| //===-- Support/Casting.h - Allow flexible, checked, casts ------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and is distributed under |
| // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines the isa<X>(), cast<X>(), dyn_cast<X>(), cast_or_null<X>(), |
| // and dyn_cast_or_null<X>() templates. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef SUPPORT_CASTING_H |
| #define SUPPORT_CASTING_H |
| |
| namespace llvm { |
| |
| //===----------------------------------------------------------------------===// |
| // isa<x> Support Templates |
| //===----------------------------------------------------------------------===// |
| |
| template<typename FromCl> struct isa_impl_cl; |
| |
| // Define a template that can be specialized by smart pointers to reflect the |
| // fact that they are automatically dereferenced, and are not involved with the |
| // template selection process... the default implementation is a noop. |
| // |
| template<typename From> struct simplify_type { |
| typedef From SimpleType; // The real type this represents... |
| |
| // An accessor to get the real value... |
| static SimpleType &getSimplifiedValue(From &Val) { return Val; } |
| }; |
| |
| template<typename From> struct simplify_type<const From> { |
| typedef const From SimpleType; |
| static SimpleType &getSimplifiedValue(const From &Val) { |
| return simplify_type<From>::getSimplifiedValue(static_cast<From&>(Val)); |
| } |
| }; |
| |
| |
| // isa<X> - Return true if the parameter to the template is an instance of the |
| // template type argument. Used like this: |
| // |
| // if (isa<Type*>(myVal)) { ... } |
| // |
| template <typename To, typename From> |
| inline bool isa_impl(const From &Val) { |
| return To::classof(&Val); |
| } |
| |
| template<typename To, typename From, typename SimpleType> |
| struct isa_impl_wrap { |
| // When From != SimplifiedType, we can simplify the type some more by using |
| // the simplify_type template. |
| static bool doit(const From &Val) { |
| return isa_impl_cl<const SimpleType>::template |
| isa<To>(simplify_type<const From>::getSimplifiedValue(Val)); |
| } |
| }; |
| |
| template<typename To, typename FromTy> |
| struct isa_impl_wrap<To, const FromTy, const FromTy> { |
| // When From == SimpleType, we are as simple as we are going to get. |
| static bool doit(const FromTy &Val) { |
| return isa_impl<To,FromTy>(Val); |
| } |
| }; |
| |
| // isa_impl_cl - Use class partial specialization to transform types to a single |
| // canonical form for isa_impl. |
| // |
| template<typename FromCl> |
| struct isa_impl_cl { |
| template<class ToCl> |
| static bool isa(const FromCl &Val) { |
| return isa_impl_wrap<ToCl,const FromCl, |
| typename simplify_type<const FromCl>::SimpleType>::doit(Val); |
| } |
| }; |
| |
| // Specialization used to strip const qualifiers off of the FromCl type... |
| template<typename FromCl> |
| struct isa_impl_cl<const FromCl> { |
| template<class ToCl> |
| static bool isa(const FromCl &Val) { |
| return isa_impl_cl<FromCl>::template isa<ToCl>(Val); |
| } |
| }; |
| |
| // Define pointer traits in terms of base traits... |
| template<class FromCl> |
| struct isa_impl_cl<FromCl*> { |
| template<class ToCl> |
| static bool isa(FromCl *Val) { |
| return isa_impl_cl<FromCl>::template isa<ToCl>(*Val); |
| } |
| }; |
| |
| // Define reference traits in terms of base traits... |
| template<class FromCl> |
| struct isa_impl_cl<FromCl&> { |
| template<class ToCl> |
| static bool isa(FromCl &Val) { |
| return isa_impl_cl<FromCl>::template isa<ToCl>(&Val); |
| } |
| }; |
| |
| template <class X, class Y> |
| inline bool isa(const Y &Val) { |
| return isa_impl_cl<Y>::template isa<X>(Val); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // cast<x> Support Templates |
| //===----------------------------------------------------------------------===// |
| |
| template<class To, class From> struct cast_retty; |
| |
| |
| // Calculate what type the 'cast' function should return, based on a requested |
| // type of To and a source type of From. |
| template<class To, class From> struct cast_retty_impl { |
| typedef To& ret_type; // Normal case, return Ty& |
| }; |
| template<class To, class From> struct cast_retty_impl<To, const From> { |
| typedef const To &ret_type; // Normal case, return Ty& |
| }; |
| |
| template<class To, class From> struct cast_retty_impl<To, From*> { |
| typedef To* ret_type; // Pointer arg case, return Ty* |
| }; |
| |
| template<class To, class From> struct cast_retty_impl<To, const From*> { |
| typedef const To* ret_type; // Constant pointer arg case, return const Ty* |
| }; |
| |
| template<class To, class From> struct cast_retty_impl<To, const From*const> { |
| typedef const To* ret_type; // Constant pointer arg case, return const Ty* |
| }; |
| |
| |
| template<class To, class From, class SimpleFrom> |
| struct cast_retty_wrap { |
| // When the simplified type and the from type are not the same, use the type |
| // simplifier to reduce the type, then reuse cast_retty_impl to get the |
| // resultant type. |
| typedef typename cast_retty<To, SimpleFrom>::ret_type ret_type; |
| }; |
| |
| template<class To, class FromTy> |
| struct cast_retty_wrap<To, FromTy, FromTy> { |
| // When the simplified type is equal to the from type, use it directly. |
| typedef typename cast_retty_impl<To,FromTy>::ret_type ret_type; |
| }; |
| |
| template<class To, class From> |
| struct cast_retty { |
| typedef typename cast_retty_wrap<To, From, |
| typename simplify_type<From>::SimpleType>::ret_type ret_type; |
| }; |
| |
| // Ensure the non-simple values are converted using the simplify_type template |
| // that may be specialized by smart pointers... |
| // |
| template<class To, class From, class SimpleFrom> struct cast_convert_val { |
| // This is not a simple type, use the template to simplify it... |
| static typename cast_retty<To, From>::ret_type doit(const From &Val) { |
| return cast_convert_val<To, SimpleFrom, |
| typename simplify_type<SimpleFrom>::SimpleType>::doit( |
| simplify_type<From>::getSimplifiedValue(Val)); |
| } |
| }; |
| |
| template<class To, class FromTy> struct cast_convert_val<To,FromTy,FromTy> { |
| // This _is_ a simple type, just cast it. |
| static typename cast_retty<To, FromTy>::ret_type doit(const FromTy &Val) { |
| return reinterpret_cast<typename cast_retty<To, FromTy>::ret_type>( |
| const_cast<FromTy&>(Val)); |
| } |
| }; |
| |
| |
| |
| // cast<X> - Return the argument parameter cast to the specified type. This |
| // casting operator asserts that the type is correct, so it does not return null |
| // on failure. But it will correctly return NULL when the input is NULL. |
| // Used Like this: |
| // |
| // cast<Instruction>(myVal)->getParent() |
| // |
| template <class X, class Y> |
| inline typename cast_retty<X, Y>::ret_type cast(const Y &Val) { |
| assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!"); |
| return cast_convert_val<X, Y, |
| typename simplify_type<Y>::SimpleType>::doit(Val); |
| } |
| |
| // cast_or_null<X> - Functionally identical to cast, except that a null value is |
| // accepted. |
| // |
| template <class X, class Y> |
| inline typename cast_retty<X, Y*>::ret_type cast_or_null(Y *Val) { |
| if (Val == 0) return 0; |
| assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!"); |
| return cast<X>(Val); |
| } |
| |
| |
| // dyn_cast<X> - Return the argument parameter cast to the specified type. This |
| // casting operator returns null if the argument is of the wrong type, so it can |
| // be used to test for a type as well as cast if successful. This should be |
| // used in the context of an if statement like this: |
| // |
| // if (const Instruction *I = dyn_cast<Instruction>(myVal)) { ... } |
| // |
| |
| template <class X, class Y> |
| inline typename cast_retty<X, Y>::ret_type dyn_cast(Y Val) { |
| return isa<X>(Val) ? cast<X, Y>(Val) : 0; |
| } |
| |
| // dyn_cast_or_null<X> - Functionally identical to dyn_cast, except that a null |
| // value is accepted. |
| // |
| template <class X, class Y> |
| inline typename cast_retty<X, Y>::ret_type dyn_cast_or_null(Y Val) { |
| return (Val && isa<X>(Val)) ? cast<X, Y>(Val) : 0; |
| } |
| |
| |
| #ifdef DEBUG_CAST_OPERATORS |
| #include <iostream> |
| |
| struct bar { |
| bar() {} |
| private: |
| bar(const bar &); |
| }; |
| struct foo { |
| void ext() const; |
| /* static bool classof(const bar *X) { |
| cerr << "Classof: " << X << "\n"; |
| return true; |
| }*/ |
| }; |
| |
| template <> inline bool isa_impl<foo,bar>(const bar &Val) { |
| cerr << "Classof: " << &Val << "\n"; |
| return true; |
| } |
| |
| |
| bar *fub(); |
| void test(bar &B1, const bar *B2) { |
| // test various configurations of const |
| const bar &B3 = B1; |
| const bar *const B4 = B2; |
| |
| // test isa |
| if (!isa<foo>(B1)) return; |
| if (!isa<foo>(B2)) return; |
| if (!isa<foo>(B3)) return; |
| if (!isa<foo>(B4)) return; |
| |
| // test cast |
| foo &F1 = cast<foo>(B1); |
| const foo *F3 = cast<foo>(B2); |
| const foo *F4 = cast<foo>(B2); |
| const foo &F8 = cast<foo>(B3); |
| const foo *F9 = cast<foo>(B4); |
| foo *F10 = cast<foo>(fub()); |
| |
| // test cast_or_null |
| const foo *F11 = cast_or_null<foo>(B2); |
| const foo *F12 = cast_or_null<foo>(B2); |
| const foo *F13 = cast_or_null<foo>(B4); |
| const foo *F14 = cast_or_null<foo>(fub()); // Shouldn't print. |
| |
| // These lines are errors... |
| //foo *F20 = cast<foo>(B2); // Yields const foo* |
| //foo &F21 = cast<foo>(B3); // Yields const foo& |
| //foo *F22 = cast<foo>(B4); // Yields const foo* |
| //foo &F23 = cast_or_null<foo>(B1); |
| //const foo &F24 = cast_or_null<foo>(B3); |
| } |
| |
| bar *fub() { return 0; } |
| void main() { |
| bar B; |
| test(B, &B); |
| } |
| |
| #endif |
| |
| } // End llvm namespace |
| |
| #endif |