Further reduce instance creations

yorkie/src/main/kotlin/dev/yorkie/api/ElementConverter.kt

@@ -285,7 +285,7 @@ internal fun CrdtObject.toPBJsonObject(): PBJsonElement {
     }
 }
 
-internal fun List<ElementRht.Node<CrdtElement>>.toPBRhtNodes(): List<PBRhtNode> {
+internal fun Iterable<ElementRht.Node<CrdtElement>>.toPBRhtNodes(): List<PBRhtNode> {
     return map {
         rHTNode {
             key = it.strKey

yorkie/src/main/kotlin/dev/yorkie/document/change/ChangeContext.kt

@@ -18,12 +18,9 @@ internal data class ChangeContext(
     val root: CrdtRoot,
     val message: String? = null,
     var presenceChange: PresenceChange? = null,
-    private val _operations: MutableList<Operation> = mutableListOf(),
+    private val operations: MutableList<Operation> = mutableListOf(),
     private var delimiter: UInt = TimeTicket.INITIAL_DELIMITER,
 ) {
-    val operations: List<Operation>
-        get() = _operations.toList()
-
     /**
      * Returns whether this context has change or not.
      */
@@ -40,7 +37,7 @@ internal data class ChangeContext(
      * Pushes the given operation to this context.
      */
     fun push(operation: Operation) {
-        _operations.add(operation)
+        operations.add(operation)
     }
 
     /**

yorkie/src/main/kotlin/dev/yorkie/document/crdt/CrdtObject.kt

@@ -12,8 +12,8 @@ internal data class CrdtObject(
     override var _removedAt: TimeTicket? = null,
     private val rht: ElementRht<CrdtElement> = ElementRht(),
 ) : CrdtContainer(), Iterable<Pair<String, CrdtElement>> {
-    val memberNodes
-        get() = rht.toList()
+    val memberNodes: Iterable<ElementRht.Node<CrdtElement>>
+        get() = rht
 
     /**
      * Returns the array of keys in this object.

yorkie/src/main/kotlin/dev/yorkie/document/crdt/CrdtTree.kt

@@ -775,8 +775,8 @@ internal data class CrdtTreeNode private constructor(
 
     var insNextID: CrdtTreeNodeID? = null
 
-    val rhtNodes: List<RhtNode>
-        get() = _attributes.toList()
+    val rhtNodes: Iterable<RhtNode>
+        get() = _attributes
 
     init {
         _value?.let { value = it }
@@ -860,13 +860,13 @@ internal data class CrdtTreeNode private constructor(
      * Copies itself deeply.
      */
     fun deepCopy(): CrdtTreeNode {
+        val childNodes = mutableListOf<CrdtTreeNode>()
+        allChildren.forEach {
+            childNodes.add(it.deepCopy())
+        }
         return copy(
             _value = _value,
-            childNodes = IndexTreeNodeList(
-                allChildren.map { child ->
-                    child.deepCopy()
-                }.toMutableList(),
-            ),
+            childNodes = IndexTreeNodeList(childNodes),
             _attributes = _attributes.deepCopy(),
         ).also {
             it.allChildren.forEach { child ->

yorkie/src/main/kotlin/dev/yorkie/document/crdt/RgaTreeSplit.kt

@@ -205,7 +205,7 @@ internal class RgaTreeSplit<T : RgaTreeSplitValue<T>> :
         val removedNodes = mutableMapOf<RgaTreeSplitNodeID, RgaTreeSplitNode<T>>()
 
         // First, we need to collect indexes for change.
-        val changes = makeChanges(nodesToKeep, executedAt).toMutableList()
+        val changes = makeChanges(nodesToKeep, executedAt)
         nodesToDelete.forEach { node ->
             // Then, make nodes be tombstones and map that.
             val actorID = node.createdAt.actorID
@@ -269,26 +269,27 @@ internal class RgaTreeSplit<T : RgaTreeSplitValue<T>> :
     private fun makeChanges(
         boundaries: List<RgaTreeSplitNode<T>?>,
         executedAt: TimeTicket,
-    ): List<ContentChange> {
-        return buildList {
-            var (fromIndex, toIndex) = 0 to 0
-            for (index in 0 until boundaries.lastIndex) {
-                val leftBoundary = boundaries[index]
-                val rightBoundary = boundaries[index + 1]
-                if (leftBoundary?.next == rightBoundary) continue
-
-                fromIndex =
-                    findIndexesFromRange(requireNotNull(leftBoundary?.next).createPosRange()).first
-                toIndex = if (rightBoundary == null) {
-                    treeByIndex.length
-                } else {
-                    findIndexesFromRange(requireNotNull(rightBoundary.prev).createPosRange()).second
-                }
-            }
-            if (fromIndex < toIndex) {
-                add(ContentChange(executedAt.actorID, fromIndex, toIndex))
+    ): MutableList<ContentChange> {
+        val changes = mutableListOf<ContentChange>()
+        var (fromIndex, toIndex) = 0 to 0
+        for (index in 0 until boundaries.lastIndex) {
+            val leftBoundary = boundaries[index]
+            val rightBoundary = boundaries[index + 1]
+            if (leftBoundary?.next == rightBoundary) continue
+
+            fromIndex =
+                findIndexesFromRange(requireNotNull(leftBoundary?.next).createPosRange()).first
+            toIndex = if (rightBoundary == null) {
+                treeByIndex.length
+            } else {
+                findIndexesFromRange(requireNotNull(rightBoundary.prev).createPosRange()).second
             }
-        }.reversed()
+        }
+        if (fromIndex < toIndex) {
+            changes.add(ContentChange(executedAt.actorID, fromIndex, toIndex))
+        }
+        changes.reverse()
+        return changes
     }
 
     fun findIndexesFromRange(range: RgaTreeSplitPosRange): Pair<Int, Int> {

yorkie/src/main/kotlin/dev/yorkie/document/crdt/TextInfo.kt

@@ -34,8 +34,8 @@ internal data class TextValue(
     val attributes
         get() = _attributes.nodeKeyValueMap
 
