simple parser math string

Parse string to C# Expression Tree

Unary operations: +, - Binary operations with priority: +,-,*,/
Expression in brackets.
Built-in function (case insensitive): sin, cos, exp

For binary operations, (except +,-) and functions available prefix, infix, postfix notation

In case + and - operations: in prefix notation identify as unary, infix and postfix - work as expected