Examples of LL(1), LR(1), LR(0), LALR(1) grammars?
Examples from wikipedia LL(1) grammar S -> F S -> ( S + F ) F -> a input ( a + a ) parsing steps S -> “(” S “+” F “)” -> ( “F” + F ) -> ( “a” + F ) -> ( a + “a” ) LR(0) grammar (1) E … Read more
ll
How to identify whether a grammar is LL(1), LR(0) or SLR(1)?
To check if a grammar is LL(1), one option is to construct the LL(1) parsing table and check for any conflicts. These conflicts can be FIRST/FIRST conflicts, where two different productions would have to be predicted for a nonterminal/terminal pair. FIRST/FOLLOW conflicts, where two different productions are predicted, one representing that some production should be … Read more
Difference between an LL and Recursive Descent parser?
LL is usually a more efficient parsing technique than recursive-descent. In fact, a naive recursive-descent parser will actually be O(k^n) (where n is the input size) in the worst case. Some techniques such as memoization (which yields a Packrat parser) can improve this as well as extend the class of grammars accepted by the parser, … Read more
What is the difference between LL and LR parsing?
At a high level, the difference between LL parsing and LR parsing is that LL parsers begin at the start symbol and try to apply productions to arrive at the target string, whereas LR parsers begin at the target string and try to arrive back at the start symbol. An LL parse is a left-to-right, … Read more