README: Math Expr Evaluator

Brief:

An arithmetic expression evaluator written in C++. It uses a recursive descent parser & AST approach for basic syntax checking and later support for additional syntax if needed.

Grammar:

; Some tokens!
whitespace ::= (SP | TAB | CR | LF)+
number ::= (DIGIT | ".")+
operators ::= "+" | "-" | "*" | "/"

; Note: Start parsing from lower precedence and descend to tighter binding precedence rule if needed!
expr ::= term
term ::= factor (("+" | "-") factor)*
factor ::= power (("*" | "/") power)*
power ::= unary ("^" unary)*
unary ::= ?("-") number | "(" expr ")"

Some extras:

• I must add parenthesis support soon. DONE
• Add a REPL for expressions? DONE
• Make error messages more detailed?