feat: tree-structure-compose (LazyTree) + O(n) addChild cycle check

- New published module tree-structure-compose: a LazyTree composable for Compose
  Multiplatform (JVM/desktop, iOS, Wasm) with lazy rendering and expand/collapse.
- Fix an O(n^2) regression in addChild(): only walk ancestors for cycle detection
  when the child already has a subtree (a fresh leaf can never form a cycle), so
  building deep trees is O(n) again. Caught by the deep-chain stack-safety test on JS.
- README: Compose usage section; align all install snippets to 4.0.0.
- Version catalog: Compose Multiplatform + compose-compiler plugins.

Verified locally: JVM, JS(node), Wasm(node), iOS-simulator tests + apiCheck all green;
Compose module compiles for JVM, Wasm and iOS.

.circleci_turned_off/config.yml

@@ -1,86 +0,0 @@
-version: 2.1
-jobs:
-  build:
-    working_directory: ~/code
-    docker:
-      - image: circleci/android:api-29
-    environment:
-      JVM_OPTS: -Xmx3200m
-    steps:
-      - checkout
-      - restore_cache:
-          key: jars-{{ checksum "build.gradle" }}-{{ checksum  "app/build.gradle" }}
-      - run:
-          name: Download Dependencies
-          command: ./gradlew androidDependencies
-      - save_cache:
-          paths:
-            - ~/.gradle
-          key: jars-{{ checksum "build.gradle" }}-{{ checksum  "app/build.gradle" }}
-
-  tests:
-    working_directory: ~/code
-    docker:
-      - image: circleci/android:api-29
-    environment:
-      JVM_OPTS: -Xmx3200m
-    steps:
-      - checkout
-      - restore_cache:
-          key: jars-{{ checksum "build.gradle" }}-{{ checksum  "app/build.gradle" }}
-      - store_artifacts:
-          path: app/build/reports
-          destination: reports
-      - run:
-          name: Run Lint Test
-          command: ./gradlew lint
-      - run:
-          name: Run Tests
-          command: ./gradlew lint test
-      - store_artifacts:
-          path: app/build/reports
-          destination: reports
-      - store_test_results:
-          path: app/build/test-results
-
-  deploy:
-    working_directory: ~/code
-    docker:
-      - image: circleci/android:api-29
-    environment:
-      JVM_OPTS: -Xmx3200m
-    steps:
-      - checkout
-      - restore_cache:
-          key: jars-{{ checksum "build.gradle" }}-{{ checksum  "app/build.gradle" }}
-      - run:
-          name: Build Library
-          command: ./gradlew :treedatastructure:assembleRelease
-      - run:
-          name: Export key
-          command: |
-            mkdir treedatastructure/maven
-            echo ${GPG_KEY_CONTENTS} | base64 -d --ignore-garbage > treedatastructure/maven/secret.gpg
-      - run:
-          name: Staging
-          command: ./gradlew :treedatastructure:publishReleasePublicationToSonatypeRepository
-      - run:
-          name: Release Library
-          command: ./gradlew closeAndReleaseRepository
-
-workflows:
-  version: 2.1
-  build-and-deploy:
-    jobs:
-      - build:
-          filters:  # required since `deploy` has tag filters AND requires `build`
-            tags:
-              only: /.*/
-      - deploy:
-          requires:
-            - build
-          filters:
-            tags:
-              only: /v[0-9]{1,3}\.[0-9]{1,3}\.?[0-9]{0,3}/
-            branches:
-              ignore: /.*/

.github/workflows/publish.yml

@@ -1,38 +0,0 @@
-name: Publish
-
-on:
-  release:
-    # We'll run this workflow when a new GitHub release is created
-    types: [released]
-
-jobs:
-  publish:
-    name: Release build and publish
-    runs-on: ubuntu-latest
-    steps:
-      - name: Check out code
-        uses: actions/checkout@v2
-      - name: Set up JDK 11
-        uses: actions/setup-java@v2
-        with:
-          distribution: adopt
-          java-version: 11
-
-        # Builds the release artifacts of the library
-      - name: Release build
-        run: ./gradlew :treedatastructure:assembleRelease
-
-        # Generates other artifacts (javadocJar is optional)
-      - name: Source jar and dokka
-        run: ./gradlew androidSourcesJar javadocJar
-
-        # Runs upload, and then closes & releases the repository
-      - name: Publish to MavenCentral
-        run: ./gradlew publishReleasePublicationToSonatypeRepository --max-workers 1 closeAndReleaseSonatypeStagingRepository
-        env:
-          OSSRH_USERNAME: ${{ secrets.OSSRH_USERNAME }}
-          OSSRH_PASSWORD: ${{ secrets.OSSRH_PASSWORD }}
-          SIGNING_KEY_ID: ${{ secrets.SIGNING_KEY_ID }}
-          SIGNING_PASSWORD: ${{ secrets.SIGNING_PASSWORD }}
-          SIGNING_KEY: ${{ secrets.SIGNING_KEY }}
-          SONATYPE_STAGING_PROFILE_ID: ${{ secrets.SONATYPE_STAGING_PROFILE_ID }}

.github/workflows/publishRelease.yml

@@ -0,0 +1,36 @@
+name: Publish
+
+on:
+  release:
+    # We'll run this workflow when a new GitHub release is created
+    types: [released]
+
+
+jobs:
+  test:
+    uses: ./.github/workflows/test.yml
+    secrets: inherit
+
+  publish:
+    needs: test
+    name: Publish Production
+    environment: production
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: '21'
+
+        # Runs upload, and then closes & releases the repository
+      - name: Publish to MavenCentral
+        run: ./gradlew publishToMavenCentral
+        env:
+          ORG_GRADLE_PROJECT_mavenCentralUsername: ${{ secrets.MAVEN_CENTRAL_USERNAME }}
+          ORG_GRADLE_PROJECT_mavenCentralPassword: ${{ secrets.MAVEN_CENTRAL_PASSWORD }}
+          ORG_GRADLE_PROJECT_signingInMemoryKey: ${{ secrets.SIGNING_KEY }}
+          ORG_GRADLE_PROJECT_signingInMemoryKeyPassword: ${{ secrets.SIGNING_PASSWORD }}
+          SNAPSHOT: false

.github/workflows/test.yml

@@ -0,0 +1,31 @@
+name: Test
+
+on:
+  push:
+    branches-ignore: [master]
+  workflow_call:
+
+jobs:
+  test:
+    name: ${{ matrix.name }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: JVM / JS / Wasm / Native + API check
+            os: ubuntu-latest
+            tasks: jvmTest jsNodeTest wasmJsNodeTest nativeTest apiCheck
+          - name: iOS
+            os: macos-latest
+            tasks: iosSimulatorArm64Test
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: '21'
+      - name: Test
+        run: ./gradlew ${{ matrix.tasks }} --console=plain

.gitignore

@@ -9,6 +9,7 @@
 /.idea/assetWizardSettings.xml
 .DS_Store
 /build
+build/
 /captures
 .externalNativeBuild
 .cxx
@@ -16,3 +17,4 @@
 /.idea/compiler.xml
 /.idea/jarRepositories.xml
 /.idea/deploymentTargetDropDown.xml
+/.idea/

.idea/codeStyles/Project.xml

@@ -1,125 +0,0 @@
-<component name="ProjectCodeStyleConfiguration">
-  <code_scheme name="Project" version="173">
-    <JetCodeStyleSettings>
-      <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
-    </JetCodeStyleSettings>
-    <MarkdownNavigatorCodeStyleSettings>
-      <option name="RIGHT_MARGIN" value="72" />
-    </MarkdownNavigatorCodeStyleSettings>
-    <codeStyleSettings language="XML">
-      <indentOptions>
-        <option name="CONTINUATION_INDENT_SIZE" value="4" />
-      </indentOptions>
-      <arrangement>
-        <rules>
-          <section>
-            <rule>
-              <match>
-                <AND>
-                  <NAME>xmlns:android</NAME>
-                  <XML_ATTRIBUTE />
-                  <XML_NAMESPACE>^$</XML_NAMESPACE>
-                </AND>
-              </match>
-            </rule>
-          </section>
-          <section>
-            <rule>
-              <match>
-                <AND>
-                  <NAME>xmlns:.*</NAME>
-                  <XML_ATTRIBUTE />
-                  <XML_NAMESPACE>^$</XML_NAMESPACE>
-                </AND>
-              </match>
-              <order>BY_NAME</order>
-            </rule>
-          </section>
-          <section>
-            <rule>
-              <match>
-                <AND>
-                  <NAME>.*:id</NAME>
-                  <XML_ATTRIBUTE />
-                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
-                </AND>
-              </match>
-            </rule>
-          </section>
-          <section>
-            <rule>
-              <match>
-                <AND>
-                  <NAME>.*:name</NAME>
-                  <XML_ATTRIBUTE />
-                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
-                </AND>
-              </match>
-            </rule>
-          </section>
-          <section>
-            <rule>
-              <match>
-                <AND>
-                  <NAME>name</NAME>
-                  <XML_ATTRIBUTE />
-                  <XML_NAMESPACE>^$</XML_NAMESPACE>
-                </AND>
-              </match>
-            </rule>
-          </section>
-          <section>
-            <rule>
-              <match>
-                <AND>
-                  <NAME>style</NAME>
-                  <XML_ATTRIBUTE />
-                  <XML_NAMESPACE>^$</XML_NAMESPACE>
-                </AND>
-              </match>
-            </rule>
-          </section>
-          <section>
-            <rule>
-              <match>
-                <AND>
-                  <NAME>.*</NAME>
-                  <XML_ATTRIBUTE />
-                  <XML_NAMESPACE>^$</XML_NAMESPACE>
-                </AND>
-              </match>
-              <order>BY_NAME</order>
-            </rule>
-          </section>
-          <section>
-            <rule>
-              <match>
-                <AND>
-                  <NAME>.*</NAME>
-                  <XML_ATTRIBUTE />
-                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
-                </AND>
-              </match>
-              <order>ANDROID_ATTRIBUTE_ORDER</order>
-            </rule>
-          </section>
-          <section>
-            <rule>
-              <match>
-                <AND>
-                  <NAME>.*</NAME>
-                  <XML_ATTRIBUTE />
-                  <XML_NAMESPACE>.*</XML_NAMESPACE>
-                </AND>
-              </match>
-              <order>BY_NAME</order>
-            </rule>
-          </section>
-        </rules>
-      </arrangement>
-    </codeStyleSettings>
-    <codeStyleSettings language="kotlin">
-      <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
-    </codeStyleSettings>
-  </code_scheme>
-</component>

.idea/codeStyles/codeStyleConfig.xml

@@ -1,5 +0,0 @@
-<component name="ProjectCodeStyleConfiguration">
-  <state>
-    <option name="USE_PER_PROJECT_SETTINGS" value="true" />
-  </state>
-</component>

.idea/gradle.xml

@@ -1,22 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="GradleMigrationSettings" migrationVersion="1" />
-  <component name="GradleSettings">
-    <option name="linkedExternalProjectsSettings">
-      <GradleProjectSettings>
-        <option name="testRunner" value="GRADLE" />
-        <option name="distributionType" value="DEFAULT_WRAPPED" />
-        <option name="externalProjectPath" value="$PROJECT_DIR$" />
-        <option name="gradleJvm" value="11 (2)" />
-        <option name="modules">
-          <set>
-            <option value="$PROJECT_DIR$" />
-            <option value="$PROJECT_DIR$/app" />
-            <option value="$PROJECT_DIR$/treedatastructure" />
-          </set>
-        </option>
-        <option name="resolveModulePerSourceSet" value="false" />
-      </GradleProjectSettings>
-    </option>
-  </component>
-</project>

.idea/misc.xml

@@ -1,9 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_11" project-jdk-name="1.8" project-jdk-type="JavaSDK">
-    <output url="file://$PROJECT_DIR$/build/classes" />
-  </component>
-  <component name="ProjectType">
-    <option name="id" value="Android" />
-  </component>
-</project>

.idea/vcs.xml

@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="VcsDirectoryMappings">
-    <mapping directory="" vcs="Git" />
-  </component>
-</project>

CHANGELOG.md

@@ -0,0 +1,79 @@
+# Changelog
+
+All notable changes to this project are documented here. The format is based on
+[Keep a Changelog](https://keepachangelog.com/en/1.1.0/), and this project adheres to
+[Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+## [4.0.0]
+
+A breaking release that cleans up the core API and enforces an explicit public surface.
+
+### Changed (breaking)
+- `TreeNode.treeIterator` is now a read-only `val` (set it via the constructor). Use
+  `iterator(order)` or `asSequence(order)` to traverse in a different order per call.
+- `removeChild(child)` now only removes a **direct** child of the receiver (previously it removed
+  the node from its actual parent regardless). Use `child.detach()` to unhook a node from wherever
+  it lives.
+- `addChild(child)` now throws `TreeNodeException` if `child` already has a parent or if the
+  attachment would create a cycle. Call `detach()` first to move a node.
+- `clear()` no longer detaches the receiver from its own parent; it only removes its descendants.
+- `path(descendant)` now returns `List<TreeNode<T>>?` (`null` when `descendant` is the root or not a
+  descendant) instead of throwing `TreeNodeException`.
+
+### Added
+- `TreeNode.detach()` — removes a node from its parent.
+- `TreeNode.iterator(order)` — a one-shot iterator in a specific order.
+- Strict `explicitApi()` mode across all modules.
+- New `tree-structure-compose` module: a `LazyTree` composable for Compose Multiplatform.
+
+### Migration
+- `node.treeIterator = PostOrder; for (n in node) { … }` → `for (n in node.asSequence(PostOrder)) { … }`
+- `root.removeChild(deepNode)` → `deepNode.detach()`
+- `try { node.path(x) } catch (e: TreeNodeException) { … }` → `node.path(x)?.let { … }`
+
+## [3.4.0]
+
+### Added
+- Lazy `Sequence` traversal: `asSequence(order)`, `preOrderSequence()`, `postOrderSequence()`,
+  `levelOrderSequence()` — composes with the Kotlin stdlib and short-circuits.
+- Navigation extensions: `isLeaf`, `degree`, `root()`, `ancestors()`, `siblings()`, `leaves()`,
+  `descendants()`.
+- Functional extensions: `findNode`, `filterNodes`, `anyNode`, `allNodes`, `countNodes`,
+  `foldNodes`, `mapValues`, `deepCopy`, `structurallyEquals` (all stack-safe).
+- New optional modules published as separate artifacts:
+  - `tree-structure-serialization` — `kotlinx.serialization` support via a `TreeNodeDto`.
+  - `tree-structure-coroutines` — `Flow` traversal (`asFlow`, `preOrderFlow`, …).
+- `CHANGELOG.md`, expanded README examples, and class-level KDoc (thread-safety / complexity).
+
+### Changed
+- `nodeCount()`, `height()`, `clear()` and the post-order iterator are now iterative — deep or
+  degenerate (linear) trees no longer throw `StackOverflowError`.
+- Migrated to Kotlin 2.x (K2 compiler) and introduced a Gradle version catalog.
+- Build now uses `binary-compatibility-validator` (committed `.api` baselines) and Kover.
+
+## [3.1.5]
+
+### Fixed
+- Removed a stray `println` in `TreeNode.removeChild()` that printed to stdout on every removal.
+
+### Removed
+- Deleted the `Example.ws.kts` worksheet and the `kotlin("script-runtime")` dependency from the
+  published JVM artifact, plus the leftover `ExampleUnitTest` template test.
+
+### Changed
+- Bumped `actions/checkout` v2 → v4 in CI workflows.
+
+## [3.1.4]
+- Updated Kotlin and JS dependencies; added the `wasmJs` target.
+
+## [3.1.3]
+- iOS targets and Maven Central (Sonatype Central Portal) publishing.
+
+[Unreleased]: https://github.com/AdrianKuta/Tree-Data-Structure/compare/v4.0.0...HEAD
+[4.0.0]: https://github.com/AdrianKuta/Tree-Data-Structure/compare/v3.4.0...v4.0.0
+[3.4.0]: https://github.com/AdrianKuta/Tree-Data-Structure/compare/v3.1.5...v3.4.0
+[3.1.5]: https://github.com/AdrianKuta/Tree-Data-Structure/compare/v3.1.3...v3.1.5
+[3.1.4]: https://github.com/AdrianKuta/Tree-Data-Structure/releases/tag/v3.1.4
+[3.1.3]: https://github.com/AdrianKuta/Tree-Data-Structure/releases/tag/v3.1.3

README.md

@@ -1,9 +1,44 @@
 # Tree (Data Structure)
 [![maven](https://img.shields.io/maven-central/v/com.github.adriankuta/tree-structure?style=plastic)](https://mvnrepository.com/artifact/com.github.adriankuta/tree-structure)
-[![License: MIT](https://img.shields.io/github/license/AdrianKuta/Tree-Data-Structure?style=plastic)](https://github.com/AdrianKuta/Design-Patterns-Kotlin/blob/master/LICENSE)
+[![License: MIT](https://img.shields.io/github/license/AdrianKuta/Tree-Data-Structure?style=plastic)](https://github.com/AdrianKuta/Tree-Data-Structure/blob/master/LICENSE)
-[![CircleCI](https://img.shields.io/circleci/build/github/AdrianKuta/Tree-Data-Structure/master?label=CircleCI&style=plastic&logo=circleci)](https://circleci.com/gh/AdrianKuta/Tree-Data-Structure)
+[![Publish](https://github.com/AdrianKuta/Tree-Data-Structure/actions/workflows/publishRelease.yml/badge.svg)](https://github.com/AdrianKuta/Tree-Data-Structure/actions/workflows/publishRelease.yml)
 
