Clive - C Live Editor

A minimal, lightweight text editor built from scratch in C, inspired by Vim's modal editing philosophy. Clive runs directly in your terminal and provides a distraction-free editing experience with just the essentials.

What is Clive?

Clive is a terminal-based text editor that implements core Vim-like functionality without the complexity of a full-featured editor. It operates in raw terminal mode, giving you direct control over every keystroke and screen update. The name "Clive" is a play on "C Live" - a live editor written in C.

Why Build This?

This project was born from a desire to understand how text editors work at a fundamental level. By building Clive, I learned:

• How terminal control works through escape sequences and raw mode
• The intricacies of cursor positioning and screen rendering
• Modal editing patterns and state management
• File I/O operations and buffer management
• Low-level input handling and keyboard event processing

Building a text editor from scratch strips away all abstractions and forces you to think about every detail - from how backspace works to how lines are stored in memory. It's an exercise in understanding the tools we use every day.

Features

Modal Editing

• Normal Mode: Navigate and manipulate text with single-key commands
• Insert Mode: Type and edit text naturally
• Command Mode: Execute editor commands like save and quit

Core Functionality

• Open and edit existing files or create new ones
• Line-based text buffer supporting up to 1000 lines
• Multiple cursor movement options (arrow keys and Vim-style hjkl)
• Line numbers displayed alongside your text
• Status bar showing filename, modification status, and cursor position
• Unsaved changes indicator to prevent accidental data loss
• Clipboard support for copying and pasting lines
• Bidirectional text search with pattern matching
• Quick line navigation (jump to start/end of line)

Normal Mode Commands

Navigation

• h or ← - Move cursor left
• j or ↓ - Move cursor down
• k or ↑ - Move cursor up
• l or → - Move cursor right
• 0 - Jump to beginning of line
• $ - Jump to end of line

Editing

• i - Enter insert mode at cursor position
• o - Open a new line below current line and enter insert mode
• O - Open a new line above current line and enter insert mode
• x - Delete character under cursor
• d - Delete current line

Copy and Paste

• y - Yank (copy) current line to clipboard
• p - Put (paste) clipboard content below current line

Search

• / - Search forward (type search term and press Enter)
• ? - Search backward (type search term and press Enter)
• n - Jump to next search match (forward)
• N - Jump to previous search match (backward)

Mode Switching

• : - Enter command mode

Insert Mode Commands

• Esc - Return to normal mode
• Enter - Create new line at cursor position
• Backspace - Delete character before cursor
• h/j/k/l or Arrow keys - Navigate while editing
• Any printable character - Insert at cursor

Command Mode

File Operations

• :w - Save current file
• :w filename - Save as new filename
• :wq - Save and quit
• :q - Quit (blocked if unsaved changes exist)
• :q! - Force quit without saving

Search Operations

• /searchterm - Search forward for "searchterm"
• ?searchterm - Search backward for "searchterm"

General

• Esc - Cancel command and return to normal mode
• Backspace - Delete character in command buffer

How to Build and Run

Prerequisites

• GCC or any C compiler
• Unix-like operating system (Linux, macOS, WSL)
• Terminal emulator

Building

gcc -o clive clive.c -Wall -Wextra

Or use the provided Makefile:

make

Running

# Create new file or edit existing
./clive filename.txt

# Start with empty buffer
./clive

Complete Command Reference

Normal Mode

Command	Action	Example Use Case
h	Move left	Navigate character by character
j	Move down	Navigate line by line
k	Move up	Navigate line by line
l	Move right	Navigate character by character
←↓↑→	Arrow key movement	Alternative to hjkl
0	Jump to line start	Quick navigation to beginning
$	Jump to line end	Quick navigation to end
i	Enter insert mode	Start typing at cursor
o	Open line below	Add new line and start typing
O	Open line above	Insert line before current
x	Delete character	Remove single character
d	Delete line	Remove entire line
y	Yank (copy) line	Copy line to clipboard
p	Put (paste) line	Paste clipboard below
/text	Search forward	Find "text" going down
?text	Search backward	Find "text" going up
n	Next match	Jump to next search result
N	Previous match	Jump to previous search result
:	Command mode	Execute editor commands

