array.hpp

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#ifndef GKO_CORE_BASE_ARRAY_H_
#define GKO_CORE_BASE_ARRAY_H_


#include <memory>
#include <utility>


#include <ginkgo/core/base/exception.hpp>
#include <ginkgo/core/base/executor.hpp>
#include <ginkgo/core/base/types.hpp>
#include <ginkgo/core/base/utils.hpp>


namespace gko {


template <typename ValueType>
class Array {
public:
    using value_type = ValueType;

    using default_deleter = executor_deleter<value_type[]>;

    using view_deleter = null_deleter<value_type[]>;

    Array() noexcept
        : num_elems_(0),
          data_(nullptr, default_deleter{nullptr}),
          exec_(nullptr)
    {}

    Array(std::shared_ptr<const Executor> exec) noexcept
        : num_elems_(0),
          data_(nullptr, default_deleter{exec}),
          exec_(std::move(exec))
    {}

    Array(std::shared_ptr<const Executor> exec, size_type num_elems)
        : num_elems_(num_elems),
          data_(nullptr, default_deleter{exec}),
          exec_(std::move(exec))
    {
        if (num_elems > 0) {
            data_.reset(exec_->alloc<value_type>(num_elems));
        }
    }

    template <typename DeleterType>
    Array(std::shared_ptr<const Executor> exec, size_type num_elems,
          value_type *data, DeleterType deleter)
        : num_elems_{num_elems}, data_(data, deleter), exec_{exec}
    {}

    Array(std::shared_ptr<const Executor> exec, size_type num_elems,
          value_type *data)
        : Array(exec, num_elems, data, default_deleter{exec})
    {}

    template <typename RandomAccessIterator>
    Array(std::shared_ptr<const Executor> exec, RandomAccessIterator begin,
          RandomAccessIterator end)
        : Array(exec)
    {
        Array tmp(exec->get_master(), end - begin);
        int i = 0;
        for (auto it = begin; it != end; ++it, ++i) {
            tmp.data_[i] = *it;
        }
        *this = std::move(tmp);
    }

    template <typename T>
    Array(std::shared_ptr<const Executor> exec,
          std::initializer_list<T> init_list)
        : Array(exec, begin(init_list), end(init_list))
    {}

    Array(std::shared_ptr<const Executor> exec, const Array &other)
        : Array(exec)
    {
        *this = other;
    }

    Array(const Array &other) : Array(other.get_executor(), other) {}

    Array(std::shared_ptr<const Executor> exec, Array &&other) : Array(exec)
    {
        *this = std::move(other);
    }

    Array(Array &&other) : Array(other.get_executor(), std::move(other)) {}

    static Array view(std::shared_ptr<const Executor> exec, size_type num_elems,
                      value_type *data)
    {
        return Array{exec, num_elems, data, view_deleter{}};
    }

    Array &operator=(const Array &other)
    {
        if (&other == this) {
            return *this;
        }
        if (exec_ == nullptr) {
            exec_ = other.get_executor();
            data_ = data_manager{nullptr, other.data_.get_deleter()};
        }
        if (other.get_executor() == nullptr) {
            this->resize_and_reset(0);
            return *this;
        }
        this->resize_and_reset(other.get_num_elems());
        exec_->copy_from(other.get_executor().get(), num_elems_,
                         other.get_const_data(), this->get_data());
        return *this;
    }

    Array &operator=(Array &&other)
    {
        if (&other == this) {
            return *this;
        }
        if (exec_ == nullptr) {
            exec_ = other.get_executor();
            data_ = data_manager{nullptr, other.data_.get_deleter()};
        }
        if (other.get_executor() == nullptr) {
            this->resize_and_reset(0);
            return *this;
        }
        if (exec_ == other.get_executor() &&
            data_.get_deleter().target_type() != typeid(view_deleter)) {
            // same device and not a view, only move the pointer
            using std::swap;
            swap(data_, other.data_);
            swap(num_elems_, other.num_elems_);
        } else {
            // different device or a view, copy the data
            *this = other;
        }
        return *this;
    }

    void clear() noexcept
    {
        num_elems_ = 0;
        data_.reset(nullptr);
    }

    void resize_and_reset(size_type num_elems)
    {
        if (num_elems == num_elems_) {
            return;
        }
        if (exec_ == nullptr) {
            throw gko::NotSupported(__FILE__, __LINE__, __func__,
                                    "gko::Executor (nullptr)");
        }
        num_elems_ = num_elems;
        if (num_elems > 0) {
            data_.reset(exec_->alloc<value_type>(num_elems));
        } else {
            data_.reset(nullptr);
        }
    }

    size_type get_num_elems() const noexcept { return num_elems_; }

    value_type *get_data() noexcept { return data_.get(); }

    const value_type *get_const_data() const noexcept { return data_.get(); }

    std::shared_ptr<const Executor> get_executor() const noexcept
    {
        return exec_;
    }

    void set_executor(std::shared_ptr<const Executor> exec)
    {
        if (exec == exec_) {
            // moving to the same executor, no-op
            return;
        }
        Array tmp(std::move(exec));
        tmp = *this;
        exec_ = std::move(tmp.exec_);
        data_ = std::move(tmp.data_);
    }

private:
    using data_manager =
        std::unique_ptr<value_type[], std::function<void(value_type[])>>;

    size_type num_elems_;
    data_manager data_;
    std::shared_ptr<const Executor> exec_;
};


}  // namespace gko


#endif  // GKO_CORE_BASE_ARRAY_H_