inc/rtl/ref.hxx

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 *
 * Licensed to the Apache Software Foundation (ASF) under one
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 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
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#ifndef _RTL_REF_HXX_
#define _RTL_REF_HXX_

#include <sal/types.h>
#include <osl/diagnose.h>
#include <osl/interlck.h>

namespace rtl
{

/** Interface for a reference type.
*/
class IReference
{
public:
    /** @see osl_incrementInterlockedCount.
     */
    virtual oslInterlockedCount SAL_CALL acquire() = 0;

    /** @see osl_decrementInterlockedCount.
     */
    virtual oslInterlockedCount SAL_CALL release() = 0;
};


/** Template reference class for reference type derived from IReference.
*/
template <class reference_type>
class Reference
{
    /** The <b>reference_type</b> body pointer.
     */
    reference_type * m_pBody;


public:
    /** Constructor...
     */
    inline Reference()
        : m_pBody (0)
    {}


    /** Constructor...
     */
    inline Reference (reference_type * pBody)
        : m_pBody (pBody)
    {
        if (m_pBody)
            m_pBody->acquire();
    }


    /** Copy constructor...
     */
    inline Reference (const Reference<reference_type> & handle)
        : m_pBody (handle.m_pBody)
    {
        if (m_pBody)
            m_pBody->acquire();
    }


    /** Destructor...
     */
    inline ~Reference()
    {
        if (m_pBody)
            m_pBody->release();
    }

    /** Set...
        Similar to assignment.
     */
    inline Reference<reference_type> &
    SAL_CALL set (reference_type * pBody)
    {
        if (pBody)
            pBody->acquire();
        reference_type * const pOld = m_pBody;
        m_pBody = pBody;
        if (pOld)
            pOld->release();
        return *this;
    }

    /** Assignment.
        Unbinds this instance from its body (if bound) and
        bind it to the body represented by the handle.
     */
    inline Reference<reference_type> &
    SAL_CALL operator= (const Reference<reference_type> & handle)
    {
        return set( handle.m_pBody );
    }

    /** Assignment...
     */
    inline Reference<reference_type> &
    SAL_CALL operator= (reference_type * pBody)
    {
        return set( pBody );
    }

    /** Unbind the body from this handle.
        Note that for a handle representing a large body,
        "handle.clear().set(new body());" _might_
        perform a little bit better than "handle.set(new body());",
        since in the second case two large objects exist in memory
        (the old body and the new body).
     */
    inline Reference<reference_type> & SAL_CALL clear()
    {
        if (m_pBody)
        {
            reference_type * const pOld = m_pBody;
            m_pBody = 0;
            pOld->release();
        }
        return *this;
    }


    /** Get the body. Can be used instead of operator->().
        I.e. handle->someBodyOp() and handle.get()->someBodyOp()
        are the same.
     */
    inline reference_type * SAL_CALL get() const
    {
        return m_pBody;
    }


    /** Probably most common used: handle->someBodyOp().
     */
    inline reference_type * SAL_CALL operator->() const
    {
        OSL_PRECOND(m_pBody, "Reference::operator->() : null body");
        return m_pBody;
    }


    /** Allows (*handle).someBodyOp().
    */
    inline reference_type & SAL_CALL operator*() const
    {
        OSL_PRECOND(m_pBody, "Reference::operator*() : null body");
        return *m_pBody;
    }


    /** Returns True if the handle does point to a valid body.
     */
    inline sal_Bool SAL_CALL is() const
    {
        return (m_pBody != 0);
    }


    /** Returns True if this points to pBody.
     */
    inline sal_Bool SAL_CALL operator== (const reference_type * pBody) const
    {
        return (m_pBody == pBody);
    }


    /** Returns True if handle points to the same body.
     */
    inline sal_Bool
    SAL_CALL operator== (const Reference<reference_type> & handle) const
    {
        return (m_pBody == handle.m_pBody);
    }


    /** Needed to place References into STL collection.
     */
    inline sal_Bool
    SAL_CALL operator!= (const Reference<reference_type> & handle) const
    {
        return (m_pBody != handle.m_pBody);
    }


    /** Needed to place References into STL collection.
     */
    inline sal_Bool
    SAL_CALL operator< (const Reference<reference_type> & handle) const
    {
        return (m_pBody < handle.m_pBody);
    }


    /** Needed to place References into STL collection.
     */
    inline sal_Bool
    SAL_CALL operator> (const Reference<reference_type> & handle) const
    {
        return (m_pBody > handle.m_pBody);
    }
};

/** @internal
    Enables boost::mem_fn and boost::bind to recognize Reference.
*/
template <typename T>
inline T * get_pointer( Reference<T> const& r )
{
    return r.get();
}

} // namespace rtl

#endif /* !_RTL_REF_HXX_ */