Plugin.h

/******************************************************************************
DSPatch - The Refreshingly Simple C++ Dataflow Framework
Copyright (c) 2024, Marcus Tomlinson
 
BSD 2-Clause License
 
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
 
1. Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.
 
2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.
 
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
******************************************************************************/
 
#pragma once
 
#include "Component.h"
 
#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#undef WIN32_LEAN_AND_MEAN
#define DLLEXPORT __declspec( dllexport )
#else
#include <dlfcn.h>
#define DLLEXPORT
#endif
 
#include <string>
 
#define EXPORT_PLUGIN( classname, ... )          \
    extern "C"                                   \
    {                                            \
        DLLEXPORT DSPatch::Component* Create()   \
        {                                        \
            return new classname( __VA_ARGS__ ); \
        }                                        \
    }
 
namespace DSPatch
{
 
 
class Plugin final
{
public:
    Plugin( const Plugin& ) = delete;
    Plugin& operator=( const Plugin& ) = delete;
 
    explicit Plugin( const std::string& pluginPath );
    ~Plugin();
 
    bool IsLoaded() const;
 
    Component::SPtr Create() const;
 
private:
    typedef DSPatch::Component* ( *Create_t )();
 
    void* _handle = nullptr;
    Create_t _create = nullptr;
};
 
inline Plugin::Plugin( const std::string& pluginPath )
{
    // open library
#ifdef _WIN32
    _handle = LoadLibrary( pluginPath.c_str() );
#else
    _handle = dlopen( pluginPath.c_str(), RTLD_NOW );
#endif
 
    if ( _handle )
    {
        // load symbols
#ifdef _WIN32
        _create = (Create_t)GetProcAddress( (HMODULE)_handle, "Create" );
#else
        _create = (Create_t)dlsym( _handle, "Create" );
#endif
 
        if ( !_create )
        {
#ifdef _WIN32
            FreeLibrary( (HMODULE)_handle );
#else
            dlclose( _handle );
#endif
 
            _handle = nullptr;
        }
    }
}
 
inline Plugin::~Plugin()
{
    // close library
    if ( _handle )
    {
#ifdef _WIN32
        FreeLibrary( (HMODULE)_handle );
#else
        dlclose( _handle );
#endif
    }
}
 
// cppcheck-suppress unusedFunction
inline bool Plugin::IsLoaded() const
{
    return _handle;
}
 
// cppcheck-suppress unusedFunction
inline Component::SPtr Plugin::Create() const
{
    if ( _handle )
    {
        return Component::SPtr( _create() );
    }
    return nullptr;
}
 
}  // namespace DSPatch