PluginLibrary.h

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/*
 * This file is part of KnowRob, please consult
 * https://github.com/knowrob/knowrob for license details.
 */
 
#ifndef KNOWROB_PLUGIN_LIBRARY_H_
#define KNOWROB_PLUGIN_LIBRARY_H_
 
#include <string>
#include <memory>
#include <dlfcn.h>
#include "knowrob/plugins/PluginFactory.h"
#include "knowrob/Logger.h"
 
namespace knowrob {
    template<class T>
    class PluginLibrary : public PluginFactory<T> {
    public:
        explicit PluginLibrary(std::string_view dllPath)
                : dllPath_(dllPath),
                  handle_(nullptr),
                  create_(nullptr),
                  get_name_(nullptr) {
        }
 
        ~PluginLibrary() override {
            if (handle_) {
                dlclose(handle_);
                handle_ = nullptr;
            }
        }
 
        PluginLibrary(const PluginLibrary &) = delete;
 
        bool isLoaded() {
            return (create_ != nullptr && get_name_ != nullptr);
        }
 
        bool loadDLL() {
            handle_ = dlopen(dllPath_.c_str(), RTLD_LAZY);
            // Throw the error if the library could not be loaded
            if (!handle_) {
                KB_ERROR("dlopen failed: {}", dlerror());
            };
            if (handle_ != nullptr) {
                create_ = (std::shared_ptr<T> (*)()) dlsym(handle_, "knowrob_createPlugin");
                get_name_ = (char *(*)()) dlsym(handle_, "knowrob_getPluginName");
                return isLoaded();
            } else {
                return false;
            }
        }
 
        // Override PluginFactory
        std::shared_ptr<NamedPlugin<T>> create(std::string_view pluginID) override {
            return std::make_shared<NamedPlugin<T>>(pluginID, PluginLanguage::CPP, create_());
        }
 
        // Override PluginFactory
        std::string_view name() const override { return name_; };
 
    protected:
        const std::string dllPath_;
        std::string name_;
        // handle of opened library
        void *handle_;
 
        // a factory function used to create new instances of a backend.
        std::shared_ptr<T> (*create_)();
 
        // a function that returns the name of the plugin
        char *(*get_name_)();
    };
}
 
#endif //KNOWROB_PLUGIN_LIBRARY_H_