Calculator

Console application, that receives a string expression as an input and performs calculation in 4 steps:

1. Tokenizer - splits input string into array of tokens (digits, operators and braces).
2. Parser - using visitor pattern parses each token into specific token value (Digit, Sum, etc.), checks whether all tokens are valid.
3. Sorter - sorts an array of token values into Reverse Polish Notation.
4. Gardener - creates an expression tree, checks whether initial string was valid (each operator has exactly 2 operands). The result expression can be calculated by calling a single method Calculate().

Example

//Input string 
11*3-(19+5)/2

1. Array of tokens

["11", "*", "3", "-", "(", "19", "+", "5", ")", "/", "2"]

2. Array of token values

[  
    Digit("11"),   
    Multiply("*"),   
    Digit("3"),   
    Substraction("-"),   
    LeftBrace("("),   
    Digit("19"),   
    Sun("+"),   
    Digit("5"),   
    RightBrace(")"),   
    Division("/"),   
    Digit("2")  
]

3. Array of token values sorted in RPN

[  
    Digit("11"),   
    Digit("3"),   
    Multiply("*"),   
    Digit("19"),   
    Digit("5"),   
    Sun("+"),   
    Digit("2"),  
    Division("/"),   
    Substraction("-")  
]

4. Expression tree