CLI RPN Calculator

Command-line (CLI) Reverse Polish Notation (RPN) calculator using ruby language.

Features

• The calculator uses standard ruby input STDIN and standard output STDOUT.
• Four standard arithmetic operators: addition +, multiplication *, subtraction -, division /.
• The calculator exit when it receives a q command or an end of input indicator (EOF / Ctrl+D).
• The calculator returns information when it receives a i.
• The calculator returns welcome message when it receives a w.
• The calculator returns returns link to wikipedia when it receives a ?.
• The calculator returns stack when it receives a s.
• The calculator clears the stack when it receives a c.

Installation

Clone this GitHub repository:

$ git clone [email protected]:maxsuhak/cli_rpn_calculator.git

System Requirements

This application requires ruby-2.6.6 to be installed.

Setup

Setup this application locally:

$ bundle install

Testing

Test this application locally:

$ rspec spec

Note: All 82 tests should be passed.

Usage

There are three ways to run the RPN calculator:

Rake Task

$ rake console

Ruby Script

$ ruby start.rb

Docker

$ docker-compose run app

Sample

Welcome to the CLI RPN Calculator!
Press 'i' for instructions on use.
Press '?' for a link to more info about RPN.
Press 's' to see the current stack.
Press 'c' to clear the current stack.
Press 'w' to repeat this welcome message.
Press 'q' to quit.
> 5
5.0
> 8
8.0
> +
13.0
> q
Calculation terminated. Goodbye!

Technical / architectural choices

• Created a command-line (CLI), Reverse Polish Notation (RPN) calculator for people who are comfortable with UNIX-like CLI utilities.
• Followed gem similar standard structure of code organization for future rebuilding the code into gem uses tty.
• Classes abide by the Single Responsibility Principle.
• Implemented 4 basic operators, 6 commands and a standard IO interface.
• A standard IO interface IOProviders::Base is built with extension to new, IO-like interfaces, class IOProviders::Console has been extracted.
• There are separate operator and command classes.
• Logs are stored and located into tmp/.
• Code is RuboCop consistent.
• Code is well tested for prevent regression used RSpec.
• Configured GitHub workflow actions for prevent regressions.

Folders and files structure:

▾ cli_rpn_calculator/
├── ▾ .github/
│   ├── ▾ workflows/
│   │   └── ruby.yml
│   └── pull_request_template.md
├── ▾ bin/
│   └── boot.rb
├── ▾ lib/
│   ├── ▾ cli_rpn_calculator/
│   │   ├── ▾ commands/
│   │   │   ├── base.rb
│   │   │   ├── check_stack.rb
│   │   │   ├── clear_stack.rb
│   │   │   ├── instructions.rb
│   │   │   ├── welcome_message.rb
│   │   │   └── wikipedia.rb
│   │   ├── ▾ helpers/
│   │   │   ├── file_log.rb
│   │   │   └── tokenizer.rb
│   │   ├── ▾ io_providers/
│   │   │   ├── base.rb
│   │   │   └── console.rb
│   │   ├── ▾ operators/
│   │   │   ├── addition.rb
│   │   │   ├── base.rb
│   │   │   ├── division.rb
│   │   │   ├── multiplication.rb
│   │   │   └── subtraction.rb
│   │   └── cli.rb
│   └── cli_rpn_calculator.rb
├── ▾ spec/
│   ├── ▾ lib/
│   │   ├── ▾ cli_rpn_calculator/
│   │   │   ├── ▾ commands/
│   │   │   │   ├── base_spec.rb
│   │   │   │   ├── check_stack_spec.rb
│   │   │   │   ├── clear_stack_spec.rb
│   │   │   │   ├── instructions_spec.rb
│   │   │   │   ├── welcome_message_spec.rb
│   │   │   │   └── wikipedia_spec.rb
│   │   │   ├── ▾ helpers/
│   │   │   │   ├── file_log_spec.rb
│   │   │   │   └── tokenizer_spec.rb
│   │   │   ├── ▾ io_providers/
│   │   │   │   ├── base_spec.rb
│   │   │   │   └── console_spec.rb
│   │   │   ├── ▾ operators/
│   │   │   │   ├── addition_spec.rb
│   │   │   │   ├── base_spec.rb
│   │   │   │   ├── division_spec.rb
│   │   │   │   ├── multiplication_spec.rb
│   │   │   │   └── subtraction_spec.rb
│   │   │   └── cli_spec.rb
│   │   └── cli_rpn_calculator_spec.rb
│   └── spec_helper.rb
├── ▾ tmp/
│   └── .keep
├── .gitignore
├── .rspec
├── .rubocop.yml
├── .ruby-version
├── docker-compose.yml
├── Gemfile
├── Gemfile.lock
├── Rakefile
├── README.md
└── start.rb

Trade-offs / possible improvements

• Well describe all classes and methods.
• Rebuild the code into gem and store it to RubyGems.org.
• Improve calculator to work with options.
• Create additional IO Interfaces.
• Refactor class CLI.
• Refactor validations.
• Improve errors handling.
• Refactor getting operators and commands list to make it automated.
• Add I18n.
• More test coverage.
• Add gem simplecov for track test coverage.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/maxsuhak/cli_rpn_calculator.