-Simple implementation to store object in tree structure.
+Lightweight Kotlin Multiplatform tree data structure for Kotlin and Java. Includes a small DSL, multiple traversal iterators, and pretty-print support.
+
+- Kotlin Multiplatform (JVM, JS, Wasm, iOS, and Native host)
+- Pre-order, Post-order, and Level-order iteration
+- Lazy `Sequence` traversal that composes with the Kotlin stdlib (`map`/`filter`/`firstOrNull`…)
+- Navigation helpers: `root()`, `ancestors()`, `siblings()`, `leaves()`, `descendants()`, `isLeaf`, `degree`
+- Functional helpers: `findNode`, `filterNodes`, `anyNode`, `allNodes`, `foldNodes`, `mapValues`, `deepCopy`, `structurallyEquals`
+- Stack-safe: traversal and `height()`/`nodeCount()`/`clear()` handle arbitrarily deep trees without `StackOverflowError`
+- Simple DSL: tree { child(...) }
+- Utilities: nodeCount(), height(), depth(), path(), prettyString(), clear(), removeChild()
+
+## Installation
+
+Gradle (Kotlin DSL):
+```kotlin
+// commonMain for KMP projects, or any sourceSet/module where you need it
+dependencies {
+    implementation("com.github.adriankuta:tree-structure:4.0.0") // see badge above for the latest version
+}
+```
+
+Gradle (Groovy):
+```groovy
+dependencies {
+    implementation "com.github.adriankuta:tree-structure:4.0.0" // see badge above for the latest
+}
+```
+
+Maven:
+```xml
+<dependency>
+  <groupId>com.github.adriankuta</groupId>
+  <artifactId>tree-structure</artifactId>
+  <version>4.0.0</version>
+</dependency>
+```
 
 ## Usage
 
@@ -25,19 +60,15 @@ europe.addChild(france)
 println(root.prettyString())
 ```
 
-**Pretty Kotlin**
+**Pretty Kotlin (DSL)**
-
 ```kotlin
-val root =
+val root = tree("World") {
-    tree("World") {
+    child("North America") { child("USA") }
-        child("North America") {
+    child("Europe") {
-            child("USA")
+        child("Poland")
-        }
+        child("Germany")
-        child("Europe") {
-            child("Poland")
-            child("Germany")
-        }
     }
+}
 ```
 
 **Java**
@@ -58,8 +89,7 @@ europe.addChild(france);
 System.out.println(root.prettyString());
 ```
 
-*Output:*
+Output:
-
 ```
 World
 ├── North America
@@ -69,11 +99,157 @@ World
     └── France
 ```
 
+### Traversal and utilities
+```kotlin
+val root = TreeNode("root")
+// ... build your tree
 
-## Download
+// Choose iteration order per call (the default order is set in the constructor and is read-only)
+for (node in root.asSequence(TreeNodeIterators.PostOrder)) println(node.value)
+
+// Utilities
+root.nodeCount()   // number of descendants
+root.height()      // longest path to a leaf (in edges)
+root.depth()       // distance from current node to the root
+val path = root.path(root.children.first()) // nodes from descendant up to root
+
+// Mutations — removeChild removes a *direct* child; detach() unhooks a node from wherever it lives
+val child = root.children.first()
+root.removeChild(child)   // child is now detached from root
+root.clear()              // remove all descendants of root
+```
+
+### Lazy traversal with Sequence
+
+Traversal is exposed as a lazy `Sequence`, so it composes with the Kotlin standard library and
+short-circuits (it never materializes the whole tree just to find one node):
+
+```kotlin
+val tree = tree("World") {
+    child("North America") { child("USA") }
+    child("Europe") {
+        child("Poland")
+        child("Germany")
+    }
+}
+
+// Pick an order explicitly — no need to mutate the node's state.
+tree.preOrderSequence().map { it.value }.toList()    // [World, North America, USA, Europe, Poland, Germany]
+tree.levelOrderSequence().first { it.value == "USA" } // stops as soon as it's found
+tree.asSequence(TreeNodeIterators.PostOrder).count()  // 6
+```
+
+### Navigation
+
+```kotlin
+val usa = tree.findNode { it == "USA" }!!
+
+usa.isLeaf           // true
+usa.depth()          // 2
+usa.root().value     // "World"
+usa.ancestors().map { it.value } // [North America, World]
+tree.leaves().map { it.value }   // [USA, Poland, Germany]
+val europe = tree.findNode { it == "Europe" }!!
+europe.children.first().siblings().map { it.value } // [Germany]
+```
+
+### Functional operations
+
+```kotlin
+tree.anyNode { it == "Poland" }            // true
+tree.filterNodes { it.length > 5 }         // nodes whose value is longer than 5 chars
+tree.countNodes { it.startsWith("U") }     // 1
+
+// Transform values into a brand-new tree (the original is untouched); stack-safe.
+val lengths: TreeNode<Int> = tree.mapValues { it.length }
+
+// Deep copy + structural comparison.
+val copy = tree.deepCopy()
+tree.structurallyEquals(copy)              // true (same values, same shape, different nodes)
+```
+
+## Optional modules
+
+The core `tree-structure` artifact has no third-party dependencies. Ecosystem integrations ship as
+separate, opt-in artifacts that depend on the core.
+
+### Serialization — `tree-structure-serialization`
+
+`kotlinx.serialization` support. A `TreeNode` holds a parent back-reference (a cycle), so it cannot
+be `@Serializable` directly — convert to/from the acyclic `TreeNodeDto` instead.
+
+```kotlin
+implementation("com.github.adriankuta:tree-structure-serialization:4.0.0")
+```
+
+```kotlin
+val json = Json.encodeToString(tree.toDto())
+val restored = Json.decodeFromString<TreeNodeDto<String>>(json).toTreeNode()
+```
+
+### Coroutines — `tree-structure-coroutines`
+
+Traverse a tree as a cold `Flow` (handy in coroutine/`ViewModel` pipelines).
+
+```kotlin
+implementation("com.github.adriankuta:tree-structure-coroutines:4.0.0")
+```
+
+```kotlin
+tree.preOrderFlow().collect { println(it.value) }
+tree.asFlow(TreeNodeIterators.LevelOrder).map { it.value }
+```
+
+### Compose UI — `tree-structure-compose`
+
+A `LazyTree` composable for Compose Multiplatform (JVM/desktop, iOS, Wasm). Only the visible nodes
+are composed, and you decide how each node looks:
+
+```kotlin
+implementation("com.github.adriankuta:tree-structure-compose:4.0.0")
+```
+
+```kotlin
+LazyTree(root) { node, depth, expanded, toggle ->
+    Row(Modifier.padding(start = (depth * 16).dp).clickable(onClick = toggle)) {
+        if (!node.isLeaf) Text(if (expanded) "▾ " else "▸ ")
+        Text(node.value.toString())
+    }
+}
+```
+
+## Publishing to Maven Central (central.sonatype.com)
+
+This project is configured to publish artifacts to Maven Central via the Sonatype Central Portal.
+
+There are two supported ways to publish:
+
+1) Via GitHub Actions (recommended)
+- Create a GitHub Release (tag) in this repository. When a release is published, the workflow .github/workflows/publishRelease.yml runs automatically.
+- The workflow uses the Gradle task publishToMavenCentral to upload artifacts through the Central Portal.
+- Make sure these repository secrets are configured in GitHub:
+  - MAVEN_CENTRAL_USERNAME — Your Sonatype Central username (not email).
+  - MAVEN_CENTRAL_PASSWORD — Your Sonatype Central password or a token from central.sonatype.com.
+  - SIGNING_KEY — ASCII‑armored GPG private key (exported, single line; for in‑memory signing).
+  - SIGNING_PASSWORD — Passphrase for the key above.
+- The workflow uses JDK 21 and publishes the version defined in build.gradle.kts.
+
+2) Locally via Gradle
+- Ensure you have a Sonatype Central account and that the groupId com.github.adriankuta is verified in central.sonatype.com (Namespace Rules → Verify).
+- Export the same credentials/signing values as environment variables or pass them as Gradle properties:
+  - ORG_GRADLE_PROJECT_mavenCentralUsername
+  - ORG_GRADLE_PROJECT_mavenCentralPassword
+  - ORG_GRADLE_PROJECT_signingInMemoryKey
+  - ORG_GRADLE_PROJECT_signingInMemoryKeyPassword
+- Then run:
+  - ./gradlew publishToMavenCentral
+- For snapshot publishing, set -Psnapshot=true (the version is derived from PUBLISH_VERSION with -SNAPSHOT).
+
+Notes
+- Publishing is powered by the com.vanniktech.maven.publish Gradle plugin and Sonatype Central Portal (no legacy Nexus staging URLs needed).
+- The plugin is configured to sign all publications. Coordinates and POM metadata are defined in build.gradle.kts.
+- If using the combined task is preferred, you can also run publishAndReleaseToMavenCentral when automatic release is enabled; this repository currently uploads with publishToMavenCentral from CI.
 
-    implementation "com.github.adriankuta:tree-structure:$latest_versions"
-    
 ## License
 
 MIT License
@@ -97,3 +273,5 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
+
+---

_config.yml

@@ -1,3 +0,0 @@
-theme: jekyll-theme-minimal
-title: Tree Data Structure
-logo: images/console_output.png

api/tree-structure.api

@@ -0,0 +1,101 @@
+public abstract interface class com/github/adriankuta/datastructure/tree/ChildDeclarationInterface {
+	public abstract synthetic fun child (Ljava/lang/Object;Lkotlin/jvm/functions/Function1;)Lcom/github/adriankuta/datastructure/tree/TreeNode;
+}
+
+public final class com/github/adriankuta/datastructure/tree/ChildDeclarationInterface$DefaultImpls {
+	public static synthetic fun child$default (Lcom/github/adriankuta/datastructure/tree/ChildDeclarationInterface;Ljava/lang/Object;Lkotlin/jvm/functions/Function1;ILjava/lang/Object;)Lcom/github/adriankuta/datastructure/tree/TreeNode;
+}
+
+public class com/github/adriankuta/datastructure/tree/TreeNode : com/github/adriankuta/datastructure/tree/ChildDeclarationInterface, java/lang/Iterable, kotlin/jvm/internal/markers/KMappedMarker {
+	public fun <init> (Ljava/lang/Object;Lcom/github/adriankuta/datastructure/tree/iterators/TreeNodeIterators;)V
+	public synthetic fun <init> (Ljava/lang/Object;Lcom/github/adriankuta/datastructure/tree/iterators/TreeNodeIterators;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
+	public final fun addChild (Lcom/github/adriankuta/datastructure/tree/TreeNode;)V
+	public synthetic fun child (Ljava/lang/Object;Lkotlin/jvm/functions/Function1;)Lcom/github/adriankuta/datastructure/tree/TreeNode;
+	public final fun clear ()V
+	public final fun depth ()I
+	public final fun detach ()Z
+	public final fun getChildren ()Ljava/util/List;
+	public final fun getParent ()Lcom/github/adriankuta/datastructure/tree/TreeNode;
+	public final fun getTreeIterator ()Lcom/github/adriankuta/datastructure/tree/iterators/TreeNodeIterators;
+	public final fun getValue ()Ljava/lang/Object;
+	public final fun height ()I
+	public final fun isRoot ()Z
+	public fun iterator ()Ljava/util/Iterator;
+	public final fun iterator (Lcom/github/adriankuta/datastructure/tree/iterators/TreeNodeIterators;)Ljava/util/Iterator;
+	public final fun nodeCount ()I
+	public final fun path (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Ljava/util/List;
+	public final fun prettyString ()Ljava/lang/String;
+	public final fun removeChild (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Z
+	public fun toString ()Ljava/lang/String;
+}
+
+public final class com/github/adriankuta/datastructure/tree/TreeNodeFunctionalExtKt {
+	public static final fun allNodes (Lcom/github/adriankuta/datastructure/tree/TreeNode;Lkotlin/jvm/functions/Function1;)Z
+	public static final fun anyNode (Lcom/github/adriankuta/datastructure/tree/TreeNode;Lkotlin/jvm/functions/Function1;)Z
+	public static final fun countNodes (Lcom/github/adriankuta/datastructure/tree/TreeNode;Lkotlin/jvm/functions/Function1;)I
+	public static final fun deepCopy (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Lcom/github/adriankuta/datastructure/tree/TreeNode;
+	public static final fun filterNodes (Lcom/github/adriankuta/datastructure/tree/TreeNode;Lkotlin/jvm/functions/Function1;)Ljava/util/List;
+	public static final fun findNode (Lcom/github/adriankuta/datastructure/tree/TreeNode;Lkotlin/jvm/functions/Function1;)Lcom/github/adriankuta/datastructure/tree/TreeNode;
+	public static final fun foldNodes (Lcom/github/adriankuta/datastructure/tree/TreeNode;Ljava/lang/Object;Lkotlin/jvm/functions/Function2;)Ljava/lang/Object;
+	public static final fun mapValues (Lcom/github/adriankuta/datastructure/tree/TreeNode;Lkotlin/jvm/functions/Function1;)Lcom/github/adriankuta/datastructure/tree/TreeNode;
+	public static final fun structurallyEquals (Lcom/github/adriankuta/datastructure/tree/TreeNode;Lcom/github/adriankuta/datastructure/tree/TreeNode;)Z
+}
+
+public final class com/github/adriankuta/datastructure/tree/TreeNodeNavigationExtKt {
+	public static final fun ancestors (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Ljava/util/List;
+	public static final fun descendants (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Ljava/util/List;
+	public static final fun getDegree (Lcom/github/adriankuta/datastructure/tree/TreeNode;)I
+	public static final fun isLeaf (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Z
+	public static final fun leaves (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Ljava/util/List;
+	public static final fun root (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Lcom/github/adriankuta/datastructure/tree/TreeNode;
+	public static final fun siblings (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Ljava/util/List;
+}
+
+public final class com/github/adriankuta/datastructure/tree/TreeNodeSequenceExtKt {
+	public static final fun asSequence (Lcom/github/adriankuta/datastructure/tree/TreeNode;Lcom/github/adriankuta/datastructure/tree/iterators/TreeNodeIterators;)Lkotlin/sequences/Sequence;
+	public static synthetic fun asSequence$default (Lcom/github/adriankuta/datastructure/tree/TreeNode;Lcom/github/adriankuta/datastructure/tree/iterators/TreeNodeIterators;ILjava/lang/Object;)Lkotlin/sequences/Sequence;
+	public static final fun levelOrderSequence (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Lkotlin/sequences/Sequence;
+	public static final fun postOrderSequence (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Lkotlin/sequences/Sequence;
+	public static final fun preOrderSequence (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Lkotlin/sequences/Sequence;
+}
+
+public final class com/github/adriankuta/datastructure/tree/exceptions/TreeNodeException : java/lang/RuntimeException {
+	public fun <init> ()V
+	public fun <init> (Ljava/lang/String;)V
+	public fun <init> (Ljava/lang/String;Ljava/lang/Throwable;)V
+	public synthetic fun <init> (Ljava/lang/String;Ljava/lang/Throwable;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
+}
+
+public final class com/github/adriankuta/datastructure/tree/iterators/LevelOrderTreeIterator : java/util/Iterator, kotlin/jvm/internal/markers/KMappedMarker {
+	public fun <init> (Lcom/github/adriankuta/datastructure/tree/TreeNode;)V
+	public fun hasNext ()Z
+	public fun next ()Lcom/github/adriankuta/datastructure/tree/TreeNode;
+	public synthetic fun next ()Ljava/lang/Object;
+	public fun remove ()V
+}
+
+public final class com/github/adriankuta/datastructure/tree/iterators/PostOrderTreeIterator : java/util/Iterator, kotlin/jvm/internal/markers/KMappedMarker {
+	public fun <init> (Lcom/github/adriankuta/datastructure/tree/TreeNode;)V
+	public fun hasNext ()Z
+	public fun next ()Lcom/github/adriankuta/datastructure/tree/TreeNode;
+	public synthetic fun next ()Ljava/lang/Object;
+	public fun remove ()V
+}
+
+public final class com/github/adriankuta/datastructure/tree/iterators/PreOrderTreeIterator : java/util/Iterator, kotlin/jvm/internal/markers/KMappedMarker {
+	public fun <init> (Lcom/github/adriankuta/datastructure/tree/TreeNode;)V
+	public fun hasNext ()Z
+	public fun next ()Lcom/github/adriankuta/datastructure/tree/TreeNode;
+	public synthetic fun next ()Ljava/lang/Object;
+	public fun remove ()V
+}
+
+public final class com/github/adriankuta/datastructure/tree/iterators/TreeNodeIterators : java/lang/Enum {
+	public static final field LevelOrder Lcom/github/adriankuta/datastructure/tree/iterators/TreeNodeIterators;
+	public static final field PostOrder Lcom/github/adriankuta/datastructure/tree/iterators/TreeNodeIterators;
+	public static final field PreOrder Lcom/github/adriankuta/datastructure/tree/iterators/TreeNodeIterators;
+	public static fun getEntries ()Lkotlin/enums/EnumEntries;
+	public static fun valueOf (Ljava/lang/String;)Lcom/github/adriankuta/datastructure/tree/iterators/TreeNodeIterators;
+	public static fun values ()[Lcom/github/adriankuta/datastructure/tree/iterators/TreeNodeIterators;
+}
+

app/.gitignore

@@ -1 +0,0 @@
-/build

app/build.gradle

@@ -1,33 +0,0 @@
-apply plugin: 'com.android.application'
-apply plugin: 'kotlin-android'
-
-android {
-    compileSdkVersion 31
-    buildToolsVersion "31.0.0"
-    defaultConfig {
-        applicationId "com.github.adriankuta.treedatastructure"
-        minSdkVersion 15
-        targetSdkVersion 31
-        versionCode 1
-        versionName "1.0"
-        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
-    }
-    buildTypes {
-        release {
-            minifyEnabled false
-            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
-        }
-    }
-}
-
-dependencies {
-    implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
-    implementation 'androidx.appcompat:appcompat:1.3.1'
-    implementation 'androidx.core:core-ktx:1.6.0'
-    implementation 'androidx.constraintlayout:constraintlayout:2.1.0'
-    implementation 'com.github.adriankuta:tree-structure:1.2.3'
-    testImplementation 'junit:junit:4.13.2'
-    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
-    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
-}

app/proguard-rules.pro

@@ -1,21 +0,0 @@
-# Add project specific ProGuard rules here.
-# You can control the set of applied configuration files using the
-# proguardFiles setting in build.gradle.
-#
-# For more details, see
-#   http://developer.android.com/guide/developing/tools/proguard.html
-
-# If your project uses WebView with JS, uncomment the following
-# and specify the fully qualified class name to the JavaScript interface
-# class:
-#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
-#   public *;
-#}
-
-# Uncomment this to preserve the line number information for
-# debugging stack traces.
-#-keepattributes SourceFile,LineNumberTable
-
-# If you keep the line number information, uncomment this to
-# hide the original source file name.
-#-renamesourcefileattribute SourceFile

app/src/androidTest/java/com/github/adriankuta/treedatastructure/ExampleInstrumentedTest.kt

