peek_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_PEEK_CELL_HPP
#define LIVE_CELLS_PEEK_CELL_HPP
 
#include "keys.hpp"
#include "cell_state.hpp"
#include "stateful_cell.hpp"
 
namespace live_cells {
    struct peek_cell_key : value_key<key_ref> {
        using value_key<key_ref>::value_key;
    };
 
    template <typename C>
    class peek_cell_state : public cell_state, public observer {
    public:
        peek_cell_state(key_ref k, C cell) :
            cell_state(k),
            cell(cell) {}
 
        void will_update(const key_ref &k) override {}
        void update(const key_ref &k, bool) override {}
 
    protected:
        void init() override {
            cell_state::init();
            cell.add_observer(std::dynamic_pointer_cast<observer>(this->shared_from_this()));
        }
 
        void pause() override {
            cell.remove_observer(std::dynamic_pointer_cast<observer>(this->shared_from_this()));
            cell_state::pause();
        }
 
    private:
        C cell;
    };
 
    template <Cell C>
    class peek_cell : public stateful_cell<peek_cell_state<C>> {
        typedef stateful_cell<peek_cell_state<C>> parent;
 
    public:
        typedef C::value_type value_type;
 
        peek_cell(const C &cell) :
            parent(key_ref::create<peek_cell_key>(cell.key()), cell),
            cell(cell) {}
 
        typename C::value_type value() const {
            return cell.value();
        }
 
        typename C::value_type operator()() const {
            argument_tracker::global().track_argument(*this);
            return value();
        }
 
    private:
        const C cell;
    };
 
    template <typename C>
    auto peek(const C &cell) {
        return peek_cell<C>(cell);
    }
 
    namespace ops {
 
        constexpr auto peek = [] (const Cell auto &cell) {
            return live_cells::peek(cell);
        };
 
    }  // ops
 
}  // live_cells
 
#endif /* LIVE_CELLS_PEEK_CELL_HPP */