I'm currently having a look at GNU Bison to parse program code (or actually to extend a program that uses Bison for doing that). I understand that Bison can only (or: best) handle LR(1) grammars, i.e. a special form of context-free grammars; and I actually also (believe to) understand the rules of context-free and LR(1) grammars.
However, somehow I'm lacking a good understanding of the notion of a LR(1) grammar. Assume SQL, for instance. SQL incorporates - I believe - a context-free grammar. But is it also a LR(1) grammar? How could I tell? And if yes, what would violate the LR(1) rules?
LR(1) means that you can choose proper rule to reduce by knowing all tokens that will be reduced plus one token after them. There are no problems with AND in boolean queries and in BETWEEN operation. The following grammar, for example is LL(1), and thus is LR(1) too:
expr ::= and_expr | between_expr | variable
and_expr ::= expr "and" expr
between_expr ::= "between" expr "and" expr
variable ::= x
I believe that the whole SQL grammar is even simpler than LR(1). Probably LR(0) or even LL(n).