ScopedHandle.h

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//===========================================================================
/*!
 * 
 *
 * \brief       A scoped_ptr like container for C type handles
 * 
 * 
 * \par
 * This class provides RAII handle management to Shark
 * 
 * 
 * 
 *
 * \author      B. Li
 * \date        2012
 *
 *
 * \par Copyright 1995-2017 Shark Development Team
 * 
 * <BR><HR>
 * This file is part of Shark.
 * <http://shark-ml.org/>
 * 
 * Shark is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published 
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * Shark is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with Shark.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
//===========================================================================

#ifndef SHARK_CORE_UTILITY_SCOPED_HANDLE_H
#define SHARK_CORE_UTILITY_SCOPED_HANDLE_H

#include "shark/Core/Exception.h"

#include <boost/assert.hpp>
#include <boost/bind/arg.hpp>
#include <boost/format.hpp>
#include <boost/function.hpp>
#include <boost/lambda/lambda.hpp>
#include <boost/noncopyable.hpp>

namespace shark {

/// A handle container which usually taking C style handle such as file Id
/// @tparam T The type of handle the container holds
template <typename T>
class ScopedHandle : private boost::noncopyable
{
public:

    /// The typedef of deleter for type a T
    typedef boost::function<void (const T&) > DeleterType;

    /// Type of verifier which should return true for valid handle, and false otherwise
    typedef boost::function<bool (const T&) > VerifierType;

    /// Constructor
    /// @param handle
    ///     The handle container will hold
    /// @param deleter
    ///     The deleter used for freeing a handle which should return true for valid handles, false otherwise
    /// @param handleDescription
    ///     A description of handle for easy debugging in case of validation failure
    ScopedHandle(
        const T& handle,
        const DeleterType& deleter,
        const std::string& handleDescription = "")
    :
        m_handle(handle),
        m_isValidHandle(true), // null verifier means valid handle
        m_deleter(deleter)
    {
        BOOST_ASSERT(deleter);
        if (!m_isValidHandle)
            throw SHARKEXCEPTION((boost::format("%s (FAILED)") % handleDescription).str());
    }

    ~ScopedHandle()
    {
        if (m_isValidHandle)
            m_deleter(m_handle);
    }

    /// The only way to access handle externally
    const T& operator*() const { return m_handle; }

private:

    const T m_handle;
    const bool m_isValidHandle;
    const DeleterType m_deleter;
};

} // namespace shark {

#endif // SHARK_CORE_SCOPED_HANDLE_H