Knit: A command-line text editor written in Kotlin.

Welcome to Knit, a command-line text editor written in Kotlin.

In this personal project, I build my own text editor with only basic features, using Kotlin.

Note

1. I started this project for learning purposes. Please do not use Knit for serious editing work—but feel free to play around with it!
2. I’m writing a tutorial on how to craft a text editor in Kotlin. I’ll announce it on my blog (mtkrm.com) once it’s ready.

Screen.Recording.2025-02-19.at.15.43.07.mov

How it stores text buffer: Doubly-Linked List

Knit uses a doubly-linked list to manage its text buffer. Each line of text is stored as a node in the list. This allows efficient insertion and deletion between lines while modifying a line can be expensive.

Hello, World!
This is Knit.
Goodbye!
  +-------------------------+     +-------------------------+     +---------------------+
  |        Line 1           | <-> |         Line 2          | <-> |       Line 3        |
  | "Hello, World!"         |     | "This is Knit."         |     | "Goodbye!"          |
  | prev: null              |     | prev: Line 1            |     | prev: Line 2        |
  | next: Line 2            |     | next: Line 3            |     | next: null          |
  +-------------------------+     +-------------------------+     +---------------------+

How to Try Knit

1. Generate the JAR File

   • After cloning this repo, run:

     ./gradlew shadowJar

   • The JAR file (e.g. knit-0.1.jar) will be generated in the build/libs/ folder.

2. Run the JAR File

   • In the terminal, run:

     java -jar build/libs/knit-1.0.jar

   • This will launch Knit in your terminal.

Features

• Arrows

  • Supports up, down, left, and right arrow keys.
  • Missing support for jump moves (Command + arrow keys).

• Text Input

  • Inserts characters at the cursor position.

• Commands

  • Supports Enter/Line Feed, Carriage Return, and Delete.
  • Missing support for saving the text buffer to a designated file (currently, it only displays the buffer).
  • Missing support for Quit, Save, Exit, and many other commands.

• Ambitious Goals

  • Undo/redo functionality.
  • Copy/paste functionality.
  • Syntax highlighting.

Guide to the codebase

• Main application logic: Main.kt, EditorApp.kt
• User input handling: controller/
• State management: managers/
• Data models: models/
• Testing: tests for controllers are located in src/test/kotlin/controller/