Insert Mode

Command	Action
Esc	Exit to normal mode
Enter	New line at cursor
Backspace	Delete previous character
Arrow keys	Navigate while inserting
h/j/k/l	Navigate while inserting
Any character	Insert at cursor position

Command Mode

Command	Action	Notes
:w	Write (save) file	Requires filename
:w filename	Save as filename	Sets new filename
:q	Quit editor	Blocked if unsaved changes
:q!	Force quit	Discards unsaved changes
:wq	Write and quit	Save then exit
/pattern	Search forward	Moves cursor to match
?pattern	Search backward	Moves cursor to match
Esc	Cancel command	Return to normal mode

Usage Tips

1. Start in normal mode - you cannot type immediately
2. Press i to enter insert mode and start typing
3. Press Esc to return to normal mode from any other mode
4. Use :w frequently to save your work
5. The status bar shows [+] when you have unsaved changes
6. Line numbers help you track your position in the file
7. Use h, j, k, l for Vim-style navigation or arrow keys if you prefer
8. Search with / for forward search or ? for backward search
9. After searching, use n to jump to next match or N for previous match
10. Copy a line with y and paste it below with p
11. Delete entire lines quickly with d
12. Use 0 and $ to jump to line boundaries instantly

Common Workflows

Editing a File

./clive myfile.txt    # Open file
i                     # Enter insert mode
# Type your content
Esc                   # Return to normal mode
:w                    # Save
:q                    # Quit

Searching and Replacing Text

/searchterm           # Find text forward
n                     # Jump to next occurrence
i                     # Enter insert mode to edit
# Make your changes
Esc                   # Back to normal mode
n                     # Continue to next match

Copying and Rearranging Lines

y                     # Yank (copy) current line
j                     # Move down
p                     # Paste below current line
d                     # Delete a line you don't need

Quick Navigation

0                     # Jump to start of line
$                     # Jump to end of line
k k k                 # Move up 3 lines
j j                   # Move down 2 lines

Current Limitations

• Maximum 1000 lines per file
• Maximum 256 characters per line
• No syntax highlighting
• No undo/redo functionality
• Clipboard only holds one line at a time
• No visual selection mode
• No multi-line copy/paste operations
• No split windows or tabs
• No configuration file
• Search wraps around but doesn't indicate when it does

Future Enhancements

High Priority

• Undo/Redo: Implement a command history stack to reverse changes
• Search and Replace: Add :s/old/new/ command for text substitution
• Visual Mode: Select and manipulate blocks of text (v, V commands)
• Multi-line Clipboard: Copy and paste multiple lines (dd, yy with counts)
• Search Wrap Indicator: Show message when search wraps around file
• Regex Search: Support regular expressions in search patterns

Medium Priority

• Syntax Highlighting: Color coding for common programming languages
• Multiple Buffers: Edit multiple files in one session
• Configuration: Read settings from a .cliverc file
• Better Error Messages: Display helpful messages in the status bar
• Word Movement: Jump by words (w, b, e) instead of characters
• Jump to Line: Go to specific line number (:123)

Nice to Have

• Auto-indentation: Maintain indentation on new lines
• Line Wrapping: Handle lines longer than terminal width
• Mouse Support: Click to position cursor
• Split Windows: View multiple files side by side
• Macros: Record and replay command sequences
• Plugin System: Extend functionality without modifying core
• UTF-8 Support: Handle international characters properly
• Incremental Search: Highlight matches as you type

Technical Improvements

• Dynamic Buffer: Remove line count and length limits
• Efficient Rendering: Only redraw changed portions of screen
• Gap Buffer: More efficient text insertion and deletion
• Crash Recovery: Auto-save and recover from unexpected exits
• Memory Optimization: Handle large files without loading entirely into RAM

Technical Details

Clive uses POSIX terminal control to achieve raw mode input handling. It disables canonical mode, echo, and signal generation to capture every keystroke. Screen updates are performed using ANSI escape sequences for cursor positioning and screen clearing.

The editor maintains a simple array-based buffer where each line is a fixed-size character array. While not the most memory-efficient approach, it keeps the implementation straightforward and easy to understand.

Contributing

This is a learning project, but suggestions and improvements are welcome. The code prioritizes readability and educational value over performance optimization.

License

Free to use, modify, and learn from. No warranties provided.