src/librustc/ty/cast.rs

   1 // Helpers for handling cast expressions, used in both
   2 // typeck and codegen.
   3
   4 use crate::ty::{self, Ty};
   5
   6 use syntax::ast;
   7 use rustc_macros::HashStable;
   8
   9 /// Types that are represented as ints.
  10 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  11 pub enum IntTy {
  12     U(ast::UintTy),
  13     I,
  14     CEnum,
  15     Bool,
  16     Char
  17 }
  18
  19 // Valid types for the result of a non-coercion cast
  20 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  21 pub enum CastTy<'tcx> {
  22     /// Various types that are represented as ints and handled mostly
  23     /// in the same way, merged for easier matching.
  24     Int(IntTy),
  25     /// Floating-Point types
  26     Float,
  27     /// Function Pointers
  28     FnPtr,
  29     /// Raw pointers
  30     Ptr(ty::TypeAndMut<'tcx>),
  31     /// References
  32     RPtr(ty::TypeAndMut<'tcx>),
  33 }
  34
  35 /// Cast Kind. See RFC 401 (or librustc_typeck/check/cast.rs)
  36 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
  37 pub enum CastKind {
  38     CoercionCast,
  39     PtrPtrCast,
  40     PtrAddrCast,
  41     AddrPtrCast,
  42     NumericCast,
  43     EnumCast,
  44     PrimIntCast,
  45     U8CharCast,
  46     ArrayPtrCast,
  47     FnPtrPtrCast,
  48     FnPtrAddrCast
  49 }
  50
  51 impl<'tcx> CastTy<'tcx> {
  52     /// Returns `Some` for integral/pointer casts.
  53     /// casts like unsizing casts will return `None`
  54     pub fn from_ty(t: Ty<'tcx>) -> Option<CastTy<'tcx>> {
  55         match t.kind {
  56             ty::Bool => Some(CastTy::Int(IntTy::Bool)),
  57             ty::Char => Some(CastTy::Int(IntTy::Char)),
  58             ty::Int(_) => Some(CastTy::Int(IntTy::I)),
  59             ty::Infer(ty::InferTy::IntVar(_)) => Some(CastTy::Int(IntTy::I)),
  60             ty::Infer(ty::InferTy::FloatVar(_)) => Some(CastTy::Float),
  61             ty::Uint(u) => Some(CastTy::Int(IntTy::U(u))),
  62             ty::Float(_) => Some(CastTy::Float),
  63             ty::Adt(d,_) if d.is_enum() && d.is_payloadfree() =>
  64                 Some(CastTy::Int(IntTy::CEnum)),
  65             ty::RawPtr(mt) => Some(CastTy::Ptr(mt)),
  66             ty::Ref(_, ty, mutbl) => Some(CastTy::RPtr(ty::TypeAndMut { ty, mutbl })),
  67             ty::FnPtr(..) => Some(CastTy::FnPtr),
  68             _ => None,
  69         }
  70     }
  71 }