urho3d/Engine/Core/Variant.h

//
// Urho3D Engine
// Copyright (c) 2008-2012 Lasse Öörni
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//

#pragma once

#include "Color.h"
#include "HashMap.h"
#include "Quaternion.h"
#include "StringHash.h"
#include "Vector4.h"

namespace Urho3D
{

/// Variant's supported types.
enum VariantType
{
    VAR_NONE = 0,
    VAR_INT,
    VAR_BOOL,
    VAR_FLOAT,
    VAR_VECTOR2,
    VAR_VECTOR3,
    VAR_VECTOR4,
    VAR_QUATERNION,
    VAR_COLOR,
    VAR_STRING,
    VAR_BUFFER,
    VAR_PTR,
    VAR_RESOURCEREF,
    VAR_RESOURCEREFLIST,
    VAR_VARIANTVECTOR,
    VAR_VARIANTMAP
};

/// Union for the possible variant values. Also stores non-POD objects such as String which must not exceed 16 bytes in size.
struct VariantValue
{
    union
    {
        int int_;
        bool bool_;
        float float_;
        void* ptr_;
    };
    
    float y_;
    float z_;
    float w_;
};

/// Typed resource reference.
struct ResourceRef
{
    /// Construct.
    ResourceRef()
    {
    }
    
    /// Construct with type only and empty id.
    ResourceRef(ShortStringHash type) :
        type_(type)
    {
    }
    
    /// Construct with type and id.
    ResourceRef(ShortStringHash type, StringHash id) :
        type_(type),
        id_(id)
    {
    }
    
    // Construct from another ResourceRef.
    ResourceRef(const ResourceRef& rhs) :
        type_(rhs.type_),
        id_(rhs.id_)
    {
    }
    
    /// Object type.
    ShortStringHash type_;
    /// Object identifier, for example name hash.
    StringHash id_;
    
    /// Test for equality with another reference.
    bool operator == (const ResourceRef& rhs) const { return type_ == rhs.type_ && id_ == rhs.id_; }
    /// Test for inequality with another reference.
    bool operator != (const ResourceRef& rhs) const { return type_ != rhs.type_ || id_ != rhs.id_; }
};

/// %List of typed resource references.
struct ResourceRefList
{
    /// Construct.
    ResourceRefList()
    {
    }
    
    /// Construct with type only.
    ResourceRefList(ShortStringHash type) :
        type_(type)
    {
    }
    /// Construct with type and id list.
    ResourceRefList(ShortStringHash type, const Vector<StringHash>& ids) :
        type_(type),
        ids_(ids)
    {
    }
    
    /// Object type.
    ShortStringHash type_;
    /// List of object identifiers, for example name hashes.
    Vector<StringHash> ids_;
    
    /// Test for equality with another reference list.
    bool operator == (const ResourceRefList& rhs) const { return type_ == rhs.type_ && ids_ == rhs.ids_; }
    /// Test for inequality with another reference list.
    bool operator != (const ResourceRefList& rhs) const { return type_ != rhs.type_ || ids_ != rhs.ids_; }
};

class Variant;

/// Vector of variants.
typedef Vector<Variant> VariantVector;
/// Map of variants.
typedef HashMap<ShortStringHash, Variant> VariantMap;

/// Variable that supports a fixed set of types.
class Variant
{
public:
    /// Construct empty.
    Variant() :
        type_(VAR_NONE)
    {
    }
    
    /// Construct from integer.
    Variant(int value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from unsigned integer.
    Variant(unsigned value) :
        type_(VAR_NONE)
    {
        *this = (int)value;
    }
    
    /// Construct from a string hash (convert to integer.)
    Variant(const StringHash& value) :
        type_(VAR_NONE)
    {
        *this = (int)value.Value();
    }
    
    /// Construct from a short string hash (convert to integer.)
    Variant(const ShortStringHash& value) :
        type_(VAR_NONE)
    {
        *this = (int)value.Value();
    }
    