@@ -1,24 +0,0 @@
-package com.github.adriankuta.treedatastructure
-
-import androidx.test.platform.app.InstrumentationRegistry
-import androidx.test.ext.junit.runners.AndroidJUnit4
-
-import org.junit.Test
-import org.junit.runner.RunWith
-
-import org.junit.Assert.*
-
-/**
- * Instrumented test, which will execute on an Android device.
- *
- * See [testing documentation](http://d.android.com/tools/testing).
- */
-@RunWith(AndroidJUnit4::class)
-class ExampleInstrumentedTest {
-    @Test
-    fun useAppContext() {
-        // Context of the app under test.
-        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
-        assertEquals("com.github.adriankuta.treedatastructure", appContext.packageName)
-    }
-}

app/src/main/AndroidManifest.xml

@@ -1,22 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    package="com.github.adriankuta.treedatastructure">
-
-    <application
-        android:allowBackup="true"
-        android:icon="@mipmap/ic_launcher"
-        android:label="@string/app_name"
-        android:roundIcon="@mipmap/ic_launcher_round"
-        android:supportsRtl="true"
-        android:theme="@style/AppTheme">
-        <activity android:name=".MainActivity"
-            android:exported="true">
-            <intent-filter>
-                <action android:name="android.intent.action.MAIN" />
-
-                <category android:name="android.intent.category.LAUNCHER" />
-            </intent-filter>
-        </activity>
-    </application>
-
-</manifest>

app/src/main/java/com/github/adriankuta/treedatastructure/MainActivity.kt

@@ -1,29 +0,0 @@
-package com.github.adriankuta.treedatastructure
-
-import androidx.appcompat.app.AppCompatActivity
-import android.os.Bundle
-import android.util.Log
-import com.github.adriankuta.datastructure.tree.tree
-
-class MainActivity : AppCompatActivity() {
-
-    override fun onCreate(savedInstanceState: Bundle?) {
-        super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_main)
-
-        val root =
-            tree("World") {
-                child("North America") {
-                    child("USA") {
-                        child("LA")
-                        child("New York")
-                    }
-                }
-                child("Europe") {
-                    child("Poland")
-                    child("Germany")
-                }
-            }
-        Log.d("DEBUG_TAG", root.prettyString())
-    }
-}

app/src/main/res/drawable-v24/ic_launcher_foreground.xml

@@ -1,34 +0,0 @@
-<vector xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:aapt="http://schemas.android.com/aapt"
-    android:width="108dp"
-    android:height="108dp"
-    android:viewportWidth="108"
-    android:viewportHeight="108">
-    <path
-        android:fillType="evenOdd"
-        android:pathData="M32,64C32,64 38.39,52.99 44.13,50.95C51.37,48.37 70.14,49.57 70.14,49.57L108.26,87.69L108,109.01L75.97,107.97L32,64Z"
-        android:strokeWidth="1"
-        android:strokeColor="#00000000">
-        <aapt:attr name="android:fillColor">
-            <gradient
-                android:endX="78.5885"
-                android:endY="90.9159"
-                android:startX="48.7653"
-                android:startY="61.0927"
-                android:type="linear">
-                <item
-                    android:color="#44000000"
-                    android:offset="0.0" />
-                <item
-                    android:color="#00000000"
-                    android:offset="1.0" />
-            </gradient>
-        </aapt:attr>
-    </path>
-    <path
-        android:fillColor="#FFFFFF"
-        android:fillType="nonZero"
-        android:pathData="M66.94,46.02L66.94,46.02C72.44,50.07 76,56.61 76,64L32,64C32,56.61 35.56,50.11 40.98,46.06L36.18,41.19C35.45,40.45 35.45,39.3 36.18,38.56C36.91,37.81 38.05,37.81 38.78,38.56L44.25,44.05C47.18,42.57 50.48,41.71 54,41.71C57.48,41.71 60.78,42.57 63.68,44.05L69.11,38.56C69.84,37.81 70.98,37.81 71.71,38.56C72.44,39.3 72.44,40.45 71.71,41.19L66.94,46.02ZM62.94,56.92C64.08,56.92 65,56.01 65,54.88C65,53.76 64.08,52.85 62.94,52.85C61.8,52.85 60.88,53.76 60.88,54.88C60.88,56.01 61.8,56.92 62.94,56.92ZM45.06,56.92C46.2,56.92 47.13,56.01 47.13,54.88C47.13,53.76 46.2,52.85 45.06,52.85C43.92,52.85 43,53.76 43,54.88C43,56.01 43.92,56.92 45.06,56.92Z"
-        android:strokeWidth="1"
-        android:strokeColor="#00000000" />
-</vector>

app/src/main/res/drawable/ic_launcher_background.xml

@@ -1,170 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<vector xmlns:android="http://schemas.android.com/apk/res/android"
-    android:width="108dp"
-    android:height="108dp"
-    android:viewportWidth="108"
-    android:viewportHeight="108">
-    <path
-        android:fillColor="#008577"
-        android:pathData="M0,0h108v108h-108z" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M9,0L9,108"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M19,0L19,108"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M29,0L29,108"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M39,0L39,108"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M49,0L49,108"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M59,0L59,108"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M69,0L69,108"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M79,0L79,108"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M89,0L89,108"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M99,0L99,108"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M0,9L108,9"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M0,19L108,19"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M0,29L108,29"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M0,39L108,39"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M0,49L108,49"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M0,59L108,59"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M0,69L108,69"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M0,79L108,79"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M0,89L108,89"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M0,99L108,99"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M19,29L89,29"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M19,39L89,39"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M19,49L89,49"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M19,59L89,59"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M19,69L89,69"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M19,79L89,79"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M29,19L29,89"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M39,19L39,89"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M49,19L49,89"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M59,19L59,89"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M69,19L69,89"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-    <path
-        android:fillColor="#00000000"
-        android:pathData="M79,19L79,89"
-        android:strokeWidth="0.8"
-        android:strokeColor="#33FFFFFF" />
-</vector>

app/src/main/res/layout/activity_main.xml

@@ -1,18 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    xmlns:tools="http://schemas.android.com/tools"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    tools:context=".MainActivity">
-
-    <TextView
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:text="Hello World!"
-        app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintLeft_toLeftOf="parent"
-        app:layout_constraintRight_toRightOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
-
-</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
-    <background android:drawable="@drawable/ic_launcher_background" />
-    <foreground android:drawable="@drawable/ic_launcher_foreground" />
-</adaptive-icon>

app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml

@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
-    <background android:drawable="@drawable/ic_launcher_background" />
-    <foreground android:drawable="@drawable/ic_launcher_foreground" />
-</adaptive-icon>

app/src/main/res/values/colors.xml

@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<resources>
-    <color name="colorPrimary">#008577</color>
-    <color name="colorPrimaryDark">#00574B</color>
-    <color name="colorAccent">#D81B60</color>
-</resources>

app/src/main/res/values/strings.xml

@@ -1,3 +0,0 @@
-<resources>
-    <string name="app_name">Tree Data Structure</string>
-</resources>

app/src/main/res/values/styles.xml

@@ -1,11 +0,0 @@
-<resources>
-
-    <!-- Base application theme. -->
-    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
-        <!-- Customize your theme here. -->
-        <item name="colorPrimary">@color/colorPrimary</item>
-        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
-        <item name="colorAccent">@color/colorAccent</item>
-    </style>
-
-</resources>

app/src/test/java/com/github/adriankuta/treedatastructure/ExampleUnitTest.kt

@@ -1,17 +0,0 @@
-package com.github.adriankuta.treedatastructure
-
-import org.junit.Test
-
-import org.junit.Assert.*
-
-/**
- * Example local unit test, which will execute on the development machine (host).
- *
- * See [testing documentation](http://d.android.com/tools/testing).
- */
-class ExampleUnitTest {
-    @Test
-    fun addition_isCorrect() {
-        assertEquals(4, 2 + 2)
-    }
-}

build.gradle

@@ -1,32 +0,0 @@
-// Top-level build file where you can add configuration options common to all sub-projects/modules.
-
-buildscript {
-    ext.kotlin_version = '1.5.30'
-    repositories {
-        google()
-        mavenCentral()
-    }
-    dependencies {
-        classpath 'com.android.tools.build:gradle:7.0.2'
-        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
-        // NOTE: Do not place your application dependencies here; they belong
-        // in the individual module build.gradle files
-    }
-}
-
-plugins {
-    id("io.github.gradle-nexus.publish-plugin") version "1.1.0"
-    id("org.jetbrains.dokka") version "1.5.0"
-}
-
-allprojects {
-    repositories {
-        google()
-        mavenCentral()
-    }
-}
-
-task clean(type: Delete) {
-    delete rootProject.buildDir
-}
-apply from: "${rootDir}/scripts/publish-root.gradle"

build.gradle.kts

@@ -0,0 +1,99 @@
+import org.jetbrains.kotlin.gradle.ExperimentalWasmDsl
+
+plugins {
+    alias(libs.plugins.kotlinMultiplatform)
+    alias(libs.plugins.dokka)
+    alias(libs.plugins.mavenPublish)
+    alias(libs.plugins.binaryCompatibilityValidator)
+    alias(libs.plugins.kover)
+    signing
+}
+
+val PUBLISH_GROUP_ID = "com.github.adriankuta"
+val PUBLISH_ARTIFACT_ID = "tree-structure"    // base artifact; KMP will add -jvm, -ios*, etc.
+val PUBLISH_VERSION = "4.0.0"
+
+val snapshot: String? by project
+
+group = PUBLISH_GROUP_ID
+version = if (snapshot.toBoolean()) "$PUBLISH_VERSION-SNAPSHOT" else PUBLISH_VERSION
+
+mavenPublishing {
+    // Central Portal + auto release when we call publishAndReleaseToMavenCentral
+    publishToMavenCentral(automaticRelease = false)
+    signAllPublications()
+
+    coordinates(PUBLISH_GROUP_ID, PUBLISH_ARTIFACT_ID, version.toString())
+
+    pom {
+        name.set("Tree Data Structure")
+        description.set(
+            "Lightweight n-ary tree data structure for Kotlin Multiplatform (JVM, JS, Wasm, iOS, " +
+                "Native). DSL, pre/post/level-order traversal, lazy Sequence traversal, and pretty-print.",
+        )
+        url.set("https://github.com/AdrianKuta/Tree-Data-Structure")
+
+        licenses {
+            license {
+                name.set("MIT License")
+                url.set("https://opensource.org/licenses/MIT")
+                distribution.set("repo")
+            }
+        }
+        developers {
+            developer {
+                id.set("AdrianKuta")
+                name.set("Adrian Kuta")
+                email.set("adrian.kuta93@gmail.com")
+            }
+        }
+        scm {
+            url.set("https://github.com/AdrianKuta/Tree-Data-Structure")
+            connection.set("scm:git:https://github.com/AdrianKuta/Tree-Data-Structure.git")
+            developerConnection.set("scm:git:ssh://git@github.com/AdrianKuta/Tree-Data-Structure.git")
+        }
+    }
+}
+
+repositories {
+    mavenCentral()
+}
+
+kotlin {
+    explicitApi()
+    jvmToolchain(21)
+
+    jvm()
+
+    js(IR) {
+        browser()
+        nodejs()
+    }
+
+    @OptIn(ExperimentalWasmDsl::class)
+    wasmJs {
+        browser()
+        nodejs()
+    }
+
+    // Apple targets
+    iosX64()
+    iosArm64()
+    iosSimulatorArm64()
+
+    // Native host target
+    val hostOs = System.getProperty("os.name")
+    val isMingwX64 = hostOs.startsWith("Windows")
+    when {
+        hostOs == "Mac OS X" -> macosX64("native")
+        hostOs == "Linux" -> linuxX64("native")
+        isMingwX64 -> mingwX64("native")
+        else -> throw GradleException("Host OS is not supported in Kotlin/Native.")
+    }
+
+    sourceSets {
+        commonTest.dependencies {
+            implementation(kotlin("test"))
+        }
+    }
+}

gradle.properties

@@ -1,21 +1 @@
-# Project-wide Gradle settings.
-# IDE (e.g. Android Studio) users:
-# Gradle settings configured through the IDE *will override*
-# any settings specified in this file.
-# For more details on how to configure your build environment visit
-# http://www.gradle.org/docs/current/userguide/build_environment.html
-# Specifies the JVM arguments used for the daemon process.
-# The setting is particularly useful for tweaking memory settings.
-org.gradle.jvmargs=-Xmx1536m
-# When configured, Gradle will run in incubating parallel mode.
-# This option should only be used with decoupled projects. More details, visit
-# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
-# org.gradle.parallel=true
-# AndroidX package structure to make it clearer which packages are bundled with the
-# Android operating system, and which are packaged with your app's APK
-# https://developer.android.com/topic/libraries/support-library/androidx-rn
-android.useAndroidX=true
-# Automatically convert third-party libraries to use AndroidX
-android.enableJetifier=true
-# Kotlin code style for this project: "official" or "obsolete":
 kotlin.code.style=official

gradle/libs.versions.toml

@@ -0,0 +1,24 @@
+[versions]
+kotlin = "2.1.0"
+dokka = "1.9.20"
+mavenPublish = "0.34.0"
+binaryCompatibilityValidator = "0.16.3"
+kover = "0.8.3"
+coroutines = "1.9.0"
+kotlinxSerialization = "1.7.3"
+composeMultiplatform = "1.7.3"
+
+[plugins]
+kotlinMultiplatform = { id = "org.jetbrains.kotlin.multiplatform", version.ref = "kotlin" }
+kotlinSerialization = { id = "org.jetbrains.kotlin.plugin.serialization", version.ref = "kotlin" }
+dokka = { id = "org.jetbrains.dokka", version.ref = "dokka" }
+mavenPublish = { id = "com.vanniktech.maven.publish", version.ref = "mavenPublish" }
+binaryCompatibilityValidator = { id = "org.jetbrains.kotlinx.binary-compatibility-validator", version.ref = "binaryCompatibilityValidator" }
+kover = { id = "org.jetbrains.kotlinx.kover", version.ref = "kover" }
+composeMultiplatform = { id = "org.jetbrains.compose", version.ref = "composeMultiplatform" }
+composeCompiler = { id = "org.jetbrains.kotlin.plugin.compose", version.ref = "kotlin" }
+
+[libraries]
+kotlinx-coroutines-core = { module = "org.jetbrains.kotlinx:kotlinx-coroutines-core", version.ref = "coroutines" }
+kotlinx-coroutines-test = { module = "org.jetbrains.kotlinx:kotlinx-coroutines-test", version.ref = "coroutines" }
+kotlinx-serialization-json = { module = "org.jetbrains.kotlinx:kotlinx-serialization-json", version.ref = "kotlinxSerialization" }

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,7 @@
-#Wed Jan 08 12:28:15 CET 2020
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.0.2-all.zip

gradlew

@@ -1,78 +1,127 @@
-#!/usr/bin/env sh
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# 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
+#
+#      https://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.
+#
 
 ##############################################################################
-##
+#
-##  Gradle start up script for UN*X
+#   Gradle start up script for POSIX generated by Gradle.
-##
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
 ##############################################################################
 
 # Attempt to set APP_HOME
+
 # Resolve links: $0 may be a link
-PRG="$0"
+app_path=$0
-# Need this for relative symlinks.
+
-while [ -h "$PRG" ] ; do
+# Need this for daisy-chained symlinks.
-    ls=`ls -ld "$PRG"`
+while
-    link=`expr "$ls" : '.*-> \(.*\)$'`
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
-    if expr "$link" : '/.*' > /dev/null; then
+    [ -h "$app_path" ]
-        PRG="$link"
+do
-    else
+    ls=$( ls -ld "$app_path" )
-        PRG=`dirname "$PRG"`"/$link"
+    link=${ls#*' -> '}
-    fi
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
 done
-SAVED="`pwd`"
-cd "`dirname \"$PRG\"`/" >/dev/null
-APP_HOME="`pwd -P`"
-cd "$SAVED" >/dev/null
 
-APP_NAME="Gradle"
+# This is normally unused
-APP_BASE_NAME=`basename "$0"`
+# shellcheck disable=SC2034
-
+APP_BASE_NAME=${0##*/}
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
-DEFAULT_JVM_OPTS=""
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
-MAX_FD="maximum"
+MAX_FD=maximum
 
 warn () {
     echo "$*"
-}
+} >&2
 
 die () {
     echo
     echo "$*"
     echo
     exit 1
-}
+} >&2
 
 # OS specific support (must be 'true' or 'false').
 cygwin=false
 msys=false
 darwin=false
 nonstop=false
-case "`uname`" in
+case "$( uname )" in                #(
-  CYGWIN* )
+  CYGWIN* )         cygwin=true  ;; #(
-    cygwin=true
+  Darwin* )         darwin=true  ;; #(
-    ;;
+  MSYS* | MINGW* )  msys=true    ;; #(
-  Darwin* )
+  NONSTOP* )        nonstop=true ;;
-    darwin=true
-    ;;
-  MINGW* )
-    msys=true
-    ;;
-  NONSTOP* )
-    nonstop=true
-    ;;
 esac
 
 CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
 
+
 # Determine the Java command to use to start the JVM.
 if [ -n "$JAVA_HOME" ] ; then
     if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
         # IBM's JDK on AIX uses strange locations for the executables
-        JAVACMD="$JAVA_HOME/jre/sh/java"
+        JAVACMD=$JAVA_HOME/jre/sh/java
     else
-        JAVACMD="$JAVA_HOME/bin/java"
+        JAVACMD=$JAVA_HOME/bin/java
     fi
     if [ ! -x "$JAVACMD" ] ; then
         die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
@@ -81,92 +130,120 @@ Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
     fi
 else
-    JAVACMD="java"
+    JAVACMD=java
-    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
 
 Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
+    fi
 fi
 
 # Increase the maximum file descriptors if we can.
-if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
-    MAX_FD_LIMIT=`ulimit -H -n`
+    case $MAX_FD in #(
-    if [ $? -eq 0 ] ; then
+      max*)
-        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
-            MAX_FD="$MAX_FD_LIMIT"
+        # shellcheck disable=SC2039,SC3045
-        fi
+        MAX_FD=$( ulimit -H -n ) ||
-        ulimit -n $MAX_FD
+            warn "Could not query maximum file descriptor limit"
-        if [ $? -ne 0 ] ; then
+    esac
-            warn "Could not set maximum file descriptor limit: $MAX_FD"
+    case $MAX_FD in  #(
-        fi
+      '' | soft) :;; #(
-    else
+      *)
-        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
-    fi
+        # shellcheck disable=SC2039,SC3045
-fi
+        ulimit -n "$MAX_FD" ||
-
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
-# For Darwin, add options to specify how the application appears in the dock
-if $darwin; then
-    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
-fi
-
-# For Cygwin, switch paths to Windows format before running java
-if $cygwin ; then
-    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
-    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
-    JAVACMD=`cygpath --unix "$JAVACMD"`
-
-    # We build the pattern for arguments to be converted via cygpath
-    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
-    SEP=""
-    for dir in $ROOTDIRSRAW ; do
-        ROOTDIRS="$ROOTDIRS$SEP$dir"
-        SEP="|"
-    done
-    OURCYGPATTERN="(^($ROOTDIRS))"
-    # Add a user-defined pattern to the cygpath arguments
-    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
-        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
-    fi
-    # Now convert the arguments - kludge to limit ourselves to /bin/sh
-    i=0
-    for arg in "$@" ; do
-        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
-        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
-
-        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
-            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
-        else
-            eval `echo args$i`="\"$arg\""
-        fi
-        i=$((i+1))
-    done
-    case $i in
-        (0) set -- ;;
-        (1) set -- "$args0" ;;
-        (2) set -- "$args0" "$args1" ;;
-        (3) set -- "$args0" "$args1" "$args2" ;;
-        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
-        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
-        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
-        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
-        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
-        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
     esac
 fi
 
-# Escape application args
+# Collect all arguments for the java command, stacking in reverse order:
-save () {
+#   * args from the command line
-    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+#   * the main class name
-    echo " "
+#   * -classpath
-}
+#   * -D...appname settings
-APP_ARGS=$(save "$@")
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
 
-# Collect all arguments for the java command, following the shell quoting and substitution rules
+# For Cygwin or MSYS, switch paths to Windows format before running java
-eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
 
-# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
-if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
+
-  cd "$(dirname "$0")"
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
 fi
 
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
 exec "$JAVACMD" "$@"

gradlew.bat

@@ -1,4 +1,20 @@
-@if "%DEBUG%" == "" @echo off
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%"=="" @echo off
 @rem ##########################################################################
 @rem
 @rem  Gradle startup script for Windows
@@ -9,19 +25,23 @@
 if "%OS%"=="Windows_NT" setlocal
 
 set DIRNAME=%~dp0
-if "%DIRNAME%" == "" set DIRNAME=.
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
 @rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-set DEFAULT_JVM_OPTS=
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
 
 @rem Find java.exe
 if defined JAVA_HOME goto findJavaFromJavaHome
 
 set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto init
+if %ERRORLEVEL% equ 0 goto execute
 
 echo.
 echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
@@ -35,7 +55,7 @@ goto fail
 set JAVA_HOME=%JAVA_HOME:"=%
 set JAVA_EXE=%JAVA_HOME%/bin/java.exe
 
-if exist "%JAVA_EXE%" goto init
+if exist "%JAVA_EXE%" goto execute
 
 echo.
 echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
@@ -45,38 +65,26 @@ echo location of your Java installation.
 
 goto fail
 
-:init
-@rem Get command-line arguments, handling Windows variants
-
-if not "%OS%" == "Windows_NT" goto win9xME_args
-
-:win9xME_args
-@rem Slurp the command line arguments.
-set CMD_LINE_ARGS=
-set _SKIP=2
-
-:win9xME_args_slurp
-if "x%~1" == "x" goto execute
-
-set CMD_LINE_ARGS=%*
-
 :execute
 @rem Setup the command line
 
 set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
 
+
 @rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
 
 :end
 @rem End local scope for the variables with windows NT shell
-if "%ERRORLEVEL%"=="0" goto mainEnd
+if %ERRORLEVEL% equ 0 goto mainEnd
 
 :fail
 rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
 rem the _cmd.exe /c_ return code!
-if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+set EXIT_CODE=%ERRORLEVEL%
-exit /b 1
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
 
 :mainEnd
 if "%OS%"=="Windows_NT" endlocal

scripts/publish-module.gradle

@@ -1,86 +0,0 @@
-apply plugin: 'maven-publish'
-apply plugin: 'signing'
-apply plugin: 'org.jetbrains.dokka'
-
-task androidSourcesJar(type: Jar) {
-    archiveClassifier.set('sources')
-    if (project.plugins.findPlugin("com.android.library")) {
-        from android.sourceSets.main.java.srcDirs
-        from android.sourceSets.main.kotlin.srcDirs
-    } else {
-        from sourceSets.main.java.srcDirs
-        from sourceSets.main.kotlin.srcDirs
-    }
-}
-
-tasks.withType(dokkaHtmlPartial.getClass()).configureEach {
-    pluginsMapConfiguration.set(
-            ["org.jetbrains.dokka.base.DokkaBase": """{ "separateInheritedMembers": true}"""]
-    )
-}
-
-task javadocJar(type: Jar, dependsOn: dokkaJavadoc) {
-    archiveClassifier.set('javadoc')
-    from dokkaJavadoc.outputDirectory
-}
-
-artifacts {
-    archives androidSourcesJar
-    archives javadocJar
-}
-
-group = PUBLISH_GROUP_ID
-version = PUBLISH_VERSION
-
-afterEvaluate {
-    publishing {
-        publications {
-            release(MavenPublication) {
-                groupId PUBLISH_GROUP_ID
-                artifactId PUBLISH_ARTIFACT_ID
-                version PUBLISH_VERSION
-                if (project.plugins.findPlugin("com.android.library")) {
-                    from components.release
-                } else {
-                    from components.java
-                }
-
-                artifact androidSourcesJar
-                artifact javadocJar
-
-                pom {
-                    name = PUBLISH_ARTIFACT_ID
-                    description = 'Simple implementation to store object in tree structure.'
-                    url = 'https://github.com/AdrianKuta/Tree-Data-Structure'
-                    licenses {
-                        license {
-                            name = 'MIT License'
-                            url = 'https://www.mit.edu/~amini/LICENSE.md'
-                        }
-                    }
-                    developers {
-                        developer {
-                            name = 'Adrian Kuta'
-                            email = 'adrian.kuta93@gmail.com'
-                        }
-                    }
-                    // Version control info, if you're using GitHub, follow the format as seen here
-                    scm {
-                        connection = 'scm:git:github.com/AdrianKuta/Tree-Data-Structure.git'
-                        developerConnection = 'scm:git:ssh://github.com/AdrianKuta/Tree-Data-Structure.git'
-                        url = 'https://github.com/AdrianKuta/Tree-Data-Structure/tree/master'
-                    }
-                }
-            }
-        }
-    }
-}
-
-signing {
-    useInMemoryPgpKeys(
-            rootProject.ext["signing.keyId"],
-            rootProject.ext["signing.key"],
-            rootProject.ext["signing.password"],
-    )
-    sign publishing.publications
-}

scripts/publish-root.gradle

@@ -1,43 +0,0 @@
-// Create variables with empty default values
-ext["ossrhUsername"] = ''
-ext["ossrhPassword"] = ''
-ext["sonatypeStagingProfileId"] = ''
-ext["signing.keyId"] = ''
-ext["signing.password"] = ''
-ext["signing.key"] = ''
-ext["snapshot"] = ''
-
-File secretPropsFile = project.rootProject.file('local.properties')
-if (secretPropsFile.exists()) {
-    // Read local.properties file first if it exists
-    Properties p = new Properties()
-    new FileInputStream(secretPropsFile).withCloseable { is -> p.load(is) }
-    p.each { name, value -> ext[name] = value }
-} else {
-    // Use system environment variables
-    ext["ossrhUsername"] = System.getenv('OSSRH_USERNAME')
-    ext["ossrhPassword"] = System.getenv('OSSRH_PASSWORD')
-    ext["sonatypeStagingProfileId"] = System.getenv('SONATYPE_STAGING_PROFILE_ID')
-    ext["signing.keyId"] = System.getenv('SIGNING_KEY_ID')
-    ext["signing.password"] = System.getenv('SIGNING_PASSWORD')
-    ext["signing.key"] = System.getenv('SIGNING_KEY')
-    ext["snapshot"] = System.getenv('SNAPSHOT')
-}
-
-//if (snapshot) {
-//    ext["rootVersionName"] = Configuration.snapshotVersionName
-//} else {
-//    ext["rootVersionName"] = Configuration.versionName
-//}
-
-// Set up Sonatype repository
-nexusPublishing {
-    repositories {
-        sonatype {
-            stagingProfileId = sonatypeStagingProfileId
-            username = ossrhUsername
-            password = ossrhPassword
-            //version = rootVersionName
-        }
-    }
-}

settings.gradle

@@ -1,2 +0,0 @@
-include ':app', ':treedatastructure'
-rootProject.name='Tree Data Structure'

settings.gradle.kts

@@ -0,0 +1,5 @@
+rootProject.name = "tree-structure"
+
+include(":tree-structure-serialization")
+include(":tree-structure-coroutines")
+include(":tree-structure-compose")

src/commonMain/kotlin/com.github.adriankuta/datastructure/tree/ChildDeclarationInterface.kt

@@ -1,6 +1,8 @@
 package com.github.adriankuta.datastructure.tree
 
-interface ChildDeclarationInterface<T> {
+import kotlin.jvm.JvmSynthetic
+
+public interface ChildDeclarationInterface<T> {
 
     /**
      * This method is used to easily create child in node.
@@ -18,5 +20,5 @@ interface ChildDeclarationInterface<T> {
      * @return New created TreeNode.
      */
     @JvmSynthetic
-    fun child(value: T, childDeclaration: ChildDeclaration<T>? = null): TreeNode<T>
+    public fun child(value: T, childDeclaration: ChildDeclaration<T>? = null): TreeNode<T>
 }

src/commonMain/kotlin/com.github.adriankuta/datastructure/tree/TreeNode.kt

@@ -0,0 +1,247 @@
+package com.github.adriankuta.datastructure.tree
+
+import com.github.adriankuta.datastructure.tree.exceptions.TreeNodeException
+import com.github.adriankuta.datastructure.tree.iterators.LevelOrderTreeIterator
+import com.github.adriankuta.datastructure.tree.iterators.PostOrderTreeIterator
+import com.github.adriankuta.datastructure.tree.iterators.PreOrderTreeIterator
+import com.github.adriankuta.datastructure.tree.iterators.TreeNodeIterators
+import com.github.adriankuta.datastructure.tree.iterators.TreeNodeIterators.*
+import kotlin.jvm.JvmSynthetic
+
+/**
+ * A node in a generic, mutable n-ary tree. Each node holds a [value], a reference to its [parent]
+ * and an ordered list of [children].
+ *
+ * Iterating a node (via [iterator], or the lazy [asSequence]/[preOrderSequence] extensions) visits
+ * the node and all of its descendants. Traversal and the [height]/[nodeCount]/[clear] helpers are
+ * implemented iteratively, so they are safe on arbitrarily deep trees.
+ *
+ * **Not thread-safe.** Nodes are mutable ([addChild]/[removeChild]/[clear] mutate the structure and
+ * parent pointers). Sharing a tree across threads requires external synchronization, and the tree
+ * must not be modified while it is being iterated.
+ *
+ * Equality is by reference (identity); use the `structurallyEquals` extension to compare two trees
+ * by value and shape.
+ *
+ * @param value the value stored in this node.
+ * @param treeIterator the default traversal order used by [iterator]. Prefer the
+ *   `asSequence(order)` / `preOrderSequence()` extensions to choose an order without mutating state.
+ */
+public open class TreeNode<T>(public val value: T, public val treeIterator: TreeNodeIterators = PreOrder) : Iterable<TreeNode<T>>, ChildDeclarationInterface<T> {
+
+    private var _parent: TreeNode<T>? = null
+
+    /**
+     * The converse notion of a child, an immediate ancestor.
+     */
+    public val parent: TreeNode<T>?
+        get() = _parent
+
+    private val _children = mutableListOf<TreeNode<T>>()
+
+    /**
+     * A group of nodes with the same parent.
+     */
+    public val children: List<TreeNode<T>>
+        get() = _children
+
+    /**
+     * Checks whether the current tree node is the root of the tree
+     * @return `true` if the current tree node is root of the tree, `false` otherwise.
+     */
+    public val isRoot: Boolean
+        get() = _parent == null
+
+    /**
+     * Adds [child] as a direct child of this node.
+     *
+     * @param child a node that is not already attached to a tree. To move a node that already has a
+     *   parent, call [detach] on it first.
+     * @throws TreeNodeException if [child] already has a parent, or if attaching it here would create
+     *   a cycle (i.e. [child] is this node or one of its ancestors).
+     */
+    public fun addChild(child: TreeNode<T>) {
+        if (child._parent != null) {
+            throw TreeNodeException("$child already has a parent; call detach() before re-attaching it.")
+        }
+        if (child === this) {
+            throw TreeNodeException("Adding $child here would create a cycle.")
+        }
+        // Only a node that already has its own subtree can contain `this` and thus form a cycle.
+        // Skipping this walk for leaves keeps building deep trees O(n) instead of O(n²).
+        if (child._children.isNotEmpty()) {
+            var ancestor: TreeNode<T>? = _parent
+            while (ancestor != null) {
+                if (ancestor === child) {
+                    throw TreeNodeException("Adding $child here would create a cycle.")
+                }
+                ancestor = ancestor._parent
+            }
+        }
+        child._parent = this
+        _children.add(child)
+    }
+
+    /**
+     * Detaches this node from its parent, removing it from the parent's [children].
+     *
+     * @return `true` if this node was attached and is now detached; `false` if it was already a root.
+     */
+    public fun detach(): Boolean {
+        val currentParent = _parent ?: return false
+        currentParent._children.remove(this)
+        _parent = null
+        return true
+    }
+
+    @JvmSynthetic
+    public override fun child(value: T, childDeclaration: ChildDeclaration<T>?): TreeNode<T> {
+        val newChild = TreeNode(value)
+        newChild._parent = this
+        if (childDeclaration != null)
+            newChild.childDeclaration()
+        _children.add(newChild)
+        return newChild
+    }
+
+    /**
+     * Removes [child] from this node's direct [children], if present.
+     *
+     * This only removes a *direct* child of the receiver; it does not reach into other nodes. To
+     * remove a node from wherever it currently lives, call [detach] on it instead.
+     *
+     * @return `true` if [child] was a direct child and has been removed; `false` otherwise.
+     */
+    public fun removeChild(child: TreeNode<T>): Boolean {
+        val removed = _children.remove(child)
+        if (removed) child._parent = null
+        return removed
+    }
+
+    /**
+     * This function go through tree and counts children. Root element is not counted.
+     * @return All child and nested child count.
+     */
+    public fun nodeCount(): Int {
+        var count = 0
+        val stack = ArrayDeque<TreeNode<T>>()
+        stack.addAll(_children)
+        while (stack.isNotEmpty()) {
+            val node = stack.removeLast()
+            count++
+            stack.addAll(node._children)
+        }
+        return count
+    }
+
+    /**
+     * @return The number of edges on the longest path between current node and a descendant leaf.
+     */
+    public fun height(): Int {
+        var maxDepth = 0
+        val stack = ArrayDeque<Pair<TreeNode<T>, Int>>()
+        stack.addLast(this to 0)
+        while (stack.isNotEmpty()) {
+            val (node, depthSoFar) = stack.removeLast()
+            if (depthSoFar > maxDepth) maxDepth = depthSoFar
+            node._children.forEach { stack.addLast(it to depthSoFar + 1) }
+        }
+        return maxDepth
+    }
+
+    /**
+     * Distance is the number of edges along the shortest path between two nodes.
+     * @return The distance between current node and the root.
+     */
+    public fun depth(): Int {
+        var depth = 0
+        var tempParent = parent
+
+        while (tempParent != null) {
+            depth++
+            tempParent = tempParent.parent
+        }
+        return depth
+    }
+
+    /**
+     * Returns the chain of nodes from [descendant] up to and including this node, or `null` if
+     * [descendant] is not a strict descendant of this node.
+     *
+     * @param descendant the node to walk up from.
+     * @return the path `[descendant, …, this]`, or `null` if [descendant] is the root or is not
+     *   located in this node's subtree.
+     */
+    public fun path(descendant: TreeNode<T>): List<TreeNode<T>>? {
+        if (descendant.isRoot) return null
+        val path = mutableListOf<TreeNode<T>>()
+        var node = descendant
+        path.add(node)
+        while (!node.isRoot) {
+            node = node.parent!!
+            path.add(node)
+            if (node == this) return path
+        }
+        return null
+    }
+
+    /**
+     * Removes every descendant of this node. Afterwards [children] is empty and all former
+     * descendants are detached (their parent is `null`). This node itself stays attached to its own
+     * parent.
+     */
+    public fun clear() {
+        val descendants = ArrayDeque<TreeNode<T>>()
+        val stack = ArrayDeque<TreeNode<T>>()
+        stack.addAll(_children)
+        while (stack.isNotEmpty()) {
+            val node = stack.removeLast()
+            descendants.addLast(node)
+            stack.addAll(node._children)
+        }
+        descendants.forEach { node ->
+            node._parent = null
+            node._children.clear()
+        }
+        _children.clear()
+    }
+
+    public override fun toString(): String {
+        return value.toString()
+    }
+
+    public fun prettyString(): String {
+        val stringBuilder = StringBuilder()
+        print(stringBuilder, "", "")
+        return stringBuilder.toString()
+    }
+
+    private fun print(stringBuilder: StringBuilder, prefix: String, childrenPrefix: String) {
+        stringBuilder.append(prefix)
+        stringBuilder.append(value)
+        stringBuilder.append('\n')
+        val childIterator = _children.iterator()
+        while (childIterator.hasNext()) {
+            val node = childIterator.next()
+            if (childIterator.hasNext()) {
+                node.print(stringBuilder, "$childrenPrefix├── ", "$childrenPrefix│   ")
+            } else {
+                node.print(stringBuilder, "$childrenPrefix└── ", "$childrenPrefix    ")
+            }
+        }
+    }
+
+    /**
+     * Returns an iterator over this node and its descendants using the default [treeIterator] order.
+     * Use [iterator] with an explicit order, or the `asSequence(order)` extension, to traverse in a
+     * different order without changing this node's default.
+     */
+    public override fun iterator(): Iterator<TreeNode<T>> = iterator(treeIterator)
+
+    /** Returns an iterator over this node and its descendants in the given [order]. */
+    public fun iterator(order: TreeNodeIterators): Iterator<TreeNode<T>> = when (order) {
+        PreOrder -> PreOrderTreeIterator(this)
+        PostOrder -> PostOrderTreeIterator(this)
+        LevelOrder -> LevelOrderTreeIterator(this)
+    }
+}

