reovim

A Rust-powered neovim-like text editor.

Project Goals

• Fastest-reaction editor: Minimal latency, instant response
• Scalability: Handles large files and complex operations
• Zero-warning policy: All code must compile warning-free

Features

Core Editing

• Modal editing (Normal, Insert, Visual, Command modes)
• Vim-style keybindings (h/j/k/l navigation, w/b word motions)
• Operators with motions (d, y, c + motion)
• Visual selection with yank/delete
• Undo/Redo (u, Ctrl-r)
• Registers for copy/paste

Navigation

• Range-Finder plugin - Unified jump navigation and code visibility
  • Multi-char jump (s + 2 chars) - Leap-style navigation with smart auto-jump
  • Enhanced f/t motions (f/F/t/T) - Single-char search with label selection
  • Code folding (za/zo/zc/zR/zM) - Collapse/expand code blocks
• Telescope fuzzy finder - Files, buffers, grep (Space f)
• Explorer file browser - Tree view (Space e)
• Jump list navigation (Ctrl-O, Ctrl-I)

UI

• Command-line mode (:q, :w, :wq, :set)
• Line numbers (absolute, relative, hybrid)
• Sign column - Configurable modes: auto, yes, no, number
• Virtual text - Inline diagnostic messages after line content
• Which-key popup for keybindings
• Completion engine (Ctrl-Space)
• Status line with mode, pending keys, last command
• Health check (:health) - Diagnostic system for core and plugin status
• Landing page when started without a file
• Mouse support - Click to position cursor, scroll wheel navigation

Customization

• Theme overrides - TOML-based color customization

  [editor.theme_overrides]
  "statusline.background" = { bg = "#1a1b26" }
  "gutter.line_number" = { fg = "#565f89" }
  "statusline.mode.normal" = { fg = "#1a1b26", bg = "#7aa2f7", bold = true }
  

• Supports hex colors, rgb(), ansi:N, and named colors

Syntax & Code Intelligence

• Treesitter syntax highlighting - Accurate parsing for Rust, C, JavaScript, Python, JSON, TOML, Markdown
• Semantic text objects - af/if (function), ac/ic (class/struct)

Performance

v0.8.0 introduces priority channels for dramatically improved input responsiveness:

v0.8.0 highlights:

• ~1000x input latency improvement - Priority channels separate user input from background tasks
• Zero flickering - Diff-based rendering sends only changed cells
• 2x faster rendering - Optimized render pipeline since v0.6.0
• Async architecture with tokio runtime
• Cross-platform terminal support via crossterm

Installation

cargo install reovim

Building from Source

git clone https://github.com/ds1sqe/reovim.git
cd reovim
cargo build --release

Usage

reovim [file]

Server Mode

Reovim can run as a JSON-RPC 2.0 server for programmatic control, enabling integration with external tools, IDEs, and automation scripts. The server accepts multiple sequential connections - clients can connect, disconnect, and reconnect without restarting the server.

Multi-instance support: Multiple reovim servers can run concurrently. When the default port (12521) is in use, the server automatically tries 12522, 12523, etc. Each server writes a port file to ~/.local/share/reovim/servers/<pid>.port for discovery.

# Start server (TCP on 127.0.0.1:12521 by default)
reovim --server

# With a file
reovim --server myfile.txt

# Custom TCP port
reovim --server --listen-tcp 9000

# Unix socket
reovim --listen-socket /tmp/reovim.sock

# Stdio transport (for process piping)
reovim --stdio

# Dual output: render to terminal while serving RPC
reovim --server --terminal

Server Options:

Default port: 12521 (derived from ASCII: 'r'×100 + 'e'×10 + 'o')

reo-cli Client

A CLI client tool is available for interacting with the server:

# List running servers
reo-cli list

# Inject keys and show status (colored output by default)
reo-cli keys 'iHello<Esc>'

# Choose output format
reo-cli keys --format plain_text 'gg'     # Plain text
reo-cli keys --format raw_ansi 'gg'       # ANSI colors (default)
reo-cli keys --format cell_grid 'gg'      # JSON cell grid

# Connect to custom address
reo-cli --tcp localhost:9000 keys 'j'
reo-cli --socket /tmp/reovim.sock keys 'j'

# Interactive REPL
reo-cli --interactive

Key Bindings

Most movement commands support a numeric prefix (e.g., 5j moves down 5 lines).

