| //===- llvm/Support/Casting.h - Allow flexible, checked, casts --*- C++ -*-===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines the isa<X>(), cast<X>(), dyn_cast<X>(), cast_or_null<X>(), |
| // and dyn_cast_or_null<X>() templates. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_SUPPORT_CASTING_H |
| #define LLVM_SUPPORT_CASTING_H |
| |
| #include "llvm/Support/Compiler.h" |
| #include "llvm/Support/type_traits.h" |
| #include <cassert> |
| #include <memory> |
| #include <type_traits> |
| |
| namespace llvm { |
| |
| //===----------------------------------------------------------------------===// |
| // isa<x> Support Templates |
| //===----------------------------------------------------------------------===// |
| |
| // 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 { |
| using SimpleType = From; // 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> { |
| using NonConstSimpleType = typename simplify_type<From>::SimpleType; |
| using SimpleType = |
| typename add_const_past_pointer<NonConstSimpleType>::type; |
| using RetType = |
| typename add_lvalue_reference_if_not_pointer<SimpleType>::type; |
| |
| static RetType getSimplifiedValue(const From& Val) { |
| return simplify_type<From>::getSimplifiedValue(const_cast<From&>(Val)); |
| } |
| }; |
| |
| // The core of the implementation of isa<X> is here; To and From should be |
| // the names of classes. This template can be specialized to customize the |
| // implementation of isa<> without rewriting it from scratch. |
| template <typename To, typename From, typename Enabler = void> |
| struct isa_impl { |
| static inline bool doit(const From &Val) { |
| return To::classof(&Val); |
| } |
| }; |
| |
| /// Always allow upcasts, and perform no dynamic check for them. |
| template <typename To, typename From> |
| struct isa_impl< |
| To, From, typename std::enable_if<std::is_base_of<To, From>::value>::type> { |
| static inline bool doit(const From &) { return true; } |
| }; |
| |
| template <typename To, typename From> struct isa_impl_cl { |
| static inline bool doit(const From &Val) { |
| return isa_impl<To, From>::doit(Val); |
| } |
| }; |
| |
| template <typename To, typename From> struct isa_impl_cl<To, const From> { |
| static inline bool doit(const From &Val) { |
| return isa_impl<To, From>::doit(Val); |
| } |
| }; |
| |
| template <typename To, typename From> |
| struct isa_impl_cl<To, const std::unique_ptr<From>> { |
| static inline bool doit(const std::unique_ptr<From> &Val) { |
| assert(Val && "isa<> used on a null pointer"); |
| return isa_impl_cl<To, From>::doit(*Val); |
| } |
| }; |
| |
| template <typename To, typename From> struct isa_impl_cl<To, From*> { |
| static inline bool doit(const From *Val) { |
| assert(Val && "isa<> used on a null pointer"); |
| return isa_impl<To, From>::doit(*Val); |
| } |
| }; |
| |
| template <typename To, typename From> struct isa_impl_cl<To, From*const> { |
| static inline bool doit(const From *Val) { |
| assert(Val && "isa<> used on a null pointer"); |
| return isa_impl<To, From>::doit(*Val); |
| } |
| }; |
| |
| template <typename To, typename From> struct isa_impl_cl<To, const From*> { |
| static inline bool doit(const From *Val) { |
| assert(Val && "isa<> used on a null pointer"); |
| return isa_impl<To, From>::doit(*Val); |
| } |
| }; |
| |
| template <typename To, typename From> struct isa_impl_cl<To, const From*const> { |
| static inline bool doit(const From *Val) { |
| assert(Val && "isa<> used on a null pointer"); |
| return isa_impl<To, From>::doit(*Val); |
| } |
| }; |
| |
| template<typename To, typename From, typename SimpleFrom> |
| 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_wrap<To, SimpleFrom, |
| typename simplify_type<SimpleFrom>::SimpleType>::doit( |
| simplify_type<const From>::getSimplifiedValue(Val)); |
| } |
| }; |
| |
| template<typename To, typename FromTy> |
| struct isa_impl_wrap<To, FromTy, FromTy> { |
| // When From == SimpleType, we are as simple as we are going to get. |
| static bool doit(const FromTy &Val) { |
| return isa_impl_cl<To,FromTy>::doit(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 <class X, class Y> LLVM_NODISCARD inline bool isa(const Y &Val) { |
| return isa_impl_wrap<X, const Y, |
| typename simplify_type<const Y>::SimpleType>::doit(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 { |
| using ret_type = To &; // Normal case, return Ty& |
| }; |
| template<class To, class From> struct cast_retty_impl<To, const From> { |
| using ret_type = const To &; // Normal case, return Ty& |
| }; |
| |
| template<class To, class From> struct cast_retty_impl<To, From*> { |
| using ret_type = To *; // Pointer arg case, return Ty* |
| }; |
| |
| template<class To, class From> struct cast_retty_impl<To, const From*> { |
| using ret_type = const To *; // Constant pointer arg case, return const Ty* |
| }; |
| |
| template<class To, class From> struct cast_retty_impl<To, const From*const> { |
| using ret_type = const To *; // Constant pointer arg case, return const Ty* |
| }; |
| |
| template <class To, class From> |
| struct cast_retty_impl<To, std::unique_ptr<From>> { |
| private: |
| using PointerType = typename cast_retty_impl<To, From *>::ret_type; |
| using ResultType = typename std::remove_pointer<PointerType>::type; |
| |
| public: |
| using ret_type = std::unique_ptr<ResultType>; |
| }; |
| |
| 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. |
| using ret_type = typename cast_retty<To, SimpleFrom>::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. |
| using ret_type = typename cast_retty_impl<To,FromTy>::ret_type; |
| }; |
| |
| template<class To, class From> |
| struct cast_retty { |
| using ret_type = typename cast_retty_wrap< |
| To, From, typename simplify_type<From>::SimpleType>::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(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) { |
| typename cast_retty<To, FromTy>::ret_type Res2 |
| = (typename cast_retty<To, FromTy>::ret_type)const_cast<FromTy&>(Val); |
| return Res2; |
| } |
| }; |
| |
| template <class X> struct is_simple_type { |
| static const bool value = |
| std::is_same<X, typename simplify_type<X>::SimpleType>::value; |
| }; |
| |
| // 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. It does not allow a null argument (use cast_or_null for that). |
| // It is typically used like this: |
| // |
| // cast<Instruction>(myVal)->getParent() |
| // |
| template <class X, class Y> |
| inline typename std::enable_if<!is_simple_type<Y>::value, |
| typename cast_retty<X, const Y>::ret_type>::type |
| cast(const Y &Val) { |
| assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!"); |
| return cast_convert_val< |
| X, const Y, typename simplify_type<const Y>::SimpleType>::doit(Val); |
| } |
| |
| template <class X, class Y> |
| inline typename cast_retty<X, Y>::ret_type cast(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); |
| } |
| |
| template <class X, class Y> |
| inline typename cast_retty<X, Y *>::ret_type cast(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); |
| } |
| |
| template <class X, class Y> |
| inline typename cast_retty<X, std::unique_ptr<Y>>::ret_type |
| cast(std::unique_ptr<Y> &&Val) { |
| assert(isa<X>(Val.get()) && "cast<Ty>() argument of incompatible type!"); |
| using ret_type = typename cast_retty<X, std::unique_ptr<Y>>::ret_type; |
| return ret_type( |
| cast_convert_val<X, Y *, typename simplify_type<Y *>::SimpleType>::doit( |
| Val.release())); |
| } |
| |
| // cast_or_null<X> - Functionally identical to cast, except that a null value is |
| // accepted. |
| // |
| template <class X, class Y> |
| LLVM_NODISCARD inline |
| typename std::enable_if<!is_simple_type<Y>::value, |
| typename cast_retty<X, const Y>::ret_type>::type |
| cast_or_null(const Y &Val) { |
| if (!Val) |
| return nullptr; |
| assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!"); |
| return cast<X>(Val); |
| } |
| |
| template <class X, class Y> |
| LLVM_NODISCARD inline |
| typename std::enable_if<!is_simple_type<Y>::value, |
| typename cast_retty<X, Y>::ret_type>::type |
| cast_or_null(Y &Val) { |
| if (!Val) |
| return nullptr; |
| assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!"); |
| return cast<X>(Val); |
| } |
| |
| template <class X, class Y> |
| LLVM_NODISCARD inline typename cast_retty<X, Y *>::ret_type |
| cast_or_null(Y *Val) { |
| if (!Val) return nullptr; |
| assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!"); |
| return cast<X>(Val); |
| } |
| |
| template <class X, class Y> |
| inline typename cast_retty<X, std::unique_ptr<Y>>::ret_type |
| cast_or_null(std::unique_ptr<Y> &&Val) { |
| if (!Val) |
| return nullptr; |
| return cast<X>(std::move(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> |
| LLVM_NODISCARD inline |
| typename std::enable_if<!is_simple_type<Y>::value, |
| typename cast_retty<X, const Y>::ret_type>::type |
| dyn_cast(const Y &Val) { |
| return isa<X>(Val) ? cast<X>(Val) : nullptr; |
| } |
| |
| template <class X, class Y> |
| LLVM_NODISCARD inline typename cast_retty<X, Y>::ret_type dyn_cast(Y &Val) { |
| return isa<X>(Val) ? cast<X>(Val) : nullptr; |
| } |
| |
| template <class X, class Y> |
| LLVM_NODISCARD inline typename cast_retty<X, Y *>::ret_type dyn_cast(Y *Val) { |
| return isa<X>(Val) ? cast<X>(Val) : nullptr; |
| } |
| |
| // dyn_cast_or_null<X> - Functionally identical to dyn_cast, except that a null |
| // value is accepted. |
| // |
| template <class X, class Y> |
| LLVM_NODISCARD inline |
| typename std::enable_if<!is_simple_type<Y>::value, |
| typename cast_retty<X, const Y>::ret_type>::type |
| dyn_cast_or_null(const Y &Val) { |
| return (Val && isa<X>(Val)) ? cast<X>(Val) : nullptr; |
| } |
| |
| template <class X, class Y> |
| LLVM_NODISCARD inline |
| typename std::enable_if<!is_simple_type<Y>::value, |
| typename cast_retty<X, Y>::ret_type>::type |
| dyn_cast_or_null(Y &Val) { |
| return (Val && isa<X>(Val)) ? cast<X>(Val) : nullptr; |
| } |
| |
| template <class X, class Y> |
| LLVM_NODISCARD inline typename cast_retty<X, Y *>::ret_type |
| dyn_cast_or_null(Y *Val) { |
| return (Val && isa<X>(Val)) ? cast<X>(Val) : nullptr; |
| } |
| |
| // unique_dyn_cast<X> - Given a unique_ptr<Y>, try to return a unique_ptr<X>, |
| // taking ownership of the input pointer iff isa<X>(Val) is true. If the |
| // cast is successful, From refers to nullptr on exit and the casted value |
| // is returned. If the cast is unsuccessful, the function returns nullptr |
| // and From is unchanged. |
| template <class X, class Y> |
| LLVM_NODISCARD inline auto unique_dyn_cast(std::unique_ptr<Y> &Val) |
| -> decltype(cast<X>(Val)) { |
| if (!isa<X>(Val)) |
| return nullptr; |
| return cast<X>(std::move(Val)); |
| } |
| |
| template <class X, class Y> |
| LLVM_NODISCARD inline auto unique_dyn_cast(std::unique_ptr<Y> &&Val) |
| -> decltype(cast<X>(Val)) { |
| return unique_dyn_cast<X, Y>(Val); |
| } |
| |
| // dyn_cast_or_null<X> - Functionally identical to unique_dyn_cast, except that |
| // a null value is accepted. |
| template <class X, class Y> |
| LLVM_NODISCARD inline auto unique_dyn_cast_or_null(std::unique_ptr<Y> &Val) |
| -> decltype(cast<X>(Val)) { |
| if (!Val) |
| return nullptr; |
| return unique_dyn_cast<X, Y>(Val); |
| } |
| |
| template <class X, class Y> |
| LLVM_NODISCARD inline auto unique_dyn_cast_or_null(std::unique_ptr<Y> &&Val) |
| -> decltype(cast<X>(Val)) { |
| return unique_dyn_cast_or_null<X, Y>(Val); |
| } |
| |
| } // end namespace llvm |
| |
| #endif // LLVM_SUPPORT_CASTING_H |