| 1 | /*
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| 2 | * Copyright (c) 2019 Jaroslav Jindrak
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| 3 | * All rights reserved.
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| 4 | *
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| 5 | * Redistribution and use in source and binary forms, with or without
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| 6 | * modification, are permitted provided that the following conditions
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| 7 | * are met:
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| 8 | *
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| 9 | * - Redistributions of source code must retain the above copyright
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| 10 | * notice, this list of conditions and the following disclaimer.
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| 11 | * - Redistributions in binary form must reproduce the above copyright
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| 12 | * notice, this list of conditions and the following disclaimer in the
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| 13 | * documentation and/or other materials provided with the distribution.
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| 14 | * - The name of the author may not be used to endorse or promote products
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| 15 | * derived from this software without specific prior written permission.
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| 16 | *
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 27 | */
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| 28 |
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| 29 | #ifndef LIBCPP_BITS_REFCOUNT_OBJ
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| 30 | #define LIBCPP_BITS_REFCOUNT_OBJ
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| 31 |
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| 32 | namespace std::aux
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| 33 | {
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| 34 | /**
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| 35 | * At the moment we do not have atomics, change this
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| 36 | * to std::atomic<long> once we do.
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| 37 | */
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| 38 | using refcount_t = long;
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| 39 |
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| 40 | class refcount_obj
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| 41 | {
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| 42 | public:
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| 43 | refcount_obj() = default;
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| 44 |
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| 45 | void increment() noexcept;
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| 46 | void increment_weak() noexcept;
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| 47 | bool decrement() noexcept;
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| 48 | bool decrement_weak() noexcept;
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| 49 | refcount_t refs() const noexcept;
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| 50 | refcount_t weak_refs() const noexcept;
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| 51 | bool expired() const noexcept;
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| 52 |
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| 53 | virtual ~refcount_obj() = default;
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| 54 | virtual void destroy() = 0;
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| 55 |
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| 56 | protected:
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| 57 | /**
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| 58 | * We're using a trick where refcount_ > 0
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| 59 | * means weak_refcount_ has 1 added to it,
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| 60 | * this makes it easier for weak_ptrs that
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| 61 | * can't decrement the weak_refcount_ to
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| 62 | * zero with shared_ptrs using this object.
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| 63 | */
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| 64 | refcount_t refcount_{1};
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| 65 | refcount_t weak_refcount_{1};
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| 66 | };
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| 67 | }
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| 68 |
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| 69 | #endif
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