Witch of Git - mukan/blob - src/term.rs

   1 use std::{fmt, sync::Arc};
   2
   3 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
   4 pub struct Var(pub(crate) u32);
   5
   6 #[derive(Clone, PartialEq, Eq)]
   7 pub enum Term {
   8     Var(Var),
   9     Pair(Arc<Term>, Arc<Term>),
  10     Lit(i32),
  11 }
  12
  13 impl From<&Term> for Term {
  14     fn from(term: &Term) -> Term {
  15         term.clone()
  16     }
  17 }
  18
  19 impl From<i32> for Term {
  20     fn from(i: i32) -> Term {
  21         Term::Lit(i)
  22     }
  23 }
  24
  25 impl From<Var> for Term {
  26     fn from(var: Var) -> Term {
  27         Term::Var(var)
  28     }
  29 }
  30
  31 impl<T, U> From<(T, U)> for Term
  32 where
  33     T: Into<Term>,
  34     U: Into<Term>,
  35 {
  36     fn from((t, u): (T, U)) -> Term {
  37         Term::Pair(Arc::new(t.into()), Arc::new(u.into()))
  38     }
  39 }
  40
  41 impl fmt::Display for Term {
  42     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
  43         match self {
  44             Term::Var(v) => write!(fmt, "{:?}", v),
  45             Term::Pair(l, r) => write!(fmt, "({}, {})", *l, *r),
  46             Term::Lit(i) => write!(fmt, "{}", i),
  47         }
  48     }
  49 }
  50
  51 impl fmt::Debug for Term {
  52     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
  53         write!(fmt, "{}", self)
  54     }
  55 }
  56
  57 impl fmt::Debug for Var {
  58     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
  59         write!(fmt, "x{}", self.0)
  60     }
  61 }