diff options
| -rw-r--r-- | src/nibble/mod.rs | 48 |
1 files changed, 31 insertions, 17 deletions
diff --git a/src/nibble/mod.rs b/src/nibble/mod.rs index 478580a..3fad97b 100644 --- a/src/nibble/mod.rs +++ b/src/nibble/mod.rs @@ -267,14 +267,21 @@ impl Convert for Cat { fn convert(self, context: &Context) -> ast::Term { use ast::Term; let mut iter = self.terms.into_pairs(); - let init = match iter.next_back().unwrap() { - Pair::Punctuated(_, _) => unreachable!(), - Pair::End(t) => t.convert(context), + let init = match iter.next().unwrap() { + Pair::Punctuated(t, p) => Ok((t.convert(context), p)), + Pair::End(t) => Err(t.convert(context)), }; - iter.rfold(init, |term, pair| match pair { - Pair::Punctuated(t, p) => Term::Cat(ast::Cat::new(t.convert(context), p, term)), - Pair::End(_) => unreachable!(), - }) + iter.fold(init, |term, pair|{ + let (fst, punct) = term.unwrap(); + match pair { + Pair::Punctuated(t, p) => { + Ok((Term::Cat(ast::Cat::new(fst, punct, t.convert(context))), p)) + } + Pair::End(t) => { + Err(Term::Cat(ast::Cat::new(fst, punct, t.convert(context)))) + } + } + }).unwrap_err() } } @@ -312,16 +319,23 @@ impl Parse for Alt { impl Convert for Alt { fn convert(self, context: &Context) -> ast::Term { - use ast::Term; - let mut iter = self.cats.into_pairs(); - let init = match iter.next_back().unwrap() { - Pair::Punctuated(_, _) => unreachable!(), - Pair::End(t) => t.convert(context), - }; - iter.rfold(init, |term, pair| match pair { - Pair::Punctuated(t, p) => Term::Alt(ast::Alt::new(t.convert(context), p, term)), - Pair::End(_) => unreachable!(), - }) + use ast::Term; + let mut iter = self.cats.into_pairs(); + let init = match iter.next().unwrap() { + Pair::Punctuated(t, p) => Ok((t.convert(context), p)), + Pair::End(t) => Err(t.convert(context)), + }; + iter.fold(init, |cat, pair|{ + let (left, punct) = cat.unwrap(); + match pair { + Pair::Punctuated(t, p) => { + Ok((Term::Alt(ast::Alt::new(left, punct, t.convert(context))), p)) + } + Pair::End(t) => { + Err(Term::Alt(ast::Alt::new(left, punct, t.convert(context)))) + } + } + }).unwrap_err() } } |