Normal Mode

Insert Mode

Visual Mode

Command Mode

Architecture

┌─I/O─────────────────────────────────────────────────────────┐
│  ┌──────────────┐                        ┌──────────────┐   │
│  │    CLIENT    │                        │   TERMINAL   │   │
│  │  (reo-cli)   │                        │  (crossterm) │   │
│  └──────────────┘                        └──────────────┘   │
└───────┬────────────────────────────────────────────┬────────┘
        │ input                               output │
        ▼                                            ▲
┌──────────────────┐                       ┌─────────┴──────────┐
│ InputEventBroker │                       │    FrameBuffer     │
│  (async reader)  │                       │  (diff rendering)  │
└────────┬─────────┘                       └──────────▲─────────┘
         │                                            │
         ▼                                            │
┌──────────────────┐                       ┌──────────┴─────────┐
│  KeyEventBroker  │                       │  LayerCompositor   │
│   (broadcast)    │                       │ (editor/overlays)  │
└────────┬─────────┘                       └──────────▲─────────┘
         │                                            ¦
       ┌─┴──────────────┐                             ¦
       ▼                ▼                             ¦
┌──────────────┐ ┌──────────────┐                     ¦
│CommandHandler│ │PluginHandlers│                     ¦
│(keys→command)│ │  (EventBus)  │ ◀───────────────┐  ¦
└──────┬───────┘ └──────┬───────┘                  │  ¦
       │                │                          │  ¦
       └───────┬────────┘                          │  ¦
               ▼                                   │  ¦
┌─────────────────────────────┐                    │  ¦
│      PRIORITY CHANNELS      │                    │  ¦
│  hi: user input (64)        │                    │  ¦
│  lo: background (255)       │                    │  ¦
└─────────────┬───────────────┘                    │  ¦
              ▼                                    ▼  ¦
┌─────────────────────────────┐  ┌────────────────────────────┐
│          RUNTIME            │  │           PLUGINS          │
│ ┌───────┐ ┌──────┐ ┌──────┐ │  │ Feature: range-finder,     │
│ │Buffers│ │Screen│ │ Cmds │ │  │   microscope, lsp,         │
│ └───────┘ └──────┘ └──────┘ │  │   completion, explorer     │
│ ┌──────┐                    │  │ Languages: rust, c, js,    │
│ │ Mode │                    │  │   python, json, toml, md   │
│ └──────┘                    │  └────────────────────────────┘
└──────────────┬──────────────┘                       ¦
               └-----─────────────────────────────────┘

• reovim (RUNNER) - Main binary, plugin loading
• reovim-core (CORE) - Runtime, buffers, events, screen, commands
• reovim-sys (SYS) - System abstraction layer (crossterm re-exports)

Key Design:

• Priority channels separate user input (hi) from background tasks (lo) for ~1000x latency improvement
• Diff-based rendering sends only changed cells to terminal (zero flickering)
• EventBus enables plugin-to-plugin communication without core modifications

Performance

Run benchmarks:

cargo bench -p reovim-core

Generate performance report:

cargo run -p perf-report -- update --version X.Y.Z

See perf/ for versioned benchmark results.

Documentation

• Architecture - System design and component overview
• Event System - Input handling and event flow
• Commands - Command system and keybindings
• Plugin System - Plugin architecture and development
• Rendering - Rendering systems guide
• Render Pipeline - Render stages and data flow
• Diagnostics - Sign column and virtual text configuration
• Text Objects - Delimiter and semantic text objects
• Server Mode - RPC server and multi-instance support
• Window & Buffer - Window architecture
• Animation System - Visual effects and animations
• Decoration System - Language-aware decorations
• Saturator - Background task architecture
• Color System - Color palette design
• Syntax Highlighting - Rust AST taxonomy
• Development - Setup and contributing
• Testing - Running and writing tests

License

AGPL-3.0 - See LICENSE for details.

For commercial licensing options, contact: ds1sqe@mensakorea.org