Re: Question about lexing
@5, I tried using a set of regular expressions using std::regex:
[_a-zA-Z][_a-zA-Z0-9]+ for identifiers;
[1-9]\d* for integers; and
[-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)? for reals
Problem is the last one. My professor gives the following regular expressions for each item:
Word { L ( L | D ) * }
Integer { D+ }
Real { D*.D+ | (D*.D+ (E | e) (((+| -)DDD)|DDD) }
Special { , | ( | ) | [ | ] | ; | < | > | * | / | + | - | = }Obviously, the _ in the regular _expression_ for identifiers is not within this list, but I added it because its pretty standard for any language to allow underscores in identifiers, and I don't know a language that doesn't. My first thoughtfor the special characters one was to do something like [,()\[\];<>*/+-=], but I'm not sure if that's the most accurate _expression_. I'm doing this with std::regex, but I've never used it before, so this is a new learning experience for me. I'm just happy that the STL finally includes that functionality, clunky as it might be.
Edit: also, std::variant is... Kinda nice, I guess. I suspect its a lot bulkier than normal unions though.
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