environment-variable.h

Go to the documentation of this file.

/*
 * Copyright (c) 2022 Lawrence Livermore National Laboratory
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author: Peter D. Barnes, Jr. <pdbarnes@llnl.gov>
 */
 
#ifndef ENVIRONMENT_VARIABLE_H
#define ENVIRONMENT_VARIABLE_H
 
#include <memory> // shared_ptr
#include <string>
#include <unordered_map>
#include <utility> // pair
 
namespace ns3
{
 
 
// Forward declaration
namespace tests
{
class EnvVarTestCase;
}
 
class EnvironmentVariable
{
  public:
    using KeyFoundType = std::pair<bool, std::string>;
 
    static KeyFoundType Get(const std::string& envvar,
                            const std::string& key = "",
                            const std::string& delim = ";");
 
    // Forward
    class Dictionary;
 
    static std::shared_ptr<Dictionary> GetDictionary(const std::string& envvar,
                                                     const std::string& delim = ";");
 
    class Dictionary
    {
      public:
        Dictionary(const std::string& envvar, const std::string& delim = ";");
 
        KeyFoundType Get(const std::string& key = "") const;
 
        using KeyValueStore = std::unordered_map<std::string, std::string>;
 
        KeyValueStore GetStore() const;
 
      private:
        bool m_exists;
        std::string m_variable;
        KeyValueStore m_dict;
 
    }; // class Dictionary
 
    static bool Set(const std::string& variable, const std::string& value);
 
    static bool Unset(const std::string& variable);
 
    EnvironmentVariable() = delete;
    EnvironmentVariable(const EnvironmentVariable&) = delete;
    EnvironmentVariable& operator=(const EnvironmentVariable&) = delete;
    EnvironmentVariable(EnvironmentVariable&&) = delete;
    EnvironmentVariable& operator=(EnvironmentVariable&&) = delete;
  private:
    using DictionaryList = std::unordered_map<std::string, std::shared_ptr<Dictionary>>;
 
    static DictionaryList& Instance();
 
    // Test needs to clear the instance
    friend class tests::EnvVarTestCase;
 
    static void Clear();
 
}; // class EnvironmentVariable
 
} // namespace ns3
 
#endif /* ENVIRONMENT_VARIABLE_H */