path: root/glib/src/variant.hg

/* Copyright 2010 The glibmm Development Team
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

_DEFS(glibmm,glib)

#include <glibmmconfig.h>
#include <glibmm/varianttype.h>
#include <glibmm/variantiter.h>
#include <glibmm/ustring.h>
#include <glibmm/error.h>
#include <utility>
#include <vector>
#include <map>
#include <stdexcept>
#include <typeinfo>

namespace Glib
{

/** @defgroup Variant Variant Data Types
 *
 * The Variant classes deal with strongly typed
 * variant data. A Variant stores a value along with
 * information about the type of that value. The range of possible
 * values is determined by the type. The type system used is VariantType.
 *
 * See the VariantBase class and it's derived types, such as VariantContainerBase,
 * and the Variant<> template type.
 *
 * Variant instances always have a type and a value (which are given
 * at construction time). The type and value of a Variant
 * can never change other than by the Variant itself being
 * destroyed.  A Variant cannot contain a pointer.
 *
 * Variant is heavily optimised for dealing with data in serialised
 * form. It works particularly well with data located in memory-mapped
 * files. It can perform nearly all deserialisation operations in a
 * small constant time, usually touching only a single memory page.
 * Serialised Variant data can also be sent over the network.
 *
 * Variant is largely compatible with D-Bus.  Almost all types of
 * Variant instances can be sent over D-Bus.  See VariantType for
 * exceptions.
 *
 * There is a Python-inspired text language for describing Variant
 * values. Variant includes a printer for this language and a parser
 * with type inferencing.</a>.
 */

//Note: We wrap this because it is thrown by GtkBuilder's functions.
// See https://bugzilla.gnome.org/show_bug.cgi?id=708206
// It would also be thrown by parse() if we wrap g_variant_parse().
// Now (2014-01-30) it's also thrown by Gio::Action::parse_detailed_name().
/** Exception class for Variant parse errors.
 */
_WRAP_GERROR(VariantParseError, GVariantParseError, G_VARIANT_PARSE_ERROR, NO_GTYPE)

//TODO: Add this documentation from the API if we are confident of it for the C++ wrapper:
// #GVariant is completely threadsafe.  A #GVariant instance can be
// concurrently accessed in any way from any number of threads without
// problems.
// Note that we don't copy GVariant's documentation about Memory Use because
// it seems easy to get out of sync and people can look at that C documentation if necessary.

/** This is the base class for all Variant types.
 *
 * If the actual type is known at compile-time then you should use a specific
 * Variant<>, such as Variant<int>. Otherwise, you may use get_type(),
 * is_of_type(), or cast_dynamic().
 *
 * @newin{2,28}
 * @ingroup Variant
 */
class VariantBase
{
  _CLASS_OPAQUE_COPYABLE(VariantBase, GVariant, NONE, g_variant_ref_sink, g_variant_unref)
  _CUSTOM_CTOR_CAST()
  _IGNORE(g_variant_ref, g_variant_ref_sink, g_variant_take_ref, g_variant_unref,
    g_variant_get, g_variant_get_va)
public:

  /** This typedef is just to make it more obvious that
   * our operator const void* should be used like operator bool().
   */
  typedef const void* BoolExpr;

  /** Test whether the Variant has an underlying instance.
   *
   * Mimics usage of pointers:
   * @code
   *   if (variant)
   *     do_something();
   * @endcode
   *
   * @newin{2,36}
   */
   operator BoolExpr() const;

  /** Replace the underlying GVariant.
   * This is for use by methods that take a VariantBase& as an output
   * parameter.
   *
   * @param cobject The GVariant* obtained from a C function.
   * @param take_a_reference Whether this method should take a reference, for
   * instance if the C function has not given one.
   */
  void init(const GVariant* cobject, bool take_a_reference = false);

// It's necessary to take an extra reference of the 'const GVariantType*'
// returned by g_variant_get_type() because it doesn't do that already.
#m4 _CONVERSION(`const GVariantType*',`VariantType',`Glib::wrap(const_cast<GVariantType*>($3), true)')
  _WRAP_METHOD(VariantType get_type() const, g_variant_get_type)

  _WRAP_METHOD(std::string get_type_string() const, g_variant_get_type_string)
  _WRAP_METHOD(bool is_floating() const, g_variant_is_floating)
  _WRAP_METHOD(bool is_of_type(const VariantType& type) const, g_variant_is_of_type)
  _WRAP_METHOD(bool is_container() const, g_variant_is_container)
  _WRAP_METHOD(GVariantClass classify() const, g_variant_classify)

  _WRAP_METHOD(gsize get_size() const, g_variant_get_size)
  _WRAP_METHOD(gconstpointer get_data(), g_variant_get_data)
  _WRAP_METHOD(void store(gpointer data) const, g_variant_store)

