f7e7cb349b
Original-commit: flang-compiler/f18@aa7f55e15f Reviewed-on: https://github.com/flang-compiler/f18/pull/217
83 lines
2.2 KiB
C++
83 lines
2.2 KiB
C++
// Copyright (c) 2018, NVIDIA CORPORATION. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef FORTRAN_COMMON_REFERENCE_COUNTED_H_
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#define FORTRAN_COMMON_REFERENCE_COUNTED_H_
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// A class template of smart pointers to objects with their own
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// reference counting object lifetimes that's lighter weight
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// than std::shared_ptr<>. Not thread-safe.
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namespace Fortran::common {
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// A base class for reference-counted objects. Must be public.
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template<typename A> class ReferenceCounted {
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public:
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ReferenceCounted() {}
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void TakeReference() { ++references_; }
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void DropReference() {
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if (--references_ == 0) {
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delete static_cast<A *>(this);
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}
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}
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private:
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int references_{0};
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};
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// A reference to a reference-counted object.
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template<typename A> class CountedReference {
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public:
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using type = A;
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CountedReference() {}
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CountedReference(type *m) : p_{m} { Take(); }
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CountedReference(const CountedReference &c) : p_{c.p_} { Take(); }
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CountedReference(CountedReference &&c) : p_{c.p_} { c.p_ = nullptr; }
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CountedReference &operator=(const CountedReference &c) {
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c.Take();
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Drop();
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p_ = c.p_;
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return *this;
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}
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CountedReference &operator=(CountedReference &&c) {
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A *p{c.p_};
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c.p_ = nullptr;
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Drop();
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p_ = p;
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return *this;
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}
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~CountedReference() { Drop(); }
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operator bool() const { return p_ != nullptr; }
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type *get() const { return p_; }
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type &operator*() const { return *p_; }
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type *operator->() const { return p_; }
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private:
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void Take() const {
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if (p_) {
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p_->TakeReference();
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}
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}
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void Drop() {
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if (p_) {
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p_->DropReference();
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p_ = nullptr;
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}
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}
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type *p_{nullptr};
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};
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}
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#endif // FORTRAN_COMMON_REFERENCE_COUNTED_H_
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