Heliolisk

A Vim-Like Modal Text Editor with a TUI. Built using Rust and Ratatui.

Features

• Modal Editing:
  • Navigate Mode: Fast cursor navigation, word jumps, and command entry (Normal Mode).
  • Edit Mode: Standard text typing and editing (Insert Mode).
  • Select Mode: Visual text selection and range manipulation (Visual Mode).
  • Command Mode: Ex-style colon commands (:w, :wq, :q, :qa, :e, :theme).
• Built-in File Explorer (<Space>e):
  • Dual-pane horizontal tree view with lazy directory expansion and collapse.
  • Nerd Font icons for folders and file types (.rs, .toml, .md, .json, scripts).
  • Open files directly into editor buffers or collapse directories with h/Enter.
• Syntax Highlighting:
  • Built-in heuristic highlighting with full theme integration.
  • Language support for Rust (.rs), TOML (.toml), Markdown (.md), JSON, and generic text.
• Hover Documentation (K):
  • Non-intrusive floating popup at the cursor line.
  • Comprehensive built-in documentation database for language keywords, standard types, and usage signatures.
• Decoupled LSP Manager (<Space>l):
  • Modular language server explorer with support for Rust, Python, TypeScript, Go, C/C++, TOML, and JSON.
  • Download and install official language servers into local cache (~/.local/share/heliolisk/lsp).
  • Toggle language servers on/off per language; only selected languages provide LSP hover documentation.
• Custom Color Themes (5 Built-in Presets):
  • Tokyo Night (Default)
  • Catppuccin Mocha
  • Gruvbox Dark
  • Nord
  • Solarized Dark
  • Switch anytime at runtime using :theme <name> or :colorscheme <name>.
• Customizable Multi-Chord Keybinding Engine:
  • Prefix trie router supporting multi-chord leader mappings (e.g. <Space>e, <Space>l, dw, gg).
• Robust Architecture:
  • Backed by Ropey rope data structure for fast large-file operations.
  • Per-buffer cursor memory and viewport scroll offsets.
  • Threaded non-blocking background saving with atomic tmp files.
  • Full Undo/Redo tracking cursor position alongside text history.
  • Unicode character width handling and CRLF line-ending safety.

Keybindings Reference

Key / Chord	Mode	Action
<Space>e	Navigate	Toggle File Explorer sidebar
<Space>l	Navigate	Open LSP Manager / Explorer
K	Navigate	Show Hover Documentation for word under cursor
i / a	Navigate	Enter Edit mode (before / after cursor)
o	Navigate	Open new line below and enter Edit mode
v	Navigate	Enter Select (Visual) mode
Esc	Edit / Select / Explorer / LSP	Return to Navigate mode or dismiss modals
:	Navigate	Enter Command mode
h / j / k / l	Navigate	Move cursor left / down / up / right
w / b / e	Navigate	Jump forward word / backward word / word end
^ / $	Navigate	Jump to first non-whitespace / end of line
gg / G	Navigate	Jump to top / bottom of file
dw	Navigate	Delete word to next whitespace
u / U	Navigate	Undo / Redo
Tab / Shift-Tab	Navigate	Switch to next / previous buffer
:w [filename]	Command	Save buffer asynchronously
:wq [filename]	Command	Save buffer and quit
:q / :qa	Command	Quit current buffer / Quit all
:theme <name>	Command	Switch theme (e.g. :theme tokyo-night, :theme catppuccin)
:e <path>	Command	Open file into a new buffer

File Explorer Controls

• j / k or Down / Up: Navigate directory items
• Enter or l: Open file into buffer / Toggle directory expansion
• h: Collapse current directory
• r: Refresh directory tree
• Esc or q: Return focus to editor

LSP Manager Controls

• j / k or Down / Up: Select language server
• Enter or Space: Toggle LSP enabled / disabled
• i: Download & install from official repository
• u: Uninstall / remove from cache
• Esc or q: Close LSP Manager

Screenshots

Main Editor Interface

Saved Notification

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Architecture & Design

• Pluggable & Decoupled LSP Support: Text editing and language servers are completely decoupled; users selectively enable and download language servers.
• Rope Data Structure: Backed by ropey for fast insert, delete, and line indexing on large files.
• Atomic Background I/O: Asynchronous worker thread writing to temporary files with atomic renames to prevent partial saves or crashes.
• Nerd Font Glyphs: Clean terminal aesthetics without emojis.

Contribute

I'm currently looking for people to contribute to this project, so if you are interested, fork your own copy of Heliolisk and create an issue in the project repository.

1. Fork the repo
2. Create a feature branch
3. Commit your changes
4. Push and open a Pull Request

Check out the Issues page for things to work on.

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