  _WRAP_METHOD(Glib::ustring print(bool type_annotate = false) const, g_variant_print)
  _IGNORE(g_variant_print_string)

  #m4 _CONVERSION(`const VariantBase&',`gconstpointer',`const_cast<GVariant*>(($3).gobj())')
  _WRAP_METHOD(guint hash() const, g_variant_hash)

  /** Checks if @a *this and @a other have the same type and value.
   * 
   * @newin{2,24}
   * @param other The Variant to compare with.
   * @return <tt>true</tt> if @a *this and @a other are equal.
   */
  _WRAP_METHOD(bool equal(const VariantBase& other) const, g_variant_equal)

  /** Gets a VariantBase instance that has the same value as this variant and
   * is trusted to be in normal form.
   *
   * If this variant is already trusted to be in normal form then a new
   * reference to the variant is returned.
   *
   * If this variant is not already trusted, then it is scanned to check if it
   * is in normal form. If it is found to be in normal form then it is marked
   * as trusted and a new reference to it is returned.
   *
   * If this variant is found not to be in normal form then a new trusted
   * VariantBase is created with the same value as this variant.
   *
   * It makes sense to call this function if you've received variant data from
   * untrusted sources and you want to ensure your serialised output is
   * definitely in normal form.
   *
   * @param result A location in which to store the trusted VariantBase.
   * @newin{2,24}
   */
  void get_normal_form(VariantBase& result) const;
  _IGNORE(g_variant_get_normal_form)

  _WRAP_METHOD(bool is_normal_form() const, g_variant_is_normal_form)

  /** Performs a byteswapping operation on the contents of this variant. The
   * result is that all multi-byte numeric data contained in the variant is
   * byteswapped. That includes 16, 32, and 64bit signed and unsigned integers
   * as well as file handles and double precision floating point values.
   *
   * This function is an identity mapping on any value that does not contain
   * multi-byte numeric data. That include strings, booleans, bytes and
   * containers containing only these things (recursively).
   *
   * The returned value is always in normal form and is marked as trusted.
   *
   * @param result A location in which to store the byteswapped form of this
   * variant.
   * @newin{2,24}
   */
   void byteswap(VariantBase& result) const;
   _IGNORE(g_variant_byteswap)

   _WRAP_METHOD(bool check_format_string(const std::string& format_string, bool copy_only = false) const, g_variant_check_format_string)

   //Ignore private API from gvariant-core.h:
   _IGNORE(g_variant_is_trusted, g_variant_get_type_info)

   /** Cast to a specific variant type.
    * For instance:
    * @code
    * Variant<std::string> derived = VariantBase::cast_dynamic< Variant<std::string> >(base);
    * @endcode
    *
    * @param v The variant to cast to a specific type.
    * @result The variant as a specific type.
    * @throws std::bad_cast if the Variant was not of the expected type.
    */
   template<class V_CastTo>
   static V_CastTo cast_dynamic(const VariantBase& v) throw(std::bad_cast);

   _IGNORE(g_variant_dict_new)

private:
  /** Relational operators are deleted to prevent invalid conversion
   * to const void*.
   */
  bool operator<(const VariantBase& src) const;

  /// See operator<().
  bool operator<=(const VariantBase& src) const;

  /// See operator<().
  bool operator>(const VariantBase& src) const;

  /// See operator<().
  bool operator>=(const VariantBase& src) const;

  /// See operator<().
  bool operator==(const VariantBase& src) const;

  /// See operator<().
  bool operator!=(const VariantBase& src) const;
};

template<class V_CastTo>
V_CastTo VariantBase::cast_dynamic(const VariantBase& v)
throw(std::bad_cast)
{
  if(!(v.gobj()))
  {
    return V_CastTo();
  }
  if(v.is_of_type(V_CastTo::variant_type()))
  {
    return V_CastTo(const_cast<GVariant*>(v.gobj()), true);
  }
  else
  {
   throw std::bad_cast();
  }
}

/** Base class from which string variant classes derive.
 * @newin{2,28}
 * @ingroup Variant
 */
class VariantStringBase : public VariantBase
{
  // Trick gmmproc into thinking this is derived from GVariant to wrap a
  // some methods.
  _CLASS_GENERIC(VariantStringBase, GVariant)

public:
  typedef GVariant*                     CType;
  typedef VariantStringBase             CppType;

  /// Default constructor.
  VariantStringBase();

  /** GVariant constructor.
   * @param castitem The GVariant to wrap.
   * @param take_a_reference Whether to take an extra reference of the
   * GVariant or not (not taking one could destroy the GVariant with the
   * wrapper).
   */
  explicit VariantStringBase(GVariant* castitem,  bool take_a_reference = false);

  /** Creates a D-Bus object path variant with the contents of @a string. @a
   * string must be a valid D-Bus object path. Use is_object_path() if unsure.
   *
   * @param output A location in which to store the new object path variant
   * instance.
   * @param object_path A normal nul-terminated string.
   * @newin{2,28}
   */
  static void create_object_path(VariantStringBase& output,
    const std::string& object_path);
  _IGNORE(g_variant_new_object_path)

