Reverse Polish Notation Calulator

RPN calculator (Command-line)

Introduction

The reverse polish notation calculator has a stack that can contain real numbers.

Requirements

• The calculator waits for user input and expects to receive strings containing whitespace separated lists of numbers and operators.

• Numbers are pushed on to the stack. Operators operate on numbers that are on the stack.

• Operators pop their parameters off the stack, and push their results back onto the stack.

• Available operators are +, -, *, /, sqrt, undo, clear.

  • The clear operator removes all items from the stack.
  • The undo operator undoes the previous operation. undo undo will undo the previous two operations.
  • sqrt performs a square root on the top item from the stack.
  • The +, -, *, / operators perform addition, subtraction, multiplication and division respectively on the top two items from the stack.

• After processing an input string, the calculator displays the current contents of the stack as a space-separated list.

• Numbers should be stored on the stack to at least 15 decimal places of precision, but displayed to 10 decimal places (or less if it causes no loss of precision).

• All numbers should be formatted as plain decimal strings (ie. no engineering formatting).

• If an operator cannot find a sufficient number of parameters on the stack, a warning is displayed: operator <operator> (position: <pos>): insufficient parameters

  After displaying the warning, all further processing of the string terminates and the current state of the stack is displayed.

Compile, Test, Run and Packaging

• Compile: mvn compile

• Test: mvn test

• Run: mvn exec:java

• Packaging: mvn package, compiled jar in target/ folder

Script Files

• run_build.sh: clean, compile and run unit testing

• run_deploy_local: clean, compile, run unit testing and deploy the jar file to a local folder

• run_deploy_remote: clean, compile, run unit testing and deploy the jar file to a remote target

TODO

• Use docker to build and deploy automatically to support CI and CD

• Use annotation to simplify the system. Here is an example:

   @Operator(token="+", name="Add", execType=OperatorExecType.oetMathOpOne, description="Add(x,y) = x + y")
   public double add(double x, double y) {
    return x + y;
   }
   
  

• Consider using Spring Boot to leverage DI, AOP

Author

Terry Wu E-mail: wutz2000@163.com