src/commonMain/kotlin/com.github.adriankuta/datastructure/tree/TreeNodeExt.kt

@@ -0,0 +1,25 @@
+package com.github.adriankuta.datastructure.tree
+
+import com.github.adriankuta.datastructure.tree.iterators.TreeNodeIterators
+import kotlin.jvm.JvmSynthetic
+
+public typealias ChildDeclaration<T> = ChildDeclarationInterface<T>.() -> Unit
+
+/**
+ * This method can be used to initialize new tree.
+ * ```
+ * val root = tree("World") { ... }
+ * ```
+ * @param root Root element of new tree.
+ * @see [ChildDeclarationInterface.child]
+ */
+@JvmSynthetic
+public inline fun <reified T> tree(
+    root: T,
+    defaultIterator: TreeNodeIterators = TreeNodeIterators.PreOrder,
+    childDeclaration: ChildDeclaration<T>
+): TreeNode<T> {
+    val treeNode = TreeNode(root, defaultIterator)
+    treeNode.childDeclaration()
+    return treeNode
+}

src/commonMain/kotlin/com.github.adriankuta/datastructure/tree/TreeNodeFunctionalExt.kt

@@ -0,0 +1,65 @@
+package com.github.adriankuta.datastructure.tree
+
+/** Returns the first node (pre-order) whose value matches [predicate], or `null`. Short-circuits. */
+public fun <T> TreeNode<T>.findNode(predicate: (T) -> Boolean): TreeNode<T>? =
+    preOrderSequence().firstOrNull { predicate(it.value) }
+
+/** All nodes (pre-order) whose value matches [predicate]. */
+public fun <T> TreeNode<T>.filterNodes(predicate: (T) -> Boolean): List<TreeNode<T>> =
+    preOrderSequence().filter { predicate(it.value) }.toList()
+
+/** `true` if any node's value matches [predicate]. Short-circuits. */
+public fun <T> TreeNode<T>.anyNode(predicate: (T) -> Boolean): Boolean =
+    preOrderSequence().any { predicate(it.value) }
+
+/** `true` if every node's value matches [predicate]. Short-circuits. */
+public fun <T> TreeNode<T>.allNodes(predicate: (T) -> Boolean): Boolean =
+    preOrderSequence().all { predicate(it.value) }
+
+/** Counts nodes whose value matches [predicate]. */
+public fun <T> TreeNode<T>.countNodes(predicate: (T) -> Boolean): Int =
+    preOrderSequence().count { predicate(it.value) }
+
+/** Folds [operation] over all nodes in pre-order, starting from [initial]. */
+public fun <T, R> TreeNode<T>.foldNodes(initial: R, operation: (acc: R, node: TreeNode<T>) -> R): R =
+    preOrderSequence().fold(initial) { acc, node -> operation(acc, node) }
+
+/**
+ * Returns a new tree with the same shape whose values are produced by [transform]. The original is
+ * left untouched. Stack-safe (iterative), so it handles arbitrarily deep trees.
+ */
+public fun <T, R> TreeNode<T>.mapValues(transform: (T) -> R): TreeNode<R> {
+    val newRoot = TreeNode(transform(value), treeIterator)
+    val stack = ArrayDeque<Pair<TreeNode<T>, TreeNode<R>>>()
+    stack.addLast(this to newRoot)
+    while (stack.isNotEmpty()) {
+        val (source, target) = stack.removeLast()
+        source.children.forEach { child ->
+            val mappedChild = TreeNode(transform(child.value), child.treeIterator)
+            target.addChild(mappedChild)
+            stack.addLast(child to mappedChild)
+        }
+    }
+    return newRoot
+}
+
+/** Returns an independent deep copy of this subtree (same values, same shape, new nodes). */
+public fun <T> TreeNode<T>.deepCopy(): TreeNode<T> = mapValues { it }
+
+/**
+ * Structural equality: `true` when [other] holds the same values in the same shape. Unlike
+ * [TreeNode]'s reference equality, this compares the entire subtree. Stack-safe.
+ */
+public fun <T> TreeNode<T>.structurallyEquals(other: TreeNode<T>): Boolean {
+    val stack = ArrayDeque<Pair<TreeNode<T>, TreeNode<T>>>()
+    stack.addLast(this to other)
+    while (stack.isNotEmpty()) {
+        val (a, b) = stack.removeLast()
+        if (a.value != b.value) return false
+        if (a.children.size != b.children.size) return false
+        for (i in a.children.indices) {
+            stack.addLast(a.children[i] to b.children[i])
+        }
+    }
+    return true
+}

src/commonMain/kotlin/com.github.adriankuta/datastructure/tree/TreeNodeNavigationExt.kt

@@ -0,0 +1,41 @@
+package com.github.adriankuta.datastructure.tree
+
+/** `true` when this node has no children. */
+public val <T> TreeNode<T>.isLeaf: Boolean get() = children.isEmpty()
+
+/** The number of direct children of this node. */
+public val <T> TreeNode<T>.degree: Int get() = children.size
+
+/** Walks up the parent chain and returns the topmost ancestor (the tree root). */
+public fun <T> TreeNode<T>.root(): TreeNode<T> {
+    var node = this
+    var parent = node.parent
+    while (parent != null) {
+        node = parent
+        parent = node.parent
+    }
+    return node
+}
+
+/** The chain of ancestors from the immediate [parent] up to (and including) the root. */
+public fun <T> TreeNode<T>.ancestors(): List<TreeNode<T>> {
+    val result = mutableListOf<TreeNode<T>>()
+    var parent = this.parent
+    while (parent != null) {
+        result.add(parent)
+        parent = parent.parent
+    }
+    return result
+}
+
+/** The other children of this node's parent (excludes this node). Empty for the root. */
+public fun <T> TreeNode<T>.siblings(): List<TreeNode<T>> =
+    parent?.children?.filter { it !== this } ?: emptyList()
+
+/** All leaf nodes in this subtree, in pre-order. */
+public fun <T> TreeNode<T>.leaves(): List<TreeNode<T>> =
+    preOrderSequence().filter { it.isLeaf }.toList()
+
+/** All nodes in this subtree except this node, in pre-order. */
+public fun <T> TreeNode<T>.descendants(): List<TreeNode<T>> =
+    preOrderSequence().filter { it !== this }.toList()

src/commonMain/kotlin/com.github.adriankuta/datastructure/tree/TreeNodeSequenceExt.kt

@@ -0,0 +1,31 @@
+package com.github.adriankuta.datastructure.tree
+
+import com.github.adriankuta.datastructure.tree.iterators.LevelOrderTreeIterator
+import com.github.adriankuta.datastructure.tree.iterators.PostOrderTreeIterator
+import com.github.adriankuta.datastructure.tree.iterators.PreOrderTreeIterator
+import com.github.adriankuta.datastructure.tree.iterators.TreeNodeIterators
+
+/**
+ * Lazily traverses this subtree in the given [order] as a [Sequence], without forcing the whole
+ * traversal up front. Pairs with the Kotlin stdlib, e.g.
+ * `root.asSequence().map { it.value }.firstOrNull { it == target }`.
+ */
+public fun <T> TreeNode<T>.asSequence(
+    order: TreeNodeIterators = TreeNodeIterators.PreOrder,
+): Sequence<TreeNode<T>> {
+    val self = this
+    return when (order) {
+        TreeNodeIterators.PreOrder -> Sequence { PreOrderTreeIterator(self) }
+        TreeNodeIterators.PostOrder -> Sequence { PostOrderTreeIterator(self) }
+        TreeNodeIterators.LevelOrder -> Sequence { LevelOrderTreeIterator(self) }
+    }
+}
+
+/** Lazy pre-order traversal as a [Sequence]. */
+public fun <T> TreeNode<T>.preOrderSequence(): Sequence<TreeNode<T>> = asSequence(TreeNodeIterators.PreOrder)
+
+/** Lazy post-order traversal as a [Sequence]. */
+public fun <T> TreeNode<T>.postOrderSequence(): Sequence<TreeNode<T>> = asSequence(TreeNodeIterators.PostOrder)
+
+/** Lazy level-order (breadth-first) traversal as a [Sequence]. */
+public fun <T> TreeNode<T>.levelOrderSequence(): Sequence<TreeNode<T>> = asSequence(TreeNodeIterators.LevelOrder)

src/commonMain/kotlin/com.github.adriankuta/datastructure/tree/exceptions/TreeNodeException.kt

@@ -0,0 +1,6 @@
+package com.github.adriankuta.datastructure.tree.exceptions
+
+import kotlin.jvm.JvmOverloads
+
+public class TreeNodeException @JvmOverloads constructor(message: String? = null, cause: Throwable? = null) :
+    RuntimeException(message, cause)

src/commonMain/kotlin/com.github.adriankuta/datastructure/tree/iterators/LevelOrderTreeIterator.kt

@@ -0,0 +1,39 @@
+package com.github.adriankuta.datastructure.tree.iterators
+
+import com.github.adriankuta.datastructure.tree.TreeNode
+
+/**
+ * Tree is iterated by using `Level-order Traversal Algorithm"
+ * In level-order traversal we iterating nodes level by level,
+ * starting from root, and going deeper and deeper in tree.
+ * ```
+ * E.g.
+ *                    1
+ *                  / | \
+ *                 /  |   \
+ *               2    3     4
+ *              / \       / | \
+ *             5    6    7  8  9
+ *            /   / | \
+ *           10  11 12 13
+ *
+ * Output: 1 2 3 4 5 6 7 8 9 10 11 12 13
+ * ```
+ */
+public class LevelOrderTreeIterator<T>(root: TreeNode<T>) : Iterator<TreeNode<T>> {
+
+    private val stack = ArrayDeque<TreeNode<T>>()
+
+    init {
+        stack.addLast(root)
+    }
+
+    public override fun hasNext(): Boolean = stack.isNotEmpty()
+
+    public override fun next(): TreeNode<T> {
+        val node =  stack.removeFirst()
+        node.children
+            .forEach { stack.addLast(it) }
+        return node
+    }
+}

src/commonMain/kotlin/com.github.adriankuta/datastructure/tree/iterators/PostOrderTreeIterator.kt

@@ -0,0 +1,43 @@
+package com.github.adriankuta.datastructure.tree.iterators
+
+import com.github.adriankuta.datastructure.tree.TreeNode
+
+/**
+ * Tree is iterated by using `Post-order Traversal Algorithm"
+ * In post-order traversal, we starting from most left child.
+ * First visit all children of parent, then parent.
+ * ```
+ * E.g.
+ *                    1
+ *                  / | \
+ *                 /  |   \
+ *               2    3     4
+ *              / \       / | \
+ *             5    6    7  8  9
+ *            /   / | \
+ *           10  11 12 13
+ *
+ * Output: 10 5 11 12 13 6 2 3 7 8 9 4 1
+ * ```
+ */
+public class PostOrderTreeIterator<T>(root: TreeNode<T>) : Iterator<TreeNode<T>> {
+
+    private val result = ArrayDeque<TreeNode<T>>()
+
+    init {
+        // Iterative post-order: pop a node, prepend it to `result`, then push its children
+        // left-to-right. Reading `result` front-to-back yields post-order — without the deep
+        // recursion that overflowed the stack on degenerate (linear) trees.
+        val stack = ArrayDeque<TreeNode<T>>()
+        stack.addLast(root)
+        while (stack.isNotEmpty()) {
+            val node = stack.removeLast()
+            result.addFirst(node)
+            node.children.forEach { stack.addLast(it) }
+        }
+    }
+
+    public override fun hasNext(): Boolean = result.isNotEmpty()
+
+    public override fun next(): TreeNode<T> = result.removeFirst()
+}

src/commonMain/kotlin/com.github.adriankuta/datastructure/tree/iterators/PreOrderTreeIterator.kt

@@ -0,0 +1,40 @@
+package com.github.adriankuta.datastructure.tree.iterators
+
+import com.github.adriankuta.datastructure.tree.TreeNode
+
+/**
+ * Tree is iterated by using `Pre-order Traversal Algorithm"
+ * The pre-order traversal is a topologically sorted one,
+ * because a parent node is processed before any of its child nodes is done.
+ * ```
+ * E.g.
+ *                    1
+ *                  / | \
+ *                 /  |   \
+ *               2    3     4
+ *              / \       / | \
+ *             5    6    7  8  9
+ *            /   / | \
+ *           10  11 12 13
+ *
+ * Output: 1 2 5 10 6 11 12 13 3 4 7 8 9
+ * ```
+ */
+public class PreOrderTreeIterator<T>(root: TreeNode<T>) : Iterator<TreeNode<T>> {
+
+    private val stack = ArrayDeque<TreeNode<T>>()
+
+    init {
+        stack.addLast(root)
+    }
+
+    public override fun hasNext(): Boolean = stack.isNotEmpty()
+
+    public override fun next(): TreeNode<T> {
+        val node = stack.removeLast()
+        node.children
+            .asReversed()
+            .forEach { stack.addLast(it) }
+        return node
+    }
+}

src/commonMain/kotlin/com.github.adriankuta/datastructure/tree/iterators/TreeNodeIterators.kt

@@ -0,0 +1,68 @@
+package com.github.adriankuta.datastructure.tree.iterators
+
+/**
+ * @see PreOrder
+ * @see PostOrder
+ * @see LevelOrder
+ */
+public enum class TreeNodeIterators {
+    /**
+     * Tree is iterated by using `Pre-order Traversal Algorithm"
+     * The pre-order traversal is a topologically sorted one,
+     * because a parent node is processed before any of its child nodes is done.
+     * ```
+     * E.g.
+     *                    1
+     *                  / | \
+     *                 /  |   \
+     *               2    3     4
+     *              / \       / | \
+     *             5    6    7  8  9
+     *            /   / | \
+     *           10  11 12 13
+     *
+     * Output: 1 2 5 10 6 11 12 13 3 4 7 8 9
+     * ```
+     */
+    PreOrder,
+
+    /**
+     * Tree is iterated by using `Post-order Traversal Algorithm"
+     * In post-order traversal, we starting from most left child.
+     * First visit all children of parent, then parent.
+     * ```
+     * E.g.
+     *                    1
+     *                  / | \
+     *                 /  |   \
+     *               2    3     4
+     *              / \       / | \
+     *             5    6    7  8  9
+     *            /   / | \
+     *           10  11 12 13
+     *
+     * Output: 10 5 11 12 13 6 2 3 7 8 9 4 1
+     * ```
+     */
+    PostOrder,
+
+    /**
+     * Tree is iterated by using `Level-order Traversal Algorithm"
+     * In level-order traversal we iterating nodes level by level,
+     * starting from root, and going deeper and deeper in tree.
+     * ```
+     * E.g.
+     *                    1
+     *                  / | \
+     *                 /  |   \
+     *               2    3     4
+     *              / \       / | \
+     *             5    6    7  8  9
+     *            /   / | \
+     *           10  11 12 13
+     *
+     * Output: 1 2 3 4 5 6 7 8 9 10 11 12 13
+     * ```
+     */
+    LevelOrder
+}

src/commonTest/kotlin/com.github.adriankuta/datastructure.tree/TreeNodeFunctionalTest.kt