    /// Construct from a bool.
    Variant(bool value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from a float.
    Variant(float value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from a Vector2.
    Variant(const Vector2& value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from a Vector3.
    Variant(const Vector3& value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from a Vector4.
    Variant(const Vector4& value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from a quaternion.
    Variant(const Quaternion& value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from a color.
    Variant(const Color& value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from a string.
    Variant(const String& value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from a C string.
    Variant(const char* value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from a buffer.
    Variant(const PODVector<unsigned char>& value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from a pointer.
    Variant(void* value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from a resource reference.
    Variant(const ResourceRef& value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from a resource reference list.
    Variant(const ResourceRefList& value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from a variant vector.
    Variant(const VariantVector& value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from a variant map.
    Variant(const VariantMap& value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Construct from type and value.
    Variant(const String& type, const String& value) :
        type_(VAR_NONE)
    {
        FromString(type, value);
    }
    
    /// Construct from type and value.
    Variant(VariantType type, const String& value) :
        type_(VAR_NONE)
    {
        FromString(type, value);
    }
    
    /// Construct from type and value.
    Variant(const char* type, const char* value) :
        type_(VAR_NONE)
    {
        FromString(type, value);
    }
    
    /// Construct from type and value.
    Variant(VariantType type, const char* value) :
        type_(VAR_NONE)
    {
        FromString(type, value);
    }
    
    /// Copy-construct from another variant.
    Variant(const Variant& value) :
        type_(VAR_NONE)
    {
        *this = value;
    }
    
    /// Destruct.
    ~Variant()
    {
        SetType(VAR_NONE);
    }
    
    /// Reset to empty.
    void Clear()
    {
        SetType(VAR_NONE);
    }
    
    /// Assign from another variant.
    Variant& operator = (const Variant& rhs);
    
    /// Assign from an integer.
    Variant& operator = (int rhs)
    {
        SetType(VAR_INT);
        value_.int_ = rhs;
        return *this;
    }
    
    /// Assign from an unsigned integer.
    Variant& operator = (unsigned rhs)
    {
        SetType(VAR_INT);
        value_.int_ = (int)rhs;
        return *this;
    }
    
    /// Assign from a StringHash (convert to integer.)
    Variant& operator = (const StringHash& rhs)
    {
        SetType(VAR_INT);
        value_.int_ = (int)rhs.Value();
        return *this;
    }
    
    /// Assign from a ShortStringHash (convert to integer)
    Variant& operator = (const ShortStringHash& rhs)
    {
        SetType(VAR_INT);
        value_.int_ = (int)rhs.Value();
        return *this;
    }
    
    /// Assign from a bool.
    Variant& operator = (bool rhs)
    {
        SetType(VAR_BOOL);
        value_.bool_ = rhs;
        return *this;
    }
    
    /// Assign from a float.
    Variant& operator = (float rhs)
    {
        SetType(VAR_FLOAT);
        value_.float_ = rhs;
        return *this;
    }
    
    /// Assign from a Vector2.
    Variant& operator = (const Vector2& rhs)
    {
        SetType(VAR_VECTOR2);
        *(reinterpret_cast<Vector2*>(&value_)) = rhs;
        return *this;
    }
    
    /// Assign from a Vector3.
    Variant& operator = (const Vector3& rhs)
    {
        SetType(VAR_VECTOR3);
        *(reinterpret_cast<Vector3*>(&value_)) = rhs;
        return *this;
    }
    
    /// Assign from a Vector4.
    Variant& operator = (const Vector4& rhs)
    {
        SetType(VAR_VECTOR4);
        *(reinterpret_cast<Vector4*>(&value_)) = rhs;
        return *this;
    }
    
    /// Assign from a quaternion.
    Variant& operator = (const Quaternion& rhs)
    {
        SetType(VAR_QUATERNION);
        *(reinterpret_cast<Quaternion*>(&value_)) = rhs;
        return *this;
    }
    
    /// Assign from a color.
    Variant& operator = (const Color& rhs)
    {
        SetType(VAR_COLOR);
        *(reinterpret_cast<Color*>(&value_)) = rhs;
        return *this;
    }
    
    /// Assign from a string.
    Variant& operator = (const String& rhs)
    {
        SetType(VAR_STRING);
        *(reinterpret_cast<String*>(&value_)) = rhs;
        return *this;
    }
    
