store_cell.hpp

/*
 * live_cells_cpp
 * Copyright (C) 2024  Alexander Gutev <alex.gutev@gmail.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you
 * may not use this file except in compliance with the License.  You
 * may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied.  See the License for the specific language governing
 * permissions and limitations under the License.
 */
 
#ifndef LIVE_CELLS_STORE_CELL_HPP
#define LIVE_CELLS_STORE_CELL_HPP
 
#include "keys.hpp"
#include "compute_state.hpp"
#include "stateful_cell.hpp"
#include "changes_only_state.hpp"
#include "tracker.hpp"
 
namespace live_cells {
 
    template <typename T>
    struct store_cell_key : value_key<T> {
        using value_key<T>::value_key;
    };
 
    template <Cell C>
    class store_cell_state;
 
    template <Cell C>
    class store_cell_compute_state {
        const C arg;
 
        friend class store_cell_state<C>;
 
    public:
        store_cell_compute_state(C arg) :
            arg(arg) {}
 
        C::value_type operator()(observer::ref) {
            return arg.value();
        }
    };
 
    template <Cell C>
    class store_cell_state : public compute_cell_state<store_cell_compute_state<C>> {
        typedef compute_cell_state<store_cell_compute_state<C>> parent;
 
    public:
        store_cell_state(key_ref k, C arg) :
            parent(k, arg) {}
 
    protected:
        typedef C::value_type value_type;
 
        void init() override {
            parent::init();
 
            this->compute.arg.add_observer(this->observer_ptr());
 
            try {
                // Compute the initial value
                this->value();
            }
            catch (...) {
                // Prevent exception from being propagated to caller
            }
        }
 
        void pause() override {
            this->compute.arg.remove_observer(this->observer_ptr());
            parent::pause();
        }
    };
 
    template <Cell C>
    class store_changes_only_cell_state :
        public changes_only_cell_state<store_cell_state<C>> {
        typedef changes_only_cell_state<store_cell_state<C>> parent;
 
    public:
        using parent::parent;
 
    };
 
    template <Cell C, typename State = store_cell_state<C>>
    class store_cell : public stateful_cell<State> {
        typedef stateful_cell<State> parent;
 
        typedef store_cell_key<key_ref> key_type;
 
    public:
        typedef C::value_type value_type;
 
        store_cell(C cell) :
            parent(key_ref::create<key_type>(cell.key()), cell) {}
 
        value_type value() const {
            return this->state->value();
        }
 
        value_type operator()() const {
            argument_tracker::global().track_argument(*this);
            return value();
        }
    };
 
    template <Cell C>
    auto store(const C &arg) {
        return store_cell<C>(arg);
    }
 
    template <Cell C>
    auto store(changes_only_option option, const C &arg) {
        return store_cell<C, store_changes_only_cell_state<C>>(arg);
    }
 
    namespace ops {
 
        constexpr auto store = [] (const Cell auto &cell) {
            return live_cells::store(cell);
        };
 
        constexpr auto cache = [] (const Cell auto & cell) {
            return live_cells::store(changes_only, cell);
        };
 
    }  // ops
 
}  // live_cells
 
#endif /* LIVE_CELLS_STORE_CELL_HPP */