% Shift-Reduce-Parsing mit Ausgabe der einzelnen Schritte

brule([vp,np|X], [s|X]).
brule([n,det|X], [np|X]).
brule([v|X], [vp|X]).

brule([Word|X], [Cat|X]) :-
	word(Word, Cat).

word(a, det).
word(man,n).
word(sleeps,v).

reduce(Stack, ReducedStack) :-
	brule(Stack, Stack2),
	write('Aktion: reduce'), nl,
	write('Stapel': Stack2), nl,nl,
	reduce(Stack2, ReducedStack).
reduce(Stack, Stack).


shift(Stack, [W|Rest], [W|Stack], Rest):-
	write('Aktion:shift'), nl,
	write('Stapel' : [W|Stack]),nl,
	write('Eingabekette' : Rest),nl,nl.

shift_reduce([], Stack, Stack).
shift_reduce(String, Stack, Result) :-
	shift(Stack, String, NewStack, NewString),
	reduce(NewStack, ReducedStack),
	shift_reduce(NewString, ReducedStack, Result).