hili-cat - Lightweight Syntax Highlighter for Linux

A highly optimized, minimal, and scalable command-line syntax highlighting tool written in Go. This program is designed as a more powerful alternative to the cat command with syntax highlighting capabilities, specifically for Linux operating systems.

Documentation

Complete documentation is available in multiple languages:

• English Documentation
• Persian Documentation (فارسی)

The documentation includes:

• Installation and usage instructions
• Configuration guide for adding new languages
• Architecture and design overview
• Contribution guidelines

Features

• Highly efficient: Uses a two-goroutine pipeline architecture for maximum performance
• Extensible: Supports custom syntax highlighting rules via external JSON configuration
• Minimal dependencies: Only uses Go standard library packages
• Automatic language detection: Based on file extensions
• Line ending support: Handles both LF and CRLF line endings
• Support for stdin: Can be used in command pipelines
• Standard cat compatibility: Supports common cat flags like -n, -b, -s, and -E
• Multi-language support: Includes built-in support for Go, Python, JavaScript, JSON, Markdown, XML/HTML, and SQL
• Security-focused: Uses low-level syscall operations for file I/O
• Integrated paging: Use --less flag to view large files with the less pager

Installation

System Requirements

• Operating System: Linux (not compatible with macOS or Windows)
• Dependencies:
  • Go 1.18+ (for building from source)
  • less command (for the --less flag functionality)

# Install from source
git clone https://github.com/AmirMahdyJebreily/hili-cat.git
cd hili-cat
./build.sh

# Or use the pre-built binary from releases
wget https://github.com/AmirMahdyJebreily/hili-cat/releases/download/pre-release0.0.1/hili-cat-linux-amd64
chmod +x hili-cat-linux-amd64
sudo mv hili-cat-linux-amd64 /usr/local/bin/hili-cat

Usage

# Highlight a file with automatic language detection
hili-cat main.go

# Highlight multiple files
hili-cat file1.go file2.go

# Highlight stdin with a specific language
cat main.go | hili-cat --lang go

# Use a custom configuration file
hili-cat --config /path/to/config.json main.go

# Specify line ending format
hili-cat --line-ending crlf file.go

# Show line numbers (like cat -n)
hili-cat -n file.go

# Show only non-blank line numbers (like cat -b)
hili-cat -b file.go

# Squeeze repeated blank lines (like cat -s)
hili-cat -s file.go

# Show line endings with $ marker (like cat -E)
hili-cat -E file.go

# View highlighted file using less for pagination
hili-cat --less file.go

Configuration

The default configuration is stored at /etc/highlight/config.json. A sample configuration is provided in the config directory.

You can create your own configuration file with custom syntax highlighting rules for different languages. The configuration file uses JSON format with the following structure:

{
  "languages": {
    "language-name": {
      "extensions": ["ext1", "ext2"],
      "rules": [
        {
          "name": "rule-name",
          "pattern": "regex-pattern",
          "style": "style-name"
        }
      ],
      "styles": {
        "style-name": "color-name"
      }
    }
  }
}

Available styles include:

• Text styles: bold, italic, underline
• Colors: black, red, green, yellow, blue, magenta, cyan, white
• Bright colors: brightblack, brightred, brightgreen, brightyellow, brightblue, brightmagenta, brightcyan, brightwhite

Architecture

The highlight tool uses a highly efficient two-goroutine pipeline design:

1. Reader Goroutine: Handles file I/O or stdin using low-level syscalls for maximum performance
2. Highlighter Goroutine: Processes the data and applies syntax highlighting using regex-based rules

This pipeline approach allows for efficient streaming of data, even with large files, minimizing memory usage while maintaining high performance.

Data Flow:

┌─────────┐     ┌─────────────┐     ┌───────────┐
│ Input   │────▶│ Buffered    │────▶│ Output    │
│ Source  │     │ Channel     │     │ (Stdout)  │
└─────────┘     └─────────────┘     └───────────┘
    │                                    ▲
    │                                    │
    ▼                                    │
┌──────────┐                        ┌─────────────┐
│ Reader   │                        │ Highlighter │
│ Goroutine│                        │ Goroutine   │
└──────────┘                        └─────────────┘

Options

• --config: Path to the configuration file (default: /etc/highlight/config.json)
• --lang: Language for syntax highlighting (required when reading from stdin)
• --line-ending: Line ending to use (auto, lf, crlf, default: auto)
• -n, --number: Number all output lines
• -b, --number-nonblank: Number non-blank output lines
• -s, --squeeze-blank: Suppress repeated empty output lines
• -E, --show-ends: Display $ at end of each line
• --less, --pager: Pipe output to less -R command for paged viewing
• --help: Show help message

Performance Considerations

highlight is designed with performance as a primary goal:

• Buffered I/O: Uses efficient buffer sizes for optimal read/write performance
• Regexp Optimization: Precompiles regex patterns to minimize CPU usage
• Memory Management: Minimizes allocations to reduce GC overhead
• Syscall Usage: Direct syscall usage for file operations instead of higher-level abstractions
• Channel Buffering: Properly sized channels to prevent blocking in the pipeline

Examples

Basic Usage

# Highlight a Go file with automatic language detection
highlight main.go

Piping from stdin

# Pipe the output of git diff into highlight for colored diff output
git diff | highlight --lang diff

Use in scripts

# Use highlight in a script to show syntax-highlighted output
#!/bin/bash
echo "Displaying highlighted code:"
highlight --lang go main.go

Running the Demo

The project includes a demo script that showcases the key features of the highlight tool:

# Make the demo script executable
chmod +x demo.sh

# Run the demo
./demo.sh

The demo will:

1. Build the highlight tool if needed
2. Show syntax highlighting for Go and JSON files
3. Demonstrate line numbering
4. Show how to use highlight with piped input
5. Display line endings
6. Demonstrate highlighting multiple files

Contributing

Contributions are welcome! Here are some areas where help is needed:

1. Adding support for more programming languages
2. Performance optimizations
3. Additional formatting options
4. Bug fixes and test improvements

For detailed information on how to contribute, please read the Contributing Guide.

Language Configuration

hili-cat is designed to be easily extended with support for additional programming languages. To learn how to add support for your favorite language, see the Language Configuration Guide.

Release Process

The project uses GitHub Actions to automate builds:

• Tag pre-release0.0.1 and any version with v* prefix triggers automatic builds
• Linux builds are automatically created and attached to GitHub releases
• See the workflow file in .github/workflows/linux-build.yml for details

License

See the LICENSE file for details.