Tree-Data-Structure/CHANGELOG.md

Changelog

All notable changes to this project are documented here. The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

4.2.0 - 2026-06-08

Added

• Android target. The core tree-structure module and tree-structure-compose now publish an -android variant (minSdk 21), so both can be consumed directly in Android projects.
• tree-structure-compose: a foundation-only TreeNodeRow composable — a sensible default node row (clickable, indented, with a ▾/▸ marker and no Material dependency) — plus a no-content LazyTree(root, label = …) overload that renders each node with it. The existing lambda overload is unchanged.
• A runnable Android sample app in the new samples module, with @Preview composables.

Changed

• Upgraded the Gradle wrapper to 8.10.2 and introduced Android Gradle Plugin 8.7.2 (compileSdk 35). No source or behavior changes to existing targets.

4.1.1 - 2026-06-08

Fixed

• Restored the Apple/iOS artifacts (iosArm64, iosX64, iosSimulatorArm64) for the core and every module. The release workflow published from a Linux runner, which cannot build Kotlin/Native Apple targets, so they were silently omitted from 3.1.5–4.1.0; publishing now runs on macOS. No API or behavior changes from 4.1.0 — this is a packaging fix only.

4.1.0 - 2026-06-07

Added

• Structural mutation helpers on TreeNode: insertChild, removeChildAt, replaceChild, moveChild, addChildren, and sortChildren.
• Tree query extensions: lowestCommonAncestor, distance, pathBetween, and contains for finding common ancestors, edge distances, the path between two nodes, and value membership.
• Customizable prettyString(connectors, render) extension: choose connector glyphs via TreeConnectors (Default box-drawing or Ascii) and supply a per-node renderer that receives the value, its depth and whether it is its parent's last child. The all-defaults call is byte-identical to the existing no-arg prettyString().
• New tree-structure-immutable module: a persistent ImmutableTreeNode with structural sharing (addChild/removeChild/mapValues return new roots; pre/post/level-order traversals, nodeCount, and height).

Changed

• Rewrote the README for clarity: one consistent example tree, task-oriented sections (building, traversal, navigation, functional, utilities, mutating), per-module usage, and a condensed maintainer "Releasing" section.

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.