Calculator-CLI

A powerful command-line calculator with VI-style navigation and advanced arithmetic capabilities.

Features

• VI-Style Navigation: Familiar vim-like commands for a better terminal experience
• Advanced Expression Parsing: Handle complex mathematical expressions in a single line
• Command History: Easily access and reuse previous calculations
• Operator Precedence: Correctly handles mathematical order of operations
• Error Handling: Clear error messages for invalid expressions and division by zero

Requirements

• Operating System: Unix-like OS (tested on macOS and Linux)
• Crystal Version: 1.0 or higher

Installation

1. Clone the Repository:

git clone https://github.com/evilenx/calculator-cli

2. Navigate to the Repository:

cd calculator-cli

3. Build the Program:

crystal build src/calculator-cli.cr

Usage

Run the calculator:

./calculator-cli

Navigation Commands

The calculator starts in insert mode and supports the following VI-style commands:

• ESC - Enter normal mode
• i - Enter insert mode
• k - Previous command (in normal mode)
• j - Next command (in normal mode)
• :q - Quit calculator

Expression Syntax

• Supports basic arithmetic operations: +, -, *, /, ^ (power)
• Handles floating-point numbers
• Respects operator precedence
• Allows spaces between numbers and operators

Examples

> 2 + 2
2 + 2 = 4.0

> 3 * 4 + 5
3 * 4 + 5 = 17.0

> 10 / 2 + 3 * 4
10 / 2 + 3 * 4 = 17.0

> 2 ^ 3 + 1
2 ^ 3 + 1 = 9.0

Using History

1. Type a calculation and press Enter
2. Press ESC to enter normal mode
3. Use k to scroll back through previous calculations
4. Use j to scroll forward
5. Press i to modify the selected calculation
6. Press Enter to execute

Features in Detail

Expression Parsing

• Handles both simple and complex expressions
• Supports operator precedence following mathematical rules
• Properly manages spaces between numbers and operators
• Validates input for correct mathematical syntax

VI Navigation

• Familiar to vim users
• Efficient command history access
• Quick editing capabilities
• Mode-based operation (insert/normal)

Error Handling

• Clear error messages for:
• Invalid expressions
• Division by zero
• Malformed numbers
• Unknown operators

Contributing

Contributions are welcome! Feel free to:

• Report bugs
• Suggest new features
• Submit pull requests
• Improve documentation

License

This project is licensed under the MIT License - see the LICENSE file for details.

Changelog

v0.2.0

• Added VI-style navigation
• Improved expression parsing
• Added operator precedence
• Enhanced error handling
• Added command history

v0.1.0

• Initial release
• Basic arithmetic operations
• Simple command-line interface