Arithmetic Expression Parser and Calculator

A command-line calculator that parses and evaluates mathematical expressions with support for advanced operations and error handling.

Features

• Basic arithmetic operations (+, -, *, /)
• Power operator (^)
• Unary minus support
• Parentheses handling
• Error detection for:
  • Invalid characters
  • Mismatched brackets
  • Division by zero
  • Empty input
• Reverse Polish Notation (postfix) conversion

Dependencies

• C++11 compatible compiler
• CMake (>= 3.20)

Project Structure

.
├── CMakeLists.txt      - Build configuration
├── main.cpp            - Main entry point and I/O handling
└── expressions.hpp     - Core parsing and calculation logic
    ├── Lexeme         - Token representation
    ├── parse()        - Input validation and tokenization
    ├── postfixForm()  - Shunting-yard algorithm
    └── countUp()      - Postfix expression evaluation

Implementation Details

• Lexer: Converts input string to tokens with type and priority
• Parser: Validates token sequence and detects errors
• Shunting-yard Algorithm: Converts infix to postfix notation
• Stack Machine: Evaluates postfix expressions
• Supports operator precedence:
  • Parentheses
  • Exponentiation (^)
  • Unary minus
  • Multiplication/Division
  • Addition/Subtraction

Error Handling

Examples of caught errors:

input expression: 2++3
incorrect input: error with parsing

input expression: 2/(5-5)
incorrect input: can't divide to 0

input expression: 2+(3*4
incorrect input: invalid brackets