feat: impl JindongApplier that manages the haptic node tree for Compose Runtime (#13)

* feat: impl JindongApplier that manages node trees

* fix: apply spotless check

* fix: apply spotless check and use beforeEach to create applier

* fix: apply spotless check

* test: test target index is out of bounds

* fix: remove unnecessary applier.up()

* fix: apply spotless check

Author: wisemuji

jindong/src/commonMain/kotlin/io/github/jindong/compose/JindongApplier.kt

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2026 compose-jindong
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.github.jindong.compose
+
+import androidx.compose.runtime.AbstractApplier
+import io.github.jindong.node.HapticNode
+
+/**
+ * Applier that manages the haptic node tree for Compose Runtime.
+ *
+ * This applier is responsible for:
+ * - Adding nodes to the tree ([insertTopDown], [insertBottomUp])
+ * - Removing nodes from the tree ([remove])
+ * - Moving nodes within the tree ([move])
+ * - Clearing the tree ([onClear])
+ *
+ * The applier maintains a tree of [io.github.jindong.node.HapticNode]s which will be traversed
+ * to collect [ScheduledHapticEvent]s for playback.
+ *
+ * @param root The root node of the composition tree
+ */
+internal class JindongApplier(
+  root: HapticNode,
+) : AbstractApplier<HapticNode>(root) {
+
+  override fun insertTopDown(index: Int, instance: HapticNode) {
+    current.children.add(index, instance)
+  }
+
+  override fun insertBottomUp(index: Int, instance: HapticNode) {
+    // Insertion is already handled in insertTopDown
+  }
+
+  override fun remove(index: Int, count: Int) {
+    current.children.subList(index, index + count).clear()
+  }
+
+  override fun move(from: Int, to: Int, count: Int) {
+    if (from == to) return
+
+    val items = current.children.subList(from, from + count).toList()
+    current.children.subList(from, from + count).clear()
+    current.children.addAll(to, items)
+  }
+
+  override fun onClear() {
+    root.children.clear()
+  }
+}