TeX-Formatter

Python script that automatically formats .tex files based on my somewhat opinionated formatting style. It formats LaTeX source code by applying a series of indentation passes. Each pass handles a specific LaTeX construct (e.g., environments, chapters, sections, subsections, subsubsections) by adjusting the indentation level based on the hierarchy so that the content is nested and visually easier to find.

Functionality

The script organizes indentation in five progressive stages, each corresponding to a different structural element in a LaTeX document. It begins with environments such as those defined by \begin{...} and \end{...}. When the script encounters a \begin, the indentation level increases, and it decreases again at the matching \end.

Chapters are handled next. Whenever a \chapter command appears, the lines that follow are indented more deeply, and that indentation continues until another structural command such as a new chapter or section appears, or until the document ends. Sections work the same way, introducing indentation that lasts until another major marker is found.

The pattern continues with subsections. After a \subsection command, the script applies indentation until a new chapter, section, or subsection is reached, or until the document closes. Finally, the smallest recognized unit is the subsubsection. Content beneath a \subsubsection line is indented until the script encounters another chapter, section, subsection, or subsubsection, at which point the indentation level resets.

In effect, each level of document structure deepens the indentation, and the script adjusts automatically as the text rises back out of those nested structures. adjusts automatically as the text rises back out of those nested structures.

Installation

Command Line Interface

The command line interface requires only Python 3.7+ and uses only standard library modules. No additional installation is needed:

python3 texformatter.py file.tex

Web Interface

For the web interface, you need to install Flask and its dependencies:

pip install -r requirements.txt

This installs:

• Flask 3.1.2
• Required dependencies (Werkzeug, Jinja2, etc.)

Usage

Command Line Interface

To use the script, run it from the command line with the LaTeX file you want to format as an argument:

python3 texformatter.py file.tex

By default, the script prints the formatted output to stdout. To modify the file in place, use the -i or --in-place flag:

python3 texformatter.py -i file.tex
python3 texformatter.py --in-place file.tex

Web Interface

TeX-Formatter includes a modern web interface for easy online formatting.

Quick Start:

1. Install dependencies: pip install -r requirements.txt
2. Start the server: python3 app.py
3. Open your browser to http://localhost:8080

Features:

• Clean, minimalistic design with a warm coffee shop theme
• Two large text areas for easy paste-and-format workflow
• Multiple indentation options (4 spaces, 2 spaces, or tabs)
• Copy to clipboard functionality
• Responsive design for desktop and mobile
• Keyboard shortcuts:
  • Ctrl+Enter (Cmd+Enter on Mac): Format the code
  • Ctrl+Shift+C (Cmd+Shift+C on Mac): Copy formatted code

API Endpoint:

The web interface exposes a REST API endpoint:

POST /format

• Content-Type: application/json
• Body: {"latex_code": "your code here", "indent_str": " "}
• Response: {"formatted_code": "formatted result"} or {"error": "error message"}

Example using curl:

curl -X POST http://localhost:8080/format \
  -H "Content-Type: application/json" \
  -d '{"latex_code": "\\begin{document}\nHello\n\\end{document}", "indent_str": "    "}'

Technical Details:

The web interface is built using:

• Backend: Flask (Python web framework)
• Frontend: Vanilla HTML, CSS, and JavaScript
• Styling: Custom CSS with CSS Grid and Flexbox
• Typography: System fonts with monospace for code areas

Troubleshooting:

Server won't start:

• Check that Python 3.7+ is installed: python3 --version
• Ensure Flask is installed: pip list | grep Flask
• Check if port 8080 is already in use

Formatting errors:

• Verify your LaTeX code syntax
• Check browser console for JavaScript errors
• Look at the Flask server logs for detailed error messages

Browser compatibility:

• Modern browsers (Chrome 60+, Firefox 55+, Safari 12+, Edge 79+)
• JavaScript must be enabled
• Cookies are not required

Development:

File Structure:

├── app.py                     # Flask application entry point
├── texformatter.py            # CLI entry point
├── src/
│   ├── app.py                 # Flask application logic
│   └── texformatter.py        # Core formatting logic
├── test/
│   └── test_texformatter.py   # Unit tests
├── examples/
│   ├── simple_document.tex    # Sample LaTeX document
│   ├── test_document.tex      # Test document with various features
│   └── environments_test.tex  # Environment testing document
├── templates/
│   └── index.html             # Main page template
├── static/
│   ├── style.css              # Stylesheet
│   └── script.js              # JavaScript functionality
└── requirements.txt           # Python dependencies

You can customize the web interface by:

• Modifying static/style.css for appearance
• Updating static/script.js for functionality
• Editing templates/index.html for layout
• Adjusting src/app.py for server behavior

The core formatting logic is in src/texformatter.py and is shared between the CLI and web interface.