@@ -0,0 +1,78 @@
+package com.github.adriankuta.datastructure.tree
+
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertNotSame
+import kotlin.test.assertNull
+import kotlin.test.assertSame
+import kotlin.test.assertTrue
+
+class TreeNodeFunctionalTest {
+
+    private fun sample() = tree(1) {
+        child(2) {
+            child(4)
+            child(5)
+        }
+        child(3) {
+            child(6)
+        }
+    }
+
+    @Test
+    fun findNode() {
+        assertEquals(6, sample().findNode { it == 6 }?.value)
+        assertNull(sample().findNode { it == 99 })
+    }
+
+    @Test
+    fun filterNodes() =
+        assertContentEquals(listOf(2, 4, 6), sample().filterNodes { it % 2 == 0 }.map { it.value })
+
+    @Test
+    fun anyNode() {
+        assertTrue(sample().anyNode { it == 6 })
+        assertFalse(sample().anyNode { it == 99 })
+    }
+
+    @Test
+    fun allNodes() {
+        assertTrue(sample().allNodes { it > 0 })
+        assertFalse(sample().allNodes { it < 5 })
+    }
+
+    @Test
+    fun countNodes() = assertEquals(3, sample().countNodes { it > 3 })
+
+    @Test
+    fun foldNodes() = assertEquals(21, sample().foldNodes(0) { acc, node -> acc + node.value })
+
+    @Test
+    fun mapPreservesStructureAndTransformsValues() {
+        val mapped = sample().mapValues { it * 10 }
+        assertContentEquals(
+            listOf(10, 20, 40, 50, 30, 60),
+            mapped.preOrderSequence().map { it.value }.toList(),
+        )
+    }
+
+    @Test
+    fun deepCopyIsStructurallyEqualButDistinct() {
+        val original = sample()
+        val copy = original.deepCopy()
+        assertNotSame(original, copy)
+        assertTrue(original.structurallyEquals(copy))
+    }
+
+    @Test
+    fun structurallyEqualsDistinguishesByValueAndShape() {
+        assertTrue(sample().structurallyEquals(sample()))
+        val different = tree(1) {
+            child(2) { child(4) }
+            child(3) { child(6) }
+        }
+        assertFalse(sample().structurallyEquals(different))
+    }
+}

src/commonTest/kotlin/com.github.adriankuta/datastructure.tree/TreeNodeNavigationTest.kt

@@ -0,0 +1,66 @@
+package com.github.adriankuta.datastructure.tree
+
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertSame
+import kotlin.test.assertTrue
+
+class TreeNodeNavigationTest {
+
+    private val root = TreeNode(1)
+    private val n2 = TreeNode(2)
+    private val n3 = TreeNode(3)
+    private val n4 = TreeNode(4)
+    private val n5 = TreeNode(5)
+    private val n6 = TreeNode(6)
+
+    init {
+        root.addChild(n2)
+        root.addChild(n3)
+        n2.addChild(n4)
+        n2.addChild(n5)
+        n3.addChild(n6)
+    }
+
+    @Test
+    fun isLeaf() {
+        assertTrue(n4.isLeaf)
+        assertFalse(root.isLeaf)
+    }
+
+    @Test
+    fun degree() {
+        assertEquals(2, root.degree)
+        assertEquals(0, n4.degree)
+    }
+
+    @Test
+    fun root() {
+        assertSame(root, n6.root())
+        assertSame(root, root.root())
+    }
+
+    @Test
+    fun ancestors() {
+        assertContentEquals(listOf(n2, root), n4.ancestors())
+        assertContentEquals(emptyList(), root.ancestors())
+    }
+
+    @Test
+    fun siblings() {
+        assertContentEquals(listOf(n5), n4.siblings())
+        assertContentEquals(emptyList(), root.siblings())
+    }
+
+    @Test
+    fun leaves() {
+        assertContentEquals(listOf(n4, n5, n6), root.leaves())
+    }
+
+    @Test
+    fun descendants() {
+        assertContentEquals(listOf(n2, n4, n5, n3, n6), root.descendants())
+    }
+}

src/commonTest/kotlin/com.github.adriankuta/datastructure.tree/TreeNodeSequenceTest.kt

@@ -0,0 +1,46 @@
+package com.github.adriankuta.datastructure.tree
+
+import com.github.adriankuta.datastructure.tree.iterators.TreeNodeIterators
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+import kotlin.test.assertEquals
+
+class TreeNodeSequenceTest {
+
+    private fun sample() = tree(1) {
+        child(2) {
+            child(4)
+            child(5)
+        }
+        child(3) {
+            child(6)
+        }
+    }
+
+    @Test
+    fun preOrderSequence() =
+        assertContentEquals(listOf(1, 2, 4, 5, 3, 6), sample().preOrderSequence().map { it.value }.toList())
+
+    @Test
+    fun postOrderSequence() =
+        assertContentEquals(listOf(4, 5, 2, 6, 3, 1), sample().postOrderSequence().map { it.value }.toList())
+
+    @Test
+    fun levelOrderSequence() =
+        assertContentEquals(listOf(1, 2, 3, 4, 5, 6), sample().levelOrderSequence().map { it.value }.toList())
+
+    @Test
+    fun asSequenceDefaultsToPreOrder() =
+        assertContentEquals(listOf(1, 2, 4, 5, 3, 6), sample().asSequence().map { it.value }.toList())
+
+    @Test
+    fun asSequenceHonorsExplicitOrder() =
+        assertContentEquals(
+            listOf(1, 2, 3, 4, 5, 6),
+            sample().asSequence(TreeNodeIterators.LevelOrder).map { it.value }.toList(),
+        )
+
+    @Test
+    fun sequenceShortCircuitsLazily() =
+        assertEquals(4, sample().preOrderSequence().map { it.value }.first { it == 4 })
+}

src/commonTest/kotlin/com.github.adriankuta/datastructure.tree/TreeNodeStackSafetyTest.kt

@@ -0,0 +1,47 @@
+package com.github.adriankuta.datastructure.tree
+
+import com.github.adriankuta.datastructure.tree.iterators.TreeNodeIterators
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+/**
+ * A deep, degenerate (linear) tree must not overflow the call stack. These tests build a chain
+ * thousands of nodes deep — recursive implementations of [TreeNode.height], [TreeNode.nodeCount]
+ * and the post-order iterator blow the stack here, so they pin the iterative rewrites.
+ */
+class TreeNodeStackSafetyTest {
+
+    private val depth = 50_000
+
+    private fun deepChain(): TreeNode<Int> {
+        val root = TreeNode(0)
+        var current = root
+        for (i in 1..depth) {
+            val child = TreeNode(i)
+            current.addChild(child)
+            current = child
+        }
+        return root
+    }
+
+    @Test
+    fun heightDoesNotOverflowOnDeepTree() {
+        assertEquals(depth, deepChain().height())
+    }
+
+    @Test
+    fun nodeCountDoesNotOverflowOnDeepTree() {
+        // nodeCount() excludes the root, so a chain of `depth` extra nodes counts as `depth`.
+        assertEquals(depth, deepChain().nodeCount())
+    }
+
+    @Test
+    fun postOrderIterationDoesNotOverflowOnDeepTree() {
+        assertEquals(depth + 1, deepChain().asSequence(TreeNodeIterators.PostOrder).count())
+    }
+
+    @Test
+    fun preOrderIterationDoesNotOverflowOnDeepTree() {
+        assertEquals(depth + 1, deepChain().asSequence(TreeNodeIterators.PreOrder).count())
+    }
+}

src/commonTest/kotlin/com.github.adriankuta/datastructure.tree/TreeNodeTest.kt

@@ -0,0 +1,242 @@
+package com.github.adriankuta.datastructure.tree
+
+import com.github.adriankuta.datastructure.tree.iterators.TreeNodeIterators
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertNull
+import kotlin.test.assertTrue
+
+class TreeNodeTest {
+
+    @Test
+    fun removeNodeTest() {
+        val root = TreeNode("Root")
+        val beveragesNode = TreeNode("Beverages")
+        val curdNode = TreeNode("Curd")
+        root.addChild(beveragesNode)
+        root.addChild(curdNode)
+
+        val teaNode = TreeNode("tea")
+        val coffeeNode = TreeNode("coffee")
+        val milkShakeNode = TreeNode("Milk Shake")
+        beveragesNode.addChild(teaNode)
+        beveragesNode.addChild(coffeeNode)
+        beveragesNode.addChild(milkShakeNode)
+
+        val gingerTeaNode = TreeNode("ginger tea")
+        val normalTeaNode = TreeNode("normal tea")
+        teaNode.addChild(gingerTeaNode)
+        teaNode.addChild(normalTeaNode)
+
+        val yogurtNode = TreeNode("yogurt")
+        val lassiNode = TreeNode("lassi")
+        curdNode.addChild(yogurtNode)
+        curdNode.addChild(lassiNode)
+
+        assertEquals(
+            "Root\n" +
+                    "├── Beverages\n" +
+                    "│   ├── tea\n" +
+                    "│   │   ├── ginger tea\n" +
+                    "│   │   └── normal tea\n" +
+                    "│   ├── coffee\n" +
+                    "│   └── Milk Shake\n" +
+                    "└── Curd\n" +
+                    "    ├── yogurt\n" +
+                    "    └── lassi\n",
+            root.prettyString(),
+            "Pretty print test"
+        )
+
+        root.removeChild(curdNode)
+        gingerTeaNode.detach()
+        assertEquals(
+            "Root\n" +
+                    "└── Beverages\n" +
+                    "    ├── tea\n" +
+                    "    │   └── normal tea\n" +
+                    "    ├── coffee\n" +
+                    "    └── Milk Shake\n",
+            root.prettyString(),
+            "Remove node test"
+        )
+    }
+
+    @Test
+    fun removeChildReturnsTrueWhenPresentFalseOtherwise() {
+        val root = TreeNode("Root")
+        val child = TreeNode("Child")
+        root.addChild(child)
+
+        assertTrue(root.removeChild(child), "Removing a present child returns true")
+        assertFalse(root.removeChild(child), "Removing an already-removed child returns false")
+        assertNull(child.parent, "Removed child is detached from its parent")
+        assertEquals(emptyList(), root.children)
+    }
+
+    @Test
+    fun clearTest() {
+        val root = TreeNode("Root")
+        val beveragesNode = TreeNode("Beverages")
+        val curdNode = TreeNode("Curd")
+        root.addChild(beveragesNode)
+        root.addChild(curdNode)
+
+        val teaNode = TreeNode("tea")
+        val coffeeNode = TreeNode("coffee")
+        val milkShakeNode = TreeNode("Milk Shake")
+        beveragesNode.addChild(teaNode)
+        beveragesNode.addChild(coffeeNode)
+        beveragesNode.addChild(milkShakeNode)
+
+        val gingerTeaNode = TreeNode("ginger tea")
+        val normalTeaNode = TreeNode("normal tea")
+        teaNode.addChild(gingerTeaNode)
+        teaNode.addChild(normalTeaNode)
+
+        val yogurtNode = TreeNode("yogurt")
+        val lassiNode = TreeNode("lassi")
+        curdNode.addChild(yogurtNode)
+        curdNode.addChild(lassiNode)
+
+        root.clear()
+        assertEquals(root.children, emptyList())
+        assertEquals(beveragesNode.children, emptyList())
+        assertEquals(curdNode.children, emptyList())
+        assertEquals(teaNode.children, emptyList())
+        assertEquals(coffeeNode.children, emptyList())
+        assertEquals(milkShakeNode.children, emptyList())
+        assertEquals(gingerTeaNode.children, emptyList())
+        assertEquals(normalTeaNode.children, emptyList())
+        assertEquals(yogurtNode.children, emptyList())
+        assertEquals(lassiNode.children, emptyList())
+
+        assertNull(root.parent)
+        assertNull(beveragesNode.parent)
+        assertNull(curdNode.parent)
+        assertNull(teaNode.parent)
+        assertNull(coffeeNode.parent)
+        assertNull(milkShakeNode.parent)
+        assertNull(gingerTeaNode.parent)
+        assertNull(normalTeaNode.parent)
+        assertNull(yogurtNode.parent)
+        assertNull(lassiNode.parent)
+    }
+
+    @Test
+    fun kotlinExtTest() {
+        val root = TreeNode("World")
+        val northA = TreeNode("North America")
+        val europe = TreeNode("Europe")
+        root.addChild(northA)
+        root.addChild(europe)
+
+        val usa = TreeNode("USA")
+        northA.addChild(usa)
+
+        val poland = TreeNode("Poland")
+        val france = TreeNode("France")
+        europe.addChild(poland)
+        europe.addChild(france)
+
+        val rootExt = tree("World") {
+            child("North America") {
+                child("USA")
+            }
+            child("Europe") {
+                child("Poland")
+                child("France")
+            }
+        }
+        assertEquals(root.prettyString(), rootExt.prettyString())
+    }
+
+    @Test
+    fun preOrderIteratorTest() {
+        val tree = tree("F") {
+            child("B") {
+                child("A")
+                child("D") {
+                    child("C")
+                    child("E")
+                }
+            }
+            child("G") {
+                child("I") {
+                    child("H")
+                }
+            }
+        }
+        val expectedPreOrder = listOf("F", "B", "A", "D", "C", "E", "G", "I", "H")
+        assertContentEquals(expectedPreOrder, tree.toList().map { it.toString() })
+    }
+    @Test
+    fun postOrderIteratorTest() {
+        val tree = tree("A", TreeNodeIterators.PostOrder) {
+            child("B") {
+                child("E")
+            }
+            child("C")
+            child("D") {
+                child("F")
+                child("G")
+                child("H")
+                child("I")
+                child("J")
+            }
+        }
+
+        val expectedPreOrder = listOf("E", "B", "C", "F", "G", "H", "I", "J", "D", "A")
+        assertContentEquals(expectedPreOrder, tree.toList().map { it.toString() })
+    }
+
+    @Test
+    fun secondPostOrderIteratorTest() {
+        val tree = tree(1, TreeNodeIterators.PostOrder) {
+            child(2) {
+                child(5) {
+                    child(10)
+                }
+                child(6) {
+                    child(11)
+                    child(12)
+                    child(13)
+                }
+            }
+            child(3)
+            child(4) {
+                child(7)
+                child(8)
+                child(9)
+            }
+        }
+        val expectedOrder = listOf(10, 5, 11, 12, 13, 6, 2, 3, 7, 8, 9, 4, 1)
+        assertContentEquals(expectedOrder, tree.toList().map { it.value })
+    }
+
+    @Test
+    fun levelOrderIteratorTest() {
+        val tree = tree(1, TreeNodeIterators.LevelOrder) {
+            child(2) {
+                child(5) {
+                    child(10)
+                }
+                child(6) {
+                    child(11)
+                    child(12)
+                    child(13)
+                }
+            }
+            child(3)
+            child(4) {
+                child(7)
+                child(8)
+                child(9)
+            }
+        }
+        val expectedOrder = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
+        assertContentEquals(expectedOrder, tree.toList().map { it.value })
+    }
+}

src/commonTest/kotlin/com.github.adriankuta/datastructure.tree/TreeNodeUtilitiesTest.kt

@@ -0,0 +1,53 @@
+package com.github.adriankuta.datastructure.tree
+
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+
+class TreeNodeUtilitiesTest {
+
+    private val root = TreeNode(1)
+    private val a = TreeNode(2)
+    private val b = TreeNode(3)
+
+    init {
+        root.addChild(a)
+        a.addChild(b)
+    }
+
+    @Test
+    fun nodeCountCountsDescendantsExcludingRoot() {
+        assertEquals(0, TreeNode("solo").nodeCount())
+        assertEquals(2, root.nodeCount())
+    }
+
+    @Test
+    fun heightIsLongestEdgePathToLeaf() {
+        assertEquals(0, TreeNode("solo").height())
+        assertEquals(2, root.height())
+        assertEquals(1, a.height())
+    }
+
+    @Test
+    fun depthIsDistanceToRoot() {
+        assertEquals(0, root.depth())
+        assertEquals(1, a.depth())
+        assertEquals(2, b.depth())
+    }
+
+    @Test
+    fun pathReturnsDescendantToReceiverChain() {
+        assertContentEquals(listOf(b, a, root), root.path(b))
+    }
+
+    @Test
+    fun pathReturnsNullWhenNotADescendant() {
+        assertNull(root.path(TreeNode(99)))
+    }
+
+    @Test
+    fun pathReturnsNullWhenDescendantIsRootItself() {
+        assertNull(root.path(root))
+    }
+}

src/commonTest/kotlin/com.github.adriankuta/datastructure.tree/TreeNodeV4Test.kt

@@ -0,0 +1,105 @@
+package com.github.adriankuta.datastructure.tree
+
+import com.github.adriankuta.datastructure.tree.exceptions.TreeNodeException
+import com.github.adriankuta.datastructure.tree.iterators.TreeNodeIterators
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
+import kotlin.test.assertFalse
+import kotlin.test.assertNull
+import kotlin.test.assertSame
+import kotlin.test.assertTrue
+
+class TreeNodeV4Test {
+
+    @Test
+    fun addChildRejectsNodeThatAlreadyHasAParent() {
+        val a = TreeNode("a")
+        val b = TreeNode("b")
+        a.addChild(b)
+
+        val other = TreeNode("other")
+        assertFailsWith<TreeNodeException> { other.addChild(b) }
+    }
+
+    @Test
+    fun addChildRejectsCycles() {
+        val root = TreeNode("root")
+        val child = TreeNode("child")
+        root.addChild(child)
+
+        // Attaching an ancestor under its own descendant would create a cycle.
+        assertFailsWith<TreeNodeException> { child.addChild(root) }
+        // Attaching a node under itself is also a cycle.
+        assertFailsWith<TreeNodeException> { root.addChild(root) }
+    }
+
+    @Test
+    fun detachRemovesFromParent() {
+        val root = TreeNode("root")
+        val child = TreeNode("child")
+        root.addChild(child)
+
+        assertTrue(child.detach())
+        assertNull(child.parent)
+        assertContentEquals(emptyList(), root.children)
+        // Detached node can now be re-attached elsewhere.
+        val newParent = TreeNode("newParent")
+        newParent.addChild(child)
+        assertSame(newParent, child.parent)
+    }
+
+    @Test
+    fun detachOnRootReturnsFalse() {
+        assertFalse(TreeNode("root").detach())
+    }
+
+    @Test
+    fun removeChildOnlyRemovesDirectChildren() {
+        val root = TreeNode("root")
+        val parent = TreeNode("parent")
+        val grandchild = TreeNode("grandchild")
+        root.addChild(parent)
+        parent.addChild(grandchild)
+
+        // grandchild is not a direct child of root -> no-op, returns false.
+        assertFalse(root.removeChild(grandchild))
+        assertSame(parent, grandchild.parent)
+
+        // direct child removal works.
+        assertTrue(parent.removeChild(grandchild))
+        assertNull(grandchild.parent)
+    }
+
+    @Test
+    fun clearOnNonRootKeepsItAttachedToItsParent() {
+        val root = TreeNode("root")
+        val branch = TreeNode("branch")
+        val leaf = TreeNode("leaf")
+        root.addChild(branch)
+        branch.addChild(leaf)
+
+        branch.clear()
+
+        assertContentEquals(emptyList(), branch.children)
+        assertSame(root, branch.parent)          // branch stays attached to root
+        assertContentEquals(listOf(branch), root.children)
+        assertNull(leaf.parent)                  // former descendant is detached
+    }
+
+    @Test
+    fun iteratorAcceptsExplicitOrderWithoutMutatingDefault() {
+        val tree = tree(1) {
+            child(2) { child(4) }
+            child(3)
+        }
+
+        val postOrder = tree.iterator(TreeNodeIterators.PostOrder).asSequence().map { it.value }.toList()
+        assertContentEquals(listOf(4, 2, 3, 1), postOrder)
+
+        // Default order is unchanged (PreOrder).
+        assertEquals(TreeNodeIterators.PreOrder, tree.treeIterator)
+        assertContentEquals(listOf(1, 2, 4, 3), tree.map { it.value })
+    }
+}

