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87 lines
2.5 KiB
C++
87 lines
2.5 KiB
C++
#include <Common/COWPtr.h>
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#include <iostream>
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class IColumn : public COWPtr<IColumn>
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{
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private:
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friend class COWPtr<IColumn>;
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virtual IColumn * clone() const = 0;
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public:
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virtual ~IColumn() {}
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virtual int get() const = 0;
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virtual void set(int value) = 0;
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virtual MutablePtr test() const = 0;
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};
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using ColumnPtr = IColumn::Ptr;
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using MutableColumnPtr = IColumn::MutablePtr;
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class ConcreteColumn : public COWPtrHelper<IColumn, ConcreteColumn>
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{
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private:
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friend class COWPtrHelper<IColumn, ConcreteColumn>;
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int data;
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ConcreteColumn(int data) : data(data) {}
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ConcreteColumn(const ConcreteColumn &) = default;
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MutableColumnPtr test() const override
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{
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MutableColumnPtr res = create(123);
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return res;
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}
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public:
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int get() const override { return data; }
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void set(int value) override { data = value; }
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};
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int main(int, char **)
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{
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ColumnPtr x = ConcreteColumn::create(1);
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ColumnPtr y = x->test();
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std::cerr << "values: " << x->get() << ", " << y->get() << "\n";
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std::cerr << "refcounts: " << x->use_count() << ", " << y->use_count() << "\n";
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std::cerr << "addresses: " << x.get() << ", " << y.get() << "\n";
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{
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MutableColumnPtr mutable_y = y->mutate();
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mutable_y->set(2);
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std::cerr << "refcounts: " << x->use_count() << ", " << y->use_count() << ", " << mutable_y->use_count() << "\n";
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std::cerr << "addresses: " << x.get() << ", " << y.get() << ", " << mutable_y.get() << "\n";
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y = std::move(mutable_y);
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}
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std::cerr << "values: " << x->get() << ", " << y->get() << "\n";
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std::cerr << "refcounts: " << x->use_count() << ", " << y->use_count() << "\n";
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std::cerr << "addresses: " << x.get() << ", " << y.get() << "\n";
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x = ConcreteColumn::create(0);
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std::cerr << "values: " << x->get() << ", " << y->get() << "\n";
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std::cerr << "refcounts: " << x->use_count() << ", " << y->use_count() << "\n";
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std::cerr << "addresses: " << x.get() << ", " << y.get() << "\n";
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{
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MutableColumnPtr mutable_y = y->mutate();
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mutable_y->set(3);
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std::cerr << "refcounts: " << x->use_count() << ", " << y->use_count() << ", " << mutable_y->use_count() << "\n";
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std::cerr << "addresses: " << x.get() << ", " << y.get() << ", " << mutable_y.get() << "\n";
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y = std::move(mutable_y);
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}
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std::cerr << "values: " << x->get() << ", " << y->get() << "\n";
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std::cerr << "refcounts: " << x->use_count() << ", " << y->use_count() << "\n";
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return 0;
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}
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