.mapToSortedMapWithComparator
*/
public fun Map.toSortedMap(comparator: Comparator): SortedMap =
TreeMap(comparator).apply { putAll(this@toSortedMap) }
/**
* Returns a new [SortedMap] with the specified contents, given as a list of pairs
* where the first value is the key and the second is the value.
*
* @sample samples.collections.Maps.Instantiation.sortedMapFromPairs
*/
public fun , V> sortedMapOf(vararg pairs: Pair): SortedMap =
TreeMap().apply { putAll(pairs) }
/**
* Converts this [Map] to a [Properties] object.
*
* @sample samples.collections.Maps.Transformations.mapToProperties
*/
@kotlin.internal.InlineOnly
public inline fun Map.toProperties(): Properties =
Properties().apply { putAll(this@toProperties) }
// creates a singleton copy of map, if there is specialization available in target platform, otherwise returns itself
@kotlin.internal.InlineOnly
internal actual inline fun Map.toSingletonMapOrSelf(): Map = toSingletonMap()
// creates a singleton copy of map
internal actual fun Map.toSingletonMap(): Map =
with(entries.iterator().next()) { java.util.Collections.singletonMap(key, value) }