raii.h

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright The KiCad Developers, see AUTHORS.TXT for contributors.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 3
 * of the License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
#ifndef RAII_H
#define RAII_H
 
#include <wx/window.h>
 
 
/*
 * Exception-safe (and 'return' safe) scoped handlers following the "resource allocation is
 * initialization" pattern.
 */
 
 
// Exception-safe method for nulling a pointer on destruction
class NULLER
{
public:
    NULLER( void*& aPtr ) :
            m_what( aPtr )
    {}
 
    ~NULLER()
    {
        m_what = nullptr;
    }
 
    // No copying or it can lead to double-nulling of the pointer.
    NULLER( const NULLER& ) = delete;
    NULLER& operator=( const NULLER& ) = delete;
 
private:
    void*&  m_what;
};
 
 
// Temporarily un-freeze a window, and then re-freeze on destruction
class WINDOW_THAWER
{
public:
    WINDOW_THAWER( wxWindow* aWindow ) :
            m_window( aWindow )
    {
        while( m_window->IsFrozen() )
        {
            m_window->Thaw();
            m_freezeCount++;
        }
    }
 
    ~WINDOW_THAWER()
    {
        while( m_freezeCount > 0 )
        {
            m_window->Freeze();
            m_freezeCount--;
        }
    }
 
    // No copying or it can lead to double-re-freezing of the window.
    WINDOW_THAWER( const WINDOW_THAWER& ) = delete;
    WINDOW_THAWER& operator=( const WINDOW_THAWER& ) = delete;
 
protected:
    wxWindow* m_window;
    int       m_freezeCount = 0;
};
 

class WINDOW_DISABLER
{
public:
    WINDOW_DISABLER( wxWindow* aWindow ) :
            m_win( aWindow )
    {
        if( m_win )
            m_win->Disable();
    }
 
    ~WINDOW_DISABLER()
    {
        if( m_win )
        {
            m_win->Enable();
            m_win->Raise(); // let's focus back on the parent window
        }
    }
 
    // No copying or it can lead to double-re-enabling of the window.
    WINDOW_DISABLER( const WINDOW_DISABLER& ) = delete;
    WINDOW_DISABLER& operator=( const WINDOW_DISABLER& ) = delete;
 
    void SuspendForTrueModal()
    {
        if( m_win )
            m_win->Enable();
    }
 
    void ResumeAfterTrueModal()
    {
        if( m_win )
            m_win->Disable();
    }
 
private:
    wxWindow* m_win;
};
 
 
#endif  // RAII_H