/* * Copyright (c) 2019 Jaroslav Jindrak * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * - The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #ifndef LIBCPP_BITS_REFCOUNT_OBJ #define LIBCPP_BITS_REFCOUNT_OBJ namespace std::aux { /** * At the moment we do not have atomics, change this * to std::atomic<long> once we do. */ using refcount_t = long; class refcount_obj { public: refcount_obj() = default; void increment() noexcept; void increment_weak() noexcept; bool decrement() noexcept; bool decrement_weak() noexcept; refcount_t refs() const noexcept; refcount_t weak_refs() const noexcept; bool expired() const noexcept; virtual ~refcount_obj() = default; virtual void destroy() = 0; protected: /** * We're using a trick where refcount_ > 0 * means weak_refcount_ has 1 added to it, * this makes it easier for weak_ptrs that * can't decrement the weak_refcount_ to * zero with shared_ptrs using this object. */ refcount_t refcount_{1}; refcount_t weak_refcount_{1}; }; } #endif