src/librustc/ty/cast.rs

   1 // Helpers for handling cast expressions, used in both
   2 // typeck and codegen.
   3
   4 use ty::{self, Ty};
   5
   6 use syntax::ast;
   7
   8 /// Types that are represented as ints.
   9 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  10 pub enum IntTy {
  11     U(ast::UintTy),
  12     I,
  13     CEnum,
  14     Bool,
  15     Char
  16 }
  17
  18 // Valid types for the result of a non-coercion cast
  19 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  20 pub enum CastTy<'tcx> {
  21     /// Various types that are represented as ints and handled mostly
  22     /// in the same way, merged for easier matching.
  23     Int(IntTy),
  24     /// Floating-Point types
  25     Float,
  26     /// Function Pointers
  27     FnPtr,
  28     /// Raw pointers
  29     Ptr(ty::TypeAndMut<'tcx>),
  30     /// References
  31     RPtr(ty::TypeAndMut<'tcx>),
  32 }
  33
  34 /// Cast Kind. See RFC 401 (or librustc_typeck/check/cast.rs)
  35 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
  36 pub enum CastKind {
  37     CoercionCast,
  38     PtrPtrCast,
  39     PtrAddrCast,
  40     AddrPtrCast,
  41     NumericCast,
  42     EnumCast,
  43     PrimIntCast,
  44     U8CharCast,
  45     ArrayPtrCast,
  46     FnPtrPtrCast,
  47     FnPtrAddrCast
  48 }
  49
  50 impl<'tcx> CastTy<'tcx> {
  51     /// Returns `Some` for integral/pointer casts.
  52     /// casts like unsizing casts will return `None`
  53     pub fn from_ty(t: Ty<'tcx>) -> Option<CastTy<'tcx>> {
  54         match t.sty {
  55             ty::Bool => Some(CastTy::Int(IntTy::Bool)),
  56             ty::Char => Some(CastTy::Int(IntTy::Char)),
  57             ty::Int(_) => Some(CastTy::Int(IntTy::I)),
  58             ty::Infer(ty::InferTy::IntVar(_)) => Some(CastTy::Int(IntTy::I)),
  59             ty::Infer(ty::InferTy::FloatVar(_)) => Some(CastTy::Float),
  60             ty::Uint(u) => Some(CastTy::Int(IntTy::U(u))),
  61             ty::Float(_) => Some(CastTy::Float),
  62             ty::Adt(d,_) if d.is_enum() && d.is_payloadfree() =>
  63                 Some(CastTy::Int(IntTy::CEnum)),
  64             ty::RawPtr(mt) => Some(CastTy::Ptr(mt)),
  65             ty::Ref(_, ty, mutbl) => Some(CastTy::RPtr(ty::TypeAndMut { ty, mutbl })),
  66             ty::FnPtr(..) => Some(CastTy::FnPtr),
  67             _ => None,
  68         }
  69     }
  70 }