Added longset
Robinson
parent
fd220fee63
commit
fc3eadd8f2
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@ -0,0 +1,580 @@
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/*
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* Copyright 2023 dorkbox, llc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*******************************************************************************
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* Copyright 2011 LibGDX.
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* Mario Zechner <badlogicgames></badlogicgames>@gmail.com>
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* Nathan Sweet <nathan.sweet></nathan.sweet>@gmail.com>
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package dorkbox.collections
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import dorkbox.collections.Collections.allocateIterators
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import dorkbox.collections.ObjectSet.Companion.tableSize
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import java.util.*
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/**
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* An unordered set where the items are unboxed long. No allocation is done except when growing the table size.
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*
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*
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* This class performs fast contains and remove (typically O(1), worst case O(n) but that is rare in practice). Add may be
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* slightly slower, depending on hash collisions. Hashcodes are rehashed to reduce collisions and the need to resize. Load factors
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* greater than 0.91 greatly increase the chances to resize to the next higher POT size.
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*
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*
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* Unordered sets and maps are not designed to provide especially fast iteration. Iteration is faster with OrderedSet and
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* OrderedMap.
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*
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*
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* This implementation uses linear probing with the backward shift algorithm for removal. Hashcodes are rehashed using Fibonacci
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* hashing, instead of the more common power-of-two mask, to better distribute poor hashCodes (see [Malte Skarupke's blog post](https://probablydance.com/2018/06/16/fibonacci-hashing-the-optimization-that-the-world-forgot-or-a-better-alternative-to-integer-modulo/)). Linear probing continues to work even when all hashCodes collide, just more slowly.
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*
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* @author Nathan Sweet
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* @author Tommy Ettinger
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*/
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class LongSet: MutableSet<Long> {
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companion object {
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const val version = Collections.version
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fun with(vararg array: Long): LongSet {
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val set = LongSet()
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set.addAll(array)
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return set
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}
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}
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private var size_ = 0
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var keyTable: LongArray
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var hasZeroValue = false
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private val loadFactor: Float
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private var threshold: Int
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/** Used by [.place] to bit shift the upper bits of a `long` into a usable range (>= 0 and <=
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* [.mask]). The shift can be negative, which is convenient to match the number of bits in mask: if mask is a 7-bit
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* number, a shift of -7 shifts the upper 7 bits into the lowest 7 positions. This class sets the shift > 32 and < 64,
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* which if used with an int will still move the upper bits of an int to the lower bits due to Java's implicit modulus on
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* shifts.
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*
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*
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* [.mask] can also be used to mask the low bits of a number, which may be faster for some hashcodes, if
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* [.place] is overridden.
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*/
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protected var shift: Int
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/**
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* A bitmask used to confine hashcodes to the size of the table. Must be all 1 bits in its low positions, ie a power of two
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* minus 1. If [.place] is overriden, this can be used instead of [.shift] to isolate usable bits of a
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* hash.
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*/
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protected var mask: Int
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@Transient
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private var iterator1: LongSetIterator? = null
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@Transient
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private var iterator2: LongSetIterator? = null
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/**
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* Creates a new set with an initial capacity of 51 and a load factor of 0.8
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*/
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constructor() : this(51,0.8f)
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/**
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* Creates a new set with the specified initial capacity and load factor. This set will hold initialCapacity items before
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* growing the backing table.
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*
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* @param initialCapacity The backing array size is initialCapacity / loadFactor, increased to the next power of two.
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* @param loadFactor The loadfactor used to determine backing array growth
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*/
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constructor(initialCapacity: Int = 51, loadFactor: Float = 0.8f) {
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require(!(loadFactor <= 0f || loadFactor >= 1f)) { "loadFactor must be > 0 and < 1: $loadFactor" }
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this.loadFactor = loadFactor
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val tableSize = tableSize(initialCapacity, loadFactor)
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threshold = (tableSize * loadFactor).toInt()
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mask = tableSize - 1
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shift = java.lang.Long.numberOfLeadingZeros(mask.toLong())
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keyTable = LongArray(tableSize)
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}
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/**
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* Creates a new set identical to the specified set.
