kotlin.collections.AbstractMap.kt Maven / Gradle / Ivy
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/*
* 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.
*/
/*
* Based on GWT AbstractMap
* Copyright 2007 Google Inc.
*/
package kotlin.collections
/**
* Provides a skeletal implementation of the read-only [Map] interface.
*
* The implementor is required to implement [entries] property, which should return read-only set of map entries.
*
* @param K the type of map keys. The map is invariant on its key type.
* @param V the type of map values. The map is covariant on its value type.
*/
@SinceKotlin("1.1")
public abstract class AbstractMap protected constructor() : Map {
override fun containsKey(key: K): Boolean {
return implFindEntry(key) != null
}
override fun containsValue(value: @UnsafeVariance V): Boolean = entries.any { it.value == value }
internal fun containsEntry(entry: Map.Entry<*, *>?): Boolean {
// since entry comes from @UnsafeVariance parameters it can be virtually anything
if (entry !is Map.Entry<*, *>) return false
val key = entry.key
val value = entry.value
val ourValue = get(key)
if (value != ourValue) {
return false
}
// Perhaps it was null and we don't contain the key?
if (ourValue == null && !containsKey(key)) {
return false
}
return true
}
/**
* Compares this map with other instance with the ordered structural equality.
*
* @return true, if [other] instance is a [Map] of the same size, all entries of which are contained in the [entries] set of this map.
*/
override fun equals(other: Any?): Boolean {
if (other === this) return true
if (other !is Map<*, *>) return false
if (size != other.size) return false
return other.entries.all { containsEntry(it) }
}
override operator fun get(key: K): V? = implFindEntry(key)?.value
/**
* Returns the hash code value for this map.
*
* It is the same as the hashCode of [entries] set.
*/
override fun hashCode(): Int = entries.hashCode()
override fun isEmpty(): Boolean = size == 0
override val size: Int get() = entries.size
/**
* Returns a read-only [Set] of all keys in this map.
*
* Accessing this property first time creates a keys view from [entries].
* All subsequent accesses just return the created instance.
*/
override val keys: Set
get() {
if (_keys == null) {
_keys = object : AbstractSet() {
override operator fun contains(element: K): Boolean = containsKey(element)
override operator fun iterator(): Iterator {
val entryIterator = entries.iterator()
return object : Iterator {
override fun hasNext(): Boolean = entryIterator.hasNext()
override fun next(): K = entryIterator.next().key
}
}
override val size: Int get() = [email protected]
}
}
return _keys!!
}
@kotlin.jvm.Volatile
private var _keys: Set? = null
override fun toString(): String = entries.joinToString(", ", "{", "}") { toString(it) }
private fun toString(entry: Map.Entry): String = toString(entry.key) + "=" + toString(entry.value)
private fun toString(o: Any?): String = if (o === this) "(this Map)" else o.toString()
/**
* Returns a read-only [Collection] of all values in this map.
*
* Accessing this property first time creates a values view from [entries].
* All subsequent accesses just return the created instance.
*/
override val values: Collection
get() {
if (_values == null) {
_values = object : AbstractCollection() {
override operator fun contains(element: @UnsafeVariance V): Boolean = containsValue(element)
override operator fun iterator(): Iterator {
val entryIterator = entries.iterator()
return object : Iterator {
override fun hasNext(): Boolean = entryIterator.hasNext()
override fun next(): V = entryIterator.next().value
}
}
override val size: Int get() = [email protected]
}
}
return _values!!
}
@kotlin.jvm.Volatile
private var _values: Collection? = null
private fun implFindEntry(key: K): Map.Entry? = entries.firstOrNull { it.key == key }
internal companion object {
internal fun entryHashCode(e: Map.Entry<*, *>): Int = with(e) { (key?.hashCode() ?: 0) xor (value?.hashCode() ?: 0) }
internal fun entryToString(e: Map.Entry<*, *>): String = with(e) { "$key=$value" }
internal fun entryEquals(e: Map.Entry<*, *>, other: Any?): Boolean {
if (other !is Map.Entry<*, *>) return false
return e.key == other.key && e.value == other.value
}
}
}