Added web app demo

[sidi762]

Added a new web app demo

Work in Progress

Todo:

• Implement execution time limit (maybe also memory limit?) to prevent infinite loops and attacks

Add Web Interface for Nasal Interpreter

This PR adds a web-based interface for the Nasal Interpreter, allowing users to write and execute Nasal code directly in their browser.

Implementation

Web Interpreter

• Added Node.js web server using Express
• Created C++ bindings using ffi-napi to interface with the Nasal interpreter
• Implemented nasal-web shared library for interpreter integration
• Used CodeMirror for the code editor
• Added proper error handling and output capturing
• Implemented ANSI color code conversion for error messages

Web REPL

• Interactive command-line style interface in the browser
• Multi-line input support with proper prompts (>>> and ...)
• Command history navigation (up/down arrow keys)
• Error handling with formatted error messages
• Example snippets for quick testing
• Clear screen functionality
• Auto-resizing input field

Files Added/Modified

• /nasal-web-app/ - New directory containing the web application
  • server.js - Express server implementation
  • server_repl.js - REPL server demo
  • public/index.html - Main web interface
  • public/repl.html - REPL UI
  • public/repl.js - REPL implementation
  • package.json - Node.js dependencies
• src/nasal_web.cpp - C++ bindings for the Nasal interpreter
• src/nasal_web.h - Header file for C++ bindings
• CMakeLists.txt - Updated to build the shared library
• .gitignore - Updated for Node.js and web app files

Build Instructions

1. Build the Nasal shared library:

cmake -DBUILD_SHARED_LIBS=ON .
make nasal-web

2. Set up and run the web application:

Web Interpreter

cd nasal-web-app
npm install
node server.js

and visit

http://127.0.0.1:3000/

Web REPL

cd nasal-web-app
npm install
node server_repl.js

and visit

http://127.0.0.1:3001/repl.html