2 * Copyright 2019-2020 (c) Philippe Proulx <pproulx@efficios.com>
4 * SPDX-License-Identifier: MIT
7 #ifndef BABELTRACE_CPP_COMMON_BT2_INTERNAL_BORROWED_OBJ_HPP
8 #define BABELTRACE_CPP_COMMON_BT2_INTERNAL_BORROWED_OBJ_HPP
11 #include <type_traits>
13 #include "common/assert.h"
18 template <typename ObjT, typename LibObjT, typename RefFuncsT>
22 * An instance of this class wraps a pointer to a libbabeltrace2 object
23 * of type `LibObjT` without managing any reference counting.
25 * This is an abstract base class for any libbabeltrace2 object wrapper.
27 * `LibObjT` is the direct libbabeltrace2 object type, for example
28 * `bt_stream_class` or `const bt_value`.
30 * Methods of a derived class can call libObjPtr() to access the
31 * libbabeltrace2 object pointer.
33 template <typename LibObjT>
36 static_assert(!std::is_pointer<LibObjT>::value, "`LibObjT` must not be a pointer");
39 * This makes it possible for a `BorrowedObj<const bt_something>`
40 * instance to get assigned an instance of
41 * `BorrowedObj<bt_something>` (copy constructor and assignment
44 * C++ forbids the other way around.
46 template <typename AnyLibObjT>
47 friend class BorrowedObj;
50 /* libbabeltrace2 object pointer */
51 using _LibObjPtr = LibObjT *;
53 /* This complete borrowed object */
54 using _ThisBorrowedObj = BorrowedObj<LibObjT>;
57 * Builds a borrowed object to wrap the libbabeltrace2 object
58 * pointer `libObjPtr`.
60 * `libObjPtr` must not be `nullptr`.
62 explicit BorrowedObj(const _LibObjPtr libObjPtr) noexcept : _mLibObjPtr {libObjPtr}
68 * Generic copy constructor.
70 * This converting constructor accepts both an instance of
71 * `_ThisBorrowedObj` and an instance (`other`) of
72 * `BorrowedObj<ConstLibObjT>`, where `ConstLibObjT` is the `const`
73 * version of `LibObjT`, if applicable.
75 * This makes it possible for a `BorrowedObj<const bt_something>`
76 * instance to be built from an instance of
77 * `BorrowedObj<bt_something>`. C++ forbids the other way around.
79 template <typename OtherLibObjT>
80 BorrowedObj(const BorrowedObj<OtherLibObjT>& other) noexcept : BorrowedObj {other._mLibObjPtr}
85 * Generic assignment operator.
87 * This operator accepts both an instance of
88 * `_ThisBorrowedObj` and an instance (`other`) of
89 * `BorrowedObj<ConstLibObjT>`, where `ConstLibObjT` is the `const`
90 * version of `LibObjT`, if applicable.
92 * This makes it possible for a `BorrowedObj<const bt_something>`
93 * instance to get assigned an instance of
94 * `BorrowedObj<bt_something>`. C++ forbids the other way around.
96 template <typename OtherLibObjT>
97 _ThisBorrowedObj& operator=(const BorrowedObj<OtherLibObjT>& other) noexcept
99 _mLibObjPtr = other._mLibObjPtr;
105 * Returns a hash of this object, solely based on its raw libbabeltrace2
108 std::size_t hash() const noexcept
110 return std::hash<_LibObjPtr> {}(_mLibObjPtr);
114 * Returns whether or not this object is the exact same as `other`,
115 * solely based on the raw libbabeltrace2 pointers.
117 bool isSame(const _ThisBorrowedObj& other) const noexcept
119 return _mLibObjPtr == other._mLibObjPtr;
122 /* Wrapped libbabeltrace2 object pointer */
123 _LibObjPtr libObjPtr() const noexcept
129 _LibObjPtr _mLibObjPtr;
132 } /* namespace internal */
133 } /* namespace bt2 */
135 #endif /* BABELTRACE_CPP_COMMON_BT2_INTERNAL_BORROWED_OBJ_HPP */