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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2020, Google Inc.
*
* class.cpp - Utilities and helpers for classes
*/
#include <libcamera/class.h>
/**
* \file class.h
* \brief Utilities to help constructing class interfaces
*
* The extensible class can be inherited to create public classes with stable
* ABIs.
*/
namespace libcamera {
/**
* \def LIBCAMERA_DISABLE_COPY
* \brief Disable copy construction and assignment of the \a klass
* \param klass The name of the class
*
* Example usage:
* \code{.cpp}
* class NonCopyable
* {
* public:
* NonCopyable();
* ...
*
* private:
* LIBCAMERA_DISABLE_COPY(NonCopyable)
* };
* \endcode
*/
/**
* \def LIBCAMERA_DISABLE_MOVE
* \brief Disable move construction and assignment of the \a klass
* \param klass The name of the class
*
* Example usage:
* \code{.cpp}
* class NonMoveable
* {
* public:
* NonMoveable();
* ...
*
* private:
* LIBCAMERA_DISABLE_MOVE(NonMoveable)
* };
* \endcode
*/
/**
* \def LIBCAMERA_DISABLE_COPY_AND_MOVE
* \brief Disable copy and move construction and assignment of the \a klass
* \param klass The name of the class
*
* Example usage:
* \code{.cpp}
* class NonCopyableNonMoveable
* {
* public:
* NonCopyableNonMoveable();
* ...
*
* private:
* LIBCAMERA_DISABLE_COPY_AND_MOVE(NonCopyableNonMoveable)
* };
* \endcode
*/
/**
* \def LIBCAMERA_DECLARE_PRIVATE
* \brief Declare private data for a public class
*
* The LIBCAMERA_DECLARE_PRIVATE() macro plumbs the infrastructure necessary to
* make a class manage its private data through a d-pointer. It shall be used at
* the very top of the class definition.
*/
/**
* \def LIBCAMERA_DECLARE_PUBLIC
* \brief Declare public data for a private class
* \param klass The public class name
*
* The LIBCAMERA_DECLARE_PUBLIC() macro is the counterpart of
* LIBCAMERA_DECLARE_PRIVATE() to be used in the private data class. It shall be
* used at the very top of the private class definition, with the public class
* name passed as the \a klass parameter.
*/
/**
* \def LIBCAMERA_D_PTR()
* \brief Retrieve the private data pointer
*
* This macro can be used in any member function of a class that inherits,
* directly or indirectly, from the Extensible class, to create a local
* variable named 'd' that points to the class' private data instance.
*/
/**
* \def LIBCAMERA_O_PTR()
* \brief Retrieve the public instance corresponding to the private data
*
* This macro is the counterpart of LIBCAMERA_D_PTR() for private data classes.
* It can be used in any member function of the private data class to create a
* local variable named 'o' that points to the public class instance
* corresponding to the private data.
*/
/**
* \class Extensible
* \brief Base class to manage private data through a d-pointer
*
* The Extensible class provides a base class to implement the
* <a href="https://wiki.qt.io/D-Pointer">d-pointer</a> design pattern (also
* known as <a href="https://en.wikipedia.org/wiki/Opaque_pointer">opaque pointer</a>
* or <a href="https://en.cppreference.com/w/cpp/language/pimpl">pImpl idiom</a>).
* It helps creating public classes that can be extended without breaking their
* ABI. Such classes store their private data in a separate private data object,
* referenced by a pointer in the public class (hence the name d-pointer).
*
* Classes that follow this design pattern are referred herein as extensible
* classes. To be extensible, a class PublicClass shall:
*
* - inherit from the Extensible class or from another extensible class
* - invoke the LIBCAMERA_DECLARE_PRIVATE() macro at the very top of the class
* definition
* - define a private data class named PublicClass::Private that inherits from
* the Private data class of the base class
* - invoke the LIBCAMERA_DECLARE_PUBLIC() macro at the very top of the Private
* data class definition
* - pass a pointer to a newly allocated Private data object to the constructor
* of the base class
*
* Additionally, if the PublicClass is not final, it shall expose one or more
* constructors that takes a pointer to a Private data instance, to be used by
* derived classes.
*
* The Private class is fully opaque to users of the libcamera public API.
* Internally, it can be kept private to the implementation of PublicClass, or
* be exposed to other classes. In the latter case, the members of the Private
* class need to be qualified with appropriate access specifiers. The
* PublicClass and Private classes always have full access to each other's
* protected and private members.
*/
/**
* \brief Construct an instance of an Extensible class
* \param[in] d Pointer to the private data instance
*/
Extensible::Extensible(Extensible::Private *d)
: d_(d)
{
}
/**
* \var Extensible::d_
* \brief Pointer to the private data instance
*/
/**
* \class Extensible::Private
* \brief Base class for private data managed through a d-pointer
*/
/**
* \brief Construct an instance of an Extensible class private data
* \param[in] o Pointer to the public class object
*/
Extensible::Private::Private(Extensible *o)
: o_(o)
{
}
Extensible::Private::~Private()
{
}
/**
* \var Extensible::Private::o_
* \brief Pointer to the public class object
*/
} /* namespace libcamera */
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