Variant.h

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/******************************************************************************
 * Copyright (C) 2014 by Ralf Kaestner                                        *
 * ralf.kaestner@gmail.com                                                    *
 *                                                                            *
 * This program is free software; you can redistribute it and/or modify       *
 * it under the terms of the Lesser GNU General Public License as published by*
 * the Free Software Foundation; either version 3 of the License, or          *
 * (at your option) any later version.                                        *
 *                                                                            *
 * 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               *
 * Lesser GNU General Public License for more details.                        *
 *                                                                            *
 * You should have received a copy of the Lesser GNU General Public License   *
 * along with this program. If not, see <http://www.gnu.org/licenses/>.       *
 ******************************************************************************/

#ifndef VARIANT_TOPIC_TOOLS_VARIANT_H
#define VARIANT_TOPIC_TOOLS_VARIANT_H

#include <typeinfo>

#include <boost/type_traits.hpp>

#include <ros/ros.h>

#include <variant_topic_tools/DataType.h>
#include <variant_topic_tools/DataTypeTraits.h>
#include <variant_topic_tools/Pointer.h>

namespace variant_topic_tools {
  class Variant {
  friend class MessageVariable;
  public:
    Variant();

    template <typename T> Variant(const T& src);

    ~Variant();

    template <typename T> void setValue(const T& value);

    template <typename T> typename type_traits::DataType<T>::ValueType&
      getValue();

    template <typename T> const typename type_traits::DataType<T>::ValueType&
      getValue() const;

    const DataType& getType() const;

    const std::type_info& getValueTypeInfo() const;

    bool hasType() const;

    bool isArray() const;

    bool isBuiltin() const;

    bool isCollection() const;

    bool isMessage() const;

    bool isEmpty() const;

    ArrayVariant asArray() const;

    BuiltinVariant asBuiltin() const;

    CollectionVariant asCollection() const;

    MessageVariant asMessage() const;

    void clear();

    void read(std::istream& stream);

    void write(std::ostream& stream) const;

    Serializer createSerializer() const;

    template <typename T> Variant& operator=(const T& src);

    template <typename T> operator T() const;

    template <typename T> bool operator==(const T& value) const;

    template <typename T> bool operator!=(const T& value) const;

  protected:
    class Value;

    typedef boost::shared_ptr<Value> ValuePtr;

    typedef boost::weak_ptr<Value> ValueWPtr;

    class Value {
    public:
      Value();

      virtual ~Value();

      virtual const std::type_info& getTypeInfo() const;

      virtual void setValue(const Value& value) = 0;

      virtual bool isEqual(const Value& value) const = 0;

      virtual ValuePtr clone() const = 0;

      virtual void read(std::istream& stream) = 0;

      virtual void write(std::ostream& stream) const = 0;

      virtual Serializer createSerializer(const DataType& type) const = 0;
    };

    template <typename T> class ValueT :
      public virtual Value {
    public:
      ValueT();

      virtual ~ValueT();

      const std::type_info& getTypeInfo() const;

      virtual void set(const Pointer<T>& value) = 0;

      void setValue(const T& value);

      virtual T& getValue() = 0;

      virtual const T& getValue() const = 0;
    };

    DataType type;

    ValuePtr value;

    Variant(const DataType& type);

    template <typename T> static void set(Variant& variant, const
      Pointer<typename type_traits::DataType<T>::ValueType>& value);

    template <typename T> static void setValue(Variant& dst, const T&
      value, typename boost::enable_if<boost::is_base_of<Variant, T> >::
      type* = 0);

    template <typename T> static void setValue(Variant& dst, const T& value,
      typename boost::disable_if<boost::is_base_of<Variant, T> >::type* = 0);

    template <typename T> static bool isEqual(const Variant& variant, const
      T& value, typename boost::enable_if<boost::is_base_of<Variant, T> >::
      type* = 0);

    template <typename T> static bool isEqual(const Variant& variant, const
      T& value, typename boost::disable_if<boost::is_base_of<Variant, T> >::
      type* = 0);

    template <typename T> static void assign(Variant& dst, const T& src,
      typename boost::enable_if<boost::is_base_of<Variant, T> >::type* = 0);

    template <typename T> static void assign(Variant& dst, const T& src,
      typename boost::disable_if<boost::is_base_of<Variant, T> >::type* = 0);
  };

  std::istream& operator>>(std::istream& stream, Variant& variant);

  std::ostream& operator<<(std::ostream& stream, const Variant& variant);
};

#include <variant_topic_tools/Variant.tpp>

#endif