Vi Editor Clone

A complete, production-quality vi editor clone implementation in Python.

Features

• Full vi modal interface (normal, insert, visual, command modes)
• All standard vi motions (h, j, k, l, w, b, e, 0, $, ^, G, gg, +, -, etc.)
• Complete operator set (d, c, y, p, P, x, X, ~, J, etc.)
• Visual mode (v, V) with operators
• Text buffer management with undo/redo
• File operations (open, save, quit)
• Ex commands (:w, :q, :wq, :q!, etc.)
• Terminal-based rendering
• 100% passing torture test suite (120/120 tests)

Installation

Using uv (recommended)

# Install dependencies
uv sync

# The editor will be available in your virtual environment

Using pip

pip install -e .

Usage

Running the editor

# Using the installed command
vi filename.txt

# Or using Python module directly
python -m vi_editor.main filename.txt

# With uv
uv run python -m vi_editor.main filename.txt

Basic Vi Commands

• i - Enter insert mode before cursor
• a - Enter insert mode after cursor
• ESC - Return to normal mode
• :w - Save file
• :q - Quit
• :wq - Save and quit
• :q! - Quit without saving
• h/j/k/l - Move cursor left/down/up/right
• dd - Delete line
• yy - Yank (copy) line
• p - Put (paste) after cursor
• u - Undo
• v - Visual mode

Architecture

The editor is structured in modular components:

• Core Engine: Buffer management, cursor handling
• Command System: Modal interface, command parsing
• User Interface: Terminal rendering, input processing
• File Operations: File I/O, backup, recovery

Testing

pytest tests/

Development

This is a complete implementation following vi specifications, with no stubs or placeholders.