azpect/Gim: Vim-inspired text editor written in Go. - Gim

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Go + Vim = Gim

A blazingly fast, terminal-based text editor with vim-style keybindings

Features • Installation • Keybindings • Architecture • Roadmap

✨ What is Gim?

Gim is a modern, lightweight text editor written in Go that brings the power of vim-style modal editing to your terminal. Built on the excellent Charm stack, it combines the speed of Go with the elegance of functional UI patterns.

┌──────────────────────────────────────────────────────────────┐
│  Why Gim?                                                    │
├──────────────────────────────────────────────────────────────┤
│  🚀 Fast          - Native Go performance                    │
│  🎨 Beautiful     - Lipgloss-powered terminal styling        │
│  🧠 Vim-like      - Modal editing for efficiency             │
│  🧪 Well-tested   - Comprehensive integration test suite     │
│  📦 Single binary - No dependencies, just run                │
└──────────────────────────────────────────────────────────────┘

Trade Offs

Undo Tree vs. Undo Stack

While the undo tree method that vim uses is powerful, I rarely find myself using it. A stack terminal-based approach is more natural to "non-vim" users and much simpler to implement. Implementing a feature similar to Vims undo tree would many times longer than a simple stack.

Vim-like Replace vs. Custom Replace

The way that vim's replace mode is implemented is quite complex, keeping track of the previous line backspace can only delete newly replaced characters. This is a complex feature, one that I rarely use, and even find a bit un-intuitive. Implementing replace mode in a way where all actions function the same as insert mode (other than the actual character typing) allows for a much simpler implementation, as well as a more intuitive user experience.

Replace mode implements and replaces (no pun intended) the last inserted keys of insert mode. Due to the infrequent use of replace mode, and the '.' action for insert mode, this felt like a natural trade off.

TODO List

Ops like change, and substitute and such should add to paste reg
Delete op should also add to paste reg
Gap buffer implementation (this shouldn't be TOO hard)
Alternate buffer handling and implementation
Scroll in X direction

🎯 Features

🎭 Six Editor Modes

Mode	Key	Description
Normal	`Esc`	Navigate and command - your home base
Insert	`i/a/o`	Type and create
Visual	`v`	Select characters
Visual Line	`V`	Select whole lines
Visual Block	`Ctrl+V`	Select rectangular regions
Command	`:`	Execute commands (coming soon)

⌨️ Full Motion System

         gg
          ↑
    b ←── · ──→ w/e
          ↓
          G

      0 ──────── $
      │  _       │
      └──┴───────┘
         line

Character motions: h j k l - The classics
Word motions: w e b - Jump by word boundaries
Line motions: 0 $ _ - Start, end, first non-whitespace
File motions: gg G - Top and bottom of file

🔧 Powerful Operators

Operator	Action	Examples
`d`	Delete	`dd` `dw` `d$` `dG`
`x`	Delete char	`x` `3x`

Operators compose with motions and counts!

  3    d    2w
  ↓    ↓    ↓
count  op  motion

= Delete 6 words (3 × 2)

🎪 Visual Mode Magic

Select text visually, then operate on it:

┌─────────────────────────────────┐
│ Hello, [world! How] are you?   │  ← v + motion + d
│ Hello, are you?                │  ← Result
└─────────────────────────────────┘

┌─────────────────────────────────┐
│ [Line one                    ] │
│ [Line two                    ] │  ← V + j + d
│ [Line three                  ] │
│                                │  ← All lines deleted
└─────────────────────────────────┘

🔢 Count Everything

Prefix any command with a number:

Input	Action
`5j`	Move down 5 lines
`3dd`	Delete 3 lines
`10i=Esc`	Insert `==========`
`2d3w`	Delete 6 words

🪟 Smart Scrolling

Automatic viewport following
scrollOff margin keeps context visible
Smooth cursor tracking

📦 Installation

From Source

# Clone the repository
git clone https://git.gophernest.net/azpect/TextEditor.git
cd TextEditor

# Build
go build -o gim ./cmd/gim

# Run
./gim [filename]

Quick Run

go run ./cmd/gim [filename]

⌨️ Keybindings

Normal Mode

🧭 Navigation

Key	Action
`h`	Move left
`j`	Move down
`k`	Move up
`l`	Move right
`w`	Next word start
`e`	Next word end
`b`	Previous word start
`0`	Line start
`$`	Line end
`_`	First non-whitespace
`gg`	File start
`G`	File end

