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/*
* Copyright (c) 2017-present Robert Jaros
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package pl.treksoft.kvision.utils
/*
* Copyright 2018 Nazmul Idris All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* This is a LRU cache that has no performance impact for cache insertions
* once the capacity of the cache has been reached. For cache hit,
* performance is O(1) and for cache eviction, it is O(1).
*/
class Cache<K, V>(private val capacity: Int = 50) {
private val cache = HashMap<K, V>()
private val insertionOrder = LinkedList<K>()
/**
* [HashMap] put and remove is O(1).
* More info: https://stackoverflow.com/a/4578039/2085356
*/
operator fun set(key: K, value: V): K? {
var evictedKey: K? = null
if (cache.size >= capacity) {
evictedKey = getKeyToEvict()
cache.remove(evictedKey)
}
cache[key] = value
insertionOrder.append(key)
return evictedKey
}
/**
* [HashMap] get is O(1).
* More info: https://stackoverflow.com/a/4578039/2085356
*/
operator fun get(key: K): V? = cache[key]
/**
* The head of the [insertionOrder] is removed, which is O(1), since this
* is a linked list, and it's inexpensive to remove an item from head.
* More info: https://stackoverflow.com/a/42849573/2085356
*/
private fun getKeyToEvict(): K? = insertionOrder.removeAtIndex(0)
override fun toString() = cache.toString()
}
/**
* Created by gazollajunior on 07/04/16.
*/
class Node<T>(var value: T) {
var next: Node<T>? = null
var previous: Node<T>? = null
}
class LinkedList<T> {
private var head: Node<T>? = null
var isEmpty: Boolean = head == null
fun first(): Node<T>? = head
fun last(): Node<T>? {
var node = head
return if (node != null) {
while (node?.next != null) {
node = node.next
}
node
} else {
null
}
}
fun count(): Int {
var node = head
return if (node != null) {
var counter = 1
while (node?.next != null) {
node = node.next
counter += 1
}
counter
} else {
0
}
}
fun nodeAtIndex(index: Int): Node<T>? {
if (index >= 0) {
var node = head
var i = index
while (node != null) {
if (i == 0) return node
i -= 1
node = node.next
}
}
return null
}
fun append(value: T) {
val newNode = Node(value)
val lastNode = this.last()
if (lastNode != null) {
newNode.previous = lastNode
lastNode.next = newNode
} else {
head = newNode
}
}
fun removeAll() {
head = null
}
fun removeNode(node: Node<T>): T {
val prev = node.previous
val next = node.next
if (prev != null) {
prev.next = next
} else {
head = next
}
next?.previous = prev
node.previous = null
node.next = null
return node.value
}
fun removeLast(): T? {
val last = this.last()
return if (last != null) {
removeNode(last)
} else {
null
}
}
fun removeAtIndex(index: Int): T? {
val node = nodeAtIndex(index)
return if (node != null) {
removeNode(node)
} else {
null
}
}
override fun toString(): String {
var s = "["
var node = head
while (node != null) {
s += "${node.value}"
node = node.next
if (node != null) {
s += ", "
}
}
return "$s]"
}
}
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