  _WRAP_METHOD(static bool is_object_path(const std::string& string), g_variant_is_object_path)

  /** Creates a D-Bus type signature variant with the contents of @a string. @a
   * string must be a valid D-Bus type signature. Use is_signature() if unsure.
   *
   * @param output A location in which to store the new signature variant
   * instance.
   * @param signature A normal nul-terminated string.
   * @newin{2,28}
   */
  static void create_signature(VariantStringBase& output,
    const std::string& signature);
  _IGNORE(g_variant_new_signature)

  _WRAP_METHOD(static bool is_signature(const std::string& string), g_variant_is_signature)
};

/** The base class from which multiple-item Variants derive, such as Variants
 * containing tuples or arrays.
 *
 * @newin{2,28}
 * @ingroup Variant
 */
class VariantContainerBase : public VariantBase
{
  // Trick gmmproc into thinking this is derived from GVariant to wrap a
  // some methods.
  _CLASS_GENERIC(VariantContainerBase, GVariant)

public:
  typedef GVariant*                     CType;
  typedef VariantContainerBase          CppType;

  /// Default constructor.
  VariantContainerBase();

  /** GVariant constructor.
   * @param castitem The GVariant to wrap.
   * @param take_a_reference Whether to take an extra reference of the
   * GVariant or not (not taking one could destroy the GVariant with the
   * wrapper).
   */
  explicit VariantContainerBase(GVariant* castitem, bool take_a_reference = false);

  /** Create a tuple variant from a vector of its variant children.
   * @param children The vector containing the children of the container.
   * @return The newly created tuple variant (as a VariantContainerBase).
   */
  static VariantContainerBase create_tuple(const std::vector<VariantBase>& children);

  /** Create a tuple variant with a single variant child.
   * @param child The child variant.
   * @return The newly created tuple variant (as a VariantContainerBase).
   */
  static VariantContainerBase create_tuple(const VariantBase& child);

  _WRAP_METHOD_DOCS_ONLY(g_variant_new_maybe)
  static VariantContainerBase create_maybe(const VariantType& child_type,
    const VariantBase& child = VariantBase());

  _WRAP_METHOD(gsize get_n_children() const, g_variant_n_children)

  /** Reads a child item out of this instance. This method is valid for
   * variants, maybes, arrays, tuples and dictionary entries.
   *
   * It is an error if @a index is greater than the number of child items in
   * the container. See get_n_children().
   *
   * This function is O(1).
   *
   * @param index The index of the child to fetch.
   * @param child A location in which to store the child at the specified
   * index.
   * @throw std::out_of_range
   * @newin{2,28}
   */
  void get_child(VariantBase& child, gsize index = 0) const;
  _IGNORE(g_variant_get_child, g_variant_get_child_value)

#m4 _CONVERSION(`GVariant*',`VariantBase',`Glib::wrap($3)')

  _WRAP_METHOD(VariantBase get_child(gsize index = 0), g_variant_get_child_value)

  /* TODO?:
  /// A get() method to return the contents of the variant in the container.
  template <class DataType>
  DataType get_child(gsize index = 0) const;
  */

  /** If this is a maybe-typed instance, extract its value. If the value is
   * Nothing, then this function returns <tt>0</tt>.
   *
   * @param maybe A place in which to return the value (the value may be
   * <tt>0</tt>).
   * @newin{2,28}
   */
  bool get_maybe(VariantBase& maybe) const;
  _IGNORE(g_variant_get_maybe)
};

template<>
VariantContainerBase VariantBase::cast_dynamic<VariantContainerBase>(const VariantBase& v)
throw(std::bad_cast);

/** Template class used for the specialization of the Variant<> classes.
 * @newin{2,28}
 * @ingroup Variant
 */
template<class T>
class Variant : public VariantBase
{
public:
  typedef T CppType;
};

// Each specialization has (or should have) a variant_type() method that gets
// the type. So the C g_variant_get_type() function can be ignored.
_IGNORE(g_variant_get_type)

/****************** Specializations ***********************************/

/** Specialization of Variant containing a VariantBase.
 * @newin{2,28}
 * @ingroup Variant
 */
template<>
class Variant<VariantBase> : public VariantContainerBase
{
  // Trick gmmproc into thinking this is derived from GVariant to wrap a
  // some methods.
  _CLASS_GENERIC(Variant<VariantBase>, GVariant)

public:
  typedef GVariant*                     CType;
  typedef VariantBase                   CppType;
  typedef Variant<VariantBase>          CppContainerType;

  /// Default constructor.
  Variant<VariantBase>();

