RPN Calculator is a CLI implementation of a Reverse Polish Notation Calculator. Reverse Polish Notation reads mathematical expressions from right to left such that paranthesis are not required.
4 2 + is equivelant to 4 + 2
3 2 + 4 * is equivelant to (3 + 2) * 4
4 5 2 3 * + - is equivelant to 4 - (5 + (2 * 3))
perfectly readable :)
I decided to create the application in javascript because I felt it would the most entertaining. I primarily use Typescript and don't usually play around with vanilla javascript too much so I had fun with it.
I structured the application to contain two modules: calculator and a calcreader. The calc-reader would accept a calculator module. The calculator needed to be a seperate module simply because its more business logic versus the calc-reader's interface responsibilities.
I left some //TODO items in case I ever use this as an example for another project or task in regards to input type. The requirements stated to be 'prepared' for alternative inputs (file, tcp, etc). I didn't necessary prepare for them, more made notes on where I would place that logic if the need every arose. Besides that, I wasn't able to test Ctrl+D since I'm on a windows machine; here's hoping the close clause covers it.
If I were to do anything differently, I would have created my tests first. I keep dreaming of the day I'd be a test-driven developer but the situation rarely allows it during my day to day. (Not a lot of infastructures are prepared for that kind of dev-time).
If I were to spend additional time on this project I'd likely add more features, like calculator options (choosing from infix or prefix notations), a few more expressions (% ^ ++ --) and probably include a history feature and a clear feature in the reader so the app doesn't have to be restarted.
npm i - to ensure all dependencies are installed
npm test - to run jest test cases
npm start - to begin the application
At the start of the application you will be prompted to begin input ( > )
Supported arithmatic includes + , - , * , /
Quick commands while in app
-
qwill quit the application -
swill show the current math stack