From 6410d1d37c1ea9d1d168840a7ba063facb0bc9d6 Mon Sep 17 00:00:00 2001 From: Kieran Bingham Date: Fri, 25 Jun 2021 00:09:15 +0100 Subject: libcamera/base: Move class helpers to the base library Move the class support infrastructure to the base library. Reviewed-by: Paul Elder Reviewed-by: Hirokazu Honda Reviewed-by: Laurent Pinchart Signed-off-by: Kieran Bingham --- src/libcamera/base/class.cpp | 190 +++++++++++++++++++++++++++++++++++++++++ src/libcamera/base/meson.build | 1 + 2 files changed, 191 insertions(+) create mode 100644 src/libcamera/base/class.cpp (limited to 'src/libcamera/base') diff --git a/src/libcamera/base/class.cpp b/src/libcamera/base/class.cpp new file mode 100644 index 00000000..165beafc --- /dev/null +++ b/src/libcamera/base/class.cpp @@ -0,0 +1,190 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Copyright (C) 2020, Google Inc. + * + * class.cpp - Utilities and helpers for classes + */ + +#include + +/** + * \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 + * d-pointer design pattern (also + * known as opaque pointer + * or pImpl idiom). + * 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 */ diff --git a/src/libcamera/base/meson.build b/src/libcamera/base/meson.build index 6d9ec374..302a2886 100644 --- a/src/libcamera/base/meson.build +++ b/src/libcamera/base/meson.build @@ -1,6 +1,7 @@ # SPDX-License-Identifier: CC0-1.0 libcamera_base_sources = files([ + 'class.cpp', 'utils.cpp', ]) -- cgit v1.2.1