  /** GVariant constructor.
   * @param castitem The GVariant to wrap.
   * @param take_a_reference Whether to take an extra reference of the
   * GVariant or not (not taking one could destroy the GVariant with the
   * wrapper).
   */
  explicit Variant<VariantBase>(GVariant* castitem, bool take_a_reference = false);

  /** Gets the VariantType.
   * @return The VariantType.
   * @newin{2,28}
   */
  static const VariantType& variant_type() G_GNUC_CONST;

  //This must have a create() method because otherwise it would be a copy
  //constructor.
  /** Creates a new Variant<VariantBase>.
   * @param data The value of the new Variant.
   * @return The new Variant.
   * @newin{2,28}
   */
  static Variant<VariantBase> create(const VariantBase& data);
  _IGNORE(g_variant_new_variant)

  //TODO: Documentation
  void get(VariantBase& variant) const;

  //TODO: Deprecate this in favour of get(VariantBase&)?
  _WRAP_METHOD(VariantBase get() const, g_variant_get_variant)
};

/** Specialization of Variant containing a Variant<T>.
 * @newin{2,36}
 * @ingroup Variant
 */
template<class T>
class Variant< Variant<T> > : public VariantContainerBase
{
public:
  typedef GVariant*                     CType;
  typedef Variant<T>                    CppType;
  typedef Variant<CppType>              CppContainerType;

  /// Default constructor.
  Variant< Variant<T> >();

  /** GVariant constructor.
   * @param castitem The GVariant to wrap.
   * @param take_a_reference Whether to take an extra reference of the
   * GVariant or not (not taking one could destroy the GVariant with the
   * wrapper).
   * @newin{2,36}
   */
  explicit Variant< Variant<T> >(GVariant* castitem, bool take_a_reference = false);

  /** Gets the VariantType.
   * @return The VariantType.
   * @newin{2,36}
   */
  static const VariantType& variant_type() G_GNUC_CONST;

  /** Creates a new Variant< Variant<T> >.
   * @param data The value of the new Variant.
   * @return The new Variant.
   * @newin{2,36}
   */
  static Variant< Variant<T> > create(const Variant<T>& data);

  /** Gets the contents of the Variant.
   * @return The contents of the Variant.
   * @newin{2,36}
   */
  Variant<T> get() const;
};

/** Specialization of Variant containing a Glib::ustring, for variants of type
 * string, bytestring, object path, or signature.
 * @newin{2,28}
 * @ingroup Variant
 */
template<>
class Variant<Glib::ustring> : public VariantStringBase
{
  // Trick gmmproc into thinking this is derived from GVariant to wrap a
  // some methods.
  _CLASS_GENERIC(Variant<Glib::ustring>, GVariant)
public:
  typedef char*                 CType;
  typedef Glib::ustring         CppType;

  /// Default constructor.
  Variant<Glib::ustring>();

  /** GVariant constructor.
   * @param castitem The GVariant to wrap.
   * @param take_a_reference Whether to take an extra reference of the
   * GVariant or not (not taking one could destroy the GVariant with the
   * wrapper).
   */
  explicit Variant<Glib::ustring>(GVariant* castitem,  bool take_a_reference = false);

  /** Gets the VariantType.
   * @return The VariantType.
   * @newin{2,28}
   */
  static const VariantType& variant_type() G_GNUC_CONST;

  /** Creates a new Variant<Glib::ustring>.
   * @param data The value of the new Variant.
   * @return The new Variant.
   * @newin{2,28}
   */
  static Variant<Glib::ustring> create(const Glib::ustring& data);

  //We can't use WRAP_METHOD() here because g_variant_get_string() takes an extra length parameter.
  /** Gets the contents of the Variant.
   * @return The contents of the Variant.
   * @newin{2,28}
   */
  Glib::ustring get() const;
  _IGNORE(g_variant_get_string, g_variant_dup_string)
};

template<>
Variant<Glib::ustring> VariantBase::cast_dynamic< Variant<Glib::ustring> >(const VariantBase& v)
throw(std::bad_cast);

/** Specialization of Variant containing a std::string, for variants of type
 * bytestring, object path, or signature.
 * See also Variant<Glib::ustring> for UTF-8 strings.
 * @newin{2,28}
 * @ingroup Variant
 */
template<>
class Variant<std::string> : public VariantStringBase
{
  // Trick gmmproc into thinking this is derived from GVariant to wrap a
  // some methods.
  _CLASS_GENERIC(Variant<std::string>, GVariant)
public:
  typedef char*                 CType;
  typedef std::string           CppType;

  /// Default constructor.
  Variant<std::string>();

  /** GVariant constructor.
   * @param castitem The GVariant to wrap.
   * @param take_a_reference Whether to take an extra reference of the
   * GVariant or not (not taking one could destroy the GVariant with the
   * wrapper).
   */
  explicit Variant<std::string>(GVariant* castitem, bool take_a_reference = false);

