Project I did as a part of Hyperskill course Kotlin Basics.
Simple integer calculator.
It normalizes, tokenizes, converts infix notation to RPN and calculates the result.
Normalization performs following replacements:
- whitespace removal
- multiple
+reduce to single one - odd number of
-reduce to single one - even number of
-reduce to+ -+and+-reduce to-
Infix to RPN notation conversion is handled by modified Dijkstra's Shunting Yard Algorithm. Standard described algorithm doesn't handle unary minus operator.
Handles following operations:
- addition
+
> 2+2
4
- subtraction
-
> 2-2
0
- multiplication
*
> 2*2
4
- integer division
/
> 2/2
1
- exponentiation
^
> 2^3
8
- parentheses
(,)
> (2+2)*2
8
- negation (unary operator)
-
> -5+1
-4
- neutral plus (unary operator)
+
> +5
5
- variable assignments of numbers and expressions
=
> n=5
> n
5
> b=n+5
> b
10
It implements Strategy pattern to handle different commands by separate command implementations.
When imported into IntelliJ IDEA it should just work. If not, Build -> Rebuild project.
Any comments, pull requests, issue tickets appreciated. I'm particularly interested in build improvement and tests.