Allow hashSet collisions to be located at any level

Author: Abduqodiri Qurbonzoda

kotlinx-collections-immutable/src/main/kotlin/kotlinx/collections/immutable/implementations/immutableMap/TrieNode.kt

@@ -23,7 +23,6 @@ internal const val MAX_BRANCHING_FACTOR = 32
 internal const val LOG_MAX_BRANCHING_FACTOR = 5
 internal const val MAX_BRANCHING_FACTOR_MINUS_ONE = MAX_BRANCHING_FACTOR - 1
 internal const val ENTRY_SIZE = 2
-internal const val MAX_SHIFT = 30
 
 /**
  * Gets trie index segment of the specified [index] at the level specified by [shift].

kotlinx-collections-immutable/src/main/kotlin/kotlinx/collections/immutable/implementations/immutableSet/PersistentHashSet.kt

@@ -63,7 +63,7 @@ internal class PersistentHashSet<E>(internal val node: TrieNode<E>,
     }
 
     internal companion object {
-        private val EMPTY = PersistentHashSet(TrieNode.EMPTY, 0)
+        private val EMPTY = PersistentHashSet(CompactTrieNode.EMPTY, 0)
         internal fun <E> emptyOf(): PersistentSet<E> = PersistentHashSet.EMPTY
     }
 }

kotlinx-collections-immutable/src/main/kotlin/kotlinx/collections/immutable/implementations/immutableSet/PersistentHashSetBuilder.kt

@@ -57,13 +57,13 @@ internal class PersistentHashSetBuilder<E>(private var set: PersistentHashSet<E>
     override fun remove(element: E): Boolean {
         val size = this.size
         @Suppress("UNCHECKED_CAST")
-        node = node.mutableRemove(element.hashCode(), element, 0, this) ?: TrieNode.EMPTY as TrieNode<E>
+        node = node.mutableRemove(element.hashCode(), element, 0, this) ?: CompactTrieNode.EMPTY as TrieNode<E>
         return size != this.size
     }
 
     override fun clear() {
         @Suppress("UNCHECKED_CAST")
-        node = TrieNode.EMPTY as TrieNode<E>
+        node = CompactTrieNode.EMPTY as TrieNode<E>
         size = 0
     }
 

kotlinx-collections-immutable/src/main/kotlin/kotlinx/collections/immutable/implementations/immutableSet/PersistentHashSetIterator.kt

@@ -85,7 +85,7 @@ internal open class PersistentHashSetIterator<E>(node: TrieNode<E>) : Iterator<E
 }
 
 internal class TrieNodeIterator<out E> {
-    private var buffer = TrieNode.EMPTY.buffer
+    private var buffer = CompactTrieNode.EMPTY.buffer
     private var index = 0
 
     fun reset(buffer: Array<Any?>, index: Int = 0) {

kotlinx-collections-immutable/src/main/kotlin/kotlinx/collections/immutable/implementations/immutableSet/PersistentHashSetMutableIterator.kt

@@ -47,7 +47,7 @@ internal class PersistentHashSetMutableIterator<E>(private val builder: Persiste
     }
 
     private fun resetPath(hashCode: Int, node: TrieNode<*>, element: E, pathIndex: Int) {
-        if (isCollision(node)) {
+        if (node.isCollision()) {
             val index = node.buffer.indexOf(element)
             assert(index != -1)
             path[pathIndex].reset(node.buffer, index)
@@ -56,7 +56,7 @@ internal class PersistentHashSetMutableIterator<E>(private val builder: Persiste
         }
 
         val position = 1 shl ((hashCode shr (pathIndex * LOG_MAX_BRANCHING_FACTOR)) and MAX_BRANCHING_FACTOR_MINUS_ONE)
-        val index = Integer.bitCount(node.bitmap and (position - 1))
+        val index = Integer.bitCount((node as CompactTrieNode<*>).bitmap and (position - 1))
 
         path[pathIndex].reset(node.buffer, index)
 
@@ -69,10 +69,6 @@ internal class PersistentHashSetMutableIterator<E>(private val builder: Persiste
         }
     }
 
-    private fun isCollision(node: TrieNode<*>): Boolean {
-        return node.bitmap == 0
-    }
-
     private fun checkNextWasInvoked() {
         if (!nextWasInvoked)
             throw IllegalStateException()