123 lines
3.4 KiB
Kotlin
123 lines
3.4 KiB
Kotlin
/*
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* MIT License
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*
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* Copyright (c) 2019 norangebit
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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*/
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package it.norangeb.algorithms.datastructures.dictionary
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import arrow.core.None
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import arrow.core.Option
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import arrow.core.Some
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import arrow.core.toOption
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class HashTable<K, V> : Dictionary<K, V> {
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private val array = Array<Option<Node<K, V>>>(HASHTABLE_SIZE) { None }
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private var size = 0
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override fun get(key: K): Option<V> {
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return get(array[getIndex(key)], key)
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.map { it.value }
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}
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private fun get(node: Option<Node<K, V>>, key: K): Option<Node<K, V>> {
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return node.flatMap {
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when (key) {
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it.key -> node
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else -> get(it.next, key)
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}
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}
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}
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override fun set(key: K, value: V) {
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val index = getIndex(key)
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array[index] = set(
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array[index],
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key,
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value
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).toOption()
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}
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private fun set(
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node: Option<Node<K, V>>,
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key: K,
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value: V
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): Node<K, V> {
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return node.fold(
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{
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size++
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Node(key, value)
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},
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{
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when (it.key) {
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key -> it.clone(value = value)
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else -> it.clone(next = set(it.next, key, value).toOption())
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}
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}
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)
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}
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override fun delete(key: K) {
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val index = getIndex(key)
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array[index] = delete(array[index], key)
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}
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private fun delete(node: Option<Node<K, V>>, key: K): Option<Node<K, V>> {
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return node.flatMap {
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when (it.key) {
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key -> {
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size--
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it.next
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}
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else -> it.clone(next = delete(it.next, key)).toOption()
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}
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}
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}
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override fun contains(key: K): Boolean = get(key) is Some
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override fun isEmpty(): Boolean = size == 0
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override fun size(): Int = size
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private fun getIndex(key: K): Int {
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return key.hashCode().and(0x7fffffff) % HASHTABLE_SIZE
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}
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data class Node<K, V>(
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val key: K,
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val value: V,
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val next: Option<Node<K, V>> = None
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) {
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fun clone(
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key: K = this.key,
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value: V = this.value,
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next: Option<Node<K, V>> = this.next
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) = Node(key, value, next)
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}
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companion object {
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const val HASHTABLE_SIZE = 40
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}
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} |