✏️ Entering Insert Mode

Key	Action
`i`	Insert before cursor
`a`	Insert after cursor
`I`	Insert at line start
`A`	Insert at line end
`o`	Open line below
`O`	Open line above

🗑️ Deletion

Key	Action
`x`	Delete character
`dd`	Delete line
`d{motion}`	Delete to motion
`D`	Delete to end of line

👁️ Visual Mode

Key	Action
`v`	Character visual
`V`	Line visual
`Ctrl+V`	Block visual

Insert Mode

Key	Action
`Esc`	Return to normal
`Backspace`	Delete previous char
`Delete`	Delete next char
`Ctrl+W`	Delete previous word
`Tab`	Insert tab (2 spaces)
`Enter`	New line
`↑↓←→`	Navigate

Visual Mode

All normal mode navigation keys work, plus:

Key	Action
`d`	Delete selection
`Esc`	Return to normal

🏗️ Architecture

Gim follows a clean, modular architecture inspired by the Elm Architecture (Model-Update-View):

┌─────────────────────────────────────────────────────────────┐
│                        cmd/gim/                             │
│                      Entry Point                            │
└─────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────┐
│                     internal/editor/                        │
│              Model • Update • View • Style                  │
└─────────────────────────────────────────────────────────────┘
          │                   │                    │
          ▼                   ▼                    ▼
┌─────────────────┐  ┌─────────────────┐  ┌─────────────────┐
│ internal/input/ │  │ internal/motion/│  │internal/operator│
│    Handler      │  │   h j k l w e   │  │    d (delete)   │
│    Keymap       │  │   b 0 $ gg G    │  │                 │
└─────────────────┘  └─────────────────┘  └─────────────────┘
          │                   │                    │
          └───────────────────┴────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────┐
│                     internal/action/                        │
│         Action • Motion • Operator • Position               │
│                    (Core Interfaces)                        │
└─────────────────────────────────────────────────────────────┘

Key Design Patterns

🔌 Interface-based: Actions/motions use a Model interface, enabling clean testing
🎭 State Machine: Input handler manages mode transitions and pending operations
📐 Motion Types: Linewise vs Charwise motions for proper operator behavior
🔄 Composition: Operators compose with motions (e.g., d + w = delete word)

🧪 Testing

Gim has comprehensive integration tests using the teatest library:

# Run all tests
go test ./...

# Run with verbose output
go test -v ./internal/editor/

# Run specific test
go test -v -run TestDeleteOperator ./internal/editor/

Test Coverage Areas:

✅ Basic motions (hjkl)
✅ Jump motions (gg, G, 0, $, _)
✅ Word motions (w, e, b)
✅ Delete operator with all motions
✅ Insert mode (all entry points, recording, replay)
✅ Visual mode (all three types)
✅ Scrolling behavior

🗺️ Roadmap

✅ Implemented

Modal editing (Normal, Insert, Visual, Visual Line, Visual Block)
Basic motions (hjkl, word motions, line motions)
Delete operator with motion composition
Count prefixes for all commands
Insert mode with recording/replay
Visual selection with operators
Smart scrolling with scrollOff
Relative line numbers

🚧 In Progress

Command mode (: commands)
File I/O (save/load)

🔮 Future

Operators: y (yank), c (change), p (paste)
Motions: f/F/t/T (find char), //? (search), {/} (paragraph)
Features:
- Undo/redo system
- Multiple buffers/tabs
- Syntax highlighting
- Configuration file
- Clipboard integration
- Macros (q recording)
- Marks (m and ')
- Registers (")
- Text objects (iw, a", etc.)
- Plugins system

🎨 Built With

BubbleTea - The fun, functional TUI framework
Lipgloss - Style definitions for terminal apps
Go - The language that makes it all possible

🤝 Contributing

Contributions are welcome! Whether it's:

🐛 Bug fixes
✨ New features
📖 Documentation improvements
🧪 Test coverage

Feel free to open issues and pull requests!

📜 License

This project is open source. See LICENSE for details.

_{Made with 💜 and lots of ☕}

_{"Because sometimes you just want to build your own vim"}

README.md Unescape Escape