  /** Gets the VariantType.
   * @return The VariantType.
   * @newin{2,28}
   */
  static const VariantType& variant_type() G_GNUC_CONST;

  /** Creates a new Variant<std::string>.
   * @param data The value of the new Variant.
   * @return The new Variant.
   * @newin{2,28}
   */
  static Variant<std::string> create(const std::string& data);

  //TODO: Documentation.
  std::string get() const;
  _IGNORE(g_variant_get_bytestring, g_variant_dup_bytestring)
};

template<>
Variant<std::string> VariantBase::cast_dynamic< Variant<std::string> >(const VariantBase& v)
throw(std::bad_cast);

/** Specialization of Variant containing a dictionary entry.  See also
 * Variant< std::map<K, V> >.
 * @newin{2,28}
 * @ingroup Variant
 */
template<class K, class V>
class Variant< std::pair<K, V> > : public VariantContainerBase
{
public:
  typedef std::pair<K, V>               CppType;
  typedef Variant<CppType>        CppContainerType;

  /// Default constructor.
  Variant< std::pair<K, V> >()
  : VariantContainerBase()
  {}

  /** GVariant constructor.
   * @param castitem The GVariant to wrap.
   * @param take_a_reference Whether to take an extra reference of the
   * GVariant or not (not taking one could destroy the GVariant with the
   * wrapper).
   */
  explicit Variant< std::pair<K, V> >(GVariant* castitem,
    bool take_a_reference = false)
  : VariantContainerBase(castitem, take_a_reference)
  {}

  /** Gets the VariantType.
   * @return The VariantType.
   * @newin{2,28}
   */
  static const VariantType& variant_type() G_GNUC_CONST;

  /** Creates a new Variant< std::pair<K, V> >.
   * @param data The value of the new Variant.
   * @return The new Variant.
   * @newin{2,28}
   */
  static Variant< std::pair<K, V> > create(const std::pair<K, V>& data);
  _IGNORE(g_variant_new_dict_entry)

  /** Gets the contents of the Variant.
   * @return The contents of the Variant.
   * @throw std::out_of_range
   * @newin{2,28}
   */
  std::pair<K, V> get() const;
};

/** Specialization of Variant containing an array of items.
 * @newin{2,28}
 * @ingroup Variant
 */
template<class T>
class Variant< std::vector<T> > : public VariantContainerBase
{
public:
  typedef T                     CppType;
  typedef std::vector<T>        CppContainerType;

  /// Default constructor.
  Variant< std::vector<T> >()
  : VariantContainerBase()
  {}

  /** GVariant constructor.
   * @param castitem The GVariant to wrap.
   * @param take_a_reference Whether to take an extra reference of the
   * GVariant or not (not taking one could destroy the GVariant with the
   * wrapper).
   */
  explicit Variant< std::vector<T> >(GVariant* castitem,
    bool take_a_reference = false)
  : VariantContainerBase(castitem, take_a_reference)
  {}

  /** Gets the VariantType.
   * @return The VariantType.
   * @newin{2,28}
   */
  static const VariantType& variant_type() G_GNUC_CONST;

  /** Creates a new Variant from an array of numeric types.
   * @param data The array to use for creation.
   * @return The new Variant.
   * @newin{2,28}
   */
  static Variant< std::vector<T> > create(const std::vector<T>& data);
  _IGNORE(g_variant_new_array)

  /** Gets a specific element of the array.  It is an error if @a index is
   * greater than the number of child items in the container.  See
   * VariantContainerBase::get_n_children().
   *
   * This function is O(1).
   *
   * @param index The index of the element.
   * @return The element at index @a index.
   * @throw std::out_of_range
   * @newin{2,28}
   */
  T get_child(gsize index) const;

  /** Gets the vector of the Variant.
   * @return The vector.
   * @newin{2,28}
   */
  std::vector<T> get() const;
  _IGNORE(g_variant_get_fixed_array)

  /** Gets a VariantIter of the Variant.
   * @return the VaraintIter.
   * @newin{2,28}
   */
  VariantIter get_iter() const;
};

/** Specialization of Variant containing an array of UTF-8 capable
 * strings.
 * @newin{2,28}
 * @ingroup Variant
 */
template<>
class Variant< std::vector<Glib::ustring> > : public VariantContainerBase
{
public:
  typedef Glib::ustring                 CppType;
  typedef std::vector<Glib::ustring>    CppContainerType;

  /// Default constructor.
  Variant< std::vector<Glib::ustring> >();

  /** GVariant constructor.
   * @param castitem The GVariant to wrap.
   * @param take_a_reference Whether to take an extra reference of the
   * GVariant or not (not taking one could destroy the GVariant with the
   * wrapper).
   */
  explicit Variant< std::vector<Glib::ustring> >(GVariant* castitem, bool take_a_reference = false);

