Optimize persistent list batch updates

Author: Abduqodiri Qurbonzoda

core/commonMain/src/implementations/immutableList/AbstractListIterator.kt

@@ -21,4 +21,29 @@ internal abstract class AbstractListIterator<out E>(var index: Int, var size: In
     override fun previousIndex(): Int {
         return index - 1
     }
+
+    internal fun checkHasNext() {
+        if (!hasNext())
+            throw NoSuchElementException()
+    }
+
+    internal fun checkHasPrevious() {
+        if (!hasPrevious())
+            throw NoSuchElementException()
+    }
+}
+
+
+internal class SingleElementListIterator<E>(private val element: E, index: Int): AbstractListIterator<E>(index, 1) {
+    override fun next(): E {
+        checkHasNext()
+        index++
+        return element
+    }
+
+    override fun previous(): E {
+        checkHasPrevious()
+        index--
+        return element
+    }
 }

core/commonMain/src/implementations/immutableList/AbstractPersistentList.kt

@@ -31,11 +31,7 @@ abstract class AbstractPersistentList<E> : PersistentList<E>, AbstractList<E>()
     }
 
     override fun removeAll(elements: Collection<E>): PersistentList<E> {
-        return mutate { it.removeAll(elements) }
-    }
-
-    override fun removeAll(predicate: (E) -> Boolean): PersistentList<E> {
-        return mutate { it.removeAll(predicate) }
+        return removeAll { elements.contains(it) }
     }
 
     override fun clear(): PersistentList<E> {

core/commonMain/src/implementations/immutableList/PersistentVector.kt

@@ -9,6 +9,7 @@ import kotlinx.collections.immutable.PersistentList
 import kotlinx.collections.immutable.internal.ListImplementation.checkElementIndex
 import kotlinx.collections.immutable.internal.ListImplementation.checkPositionIndex
 import kotlinx.collections.immutable.internal.assert
+import kotlinx.collections.immutable.mutate
 
 /**
  * Persistent vector made of a trie of leaf buffers entirely filled with [MAX_BUFFER_SIZE] elements and a tail having
@@ -78,7 +79,6 @@ internal class PersistentVector<E>(private val root: Array<Any?>,
         return newRootNode
     }
 
-
     override fun add(index: Int, element: E): PersistentList<E> {
         checkPositionIndex(index, size)
         if (index == size) {
@@ -259,7 +259,11 @@ internal class PersistentVector<E>(private val root: Array<Any?>,
         return newRoot
     }
 
-    override fun builder(): PersistentList.Builder<E> {
+    override fun removeAll(predicate: (E) -> Boolean): PersistentList<E> {
+        return builder().also { it.removeAllWithPredicate(predicate) }.build()
+    }
+
+    override fun builder(): PersistentVectorBuilder<E> {
         return PersistentVectorBuilder(this, root, tail, rootShift)
     }