Created
March 4, 2019 19:53
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Pretty print a syntactic tree using prolog.
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| pptree(Term) :- | |
| functor(Term, Name, Arity), | |
| write(Name), | |
| write('('), | |
| pptree_children(Term, 1, Arity, 1). | |
| % prints atomic siblings without last | |
| pptree_children(Term, ChildN, Total, Level) :- | |
| ChildN < Total, | |
| arg(ChildN, Term, Child), | |
| atomic(Child), | |
| !, | |
| write(Child), | |
| write(','), | |
| NextChildN is ChildN + 1, | |
| pptree_children(Term, NextChildN, Total, Level). | |
| % prints last atomic sibling | |
| pptree_children(Term, ChildN, Total, _Level) :- | |
| ChildN =:= Total, | |
| arg(ChildN, Term, Child), | |
| atomic(Child), | |
| !, | |
| write(Child), | |
| write(')'). | |
| % prints non atomic siblings without last | |
| pptree_children(Term, ChildN, Total, Level) :- | |
| ChildN < Total, | |
| arg(ChildN, Term, Child), | |
| functor(Child, Name, Arity), | |
| nl, | |
| Spaces is Level * 2, | |
| NextLevel is Level + 1, | |
| tab(Spaces), | |
| write(Name), | |
| write('('), | |
| pptree_children(Child, 1, Arity, NextLevel), | |
| NextChildN is ChildN + 1, | |
| pptree_children(Term, NextChildN, Total, Level). | |
| % prints last non atomic sibling | |
| pptree_children(Term, ChildN, Total, Level) :- | |
| ChildN =:= Total, | |
| arg(ChildN, Term, Child), | |
| functor(Child, Name, Arity), | |
| nl, | |
| Spaces is Level * 2, | |
| NextLevel is Level + 1, | |
| tab(Spaces), | |
| write(Name), | |
| write('('), | |
| pptree_children(Child, 1, Arity, NextLevel), | |
| write(')'). |
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