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*/
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constructor(set: LongSet) : this((set.keyTable.size * set.loadFactor).toInt(), set.loadFactor) {
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System.arraycopy(set.keyTable, 0, keyTable, 0, set.keyTable.size)
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size_ = set.size_
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hasZeroValue = set.hasZeroValue
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}
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override val size: Int
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get() = size_
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/**
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* Returns an index >= 0 and <= [.mask] for the specified `item`.
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*
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*
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* The default implementation uses Fibonacci hashing on the item's [Object.hashCode]: the hashcode is multiplied by a
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* long constant (2 to the 64th, divided by the golden ratio) then the uppermost bits are shifted into the lowest positions to
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* obtain an index in the desired range. Multiplication by a long may be slower than int (eg on GWT) but greatly improves
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* rehashing, allowing even very poor hashcodes, such as those that only differ in their upper bits, to be used without high
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* collision rates. Fibonacci hashing has increased collision rates when all or most hashcodes are multiples of larger
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* Fibonacci numbers (see [Malte Skarupke's blog post](https://probablydance.com/2018/06/16/fibonacci-hashing-the-optimization-that-the-world-forgot-or-a-better-alternative-to-integer-modulo/)).
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*
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*
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* This method can be overriden to customizing hashing. This may be useful eg in the unlikely event that most hashcodes are
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* Fibonacci numbers, if keys provide poor or incorrect hashcodes, or to simplify hashing if keys provide high quality
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* hashcodes and don't need Fibonacci hashing: `return item.hashCode() & mask;` */
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protected fun place(item: Long): Int {
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return (item * -0x61c8864680b583ebL ushr shift).toInt()
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}
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/**
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* Returns the index of the key if already present, else -(index + 1) for the next empty index. This can be overridden in this
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* pacakge to compare for equality differently than [Object.equals].
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*/
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private fun locateKey(key: Long): Int {
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val keyTable = keyTable
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var i = place(key)
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while (true) {
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val other = keyTable[i]
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if (other == 0L) return -(i + 1) // Empty space is available.
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if (other == key) return i // Same key was found.
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i = i + 1 and mask
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}
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}
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operator fun get(key: Long): Long? {
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val i = locateKey(key)
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return if (i < 0) null else keyTable[i]
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}
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/**
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* Returns true if the key was added to the set or false if it was already in the set.
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*/
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override fun add(element: Long): Boolean {
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if (element == 0L) {
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if (hasZeroValue) return false
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hasZeroValue = true
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size_++
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return true
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}
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var i = locateKey(element)
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if (i >= 0) return false // Existing key was found.
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i = -(i + 1) // Empty space was found.
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keyTable[i] = element
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if (++size_ >= threshold) resize(keyTable.size shl 1)
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return true
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}
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override fun addAll(elements: Collection<Long>): Boolean {
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var added = false
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elements.forEach {
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added = add(it) || added
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}
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return added
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}
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fun addAll(array: LongArray) {
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addAll(array, 0, array.size)
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}
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fun addAll(array: LongArray, offset: Int, length: Int) {
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require(offset + length <= array.size) { "offset + length must be <= size: $offset + $length <= ${array.size}" }
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ensureCapacity(length)
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var i = offset
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val n = i + length
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while (i < n) {
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add(array[i])
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i++
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}
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}
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fun addAll(set: LongSet) {
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ensureCapacity(set.size_)
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if (set.hasZeroValue) add(0)
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val keyTable = set.keyTable
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var i = 0
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val n = keyTable.size
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while (i < n) {
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val key = keyTable[i]
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if (key != 0L) add(key)
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i++
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}
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}
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/**
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* Skips checks for existing keys, doesn't increment size, doesn't need to handle key 0.
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*/
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private fun addResize(key: Long) {
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val keyTable = keyTable
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var i = place(key)
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while (true) {
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if (keyTable[i] == 0L) {
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keyTable[i] = key
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return
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}
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i = (i + 1) and mask
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}
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}
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/**
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* Returns true if the key was removed.
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*/
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override fun remove(element: Long): Boolean {
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if (element == 0L) {
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if (!hasZeroValue) return false
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hasZeroValue = false
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size_--
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return true
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}
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var i = locateKey(element)
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if (i < 0) return false
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val keyTable = keyTable
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val mask = mask
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var next = (i + 1) and mask
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var k: Long
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while (keyTable[next].also { k = it } != 0L) {
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val placement = place(k)
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if ((next - placement and mask) > (i - placement and mask)) {
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keyTable[i] = k
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i = next
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}
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next = (next + 1) and mask
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}
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keyTable[i] = 0
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size_--
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return true
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}
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/**
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* Returns true if the set has one or more items.