tree-structure-compose/api/tree-structure-compose.api

@@ -0,0 +1,4 @@
+public final class com/github/adriankuta/datastructure/tree/compose/LazyTreeKt {
+	public static final fun LazyTree (Lcom/github/adriankuta/datastructure/tree/TreeNode;Landroidx/compose/ui/Modifier;ZLkotlin/jvm/functions/Function6;Landroidx/compose/runtime/Composer;II)V
+}
+

tree-structure-compose/build.gradle.kts

@@ -0,0 +1,74 @@
+import org.jetbrains.kotlin.gradle.ExperimentalWasmDsl
+
+plugins {
+    alias(libs.plugins.kotlinMultiplatform)
+    alias(libs.plugins.composeMultiplatform)
+    alias(libs.plugins.composeCompiler)
+    alias(libs.plugins.dokka)
+    alias(libs.plugins.mavenPublish)
+    signing
+}
+
+group = "com.github.adriankuta"
+version = rootProject.version
+
+mavenPublishing {
+    publishToMavenCentral(automaticRelease = false)
+    signAllPublications()
+
+    coordinates("com.github.adriankuta", "tree-structure-compose", version.toString())
+
+    pom {
+        name.set("Tree Data Structure — Compose Multiplatform")
+        description.set("A LazyTree composable (expand/collapse, lazy rendering) for the tree-structure library.")
+        url.set("https://github.com/AdrianKuta/Tree-Data-Structure")
+        licenses {
+            license {
+                name.set("MIT License")
+                url.set("https://opensource.org/licenses/MIT")
+                distribution.set("repo")
+            }
+        }
+        developers {
+            developer {
+                id.set("AdrianKuta")
+                name.set("Adrian Kuta")
+                email.set("adrian.kuta93@gmail.com")
+            }
+        }
+        scm {
+            url.set("https://github.com/AdrianKuta/Tree-Data-Structure")
+            connection.set("scm:git:https://github.com/AdrianKuta/Tree-Data-Structure.git")
+            developerConnection.set("scm:git:ssh://git@github.com/AdrianKuta/Tree-Data-Structure.git")
+        }
+    }
+}
+
+repositories {
+    mavenCentral()
+    google()
+}
+
+kotlin {
+    explicitApi()
+    jvmToolchain(21)
+
+    jvm()
+
+    @OptIn(ExperimentalWasmDsl::class)
+    wasmJs {
+        browser()
+    }
+
+    iosX64()
+    iosArm64()
+    iosSimulatorArm64()
+
+    sourceSets {
+        commonMain.dependencies {
+            api(project(":"))
+            implementation(compose.runtime)
+            implementation(compose.foundation)
+        }
+    }
+}

tree-structure-compose/src/commonMain/kotlin/com.github.adriankuta/datastructure/tree/compose/LazyTree.kt

@@ -0,0 +1,71 @@
+package com.github.adriankuta.datastructure.tree.compose
+
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.mutableStateMapOf
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Modifier
+import com.github.adriankuta.datastructure.tree.TreeNode
+
+/**
+ * A lazily-rendered, expand/collapse tree for Compose Multiplatform. Only the currently-visible
+ * nodes are composed, so it scales to large trees. Expansion state is remembered internally, keyed
+ * by node identity.
+ *
+ * ```
+ * LazyTree(root) { node, depth, expanded, toggle ->
+ *     Row(Modifier.padding(start = (depth * 16).dp).clickable(onClick = toggle)) {
+ *         if (!node.isLeaf) Text(if (expanded) "▾" else "▸")
+ *         Text(node.value.toString())
+ *     }
+ * }
+ * ```
+ *
+ * @param root the root of the tree to display.
+ * @param modifier the [Modifier] applied to the underlying [LazyColumn].
+ * @param initiallyExpanded whether nodes start expanded.
+ * @param nodeContent renders a single node. Receives the node, its depth (root = 0), whether it is
+ *   expanded, and a `toggle` callback that flips this node's expansion state.
+ */
+@Composable
+public fun <T> LazyTree(
+    root: TreeNode<T>,
+    modifier: Modifier = Modifier,
+    initiallyExpanded: Boolean = true,
+    nodeContent: @Composable (node: TreeNode<T>, depth: Int, expanded: Boolean, toggle: () -> Unit) -> Unit,
+) {
+    val expansion = remember(root) { mutableStateMapOf<TreeNode<T>, Boolean>() }
+    val isExpanded: (TreeNode<T>) -> Boolean = { node -> expansion[node] ?: initiallyExpanded }
+
+    val visible = flattenVisible(root, isExpanded)
+
+    LazyColumn(modifier = modifier) {
+        items(visible.size) { index ->
+            val (node, depth) = visible[index]
+            nodeContent(node, depth, isExpanded(node)) {
+                expansion[node] = !isExpanded(node)
+            }
+        }
+    }
+}
+
+/**
+ * Flattens the tree into the list of currently-visible `(node, depth)` pairs in pre-order, skipping
+ * the subtrees of collapsed nodes. Iterative, so it is safe on deep trees.
+ */
+private fun <T> flattenVisible(
+    root: TreeNode<T>,
+    isExpanded: (TreeNode<T>) -> Boolean,
+): List<Pair<TreeNode<T>, Int>> {
+    val result = mutableListOf<Pair<TreeNode<T>, Int>>()
+    val stack = ArrayDeque<Pair<TreeNode<T>, Int>>()
+    stack.addLast(root to 0)
+    while (stack.isNotEmpty()) {
+        val (node, depth) = stack.removeLast()
+        result.add(node to depth)
+        if (isExpanded(node)) {
+            node.children.asReversed().forEach { child -> stack.addLast(child to depth + 1) }
+        }
+    }
+    return result
+}

tree-structure-coroutines/api/tree-structure-coroutines.api

@@ -0,0 +1,8 @@
+public final class com/github/adriankuta/datastructure/tree/coroutines/TreeNodeFlowExtKt {
+	public static final fun asFlow (Lcom/github/adriankuta/datastructure/tree/TreeNode;Lcom/github/adriankuta/datastructure/tree/iterators/TreeNodeIterators;)Lkotlinx/coroutines/flow/Flow;
+	public static synthetic fun asFlow$default (Lcom/github/adriankuta/datastructure/tree/TreeNode;Lcom/github/adriankuta/datastructure/tree/iterators/TreeNodeIterators;ILjava/lang/Object;)Lkotlinx/coroutines/flow/Flow;
+	public static final fun levelOrderFlow (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Lkotlinx/coroutines/flow/Flow;
+	public static final fun postOrderFlow (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Lkotlinx/coroutines/flow/Flow;
+	public static final fun preOrderFlow (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Lkotlinx/coroutines/flow/Flow;
+}
+

tree-structure-coroutines/build.gradle.kts

@@ -0,0 +1,89 @@
+import org.jetbrains.kotlin.gradle.ExperimentalWasmDsl
+
+plugins {
+    alias(libs.plugins.kotlinMultiplatform)
+    alias(libs.plugins.dokka)
+    alias(libs.plugins.mavenPublish)
+    signing
+}
+
+group = "com.github.adriankuta"
+version = rootProject.version
+
+mavenPublishing {
+    publishToMavenCentral(automaticRelease = false)
+    signAllPublications()
+
+    coordinates("com.github.adriankuta", "tree-structure-coroutines", version.toString())
+
+    pom {
+        name.set("Tree Data Structure — coroutines")
+        description.set("kotlinx.coroutines Flow traversal for the tree-structure library.")
+        url.set("https://github.com/AdrianKuta/Tree-Data-Structure")
+        licenses {
+            license {
+                name.set("MIT License")
+                url.set("https://opensource.org/licenses/MIT")
+                distribution.set("repo")
+            }
+        }
+        developers {
+            developer {
+                id.set("AdrianKuta")
+                name.set("Adrian Kuta")
+                email.set("adrian.kuta93@gmail.com")
+            }
+        }
+        scm {
+            url.set("https://github.com/AdrianKuta/Tree-Data-Structure")
+            connection.set("scm:git:https://github.com/AdrianKuta/Tree-Data-Structure.git")
+            developerConnection.set("scm:git:ssh://git@github.com/AdrianKuta/Tree-Data-Structure.git")
+        }
+    }
+}
+
+repositories {
+    mavenCentral()
+}
+
+kotlin {
+    explicitApi()
+    jvmToolchain(21)
+
+    jvm()
+
+    js(IR) {
+        browser()
+        nodejs()
+    }
+
+    @OptIn(ExperimentalWasmDsl::class)
+    wasmJs {
+        browser()
+        nodejs()
+    }
+
+    iosX64()
+    iosArm64()
+    iosSimulatorArm64()
+
+    val hostOs = System.getProperty("os.name")
+    val isMingwX64 = hostOs.startsWith("Windows")
+    when {
+        hostOs == "Mac OS X" -> macosX64("native")
+        hostOs == "Linux" -> linuxX64("native")
+        isMingwX64 -> mingwX64("native")
+        else -> throw GradleException("Host OS is not supported in Kotlin/Native.")
+    }
+
+    sourceSets {
+        commonMain.dependencies {
+            api(project(":"))
+            api(libs.kotlinx.coroutines.core)
+        }
+        commonTest.dependencies {
+            implementation(kotlin("test"))
+            implementation(libs.kotlinx.coroutines.test)
+        }
+    }
+}

tree-structure-coroutines/src/commonMain/kotlin/com.github.adriankuta/datastructure/tree/coroutines/TreeNodeFlowExt.kt

@@ -0,0 +1,24 @@
+package com.github.adriankuta.datastructure.tree.coroutines
+
+import com.github.adriankuta.datastructure.tree.TreeNode
+import com.github.adriankuta.datastructure.tree.asSequence
+import com.github.adriankuta.datastructure.tree.iterators.TreeNodeIterators
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.asFlow
+
+/**
+ * Emits this node and all of its descendants as a cold [Flow], traversed in the given [order].
+ * Useful for plugging tree traversal into coroutine/Flow pipelines (e.g. in a ViewModel).
+ */
+public fun <T> TreeNode<T>.asFlow(
+    order: TreeNodeIterators = TreeNodeIterators.PreOrder,
+): Flow<TreeNode<T>> = asSequence(order).asFlow()
+
+/** Pre-order traversal as a cold [Flow]. */
+public fun <T> TreeNode<T>.preOrderFlow(): Flow<TreeNode<T>> = asFlow(TreeNodeIterators.PreOrder)
+
+/** Post-order traversal as a cold [Flow]. */
+public fun <T> TreeNode<T>.postOrderFlow(): Flow<TreeNode<T>> = asFlow(TreeNodeIterators.PostOrder)
+
+/** Level-order (breadth-first) traversal as a cold [Flow]. */
+public fun <T> TreeNode<T>.levelOrderFlow(): Flow<TreeNode<T>> = asFlow(TreeNodeIterators.LevelOrder)

tree-structure-coroutines/src/commonTest/kotlin/com.github.adriankuta/datastructure/tree/coroutines/TreeNodeFlowTest.kt

@@ -0,0 +1,35 @@
+package com.github.adriankuta.datastructure.tree.coroutines
+
+import com.github.adriankuta.datastructure.tree.iterators.TreeNodeIterators
+import com.github.adriankuta.datastructure.tree.tree
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.toList
+import kotlinx.coroutines.test.runTest
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class TreeNodeFlowTest {
+
+    private fun sample() = tree(1) {
+        child(2) {
+            child(4)
+            child(5)
+        }
+        child(3) {
+            child(6)
+        }
+    }
+
+    @Test
+    fun preOrderFlowEmitsInPreOrder() = runTest {
+        assertEquals(listOf(1, 2, 4, 5, 3, 6), sample().preOrderFlow().map { it.value }.toList())
+    }
+
+    @Test
+    fun levelOrderFlowEmitsInLevelOrder() = runTest {
+        assertEquals(
+            listOf(1, 2, 3, 4, 5, 6),
+            sample().asFlow(TreeNodeIterators.LevelOrder).map { it.value }.toList(),
+        )
+    }
+}

tree-structure-serialization/api/tree-structure-serialization.api

@@ -0,0 +1,35 @@
+public final class com/github/adriankuta/datastructure/tree/serialization/TreeNodeDto {
+	public static final field Companion Lcom/github/adriankuta/datastructure/tree/serialization/TreeNodeDto$Companion;
+	public fun <init> (Ljava/lang/Object;Ljava/util/List;)V
+	public synthetic fun <init> (Ljava/lang/Object;Ljava/util/List;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
+	public final fun component1 ()Ljava/lang/Object;
+	public final fun component2 ()Ljava/util/List;
+	public final fun copy (Ljava/lang/Object;Ljava/util/List;)Lcom/github/adriankuta/datastructure/tree/serialization/TreeNodeDto;
+	public static synthetic fun copy$default (Lcom/github/adriankuta/datastructure/tree/serialization/TreeNodeDto;Ljava/lang/Object;Ljava/util/List;ILjava/lang/Object;)Lcom/github/adriankuta/datastructure/tree/serialization/TreeNodeDto;
+	public fun equals (Ljava/lang/Object;)Z
+	public final fun getChildren ()Ljava/util/List;
+	public final fun getValue ()Ljava/lang/Object;
+	public fun hashCode ()I
+	public fun toString ()Ljava/lang/String;
+}
+
+public synthetic class com/github/adriankuta/datastructure/tree/serialization/TreeNodeDto$$serializer : kotlinx/serialization/internal/GeneratedSerializer {
+	public fun <init> (Lkotlinx/serialization/KSerializer;)V
+	public final fun childSerializers ()[Lkotlinx/serialization/KSerializer;
+	public final fun deserialize (Lkotlinx/serialization/encoding/Decoder;)Lcom/github/adriankuta/datastructure/tree/serialization/TreeNodeDto;
+	public synthetic fun deserialize (Lkotlinx/serialization/encoding/Decoder;)Ljava/lang/Object;
+	public final fun getDescriptor ()Lkotlinx/serialization/descriptors/SerialDescriptor;
+	public final fun serialize (Lkotlinx/serialization/encoding/Encoder;Lcom/github/adriankuta/datastructure/tree/serialization/TreeNodeDto;)V
+	public synthetic fun serialize (Lkotlinx/serialization/encoding/Encoder;Ljava/lang/Object;)V
+	public final fun typeParametersSerializers ()[Lkotlinx/serialization/KSerializer;
+}
+
+public final class com/github/adriankuta/datastructure/tree/serialization/TreeNodeDto$Companion {
+	public final fun serializer (Lkotlinx/serialization/KSerializer;)Lkotlinx/serialization/KSerializer;
+}
+
+public final class com/github/adriankuta/datastructure/tree/serialization/TreeNodeDtoKt {
+	public static final fun toDto (Lcom/github/adriankuta/datastructure/tree/TreeNode;)Lcom/github/adriankuta/datastructure/tree/serialization/TreeNodeDto;
+	public static final fun toTreeNode (Lcom/github/adriankuta/datastructure/tree/serialization/TreeNodeDto;)Lcom/github/adriankuta/datastructure/tree/TreeNode;
+}
+

tree-structure-serialization/build.gradle.kts

@@ -0,0 +1,89 @@
+import org.jetbrains.kotlin.gradle.ExperimentalWasmDsl
+
+plugins {
+    alias(libs.plugins.kotlinMultiplatform)
+    alias(libs.plugins.kotlinSerialization)
+    alias(libs.plugins.dokka)
+    alias(libs.plugins.mavenPublish)
+    signing
+}
+
+group = "com.github.adriankuta"
+version = rootProject.version
+
+mavenPublishing {
+    publishToMavenCentral(automaticRelease = false)
+    signAllPublications()
+
+    coordinates("com.github.adriankuta", "tree-structure-serialization", version.toString())
+
+    pom {
+        name.set("Tree Data Structure — kotlinx.serialization")
+        description.set("kotlinx.serialization support (TreeNodeDto round-trip) for the tree-structure library.")
+        url.set("https://github.com/AdrianKuta/Tree-Data-Structure")
+        licenses {
+            license {
+                name.set("MIT License")
+                url.set("https://opensource.org/licenses/MIT")
+                distribution.set("repo")
+            }
+        }
+        developers {
+            developer {
+                id.set("AdrianKuta")
+                name.set("Adrian Kuta")
+                email.set("adrian.kuta93@gmail.com")
+            }
+        }
+        scm {
+            url.set("https://github.com/AdrianKuta/Tree-Data-Structure")
+            connection.set("scm:git:https://github.com/AdrianKuta/Tree-Data-Structure.git")
+            developerConnection.set("scm:git:ssh://git@github.com/AdrianKuta/Tree-Data-Structure.git")
+        }
+    }
+}
+
+repositories {
+    mavenCentral()
+}
+
+kotlin {
+    explicitApi()
+    jvmToolchain(21)
+
+    jvm()
+
+    js(IR) {
+        browser()
+        nodejs()
+    }
+
+    @OptIn(ExperimentalWasmDsl::class)
+    wasmJs {
+        browser()
+        nodejs()
+    }
+
+    iosX64()
+    iosArm64()
+    iosSimulatorArm64()
+
+    val hostOs = System.getProperty("os.name")
+    val isMingwX64 = hostOs.startsWith("Windows")
+    when {
+        hostOs == "Mac OS X" -> macosX64("native")
+        hostOs == "Linux" -> linuxX64("native")
+        isMingwX64 -> mingwX64("native")
+        else -> throw GradleException("Host OS is not supported in Kotlin/Native.")
+    }
+
+    sourceSets {
+        commonMain.dependencies {
+            api(project(":"))
+            api(libs.kotlinx.serialization.json)
+        }
+        commonTest.dependencies {
+            implementation(kotlin("test"))
+        }
+    }
+}

tree-structure-serialization/src/commonMain/kotlin/com.github.adriankuta/datastructure/tree/serialization/TreeNodeDto.kt

