nano-colour - colouring files using nanorc definitions

This repository provides a Perl-based syntax highlighter that leverages nanorc configuration files to provide ANSI-coloured output in the terminal, or HTML and SVG output for post-processing.

Purpose

The primary tool in this repository is nano-colour. It was designed to bring nano-style syntax highlighting to the command line, allowing you to view highlighted source code directly in your terminal or pipe it to other tools.

Features

• Syntax Auto-discovery: Automatically selects the correct highlighting rules based on the file extension.
• Support for nanorc Syntax: Parses standard nanorc files, supporting:
  • Single-line regex rules (color, icolor).
  • Multi-line rules (start="..." end="...").
  • Foreground and background color combinations.
  • bright color modifiers.
• Multiple Output Formats:
  • ANSI terminal colouring by default.
  • HTML with CSS classes for later restyling.
  • SVG with classed text spans and background rectangles.
• Flexible Input:
  • Highlights files by name.
  • Supports reading from STDIN (when syntax is specified).
• Customizable Syntax Path: Uses the NANOCOLOUR_DIR environment variable to locate highlighting definitions.

Installation

The nano-colour script is a standalone Perl script. Ensure you have Perl installed on your system.

# Add the script to your path or run it directly
chmod +x nano-colour

Usage

Basic Usage

To highlight a file, provide the filename and the directory containing .nanorc files:

./nano-colour myfile.pl examples/

Using Environment Variables

You can set NANOCOLOUR_DIR to avoid passing the directory every time:

export NANOCOLOUR_DIR=$(pwd)/examples
./nano-colour myfile.pl

Specifying Syntax Manually

Use the -s or --syntax option to force a specific highlighting scheme:

./nano-colour -s perl myfile.txt

Highlighting from STDIN

When a syntax is forced, nano-colour can read from standard input:

cat myfile.pl | ./nano-colour -s perl

Emitting HTML

Use --html to produce a wrapper <div> and a style block. The generated output uses classes such as nanocolour-fg-red and nanocolour-bg-blue, so you can restyle the output later:

./nano-colour --html myfile.pl examples/ > myfile.html

Emitting SVG

Use --svg to produce an SVG document with the same colour classes:

./nano-colour --svg myfile.pl examples/ > myfile.svg

Testing

Run the repository checks with:

./tests/run.sh

GitHub Actions runs the same command for pushes and pull requests.

Examples

The examples/ directory contains a variety of nanorc definitions for popular formats, including:

• Bash, C, HTML, JavaScript, JSON, Lua, Makefile, Markdown, Perl, Python, XML, YAML, and even nanorc itself.

License

This project is licensed under the MIT License.