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*/
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fun notEmpty(): Boolean {
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return size_ > 0
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}
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/**
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* Returns true if the set is empty.
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*/
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override fun isEmpty(): Boolean {
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return size_ == 0
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}
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/**
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* Reduces the size of the backing arrays to be the specified capacity / loadFactor, or less. If the capacity is already less,
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* nothing is done. If the set contains more items than the specified capacity, the next highest power of two capacity is used
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* instead.
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*/
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fun shrink(maximumCapacity: Int) {
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require(maximumCapacity >= 0) { "maximumCapacity must be >= 0: $maximumCapacity" }
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val tableSize = tableSize(maximumCapacity, loadFactor)
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if (keyTable.size > tableSize) resize(tableSize)
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}
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/**
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* Clears the set and reduces the size of the backing arrays to be the specified capacity / loadFactor, if they are larger.
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*/
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fun clear(maximumCapacity: Int) {
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val tableSize = tableSize(maximumCapacity, loadFactor)
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if (keyTable.size <= tableSize) {
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clear()
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return
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}
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size_ = 0
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hasZeroValue = false
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resize(tableSize)
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}
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override fun clear() {
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if (size_ == 0) return
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size_ = 0
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Arrays.fill(keyTable, 0)
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hasZeroValue = false
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}
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override fun containsAll(elements: Collection<Long>): Boolean {
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elements.forEach {
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if (!contains(it)) {
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return false
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}
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}
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return true
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}
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override operator fun contains(element: Long): Boolean {
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return if (element == 0L) {
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hasZeroValue
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} else {
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locateKey(element) >= 0
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}
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}
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fun first(): Long {
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if (hasZeroValue) return 0
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val keyTable = keyTable
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var i = 0
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val n = keyTable.size
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while (i < n) {
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if (keyTable[i] != 0L) return keyTable[i]
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i++
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}
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throw IllegalStateException("LongSet is empty.")
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}
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/**
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* Increases the size of the backing array to accommodate the specified number of additional items / loadFactor. Useful before
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* adding many items to avoid multiple backing array resizes.
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*/
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fun ensureCapacity(additionalCapacity: Int) {
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val tableSize = tableSize(size_ + additionalCapacity, loadFactor)
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if (keyTable.size < tableSize) resize(tableSize)
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}
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private fun resize(newSize: Int) {
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val oldCapacity = keyTable.size
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threshold = (newSize * loadFactor).toInt()
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mask = newSize - 1
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shift = java.lang.Long.numberOfLeadingZeros(mask.toLong())
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val oldKeyTable = keyTable
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keyTable = LongArray(newSize)
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if (size_ > 0) {
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for (i in 0 until oldCapacity) {
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val key = oldKeyTable[i]
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if (key != 0L) addResize(key)
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}
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}
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}
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override fun hashCode(): Int {
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var h = size_
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val keyTable = keyTable
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var i = 0
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val n = keyTable.size
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while (i < n) {
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val key = keyTable[i]
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if (key != 0L) h += key.toInt() // .toInt is yikes, but is a limitation of the JVM!
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i++
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}
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return h
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}
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override fun equals(other: Any?): Boolean {
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if (other !is LongSet) return false
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if (other.size_ != size_) return false
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if (other.hasZeroValue != hasZeroValue) return false
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val keyTable = keyTable
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var i = 0
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val n = keyTable.size
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while (i < n) {
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if (keyTable[i] != 0L && !other.contains(keyTable[i])) {
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return false
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}
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i++
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}
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return true
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}
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override fun toString(): String {
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if (size_ == 0) return "[]"
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val buffer = StringBuilder(32)
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buffer.append('[')
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val keyTable = keyTable
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var i = keyTable.size
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if (hasZeroValue) {
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buffer.append("0")
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}
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else {
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while (i-- > 0) {
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val key = keyTable[i]
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if (key == 0L) continue
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buffer.append(key)
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break
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}
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}
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while (i-- > 0) {
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val key = keyTable[i]
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if (key == 0L) continue
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buffer.append(", ")
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buffer.append(key)
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}
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buffer.append(']')
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return buffer.toString()
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}
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/**
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* Returns an iterator for the keys in the set. Remove is supported.
