RPN Calculator with WebAssembly

A React-based Reverse Polish Notation (RPN) calculator that uses C++ compiled to WebAssembly for high-performance mathematical expression evaluation.

Features

• Infix to Postfix Conversion: Convert standard mathematical expressions to RPN format
• WebAssembly Powered: C++ core compiled to WASM for optimal performance
• Real-time Calculation: Instant expression evaluation
• Modern UI: Clean, responsive React interface with Tailwind CSS
• Cross-platform: Works in any modern web browser

Prerequisites

• Windows: Chocolatey package manager
• Emscripten SDK: For compiling C++ to WebAssembly
• Node.js: Version 16 or higher
• npm or yarn: Package manager

Installation

1. Install Emscripten

Windows (using Chocolatey):

# Run as Administrator
choco install emscripten

Alternative Emscripten Installation:

# Clone and setup Emscripten SDK
git clone https://github.com/emscripten-core/emsdk.git
cd emsdk
emsdk install latest
emsdk activate latest
emsdk_env.bat

2. Verify Emscripten Installation

em++ -v

3. Compile C++ to WebAssembly

# Navigate to your project directory and run:
em++ src/util/rpn-calc.cpp -O3 -o src/util/out/rpn.js -s EXPORT_NAME=createRPNModule -s MODULARIZE=1 -s EXPORT_ES6=1 -s USE_ES6_IMPORT_META=0 -s "EXPORTED_FUNCTIONS=['_calculate','_formatInfix','_toPostfix','_evaluatePostfix']" -s "EXPORTED_RUNTIME_METHODS=['ccall','cwrap']"

4. Install Dependencies

npm install

5. Start Development Server

npm run dev

Project Structure

rpn-calc/
├── src/
│   ├── util/
│   │   ├── rpn-calc.cpp    # C++ RPN implementation
│   │   └── out/
            |__ rpn.js          # Compiled WebAssembly module
│   ├── App.jsx             # Main React component
│   └── main.jsx            # React entry point
├── index.html
├── package.json
└── vite.config.js

Build Commands

Development

npm run dev

Production Build

npm run build

Preview Production Build

npm run preview

Available Functions

The WebAssembly module exposes the following C++ functions:

• calculate(expression): Directly evaluate infix expression
• formatInfix(expression): Format and validate infix expression
• toPostfix(expression): Convert infix to postfix notation
• evaluatePostfix(expression): Evaluate postfix expression

Usage Examples

Enter expressions in standard mathematical notation:

• 4 + 7 / 2
• (3 + 4) * 2
• 10 - 3 * 2 + 1

The calculator will display:

• Formatted Infix: Properly spaced expression
• Postfix: RPN notation
• Result: Calculated value

Recompiling C++ Code

When you modify rpn-calc.cpp, recompile with:

em++ src/util/rpn-calc.cpp -O3 -o src/util/rpn.js -s EXPORT_NAME=createRPNModule -s MODULARIZE=1 -s EXPORT_ES6=1 -s USE_ES6_IMPORT_META=0 -s "EXPORTED_FUNCTIONS=['_calculate','_formatInfix','_toPostfix','_evaluatePostfix']" -s "EXPORTED_RUNTIME_METHODS=['ccall','cwrap']"

Emscripten Flags Explained

• -O3: Maximum optimization
• -s EXPORT_NAME=createRPNModule: Names the module factory
• -s MODULARIZE=1: Enables module pattern
• -s EXPORT_ES6=1: Generates ES6 module format
• -s USE_ES6_IMPORT_META=0: Compatibility with build tools
• EXPORTED_FUNCTIONS: C++ functions exposed to JavaScript
• EXPORTED_RUNTIME_METHODS: Emscripten helper functions

Troubleshooting

Common Issues:

1. "Module not found" errors

   • Verify Emscripten installation
   • Check file paths in compilation command

2. WebAssembly loading failures

   • Ensure rpn.js and rpn.wasm are in correct location
   • Check browser console for specific errors

3. Compilation errors

   • Run em++ -v to verify Emscripten installation
   • Check C++ code for syntax errors

Browser Compatibility

• Chrome 57+
• Firefox 52+
• Safari 11+
• Edge 16+

License

MIT License - feel free to use this project for learning and development.

Contributing

1. Fork the project
2. Create your feature branch
3. Commit your changes
4. Push to the branch
5. Open a Pull Request

---

Happy Calculating!