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/*
SPDX-FileCopyrightText: 2007 David Nolden <david.nolden.kdevelop@art-master.de>
SPDX-License-Identifier: LGPL-2.0-only
*/
#ifndef KDEVPLATFORM_DUCHAINPOINTER_H
#define KDEVPLATFORM_DUCHAINPOINTER_H
#include <QMetaType>
#include <QList>
#include <QExplicitlySharedDataPointer>
#include <language/languageexport.h>
//krazy:excludeall=dpointer
namespace KDevelop {
class DUContext;
class TopDUContext;
class DUChainBase;
class Declaration;
class AbstractFunctionDeclaration;
/**
* Whenever the du-chain is unlocked and locked again, any du-chain item may have been deleted in between.
* For that reason, the following class should be used to make sure that no deleted objects are accessed. It contains a pointer
* that will be reset to zero once the pointed object is deleted.
*
* Access to the data must still be serialized through duchain-locking. Using this comes with no additional cost.
*
* In practice this means:
* Store an instance of DUChainPointer instead of a pointer to the du-chain object.
* Then, access the eventually still existing object by calling pointer->base().
*
* To make it even more convenient see DUChainPointer
* */
class KDEVPLATFORMLANGUAGE_EXPORT DUChainPointerData
: public QSharedData
{
public:
/**
* Will return zero once the pointed-to object was deleted
* */
DUChainBase* base();
/**
* Will return zero once the pointed-to object was deleted
* */
DUChainBase* base() const;
///Default-initialization of an invalid reference
DUChainPointerData();
~DUChainPointerData();
private:
///Should not be used from outside, but is needed sometimes to construct an invalid dummy-pointer
explicit DUChainPointerData(DUChainBase* base);
friend class DUChainBase;
DUChainBase* m_base = nullptr;
Q_DISABLE_COPY(DUChainPointerData)
};
/**
* A smart-pointer similar class that conveniently wraps around DUChainPointerData without
* too many dynamic casts.
*
* It can be used like a normal pointer. In order to cast between pointer types, you should
* use the staticCast() and dynamicCast() functions as appropriate.
*
* Access must be serialized by holding the KDevelop::DUChain::lock() as appropriate for the
* function(s) being called.
**/
template <class Type>
class DUChainPointer
{
template <class OtherType>
friend class DUChainPointer;
public:
DUChainPointer() : d(QExplicitlySharedDataPointer<DUChainPointerData>(nullptr))
{
}
DUChainPointer(const DUChainPointer&) = default;
DUChainPointer(DUChainPointer&&) = default;
///This constructor includes dynamic casting. If the object cannot be casted to the type, the constructed DUChainPointer will have value zero.
template <class OtherType>
explicit DUChainPointer(OtherType* rhs)
{
if (dynamic_cast<Type*>(rhs))
d = rhs->weakPointer();
}
template <class OtherType>
explicit DUChainPointer(DUChainPointer<OtherType> rhs)
{
if (dynamic_cast<Type*>(rhs.data()))
d = rhs.d;
}
explicit DUChainPointer(QExplicitlySharedDataPointer<DUChainPointerData> rhs)
{
if (dynamic_cast<Type*>(rhs->base()))
d = rhs;
}
explicit DUChainPointer(Type* rhs)
{
if (rhs)
d = rhs->weakPointer();
}
~DUChainPointer() = default;
bool operator ==(const DUChainPointer<Type>& rhs) const
{
return d.data() == rhs.d.data();
}
bool operator !=(const DUChainPointer<Type>& rhs) const
{
return d.data() != rhs.d.data();
}
///Returns whether the pointed object is still existing
operator bool() const {
return d && d->base();
}
Type& operator*() const
{
Q_ASSERT(d);
return *static_cast<Type*>(d->base());
}
Type* operator->() const
{
Q_ASSERT(d);
return static_cast<Type*>(d->base());
}
bool operator<(const DUChainPointer<Type>& rhs) const
{
return d.data() < rhs.d.data();
}
template <class NewType>
DUChainPointer<NewType> dynamicCast() const
{
if (d && dynamic_cast<NewType*>(d->base())) //When the reference to the pointer is constant that doesn't mean that the pointed object needs to be constant
return DUChainPointer<NewType>(static_cast<NewType*>(d->base()));
else
return DUChainPointer<NewType>();
}
Type* data() const
{
if (!d)
return nullptr;
return static_cast<Type*>(d->base());
}
DUChainPointer<Type>& operator=(const DUChainPointer<Type>&) = default;
DUChainPointer<Type>& operator=(DUChainPointer<Type>&&) = default;
DUChainPointer<Type>& operator=(Type* rhs)
{
if (rhs)
d = rhs->weakPointer();
else
d = nullptr;
return *this;
}
private:
QExplicitlySharedDataPointer<DUChainPointerData> d;
};
using DUChainBasePointer = DUChainPointer<DUChainBase>;
using DUContextPointer = DUChainPointer<DUContext>;
using TopDUContextPointer = DUChainPointer<TopDUContext>;
using DeclarationPointer = DUChainPointer<Declaration>;
using FunctionDeclarationPointer = DUChainPointer<AbstractFunctionDeclaration>;
}
Q_DECLARE_METATYPE(KDevelop::DUChainBasePointer)
Q_DECLARE_METATYPE(KDevelop::DeclarationPointer)
Q_DECLARE_METATYPE(KDevelop::DUContextPointer)
Q_DECLARE_METATYPE(KDevelop::TopDUContextPointer)
#endif
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