src/librustc/middle/cast.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // Helpers for handling cast expressions, used in both
  12 // typeck and trans.
  13
  14 use middle::ty::{self, Ty};
  15
  16 use syntax::ast;
  17
  18 /// Types that are represented as ints.
  19 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  20 pub enum IntTy {
  21     U(ast::UintTy),
  22     I,
  23     CEnum,
  24     Bool,
  25     Char
  26 }
  27
  28 // Valid types for the result of a non-coercion cast
  29 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  30 pub enum CastTy<'tcx> {
  31     /// Various types that are represented as ints and handled mostly
  32     /// in the same way, merged for easier matching.
  33     Int(IntTy),
  34     /// Floating-Point types
  35     Float,
  36     /// Function Pointers
  37     FnPtr,
  38     /// Raw pointers
  39     Ptr(&'tcx ty::mt<'tcx>),
  40     /// References
  41     RPtr(&'tcx ty::mt<'tcx>),
  42 }
  43
  44 /// Cast Kind. See RFC 401 (or librustc_typeck/check/cast.rs)
  45 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
  46 pub enum CastKind {
  47     CoercionCast,
  48     PtrPtrCast,
  49     PtrAddrCast,
  50     AddrPtrCast,
  51     NumericCast,
  52     EnumCast,
  53     PrimIntCast,
  54     U8CharCast,
  55     ArrayPtrCast,
  56     FnPtrPtrCast,
  57     FnPtrAddrCast
  58 }
  59
  60 impl<'tcx> CastTy<'tcx> {
  61     pub fn from_ty(tcx: &ty::ctxt<'tcx>, t: Ty<'tcx>)
  62                    -> Option<CastTy<'tcx>> {
  63         match t.sty {
  64             ty::TyBool => Some(CastTy::Int(IntTy::Bool)),
  65             ty::TyChar => Some(CastTy::Int(IntTy::Char)),
  66             ty::TyInt(_) => Some(CastTy::Int(IntTy::I)),
  67             ty::TyUint(u) => Some(CastTy::Int(IntTy::U(u))),
  68             ty::TyFloat(_) => Some(CastTy::Float),
  69             ty::TyEnum(..) if ty::type_is_c_like_enum(
  70                 tcx, t) => Some(CastTy::Int(IntTy::CEnum)),
  71             ty::TyRawPtr(ref mt) => Some(CastTy::Ptr(mt)),
  72             ty::TyRef(_, ref mt) => Some(CastTy::RPtr(mt)),
  73             ty::TyBareFn(..) => Some(CastTy::FnPtr),
  74             _ => None,
  75         }
  76     }
  77 }