callbacks_holder.h

/*******************************************************************************
* Copyright © 2015, Sergey Radionov <rsatom_gmail.com>
* All rights reserved.
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#pragma once

#include <cassert>
#include <deque>
#include <functional>
#include <algorithm>
#include <mutex>

template<typename callback_t>
class callbacks_holder
{
protected:
    ~callbacks_holder();

public:
    virtual void register_callback( callback_t* );
    virtual void unregister_callback( callback_t* );

protected:
    void for_each_callback( const std::function<void( callback_t* )>& ) const;
    bool has_callbacks() const
        { return !_callbacks.empty(); }
    void clear_callbacks()
        { _callbacks.clear(); }

private:
    typedef std::deque<callback_t*> callbacks_t;

private:
    mutable std::mutex _callbacks_guard;
    callbacks_t _callbacks;
};

template<typename callback_t>
callbacks_holder<callback_t>::~callbacks_holder()
{
    assert( _callbacks.empty() );
}

template<typename callback_t>
void callbacks_holder<callback_t>::register_callback( callback_t* callback )
{
    std::lock_guard<std::mutex> lock( _callbacks_guard );
    assert( _callbacks.end() == std::find( _callbacks.begin(), _callbacks.end(), callback ) );
    _callbacks.push_back( callback );
}

template<typename callback_t>
void callbacks_holder<callback_t>::unregister_callback( callback_t* callback )
{
    std::lock_guard<std::mutex> lock( _callbacks_guard );
    auto it = std::find( _callbacks.begin(), _callbacks.end(), callback );
    if( it != _callbacks.end() ) {
        _callbacks.erase( it );
    }
}

template<typename callback_t>
void callbacks_holder<callback_t>::for_each_callback( const std::function<void( callback_t* )>& f ) const
{
    std::lock_guard<std::mutex> lock( _callbacks_guard );
    std::for_each( _callbacks.begin(), _callbacks.end(), f );
}