PluginLoader.h

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/*
** This file is part of eOn.
**
** SPDX-License-Identifier: BSD-3-Clause
**
** Copyright (c) 2010--present, eOn Development Team
** All rights reserved.
**
** Repo:
** https://github.com/TheochemUI/eOn
*/
#pragma once

 
#include "eon/DynLib.h"
 
#include <mutex>
#include <stdexcept>
#include <string>
#include <unordered_map>
#include <vector>
 
namespace eonc {
 
// ---------------------------------------------------------------------------
// IPluginLoader: injectable ABI. Production uses PluginLoader::instance().
// ---------------------------------------------------------------------------
class IPluginLoader {
public:
  virtual void add_config_paths(const std::string &colon_paths) = 0;

  [[nodiscard]] virtual bool lib_present(const char *lib_base) const = 0;

  [[nodiscard]] virtual const std::vector<std::string> &
  search_paths() const noexcept = 0;

  [[noreturn]] virtual void throw_not_found(const char *lib_base,
                                            const char *description) const = 0;

  template <typename Fn>
  Fn load_sym(const char *lib_base, const char *sym_name) {
    dynlib::Handle h = open_lib(lib_base);
    if (!h)
      return nullptr;
    return dynlib::loadSym<Fn>(h, sym_name);
  }
 
  virtual ~IPluginLoader() = default;
 
  IPluginLoader(const IPluginLoader &) = delete;
  IPluginLoader &operator=(const IPluginLoader &) = delete;
 
protected:
  IPluginLoader() = default;
  virtual dynlib::Handle open_lib(const char *lib_base) = 0;
};
 
// ---------------------------------------------------------------------------
// PluginLoader: process-default search path + dlopen cache (Meyer's
// singleton).
// ---------------------------------------------------------------------------
class PluginLoader : public IPluginLoader {
public:
  static PluginLoader &instance();
 
  void add_config_paths(const std::string &colon_paths) override;
 
  [[nodiscard]] bool lib_present(const char *lib_base) const override;
 
  [[nodiscard]] const std::vector<std::string> &
  search_paths() const noexcept override {
    return m_search_paths;
  }
 
  [[noreturn]] void throw_not_found(const char *lib_base,
                                    const char *description) const override;
 
  ~PluginLoader() override;
  PluginLoader(const PluginLoader &) = delete;
  PluginLoader &operator=(const PluginLoader &) = delete;
 
private:
  PluginLoader();
  friend class Runtime;
 
  dynlib::Handle open_lib(const char *lib_base) override;
  std::vector<std::string> lib_names(const char *lib_base) const;
  void append_paths(const std::string &path_str, char sep);
 
  std::vector<std::string> m_search_paths;
  mutable std::mutex m_mutex;
  std::unordered_map<std::string, dynlib::Handle> m_handles;
  std::string m_last_load_error;
  bool m_last_load_saw_file = false;
};
 
} // namespace eonc