  /** Gets the VariantType.
   * @return The VariantType.
   * @newin{2,28}
   */
  static const VariantType& variant_type() G_GNUC_CONST;

  /** Creates a new Variant from an array of strings.
   * @param data The array to use for creation.
   * @return The new Variant.
   * @newin{2,28}
   */
  static Variant< std::vector<Glib::ustring> >
    create(const std::vector<Glib::ustring>& data);

  /** Gets a specific element of the string array.  It is an error if @a index
   * is greater than the number of child items in the container.  See
   * VariantContainerBase::get_n_children().
   *
   * This function is O(1).
   *
   * @param index The index of the element.
   * @return The element at index @a index.
   * @throw std::out_of_range
   * @newin{2,28}
   */
  Glib::ustring get_child(gsize index) const;

  /** Gets the string vector of the Variant.
   * @return The vector.
   * @newin{2,28}
   */
  std::vector<Glib::ustring> get() const;
  _IGNORE(g_variant_get_strv, g_variant_dup_strv)

  /** Gets a VariantIter of the Variant.
   * @return the VaraintIter.
   * @newin{2,28}
   */
  VariantIter get_iter() const;
};

/** Specialization of Variant containing an array of non-UTF-8 strings
 * (byte string arrays).
 * @newin{2,28}
 * @ingroup Variant
 */
template<>
class Variant< std::vector<std::string> > : public VariantContainerBase
{
public:
  typedef std::string                   CppType;
  typedef std::vector<std::string>      CppContainerType;

  /// Default constructor.
  Variant< std::vector<std::string> >();

  /** GVariant constructor.
   * @param castitem The GVariant to wrap.
   * @param take_a_reference Whether to take an extra reference of the
   * GVariant or not (not taking one could destroy the GVariant with the
   * wrapper).
   */
  explicit Variant< std::vector<std::string> >(GVariant* castitem, bool take_a_reference = false);

  /** Gets the VariantType.
   * @return The VariantType.
   * @newin{2,28}
   */
  static const VariantType& variant_type() G_GNUC_CONST;

  /** Creates a new Variant from an array of strings.
   * @param data The array to use for creation.
   * @return The new Variant.
   * @newin{2,28}
   */
  static Variant< std::vector<std::string> >
    create(const std::vector<std::string>& data);

  /** Creates a new Variant from an array of D-Bus object paths.
   * @param paths The array to use for creation.
   * @return The new Variant.
   * @newin{2,36}
   */
  static Variant< std::vector<std::string> >
    create_from_object_paths(const std::vector<std::string>& paths);

  /** Gets a specific element of the string array.  It is an error if @a index
   * is greater than the number of child items in the container.  See
   * VariantContainerBase::get_n_children().
   *
   * This function is O(1).
   *
   * @param index The index of the element.
   * @return The element at index @a index.
   * @throw std::out_of_range
   * @newin{2,28}
   */
  std::string get_child(gsize index) const;

  /** Gets the string vector of the Variant.
   * @return The vector.
   * @newin{2,28}
   */
  std::vector<std::string> get() const;
  _IGNORE(g_variant_get_bytestring_array, g_variant_dup_bytestring_array)

  // Object paths are merely strings so it is possible to get them already with
  // the existing get() methods in this class.
  _IGNORE(g_variant_get_objv, g_variant_dup_objv)

  /** Gets a VariantIter of the Variant.
   * @return the VaraintIter.
   * @newin{2,28}
   */
  VariantIter get_iter() const;
};

/** Specialization of Variant containing a dictionary (a map of (key,
 * value) elements).
 * @newin{2,28}
 * @ingroup Variant
 */
template<class K, class V>
class Variant< std::map<K, V> >: public VariantContainerBase
{
public:
  typedef std::pair<K, V>               CppType;
  typedef std::map<K, V>                CppContainerType;

  /// Default constructor.
  Variant< std::map<K, V> >()
  : VariantContainerBase()
  {}

  /** GVariant constructor.
   * @param castitem The GVariant to wrap.
   * @param take_a_reference Whether to take an extra reference of the
   * GVariant or not (not taking one could destroy the GVariant with the
   * wrapper).
   */
  explicit Variant< std::map<K, V> >(GVariant* castitem,
    bool take_a_reference = false)
  : VariantContainerBase(castitem, take_a_reference)
  {}

  /** Gets the VariantType.
   * @return The VariantType.
   * @newin{2,28}
   */
  static const VariantType& variant_type() G_GNUC_CONST;

  /** Creates a new Variant containing a dictionary from a map.
   * @param data The map to use for creation.
   * @return The new Variant holding a dictionary.
   * @newin{2,28}
   */
  static Variant< std::map<K, V> > create(const std::map<K, V>& data);

  /** Gets a specific dictionary entry from the string array.  It is an error
   * if @a index is greater than the number of child items in the container.
   * See VariantContainerBase::get_n_children().
   *
   * This function is O(1).
   *
   * @param index The index of the element.
   * @return The dictionary entry at index @a index.
   * @throw std::out_of_range
   * @newin{2,28}
   */
  std::pair<K, V> get_child(gsize index) const;

