Write a recursive descent parser for this grammar:
A ::= Id "(" B ")"
B ::= Id | Id "," B

where Id ::= [a-ZA-Z]+

My question is, how to do I implement the ID?

parseId(){
accept('a' | 'b' | ... 'Z')+ [?]
}

parseB(){
parseId();
case(,):
parseB();
}

parseA(){
parseId();
accept( '(' );
parseB();
accept( ')' );
}

Thanks!

Question

Write a recursive descent parser for this grammar: 
A ::= Id "(" B ")"
B ::= Id | Id "," B

where Id ::= [a-ZA-Z]+

My question is, how to do I implement the ID?

parseId(){
    accept('a' | 'b' | ... 'Z')+ [?]
}

parseB(){
    parseId();
    case(,):
        parseB();
}

parseA(){
    parseId();
    accept( '(' );
    parseB();
    accept( ')' );
}

Thanks!

anonymous · Answer

Usually, terminal symbols like Id are handled by the lexer that's transforming your source file into tokens.

If you want to do that with a parser, you'll need to change it a bit, I guess. Try parsing something like this:

char ::= [a-zA-Z]
Id ::= char | char Id