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//===------ extensible_rtti.h - Extensible RTTI for ORC RT ------*- 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
//
//===----------------------------------------------------------------------===//
//
// \file
//
// Provides an extensible RTTI mechanism, that can be used regardless of whether
// the runtime is built with -frtti or not. This is predominantly used to
// support error handling.
//
// The RTTIRoot class defines methods for comparing type ids. Implementations
// of these methods can be injected into new classes using the RTTIExtends
// class template.
//
// E.g.
//
// @code{.cpp}
// class MyBaseClass : public RTTIExtends<MyBaseClass, RTTIRoot> {
// public:
// static char ID;
// virtual void foo() = 0;
// };
//
// class MyDerivedClass1 : public RTTIExtends<MyDerivedClass1, MyBaseClass> {
// public:
// static char ID;
// void foo() override {}
// };
//
// class MyDerivedClass2 : public RTTIExtends<MyDerivedClass2, MyBaseClass> {
// public:
// static char ID;
// void foo() override {}
// };
//
// char MyBaseClass::ID = 0;
// char MyDerivedClass1::ID = 0;
// char MyDerivedClass2:: ID = 0;
//
// void fn() {
// std::unique_ptr<MyBaseClass> B = std::make_unique<MyDerivedClass1>();
// outs() << isa<MyBaseClass>(B) << "\n"; // Outputs "1".
// outs() << isa<MyDerivedClass1>(B) << "\n"; // Outputs "1".
// outs() << isa<MyDerivedClass2>(B) << "\n"; // Outputs "0'.
// }
//
// @endcode
//
// Note:
// This header was adapted from llvm/Support/ExtensibleRTTI.h, however the
// data structures are not shared and the code need not be kept in sync.
//
//===----------------------------------------------------------------------===//
#ifndef ORC_RT_EXTENSIBLE_RTTI_H
#define ORC_RT_EXTENSIBLE_RTTI_H
namespace __orc_rt {
template <typename ThisT, typename ParentT> class RTTIExtends;
/// Base class for the extensible RTTI hierarchy.
///
/// This class defines virtual methods, dynamicClassID and isA, that enable
/// type comparisons.
class RTTIRoot {
public:
virtual ~RTTIRoot() = default;
/// Returns the class ID for this type.
static const void *classID() { return &ID; }
/// Returns the class ID for the dynamic type of this RTTIRoot instance.
virtual const void *dynamicClassID() const = 0;
/// Returns true if this class's ID matches the given class ID.
virtual bool isA(const void *const ClassID) const {
return ClassID == classID();
}
/// Check whether this instance is a subclass of QueryT.
template <typename QueryT> bool isA() const { return isA(QueryT::classID()); }
static bool classof(const RTTIRoot *R) { return R->isA<RTTIRoot>(); }
private:
virtual void anchor();
static char ID;
};
/// Inheritance utility for extensible RTTI.
///
/// Supports single inheritance only: A class can only have one
/// ExtensibleRTTI-parent (i.e. a parent for which the isa<> test will work),
/// though it can have many non-ExtensibleRTTI parents.
///
/// RTTIExtents uses CRTP so the first template argument to RTTIExtends is the
/// newly introduced type, and the *second* argument is the parent class.
///
/// class MyType : public RTTIExtends<MyType, RTTIRoot> {
/// public:
/// static char ID;
/// };
///
/// class MyDerivedType : public RTTIExtends<MyDerivedType, MyType> {
/// public:
/// static char ID;
/// };
///
template <typename ThisT, typename ParentT> class RTTIExtends : public ParentT {
public:
// Inherit constructors and isA methods from ParentT.
using ParentT::isA;
using ParentT::ParentT;
static char ID;
static const void *classID() { return &ThisT::ID; }
const void *dynamicClassID() const override { return &ThisT::ID; }
bool isA(const void *const ClassID) const override {
return ClassID == classID() || ParentT::isA(ClassID);
}
static bool classof(const RTTIRoot *R) { return R->isA<ThisT>(); }
};
template <typename ThisT, typename ParentT>
char RTTIExtends<ThisT, ParentT>::ID = 0;
/// Returns true if the given value is an instance of the template type
/// parameter.
template <typename To, typename From> bool isa(const From &Value) {
return To::classof(&Value);
}
} // end namespace __orc_rt
#endif // ORC_RT_EXTENSIBLE_RTTI_H
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