  /** Looks up a value in a dictionary Variant.
   * @param key The key to look up.
   * @param value A location in which to store the value if found.
   * @return <tt>true</tt> if the key is found, <tt>false</tt> otherwise.
   */
  bool lookup(const K& key, V& value) const;
  _IGNORE(g_variant_lookup_value, g_variant_lookup)

  /** Gets the map (the dictionary) of the Variant.
   * @return The vector.
   * @newin{2,28}
   */
  std::map<K, V> get() const;

  /** Gets a VariantIter of the Variant.
   * @return the VaraintIter.
   * @newin{2,28}
   */
  VariantIter get_iter() const;
};

} // namespace Glib


//We ignore g_variant_get_*() methods that are wrapped by Variant<> specializations, such as in variant_basictypes.h.m4.
_IGNORE(
  g_variant_get_boolean,
  g_variant_get_byte,
  g_variant_get_uint16,
  g_variant_get_int64,
  g_variant_get_int32,
  g_variant_get_int16,
  g_variant_get_uint32,
  g_variant_get_uint64,
  g_variant_get_double,
  g_variant_iter_new
)

/* Include generated specializations of Variant<> for fundamental types:
 */
#define _GLIBMM_VARIANT_H_INCLUDE_VARIANT_BASICTYPES_H
#include <glibmm/variant_basictypes.h>
#undef _GLIBMM_VARIANT_H_INCLUDE_VARIANT_BASICTYPES_H

namespace Glib
{

/*--------------------Variant< Variant<T> >---------------------*/

template<class T>
Variant< Variant<T> >::Variant()
: VariantContainerBase()
{
}

template<class T>
Variant< Variant<T> >::Variant(GVariant* castitem, bool take_a_reference)
: VariantContainerBase(castitem, take_a_reference)
{
}

// static
template<class T>
const VariantType& Variant< Variant<T> >::variant_type()
{
  return VARIANT_TYPE_VARIANT;
}

template<class T>
Variant< Variant<T> > Variant< Variant<T> >::create(const Variant<T>& data)
{
  Variant< Variant<T> > result = Variant< Variant<T> >(
    g_variant_new_variant(const_cast<GVariant*>(data.gobj())));
  return result;
}

template<class T>
Variant<T> Variant< Variant<T> >::get() const
{
  GVariant* const gvariant = g_variant_get_variant(gobject_);
  return Variant<T>(gvariant);
}

/*--------------------Variant< std::pair<K, V> >---------------------*/

// static
template<class K, class V>
const VariantType& Variant< std::pair<K, V> >::variant_type()
{
  static VariantType type(
    g_variant_type_new_dict_entry(Variant<K>::variant_type().gobj(),
    Variant<V>::variant_type().gobj()));

  return type;
}

template<class K, class V>
Variant< std::pair<K, V> >
Variant< std::pair<K, V> >::create(const std::pair<K, V>& data)
{
  Variant<K> key = Variant<K>::create(data.first);
  Variant<V> value = Variant<V>::create(data.second);

  Variant< std::pair<K, V> > result = Variant< std::pair<K, V> >(
    g_variant_new_dict_entry(key.gobj(), value.gobj()));

  return result;
}

template<class K, class V>
std::pair<K, V> Variant< std::pair<K, V> >::get() const
{
  // Get the key (the first element of the this VariantContainerBase).
  Variant<K> key;
  VariantContainerBase::get_child(key, 0);

  // Get the value (the second element of the this VariantContainerBase).
  Variant<V> value;
  VariantContainerBase::get_child(value, 1);

  std::pair<K, V> result(key.get(), value.get());

  return result;
}

/*---------------------Variant< std::vector<T> >---------------------*/

// static
template<class T>
const VariantType& Variant< std::vector<T> >::variant_type()
{
  static VariantType type =
    VariantType::create_array(Variant<T>::variant_type());

  return type;
}

template<class T>
Variant< std::vector<T> >
Variant< std::vector<T> >::create(const std::vector<T>& data)
{
  // Get the variant type of the elements.
  VariantType element_variant_type = Variant<T>::variant_type();

  // Get the variant type of the array.
  VariantType array_variant_type = Variant< std::vector<T> >::variant_type();

  // Create a GVariantBuilder to build the array.
  GVariantBuilder* builder = g_variant_builder_new(array_variant_type.gobj());

  // Add the elements of the vector into the builder.
  for(typename std::vector<T>::const_iterator iter = data.begin();
   iter < data.end(); iter++)
  {
    Glib::Variant<T> variant = Glib::Variant<T>::create(*iter);
    g_variant_builder_add_value(builder, variant.gobj());
  }