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*
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* If [Collections.allocateIterators] is false, the same iterator instance is returned each time this method is called.
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*
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* Use the [LongSetIterator] constructor for nested or multithreaded iteration.
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*/
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override operator fun iterator(): LongSetIterator {
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if (allocateIterators) return LongSetIterator(this)
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if (iterator1 == null) {
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iterator1 = LongSetIterator(this)
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iterator2 = LongSetIterator(this)
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}
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if (!iterator1!!.valid) {
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iterator1!!.reset()
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iterator1!!.valid = true
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iterator2!!.valid = false
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return iterator1!!
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}
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iterator2!!.reset()
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iterator2!!.valid = true
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iterator1!!.valid = false
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return iterator2!!
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}
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override fun retainAll(elements: Collection<Long>): Boolean {
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var removed = false
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keyTable.forEach {
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if (!elements.contains(it)) {
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remove(it)
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removed = true
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}
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}
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return removed
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}
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override fun removeAll(elements: Collection<Long>): Boolean {
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var removed = false
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elements.forEach {
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removed = remove(it) || removed
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}
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return removed
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}
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class LongSetIterator(val set: LongSet): MutableIterator<Long> {
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var hasNext = false
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var nextIndex = 0
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var currentIndex = 0
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var valid = true
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init {
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reset()
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}
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fun reset() {
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currentIndex = INDEX_ILLEGAL
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nextIndex = INDEX_ZERO
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if (set.hasZeroValue) hasNext = true else findNextIndex()
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}
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fun findNextIndex() {
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val keyTable = set.keyTable
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val n = keyTable.size
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while (++nextIndex < n) {
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if (keyTable[nextIndex] != 0L) {
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hasNext = true
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return
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}
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}
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hasNext = false
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||||
}
|
||||
|
||||
override fun remove() {
|
||||
var i = currentIndex
|
||||
if (i == INDEX_ZERO && set.hasZeroValue) {
|
||||
set.hasZeroValue = false
|
||||
} else if (i < 0) {
|
||||
throw IllegalStateException("next must be called before remove.")
|
||||
} else {
|
||||
val keyTable = set.keyTable
|
||||
val mask = set.mask
|
||||
var next = (i + 1) and mask
|
||||
|
||||
var key: Long
|
||||
while (keyTable[next].also { key = it } != 0L) {
|
||||
val placement = set.place(key)
|
||||
if ((next - placement and mask) > (i - placement and mask)) {
|
||||
keyTable[i] = key
|
||||
i = next
|
||||
}
|
||||
next = (next + 1) and mask
|
||||
}
|
||||
keyTable[i] = 0
|
||||
|
||||
if (i != currentIndex) --nextIndex
|
||||
currentIndex = INDEX_ILLEGAL
|
||||
set.size_--
|
||||
}
|
||||
}
|
||||
|
||||
override fun hasNext(): Boolean {
|
||||
return hasNext
|
||||
}
|
||||
|
||||
override operator fun next(): Long {
|
||||
if (!hasNext) throw NoSuchElementException()
|
||||
if (!valid) throw RuntimeException("#iterator() cannot be used nested.")
|
||||
val key = if (nextIndex == INDEX_ZERO) {
|
||||
0
|
||||
} else {
|
||||
set.keyTable[nextIndex]
|
||||
}
|
||||
|
||||
currentIndex = nextIndex
|
||||
findNextIndex()
|
||||
return key
|
||||
}
|
||||
|
||||
/** Returns a new array containing the remaining keys. */
|
||||
fun toArray(): LongArray {
|
||||
val array = LongArray(set.size)
|
||||
var index = 0
|
||||
while (hasNext()) {
|
||||
array[index++] = next()
|
||||
}
|
||||
return array
|
||||
}
|
||||
|
||||
/**
|
||||
* Adds the remaining values to the specified array.
|
||||
*/
|
||||
fun toArray(array: LongArray): LongArray {
|
||||
var index = 0
|
||||
while (hasNext) {
|
||||
array[index++] = next()
|
||||
}
|
||||
return array
|
||||
}
|
||||
|
||||
companion object {
|
||||
private const val INDEX_ILLEGAL = -2
|
||||
private const val INDEX_ZERO = -1
|
||||
}
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue