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- //===-- llvm/Support/Casting.h - Allow flexible, checked, casts -*- C++ -*-===//
- //
- // The LLVM Compiler Infrastructure
- //
- // This file 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 LLVM_SUPPORT_CASTING_H
- #define LLVM_SUPPORT_CASTING_H
- #include "Compiler.h"
- #include "type_traits.h"
- #include <cassert>
- 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 {
- 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 typename simplify_type<From>::SimpleType NonConstSimpleType;
- typedef typename add_const_past_pointer<NonConstSimpleType>::type
- SimpleType;
- typedef typename add_lvalue_reference_if_not_pointer<SimpleType>::type
- RetType;
- 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);
- }
- };
- /// \brief 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, 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_ATTRIBUTE_UNUSED_RESULT 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 {
- 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(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);
- }
- // cast_or_null<X> - Functionally identical to cast, except that a null value is
- // accepted.
- //
- template <class X, class Y>
- LLVM_ATTRIBUTE_UNUSED_RESULT 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_ATTRIBUTE_UNUSED_RESULT 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_ATTRIBUTE_UNUSED_RESULT 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);
- }
- // 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_ATTRIBUTE_UNUSED_RESULT 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_ATTRIBUTE_UNUSED_RESULT 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_ATTRIBUTE_UNUSED_RESULT 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_ATTRIBUTE_UNUSED_RESULT 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_ATTRIBUTE_UNUSED_RESULT 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_ATTRIBUTE_UNUSED_RESULT inline typename cast_retty<X, Y *>::ret_type
- dyn_cast_or_null(Y *Val) {
- return (Val && isa<X>(Val)) ? cast<X>(Val) : nullptr;
- }
- } // End llvm namespace
- #endif
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