multi_library_class_loader.h

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/*
 * Copyright (c) 2012, Willow Garage, Inc.
 * All rights reserved.
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 * modification, are permitted provided that the following conditions are met:
 *
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 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
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 *       contributors may be used to endorse or promote products derived from
 *       this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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 */

#ifndef CLASS_LOADER_MULTI_LIBRARY_CLASS_LOADER_H_DEFINED
#define CLASS_LOADER_MULTI_LIBRARY_CLASS_LOADER_H_DEFINED

#include "class_loader.h"
#include <boost/thread.hpp>

namespace class_loader
{

typedef std::string LibraryPath;
typedef std::map<LibraryPath, class_loader::ClassLoader*> LibraryToClassLoaderMap;
typedef std::vector<ClassLoader*> ClassLoaderVector;

class MultiLibraryClassLoader
{
  public:
    MultiLibraryClassLoader(bool enable_ondemand_loadunload);

    virtual ~MultiLibraryClassLoader();

    template <class Base>
    boost::shared_ptr<Base> createInstance(const std::string& class_name)
    {
      logDebug("class_loader::MultiLibraryClassLoader: Attempting to create instance of class type %s.", class_name.c_str());
      ClassLoaderVector active_loaders = getAllAvailableClassLoaders();
      for(unsigned int c = 0; c < active_loaders.size(); c++)
      {
        ClassLoader* current = active_loaders.at(c);
        if(current->isClassAvailable<Base>(class_name))
          return(current->createInstance<Base>(class_name));
      }

      throw(class_loader::CreateClassException("MultiLibraryClassLoader: Could not create object of class type " + class_name + " as no factory exists for it. Make sure that the library exists and was explicitly loaded through MultiLibraryClassLoader::loadLibrary()"));
    }

    template <class Base>
    boost::shared_ptr<Base> createInstance(const std::string& class_name, const std::string& library_path)
    {   
      ClassLoader* loader = getClassLoaderForLibrary(library_path);
      if(loader)
        return(loader->createInstance<Base>(class_name));
      else
        throw class_loader::NoClassLoaderExistsException("Could not create instance as there is no ClassLoader in MultiLibraryClassLoader bound to library " + library_path + " Ensure you called MultiLibraryClassLoader::loadLibrary()");
    }

    template <class Base>
    Base* createUnmanagedInstance(const std::string& class_name)
    {
      ClassLoaderVector active_loaders = getAllAvailableClassLoaders();
      for(unsigned int c = 0; c < active_loaders.size(); c++)
      {
        ClassLoader* current = active_loaders.at(c);
        if(current->isClassAvailable<Base>(class_name))
          return(current->createUnmanagedInstance<Base>(class_name));
      }

      throw(class_loader::CreateClassException("MultiLibraryClassLoader: Could not create class of type " + class_name));
    }

    template <class Base>
    Base* createUnmanagedInstance(const std::string& class_name, const std::string& library_path)
    {
      ClassLoader* loader = getClassLoaderForLibrary(library_path);
      if(loader)
        return(loader->createUnmanagedInstance<Base>(class_name));
      else
        throw class_loader::NoClassLoaderExistsException("Could not create instance as there is no ClassLoader in MultiLibraryClassLoader bound to library " + library_path + " Ensure you called MultiLibraryClassLoader::loadLibrary()");
    }

    template <class Base>
    bool isClassAvailable(const std::string& class_name)
    {
      std::vector<std::string> available_classes = getAvailableClasses<Base>();
      return(available_classes.end() != std::find(available_classes.begin(), available_classes.end(), class_name));
    }

    bool isLibraryAvailable(const std::string& library_path);

    template <class Base>
    std::vector<std::string> getAvailableClasses()
    {
      std::vector<std::string> available_classes;
      ClassLoaderVector loaders = getAllAvailableClassLoaders();
      for(unsigned int c = 0; c < loaders.size(); c++)
      {
        ClassLoader* current = loaders.at(c);
        std::vector<std::string> loader_classes = current->getAvailableClasses<Base>();
        available_classes.insert(available_classes.end(), loader_classes.begin(), loader_classes.end());
      }
      return(available_classes);
    }

    template <class Base>
    std::vector<std::string> getAvailableClassesForLibrary(const std::string& library_path)
    {
      ClassLoader* loader = getClassLoaderForLibrary(library_path);
      std::vector<std::string> available_classes;
      if(loader)
      {
        available_classes = loader->getAvailableClasses<Base>();
        return(available_classes);
      }
      else
        throw class_loader::NoClassLoaderExistsException("There is no ClassLoader in MultiLibraryClassLoader bound to library " + library_path + " Ensure you called MultiLibraryClassLoader::loadLibrary()");
    }

    std::vector<std::string> getRegisteredLibraries();

    void loadLibrary(const std::string& library_path);

    int unloadLibrary(const std::string& library_path);


  private:
    bool isOnDemandLoadUnloadEnabled(){return(enable_ondemand_loadunload_);}

    ClassLoader* getClassLoaderForLibrary(const std::string& library_path);

    ClassLoaderVector getAllAvailableClassLoaders();

    void shutdownAllClassLoaders();

  private:
    bool enable_ondemand_loadunload_;
    LibraryToClassLoaderMap active_class_loaders_;
    boost::mutex loader_mutex_;
};


}
#endif