compiler construction - LL1 grammar in compiling -



compiler construction - LL1 grammar in compiling -

i have question ll1 grammar. if have grammar this:

<s>::=<a> <a>::=<a> auto cat | epsilon

what first <a> can be? epsilon? , if epsilon, language not ll1! confused...

first(a) = {epsilon, car}

if non-terminal , : α production, add together first( ). if : epsilon production, add together epsilon first( ).

if : α1 α2 α3 ... αm production, add together first( α1 ) first( ). if α1 derives epsilon, add together first( α2 ) first( ). if both α1 , α2 derive epsilon, add together first( α3 ) first( ), , on.

compiler-construction programming-languages

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