Witch of Git - ess/blob - src/sexp.rs

   1 use std::borrow::Cow;
   2
   3 use span::{Span, ByteSpan};
   4
   5 /// A type representing arbitrary symbolic expressions. `Sexp` carries the
   6 /// source code location it came from along with it for later diagnostic
   7 /// purposes.
   8 #[derive(Debug, PartialEq, Clone, PartialOrd)]
   9 pub enum Sexp<'a, Loc=ByteSpan> where Loc: Span {
  10     /// A value representing a symbol.
  11     Sym(Cow<'a, str>, Loc),
  12     /// A value representing a string literal.
  13     Str(Cow<'a, str>, Loc),
  14     /// A value representing a single character.
  15     Char(char, Loc),
  16     /// A value representing an integer. Any number containing no decimal point
  17     /// will be parsed as an `Int`.
  18     Int(i64, Loc),
  19     /// A value representing a floating point number. Any number containing a
  20     /// decimal point will be parsed as a `Float`.
  21     Float(f64, Loc),
  22     /// A list of subexpressions.
  23     List(Vec<Sexp<'a, Loc>>, Loc),
  24 }
  25
  26 impl<'a, Loc> Sexp<'a, Loc> where Loc: Span {
  27     pub fn get_loc(&self) -> &Loc {
  28         match *self {
  29             Sexp::Sym(.., ref l) | Sexp::Str(.., ref l) |
  30             Sexp::Char(.., ref l) | Sexp::Int(.., ref l) |
  31             Sexp::Float(.., ref l) | Sexp::List(.., ref l) => l,
  32         }
  33     }
  34
  35     pub fn get_loc_mut(&mut self) -> &mut Loc {
  36         match *self {
  37             Sexp::Sym(.., ref mut l) | Sexp::Str(.., ref mut l) |
  38             Sexp::Char(.., ref mut l) | Sexp::Int(.., ref mut l) |
  39             Sexp::Float(.., ref mut l) | Sexp::List(.., ref mut l) => l,
  40         }
  41     }
  42 }
  43
  44 fn extend_cow<'a, T: ?Sized>(cow: &Cow<'a, T>) -> Cow<'static, T>
  45     where T: ToOwned
  46 {
  47     Cow::Owned(cow.clone().into_owned())
  48 }
  49
  50 impl<'a, Loc> Sexp<'a, Loc> where Loc: Span + Clone {
  51     pub fn to_owned(&self) -> Sexp<'static, Loc> {
  52         match *self {
  53             Sexp::Sym(ref s, ref l) => Sexp::Sym(extend_cow(s), l.clone()),
  54             Sexp::Str(ref s, ref l) => Sexp::Str(extend_cow(s), l.clone()),
  55             Sexp::Char(c, ref l) => Sexp::Char(c, l.clone()),
  56             Sexp::Int(i, ref l) => Sexp::Int(i, l.clone()),
  57             Sexp::Float(f, ref l) => Sexp::Float(f, l.clone()),
  58             Sexp::List(ref xs, ref l) =>
  59                 Sexp::List(xs.iter().map(Sexp::to_owned).collect(),
  60                            l.clone()),
  61         }
  62     }
  63 }