-    val attributesWithTimeTicket
-        get() = _attributes.toList()
+    val attributesWithTimeTicket: Iterable<RhtNode>
+        get() = _attributes
 
     override val length: Int by content::length
 

yorkie/src/main/kotlin/dev/yorkie/document/json/JsonTree.kt

@@ -123,7 +123,7 @@ public class JsonTree internal constructor(
 
         val fromPos = target.pathToPos(fromPath)
         val toPos = target.pathToPos(toPath)
-        editInternal(fromPos, toPos, contents.toList(), splitLevel)
+        editInternal(fromPos, toPos, splitLevel, *contents)
     }
 
     /**
@@ -152,19 +152,19 @@ public class JsonTree internal constructor(
 
         val fromPos = target.findPos(fromIndex)
         val toPos = target.findPos(toIndex)
-        editInternal(fromPos, toPos, contents.toList(), splitLevel)
+        editInternal(fromPos, toPos, splitLevel, *contents)
     }
 
     private fun editInternal(
         fromPos: CrdtTreePos,
         toPos: CrdtTreePos,
-        contents: List<TreeNode>,
         splitLevel: Int = 0,
+        vararg contents: TreeNode,
     ) {
         if (contents.isNotEmpty()) {
-            validateTreeNodes(contents)
+            validateTreeNodes(*contents)
             if (contents.first().type != DEFAULT_TEXT_TYPE) {
-                contents.forEach { validateTreeNodes(listOf(it)) }
+                contents.forEach { validateTreeNodes(it) }
             }
         }
 
@@ -207,7 +207,7 @@ public class JsonTree internal constructor(
     /**
      * Ensures that treeNodes consists of only one type.
      */
-    private fun validateTreeNodes(treeNodes: List<TreeNode>) {
+    private fun validateTreeNodes(vararg treeNodes: TreeNode) {
         if (treeNodes.isEmpty()) return
 
         val firstTreeNodeType = treeNodes.first().type

yorkie/src/main/kotlin/dev/yorkie/util/IndexTree.kt

@@ -238,7 +238,7 @@ internal class IndexTree<T : IndexTreeNode<T>>(val root: T) {
     }
 
     private fun addSizeOfLeftSiblings(parent: T, offset: Int): Int {
-        return parent.children.take(offset).fold(0) { acc, leftSibling ->
+        return parent.children.subList(0, offset).fold(0) { acc, leftSibling ->
             acc + if (leftSibling.isRemoved) 0 else leftSibling.paddedSize
         }
     }
@@ -411,7 +411,7 @@ internal abstract class IndexTreeNode<T : IndexTreeNode<T>>() {
      * Returns the children of the node including tombstones.
      */
     val allChildren: List<T>
-        get() = childNodes.toList()
+        get() = childNodes
 
     /**
      * Returns true if the node's children consist of only text children.
@@ -443,7 +443,7 @@ internal abstract class IndexTreeNode<T : IndexTreeNode<T>>() {
 
             // If nodes are removed, the offset of the removed node is the number of
             // nodes before the node excluding the removed nodes.
-            return allChildren.take(index).filterNot { it.isRemoved }.size
+            return allChildren.subList(0, index).filterNot { it.isRemoved }.size
         }
         return children.indexOf(node)
     }
@@ -467,20 +467,18 @@ internal abstract class IndexTreeNode<T : IndexTreeNode<T>>() {
     }
 
     /**
-     * Prepends the given nodes to the children.
+     * Prepends the given node to the children.
      */
-    fun prepend(vararg newNode: T) {
+    fun prepend(newNode: T) {
         check(!isText) {
             "Text node cannot have children"
         }
 
-        childNodes.addAll(0, newNode.toList())
-        newNode.forEach { node ->
-            node.parent = this as T
+        childNodes.add(0, newNode)
+        newNode.parent = this as T
 
-            if (!node.isRemoved) {
-                node.updateAncestorSize()
-            }
+        if (!newNode.isRemoved) {
+            newNode.updateAncestorSize()
         }
     }
 
@@ -571,23 +569,19 @@ internal abstract class IndexTreeNode<T : IndexTreeNode<T>>() {
         parent?.insertAfterInternal(this as T, clone)
         clone.updateAncestorSize()
 
-        val leftChildren = childNodes.take(offset)
-        val rightChildren = childNodes.drop(offset)
-        childNodes.clear()
-        childNodes.addAll(leftChildren)
         clone.childNodes.clear()
-        clone.childNodes.addAll(rightChildren)
+        repeat(childNodes.size - offset) {
+            val rightChild = childNodes.removeAt(offset + it)
+            clone.childNodes.add(rightChild)
+            rightChild.parent = clone
+        }
         size = childNodes.fold(0) { acc, child ->
             acc + child.paddedSize
         }
         clone.size = clone.childNodes.fold(0) { acc, child ->
             acc + child.paddedSize
         }
 
-        clone.childNodes.forEach { child ->
-            child.parent = clone
-        }
-
         return clone
     }