  // Create the variant using the builder.
  Variant< std::vector<T> > result =
    Variant< std::vector<T> >(g_variant_new(
      reinterpret_cast<gchar*>(array_variant_type.gobj()), builder));

  g_variant_builder_unref(builder);

  return result;
}

template<class T>
T Variant< std::vector<T> >::get_child(gsize index) const
{
  if(index >= g_variant_n_children(const_cast<GVariant*>(gobj())))
    throw std::out_of_range(
      "Variant< std::vector<T> >::get_child(): Index out of bounds.");

  Glib::Variant<T> variant;

  GVariant* gvariant =
    g_variant_get_child_value(const_cast<GVariant*>(gobj()), index);

  variant.init(gvariant);
  return variant.get();
}

template<class T>
std::vector<T> Variant< std::vector<T> >::get() const
{
  std::vector<T> result;

  gsize n_children = g_variant_n_children(const_cast<GVariant*>(gobj()));

  for(gsize i = 0; i < n_children; i++)
  {
    Glib::Variant<T> variant;

    GVariant* gvariant =
      g_variant_get_child_value(const_cast<GVariant*>(gobj()), i);

    variant.init(gvariant);
    result.push_back(variant.get());
  }

  return result;
}

template<class T>
VariantIter Variant< std::vector<T> >::get_iter() const
{
  // Get the variant type of the elements.
  VariantType element_variant_type = Variant<T>::variant_type();

  // Get the variant type of the array.
  VariantType array_variant_type = Variant< std::vector<T> >::variant_type();

  // Get the GVariantIter.
  GVariantIter* g_iter = 0;
  g_variant_get(const_cast<GVariant*>(gobj()),
    reinterpret_cast<gchar*>(array_variant_type.gobj()), &g_iter);

  return VariantIter(g_iter);
}

/*---------------------Variant< std::map<K, V> > --------------------*/

// static
template<class K, class V>
const VariantType& Variant< std::map<K, V> >::variant_type()
{
  static VariantType type =
    VariantType::create_array(Variant< std::pair<K, V> >::variant_type());

  return type;
}

template<class K, class V>
Variant< std::map<K, V> >
Variant< std::map<K, V> >::create(const std::map<K, V>& data)
{
  // Get the variant type of the elements.
  VariantType element_variant_type =
    Variant< std::pair<K, V> >::variant_type();

  // Get the variant type of the array.
  VariantType array_variant_type = Variant< std::map<K, V> >::variant_type();

  // Create a GVariantBuilder to build the array.
  GVariantBuilder* builder = g_variant_builder_new(array_variant_type.gobj());

  // Add the elements of the vector into the builder.
  for(typename std::map<K, V>::const_iterator iter = data.begin();
    iter != data.end(); iter++)
  {
    Variant< std::pair<K, V> > dict_entry =
      Variant< std::pair<K, V> >::create(*iter);

    g_variant_builder_add_value(builder, dict_entry.gobj());
  }

  // Create the variant using the builder.
  Variant< std::map<K, V> > result = Variant< std::map<K, V> >(g_variant_new(
    reinterpret_cast<gchar*>(array_variant_type.gobj()), builder));

  g_variant_builder_unref(builder);

  return result;
}

template<class K, class V>
std::pair<K, V>
Variant< std::map<K, V> >::get_child(gsize index) const
{
  Variant< std::pair<K, V> > dict_entry;
  VariantContainerBase::get_child(dict_entry, index);
  return dict_entry.get();
}

template<class K, class V>
bool Variant< std::map<K, V> >::lookup(const K& key, V& value) const
{
  // The code in this method pretty much reflects the g_variant_lookup_value()
  // function except that it's more general to deal with keys that are not
  // just strings.
  VariantIter iter = get_iter();

  Variant< std::pair<K, V> > entry;

  while(iter.next_value(entry))
  {
    std::pair<K, V> element = entry.get();

    if(element.first == key)
    {
      value = element.second;
      return true;
    }
  }

  return false;
}

template<class K, class V>
std::map<K, V> Variant< std::map<K, V> >::get() const
{
  std::map<K, V> result;
  VariantIter iter = get_iter();
  Variant< std::pair<K, V> > entry;

  while(iter.next_value(entry))
  {
    result.insert(entry.get());
  }

  return result;
}

template<class K, class V>
VariantIter Variant< std::map<K, V> >::get_iter() const
{
  // Get the variant type of the elements.
  VariantType element_variant_type =
    Variant< std::pair<K, V> >::variant_type();

  // Get the variant type of the array.
  VariantType array_variant_type = Variant< std::map<K, V> >::variant_type();

  // Get the GVariantIter.
  GVariantIter* g_iter = 0;
  g_variant_get(const_cast<GVariant*>(gobj()),
    reinterpret_cast<gchar*>(array_variant_type.gobj()), &g_iter);

  return VariantIter(g_iter);
}

} // namespace Glib