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:

Metric	v0.6.0	v0.7.10	v0.8.0
Window render (10 lines)	10 µs	5.3 µs	5.1 µs
Window render (10k lines)	56 µs	26 µs	23 µs
Full scroll cycle	85 µs	55 µs	48 µs
Large file (5k lines)	174 µs	87 µs	87 µs
Throughput	18k/sec	38k/sec	40k/sec
Auto-pair latency	-	~100ms	~92µs

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

# Custom TCP port
reovim server --tcp 9000

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

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

Server Options:

Flag	Description
--tcp <PORT>	Listen on custom TCP port (default: 12521)
--socket <PATH>	Listen on Unix socket
--stdio	Use stdio instead of TCP (for process piping)

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

CLI Client

The built-in CLI client provides command-line access to running servers:

# List running servers
reovim cli list

# Inject keys
reovim cli keys 'iHello<Esc>'

# Query state
reovim cli mode                           # Get current mode
reovim cli cursor                         # Get cursor position

# JSON output format
reovim cli --format json mode

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

# Interactive REPL
reovim cli -i

TUI Client

Connect to a running server with a full terminal UI:

# Auto-discover and connect
reovim tui

# Connect to specific server
reovim tui --tcp 127.0.0.1:12521

Key Bindings

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

Normal Mode

Key	Action
h/j/k/l	Move cursor left/down/up/right
w/b	Move word forward/backward
0/$	Move to line start/end
gg	Go to first line (or {n}gg to go to line n)
G	Go to last line (or {n}G to go to line n)
i	Enter insert mode
a	Enter insert mode after cursor
A	Enter insert mode at end of line
o	Open new line below and enter insert mode
O	Open new line above and enter insert mode
v	Enter visual mode
:	Enter command mode
x	Delete character
p/P	Paste after/before cursor
s	Multi-char jump (type 2 chars + label to jump)
f/F	Find char forward/backward with labels
t/T	Till char forward/backward with labels
Space e	Toggle explorer
Space f f	Telescope find files
Space f g	Telescope live grep
Space f b	Telescope buffers
Ctrl-Space	Trigger completion
za	Toggle fold at cursor
zo	Open fold at cursor
zc	Close fold at cursor
zR	Open all folds
zM	Close all folds

Insert Mode

Key	Action
Escape	Return to normal mode
Backspace	Delete character before cursor

Visual Mode

Key	Action
h/j/k/l	Extend selection
d	Delete selection
y	Yank selection
Escape	Return to normal mode

Command Mode

Command	Action
:q	Quit
:w [file]	Write (save)
:wq	Write and quit
:set nu / :set number	Show line numbers
:set nonu / :set nonumber	Hide line numbers
:set rnu / :set relativenumber	Show relative line numbers
:set nornu / :set norelativenumber	Hide relative line numbers
:set signcolumn=<mode>	Sign column: auto, yes, no, number
:set virtual_text	Enable inline diagnostic messages
:health / :checkhealth	Open health check diagnostic modal
:LspLog	Open LSP log file in editor
:profile list	Open profile picker
:profile load <name>	Load a configuration profile
:profile save <name>	Save current settings as profile

Architecture

Reovim follows a Linux kernel-inspired architecture with clear separation between mechanisms and policies.

┌─────────────────────────────────────────────────────────────┐
│  RUNNER (runner/)                              APPLICATION  │
│  ┌─────────────┐  ┌─────────────┐  ┌─────────────────────┐  │
│  │   Server    │  │   Client    │  │   Event Loop        │  │
│  │  (RPC/TCP)  │  │  (CLI/TUI)  │  │   Module Loader     │  │
│  └─────────────┘  └─────────────┘  └─────────────────────┘  │
├─────────────────────────────────────────────────────────────┤
│  MODULES (modules/)                             POLICY      │
│  Keymap, Operators, Layout, Options, Mode-Manager           │
│  → Decide HOW things behave (keybindings, defaults)         │
├─────────────────────────────────────────────────────────────┤
│  DRIVERS (lib/drivers/)                         MECHANISM   │
│  syntax/, input/, display/, lsp/, net/, vfs/, command/      │
│  → Provide services, define trait contracts                 │
├─────────────────────────────────────────────────────────────┤
│  KERNEL (lib/kernel/)                           MECHANISM   │
│  mm/ (Buffer, Position), ipc/ (EventBus), core/ (Mode)      │
│  block/ (UndoTree), sched/ (Runtime), api/ (public API)     │
│  → Core primitives, WHAT can be done                        │
└─────────────────────────────────────────────────────────────┘

Crate Structure:

• reovim (runner/) - Main binary, server/client modes, module loading
• reovim-kernel (lib/kernel/) - Core mechanisms: buffers, events, modes, undo
• reovim-driver-* (lib/drivers/) - Services: syntax, input, display, LSP, network
• reovim-module-* (modules/) - Policy modules: keymap, operators, layout

Key Design Principles:

• Mechanism vs Policy - Kernel provides WHAT (traits), modules decide HOW (behavior)
• API Boundary - Modules use ONLY reovim_kernel::api::* (compile-time enforced)
• Zero external deps in kernel - Tree-sitter lives in drivers, not kernel
• Multi-client support - Server mode with per-client viewports and independent cursors

Performance

Run benchmarks:

cargo bench -p reovim-kernel

Generate performance report:

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

See perf/ for versioned benchmark results.

Documentation

Architecture (v0.9.0+):

• Architecture Overview - Layer diagram, Linux mapping
• Kernel Overview - Core subsystems: mm/, ipc/, core/, block/
• Driver Overview - Services: syntax, input, display, LSP
• Module System - Module trait, registration
• Runner Overview - Server/client architecture

Contributing:

• Getting Started - Development setup
• Mechanism vs Policy - Core design principle
• Linux Architecture - Kernel design mapping
• Module Development - Creating modules
• Testing - Testing guide and patterns

User Guide:

• Configuration - Editor settings
• Commands - Command system and keybindings
• Text Objects - Delimiter and semantic text objects
• Server Mode - RPC server usage
• Troubleshooting - Common issues

Archive (v0.8.x legacy):

• Legacy Documentation - Pre-v0.9.0 documentation

License

AGPL-3.0 - See LICENSE for details.

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