Bring back fastutil usage

src/main/kotlin/ru/dbotthepony/kommons/collect/ConditionalSet.kt

@@ -1,5 +1,6 @@
 package ru.dbotthepony.kommons.collect
 
+import it.unimi.dsi.fastutil.objects.Object2ObjectLinkedOpenHashMap
 import java.util.function.BooleanSupplier
 import java.util.stream.Stream
 
@@ -7,15 +8,13 @@ import java.util.stream.Stream
  * Set, with values appearing and disappearing by conditions
  */
 class ConditionalSet<E : Any> : Set<E> {
-	private class Entry<E>(val value: E, var condition: BooleanSupplier)
+	private val backing = Object2ObjectLinkedOpenHashMap<E, BooleanSupplier>()
-	private val backing = ArrayList<Entry<E>>()
-	private val mapped = HashMap<E, Entry<E>>()
 
 	override val size: Int
-		get() = backing.stream().filter { it.condition.asBoolean }.count().toInt()
+		get() = backing.values.stream().filter { it.asBoolean }.count().toInt()
 
 	override fun contains(element: E): Boolean {
-		return mapped[element]?.condition?.asBoolean ?: false
+		return backing[element]?.asBoolean ?: false
 	}
 
 	override fun containsAll(elements: Collection<E>): Boolean {
@@ -23,67 +22,43 @@ class ConditionalSet<E : Any> : Set<E> {
 	}
 
 	override fun isEmpty(): Boolean {
-		return mapped.isEmpty() || mapped.values.stream().noneMatch { it.condition.asBoolean }
+		return backing.isEmpty() || backing.values.stream().noneMatch { it.asBoolean }
 	}
 
 	override fun stream(): Stream<E> {
-		return backing.stream().filter { it.condition.asBoolean }.map { it.value }
+		return backing.entries.stream().filter { it.value.asBoolean }.map { it.key }
 	}
 
 	override fun iterator(): Iterator<E> {
-		return backing.iterator().filter { it.condition.asBoolean }.map { it.value }
+		return backing.entries.iterator().filter { it.value.asBoolean }.map { it.key }
 	}
 
 	fun actuallyContains(element: E): Boolean {
-		return element in mapped
+		return element in backing
 	}
 
 	fun add(element: E, condition: BooleanSupplier): Boolean {
-		if (element in mapped) return false
+		if (element in backing) return false
-		val entry = Entry(element, condition)
+		backing[element] = condition
-		mapped[element] = entry
-		backing.add(entry)
 		return true
 	}
 
 	fun addFirst(element: E, condition: BooleanSupplier): Boolean {
-		if (element in mapped) return false
+		if (element in backing) return false
-		val entry = Entry(element, condition)
+		backing.putAndMoveToFirst(element, condition)
-		mapped[element] = entry
-		backing.add(0, entry)
 		return true
 	}
 
 	fun replace(element: E, condition: BooleanSupplier) {
-		val entry = mapped[element]
+		backing[element] = condition
-
-		if (entry != null) {
-			entry.condition = condition
-		} else {
-			add(element, condition)
-		}
 	}
 
 	fun replaceFirst(element: E, condition: BooleanSupplier) {
-		val entry = mapped[element]
+		backing.remove(element)
-
+		backing.putAndMoveToFirst(element, condition)
-		if (entry != null) {
-			entry.condition = condition
-			backing.remove(entry)
-			backing.add(0, entry)
-		} else {
-			addFirst(element, condition)
-		}
 	}
 
 	fun remove(element: E): Boolean {
-		val entry = mapped.remove(element)
+		return backing.remove(element) != null
-
-		if (entry != null) {
-			backing.remove(entry)
-			return true
-		}
-
-		return false
 	}
 }