@@ -0,0 +1,30 @@
+package com.github.adriankuta.datastructure.tree.serialization
+
+import com.github.adriankuta.datastructure.tree.TreeNode
+import kotlinx.serialization.Serializable
+
+/**
+ * A serializable, acyclic view of a [TreeNode] subtree. [TreeNode] itself holds a back-reference to
+ * its parent (a cycle), so it cannot be `@Serializable` directly — convert to/from this DTO instead.
+ *
+ * ```
+ * val json = Json.encodeToString(tree.toDto())
+ * val restored = Json.decodeFromString<TreeNodeDto<String>>(json).toTreeNode()
+ * ```
+ */
+@Serializable
+public data class TreeNodeDto<T>(
+    public val value: T,
+    public val children: List<TreeNodeDto<T>> = emptyList(),
+)
+
+/** Converts this subtree into a serializable [TreeNodeDto], preserving values and shape. */
+public fun <T> TreeNode<T>.toDto(): TreeNodeDto<T> =
+    TreeNodeDto(value, children.map { it.toDto() })
+
+/** Rebuilds a mutable [TreeNode] tree from this DTO. */
+public fun <T> TreeNodeDto<T>.toTreeNode(): TreeNode<T> {
+    val node = TreeNode(value)
+    children.forEach { node.addChild(it.toTreeNode()) }
+    return node
+}

tree-structure-serialization/src/commonTest/kotlin/com.github.adriankuta/datastructure/tree/serialization/TreeNodeSerializationTest.kt

@@ -0,0 +1,40 @@
+package com.github.adriankuta.datastructure.tree.serialization
+
+import com.github.adriankuta.datastructure.tree.structurallyEquals
+import com.github.adriankuta.datastructure.tree.tree
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+
+class TreeNodeSerializationTest {
+
+    @Test
+    fun roundTripsThroughJson() {
+        val original = tree("World") {
+            child("North America") { child("USA") }
+            child("Europe") {
+                child("Poland")
+                child("Germany")
+            }
+        }
+
+        val json = Json.encodeToString(original.toDto())
+        val restored = Json.decodeFromString<TreeNodeDto<String>>(json).toTreeNode()
+
+        assertTrue(original.structurallyEquals(restored))
+    }
+
+    @Test
+    fun dtoMirrorsTreeShape() {
+        val dto = tree(1) {
+            child(2)
+            child(3) { child(4) }
+        }.toDto()
+
+        assertEquals(1, dto.value)
+        assertEquals(2, dto.children.size)
+        assertEquals(4, dto.children[1].children[0].value)
+    }
+}

treedatastructure/.gitignore

@@ -1 +0,0 @@
-/build

treedatastructure/build.gradle

@@ -1,45 +0,0 @@
-apply plugin: 'com.android.library'
-apply plugin: 'kotlin-android'
-
-afterEvaluate {
-    generateReleaseBuildConfig.enabled = false
-}
-
-android {
-    compileSdkVersion 31
-    buildToolsVersion "31.0.0"
-
-
-    defaultConfig {
-        minSdkVersion 15
-        targetSdkVersion 31
-        versionName "2.0.2"
-        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
-        consumerProguardFiles 'consumer-rules.pro'
-    }
-
-    buildTypes {
-        release {
-            minifyEnabled false
-            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
-        }
-    }
-
-}
-
-dependencies {
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
-    implementation 'androidx.appcompat:appcompat:1.3.1'
-    implementation 'androidx.core:core-ktx:1.6.0'
-    testImplementation 'junit:junit:4.13.2'
-    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
-    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
-}
-
-ext {
-    PUBLISH_GROUP_ID = 'com.github.adriankuta'
-    PUBLISH_ARTIFACT_ID = 'tree-structure'
-    PUBLISH_VERSION = android.defaultConfig.versionName
-}
-
-apply from: "${rootProject.projectDir}/scripts/publish-module.gradle"

treedatastructure/proguard-rules.pro

@@ -1,21 +0,0 @@
-# Add project specific ProGuard rules here.
-# You can control the set of applied configuration files using the
-# proguardFiles setting in build.gradle.
-#
-# For more details, see
-#   http://developer.android.com/guide/developing/tools/proguard.html
-
-# If your project uses WebView with JS, uncomment the following
-# and specify the fully qualified class name to the JavaScript interface
-# class:
-#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
-#   public *;
-#}
-
-# Uncomment this to preserve the line number information for
-# debugging stack traces.
-#-keepattributes SourceFile,LineNumberTable
-
-# If you keep the line number information, uncomment this to
-# hide the original source file name.
-#-renamesourcefileattribute SourceFile

treedatastructure/src/androidTest/java/com/github/adriankuta/datastructure/tree/ExampleInstrumentedTest.kt

@@ -1,24 +0,0 @@
-package com.github.adriankuta.datastructure.tree
-
-import androidx.test.platform.app.InstrumentationRegistry
-import androidx.test.ext.junit.runners.AndroidJUnit4
-
-import org.junit.Test
-import org.junit.runner.RunWith
-
-import org.junit.Assert.*
-
-/**
- * Instrumented test, which will execute on an Android device.
- *
- * See [testing documentation](http://d.android.com/tools/testing).
- */
-@RunWith(AndroidJUnit4::class)
-class ExampleInstrumentedTest {
-    @Test
-    fun useAppContext() {
-        // Context of the app under test.
-        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
-        assertEquals("com.github.adriankuta.datastructure.tree.test", appContext.packageName)
-    }
-}

treedatastructure/src/main/AndroidManifest.xml

@@ -1 +0,0 @@
-<manifest package="com.github.adriankuta.datastructure.tree" />

treedatastructure/src/main/java/com/github/adriankuta/datastructure/tree/TreeNode.kt

@@ -1,140 +0,0 @@
-package com.github.adriankuta.datastructure.tree
-
-open class TreeNode<T>(val value: T) : Iterable<TreeNode<T>>, ChildDeclarationInterface<T> {
-
-    private var _parent: TreeNode<T>? = null
-    /**
-     * The converse notion of a child, an immediate ancestor.
-     */
-    val parent: TreeNode<T>?
-        get() = _parent
-
-    private val _children = mutableListOf<TreeNode<T>>()
-    /**
-     * A group of nodes with the same parent.
-     */
-    val children: List<TreeNode<T>>
-        get() = _children
-
-    /**
-     * Add new child to current node or root.
-     *
-     * @param child A node which will be directly connected to current node.
-     */
-    fun addChild(child: TreeNode<T>) {
-        child._parent = this
-        _children.add(child)
-    }
-
-    @JvmSynthetic
-    override fun child(value: T, childDeclaration: ChildDeclaration<T>?): TreeNode<T> {
-        val newChild = TreeNode(value)
-        if(childDeclaration != null)
-            newChild.childDeclaration()
-        _children.add(newChild)
-        return newChild
-    }
-
-    /**
-     * Removes a single instance of the specified node from this tree, if it is present.
-     *
-     * @return `true` if the node has been successfully removed; `false` if it was not present in the tree.
-     */
-    fun removeChild(child: TreeNode<T>): Boolean {
-        val removed = child._parent?._children?.remove(child)
-        child._parent = null
-        return removed ?: false
-    }
-
-    /**
-     * This function go through tree and counts children. Root element is not counted.
-     * @return All child and nested child count.
-     */
-    fun nodeCount(): Int {
-        if (_children.isEmpty())
-            return 0
-        return _children.size +
-                _children.sumOf { it.nodeCount() }
-    }
-
-    /**
-     * @return The number of edges on the longest path between current node and a descendant leaf.
-     */
-    fun height(): Int {
-        val childrenMaxDepth = _children.map { it.height() }
-            .maxOrNull()
-            ?: -1 // -1 because this method counts nodes, and edges are always one less then nodes.
-        return childrenMaxDepth + 1
-    }
-
-    /**
-     * Distance is the number of edges along the shortest path between two nodes.
-     * @return The distance between current node and the root.
-     */
-    fun depth(): Int {
-        var depth = 0
-        var tempParent = parent
-
-        while (tempParent != null) {
-            depth++
-            tempParent = tempParent.parent
-        }
-        return depth
-    }
-
-    /**
-     * Remove all children from root and every node in tree.
-     */
-    fun clear() {
-        _parent = null
-        _children.forEach { it.clear() }
-        _children.clear()
-    }
-
-    override fun toString(): String {
-        return value.toString()
-    }
-
-    fun prettyString(): String {
-        val stringBuilder = StringBuilder()
-        print(stringBuilder, "", "")
-        return stringBuilder.toString()
-    }
-
-    private fun print(stringBuilder: StringBuilder, prefix: String, childrenPrefix: String) {
-        stringBuilder.append(prefix)
-        stringBuilder.append(value)
-        stringBuilder.append('\n')
-        val childIterator = _children.iterator()
-        while (childIterator.hasNext()) {
-            val node = childIterator.next()
-            if (childIterator.hasNext()) {
-                node.print(stringBuilder, "$childrenPrefix├── ", "$childrenPrefix│   ")
-            } else {
-                node.print(stringBuilder, "$childrenPrefix└── ", "$childrenPrefix    ")
-            }
-        }
-    }
-
-    /**
-     * Tree is iterated by using `Pre-order Traversal Algorithm"
-     *  1. Check if the current node is empty or null.
-     *  2. Display the data part of the root (or current node).
-     *  3. Traverse the left subtree by recursively calling the pre-order function.
-     *  4. Traverse the right subtree by recursively calling the pre-order function.
-     * ```
-     * E.g.
-     *                    1
-     *                  / | \
-     *                 /  |   \
-     *               2    3     4
-     *              / \       / | \
-     *             5    6    7  8  9
-     *            /   / | \
-     *           10  11 12 13
-     *
-     * Output: 1 2 5 10 6 11 12 13 3 4 7 8 9
-     * ```
-     */
-    override fun iterator(): Iterator<TreeNode<T>> = TreeNodeIterator(this)
-}

treedatastructure/src/main/java/com/github/adriankuta/datastructure/tree/TreeNodeExt.kt

@@ -1,18 +0,0 @@
-package com.github.adriankuta.datastructure.tree
-
-typealias ChildDeclaration<T> = ChildDeclarationInterface<T>.() -> Unit
-
-/**
- * This method can be used to initialize new tree.
- * ```
- * val root = tree("World") { ... }
- * ```
- * @param root Root element of new tree.
- * @see [ChildDeclarationInterface.child]
- */
-@JvmSynthetic
-inline fun<reified T> tree(root: T, childDeclaration: ChildDeclaration<T>): TreeNode<T> {
-    val treeNode = TreeNode(root)
-    treeNode.childDeclaration()
-    return treeNode
-}

treedatastructure/src/main/java/com/github/adriankuta/datastructure/tree/TreeNodeIterator.kt

@@ -1,22 +0,0 @@
-package com.github.adriankuta.datastructure.tree
-
-import java.util.*
-
-class TreeNodeIterator<T>(root: TreeNode<T>) : Iterator<TreeNode<T>> {
-
-    private val stack = Stack<TreeNode<T>>()
-
-    init {
-        stack.push(root)
-    }
-
-    override fun hasNext(): Boolean = !stack.empty()
-
-    override fun next(): TreeNode<T> {
-        val node = stack.pop()
-        node.children
-            .asReversed()
-            .forEach { stack.push(it) }
-        return node
-    }
-}

treedatastructure/src/test/java/com/github/adriankuta/datastructure/tree/ExampleUnitTest.kt

@@ -1,17 +0,0 @@
-package com.github.adriankuta.datastructure.tree
-
-import org.junit.Test
-
-import org.junit.Assert.*
-
-/**
- * Example local unit test, which will execute on the development machine (host).
- *
- * See [testing documentation](http://d.android.com/tools/testing).
- */
-class ExampleUnitTest {
-    @Test
-    fun addition_isCorrect() {
-        assertEquals(4, 2 + 2)
-    }
-}

treedatastructure/src/test/java/com/github/adriankuta/datastructure/tree/TreeNodeTest.kt

@@ -1,142 +0,0 @@
-package com.github.adriankuta.datastructure.tree
-
-import org.hamcrest.CoreMatchers.`is`
-import org.hamcrest.CoreMatchers.nullValue
-import org.junit.Assert.assertEquals
-import org.junit.Assert.assertThat
-import org.junit.Test
-
-class TreeNodeTest {
-
-    @Test
-    fun removeNodeTest() {
-        val root = TreeNode("Root")
-        val beveragesNode = TreeNode("Beverages")
-        val curdNode = TreeNode("Curd")
-        root.addChild(beveragesNode)
-        root.addChild(curdNode)
-
-        val teaNode = TreeNode("tea")
-        val coffeeNode = TreeNode("coffee")
-        val milkShakeNode = TreeNode("Milk Shake")
-        beveragesNode.addChild(teaNode)
-        beveragesNode.addChild(coffeeNode)
-        beveragesNode.addChild(milkShakeNode)
-
-        val gingerTeaNode = TreeNode("ginger tea")
-        val normalTeaNode = TreeNode("normal tea")
-        teaNode.addChild(gingerTeaNode)
-        teaNode.addChild(normalTeaNode)
-
-        val yogurtNode = TreeNode("yogurt")
-        val lassiNode = TreeNode("lassi")
-        curdNode.addChild(yogurtNode)
-        curdNode.addChild(lassiNode)
-
-        assertEquals(
-            "Root\n" +
-                    "├── Beverages\n" +
-                    "│   ├── tea\n" +
-                    "│   │   ├── ginger tea\n" +
-                    "│   │   └── normal tea\n" +
-                    "│   ├── coffee\n" +
-                    "│   └── Milk Shake\n" +
-                    "└── Curd\n" +
-                    "    ├── yogurt\n" +
-                    "    └── lassi\n", root.toString()
-        )
-
-        println("Remove: ${curdNode.value}")
-        root.removeChild(curdNode)
-        println("Remove: ${gingerTeaNode.value}")
-        root.removeChild(gingerTeaNode)
-        assertEquals(
-            "Root\n" +
-                    "└── Beverages\n" +
-                    "    ├── tea\n" +
-                    "    │   └── normal tea\n" +
-                    "    ├── coffee\n" +
-                    "    └── Milk Shake\n", root.toString()
-        )
-    }
-
-    @Test
-    fun clearTest() {
-        val root = TreeNode("Root")
-        val beveragesNode = TreeNode("Beverages")
-        val curdNode = TreeNode("Curd")
-        root.addChild(beveragesNode)
-        root.addChild(curdNode)
-
-        val teaNode = TreeNode("tea")
-        val coffeeNode = TreeNode("coffee")
-        val milkShakeNode = TreeNode("Milk Shake")
-        beveragesNode.addChild(teaNode)
-        beveragesNode.addChild(coffeeNode)
-        beveragesNode.addChild(milkShakeNode)
-
-        val gingerTeaNode = TreeNode("ginger tea")
-        val normalTeaNode = TreeNode("normal tea")
-        teaNode.addChild(gingerTeaNode)
-        teaNode.addChild(normalTeaNode)
-
-        val yogurtNode = TreeNode("yogurt")
-        val lassiNode = TreeNode("lassi")
-        curdNode.addChild(yogurtNode)
-        curdNode.addChild(lassiNode)
-
-        println(root.toString())
-        println(curdNode.height())
-
-        root.clear()
-        assertThat(root.children, `is`(emptyList()))
-        assertThat(beveragesNode.children, `is`(emptyList()))
-        assertThat(curdNode.children, `is`(emptyList()))
-        assertThat(teaNode.children, `is`(emptyList()))
-        assertThat(coffeeNode.children, `is`(emptyList()))
-        assertThat(milkShakeNode.children, `is`(emptyList()))
-        assertThat(gingerTeaNode.children, `is`(emptyList()))
-        assertThat(normalTeaNode.children, `is`(emptyList()))
-        assertThat(yogurtNode.children, `is`(emptyList()))
-        assertThat(lassiNode.children, `is`(emptyList()))
-
-        assertThat(root.parent, `is`(nullValue()))
-        assertThat(beveragesNode.parent, `is`(nullValue()))
-        assertThat(curdNode.parent, `is`(nullValue()))
-        assertThat(teaNode.parent, `is`(nullValue()))
-        assertThat(coffeeNode.parent, `is`(nullValue()))
-        assertThat(milkShakeNode.parent, `is`(nullValue()))
-        assertThat(gingerTeaNode.parent, `is`(nullValue()))
-        assertThat(normalTeaNode.parent, `is`(nullValue()))
-        assertThat(yogurtNode.parent, `is`(nullValue()))
-        assertThat(lassiNode.parent, `is`(nullValue()))
-    }
-
-    @Test
-    fun kotlinExtTest() {
-        val root = TreeNode("World")
-        val northA = TreeNode("North America")
-        val europe = TreeNode("Europe")
-        root.addChild(northA)
-        root.addChild(europe)
-
-        val usa = TreeNode("USA")
-        northA.addChild(usa)
-
-        val poland = TreeNode("Poland")
-        val france = TreeNode("France")
-        europe.addChild(poland)
-        europe.addChild(france)
-
-        val rootExt = tree("World") {
-            child("North America") {
-                child("USA")
-            }
-            child("Europe") {
-                child("Poland")
-                child("France")
-            }
-        }
-        assertEquals(root.prettyString(), rootExt.prettyString())
-    }
-}