update prolog_parser version, allow ('|') operator in DCGs (#274)

src/prolog/machine/term_expansion.rs

@@ -12,31 +12,6 @@ use std::io::Read;
 use std::iter::Rev;
 use std::vec::IntoIter;
 
-fn unfold_by_str_once(term: &mut Term, s: &str) -> Option<(Term, Term)> {
-    if let &mut Term::Clause(_, ref name, ref mut subterms, _) = term {
-        if name.as_str() == s && subterms.len() == 2 {
-            let snd = *subterms.pop().unwrap();
-            let fst = *subterms.pop().unwrap();
-
-            return Some((fst, snd));
-        }
-    }
-
-    None
-}
-
-pub fn unfold_by_str(mut term: Term, s: &str) -> Vec<Term> {
-    let mut terms = vec![];
-
-    while let Some((fst, snd)) = unfold_by_str_once(&mut term, s) {
-        terms.push(fst);
-        term = snd;
-    }
-
-    terms.push(term);
-    terms
-}
-
 pub fn fold_by_str<I>(terms: I, mut term: Term, sym: ClauseName) -> Term
 where
     I: DoubleEndedIterator<Item = Term>,