    /// Assign from a C string.
    Variant& operator = (const char* rhs)
    {
        SetType(VAR_STRING);
        *(reinterpret_cast<String*>(&value_)) = String(rhs);
        return *this;
    }

    /// Assign from a buffer.
    Variant& operator = (const PODVector<unsigned char>& rhs)
    {
        SetType(VAR_BUFFER);
        *(reinterpret_cast<PODVector<unsigned char>*>(&value_)) = rhs;
        return *this;
    }
    
    /// Assign from a pointer.
    Variant& operator = (void* rhs)
    {
        SetType(VAR_PTR);
        value_.ptr_ = rhs;
        return *this;
    }
    
    /// Assign from a resource reference.
    Variant& operator = (const ResourceRef& rhs)
    {
        SetType(VAR_RESOURCEREF);
        *(reinterpret_cast<ResourceRef*>(&value_)) = rhs;
        return *this;
    }
    
    /// Assign from a resource reference list.
    Variant& operator = (const ResourceRefList& rhs)
    {
        SetType(VAR_RESOURCEREFLIST);
        *(reinterpret_cast<ResourceRefList*>(&value_)) = rhs;
        return *this;
    }
    
    /// Assign from a variant vector.
    Variant& operator = (const VariantVector& rhs)
    {
        SetType(VAR_VARIANTVECTOR);
        *(reinterpret_cast<VariantVector*>(&value_)) = rhs;
        return *this;
    }
    
    /// Assign from a variant map.
    Variant& operator = (const VariantMap& rhs)
    {
        SetType(VAR_VARIANTMAP);
        *(reinterpret_cast<VariantMap*>(&value_)) = rhs;
        return *this;
    }
    
    /// Test for equality with another variant.
    bool operator == (const Variant& rhs) const;
    /// Test for inequality with another variant.
    bool operator != (const Variant& rhs) const { return !(*this == rhs); }
    
    /// Test for equality with an integer. To return true, both the type and value must match.
    bool operator == (int rhs) const
    {
        if (type_ == VAR_INT)
            return value_.int_ == rhs;
        else
            return false;
    }
    
    /// Test for equality with an unsigned integer. To return true, both the type and value must match.
    bool operator == (unsigned rhs) const
    {
        if (type_ == VAR_INT)
            return value_.int_ == (int)rhs;
        else
            return false;
    }
    
    /// Test for equality with a bool. To return true, both the type and value must match.
    bool operator == (bool rhs) const
    {
        if (type_ == VAR_BOOL)
            return value_.bool_ == rhs;
        else
            return false;
    }
    
    /// Test for equality with a float. To return true, both the type and value must match.
    bool operator == (float rhs) const
    {
        if (type_ == VAR_FLOAT)
            return value_.float_ == rhs;
        else
            return false;
    }
    
    /// Test for equality with a Vector2. To return true, both the type and value must match.
    bool operator == (const Vector2& rhs) const
    {
        if (type_ == VAR_VECTOR2)
            return *(reinterpret_cast<const Vector2*>(&value_)) == rhs;
        else
            return false;
    }
    
    /// Test for equality with a Vector3. To return true, both the type and value must match.
    bool operator == (const Vector3& rhs) const
    {
        if (type_ == VAR_VECTOR3)
            return *(reinterpret_cast<const Vector3*>(&value_)) == rhs;
        else
            return false;
    }
    
    /// Test for equality with a Vector4. To return true, both the type and value must match.
    bool operator == (const Vector4& rhs) const
    {
        if (type_ == VAR_VECTOR4)
            return *(reinterpret_cast<const Vector4*>(&value_)) == rhs;
        else
            return false;
    }
    
    /// Test for equality with a quaternion. To return true, both the type and value must match.
    bool operator == (const Quaternion& rhs) const
    {
        if (type_ == VAR_QUATERNION)
            return *(reinterpret_cast<const Quaternion*>(&value_)) == rhs;
        else
            return false;
    }
    
    /// Test for equality with a color. To return true, both the type and value must match.
    bool operator == (const Color& rhs) const
    {
        if (type_ == VAR_COLOR)
            return *(reinterpret_cast<const Color*>(&value_)) == rhs;
        else
            return false;
    }
    
    /// Test for equality with a string. To return true, both the type and value must match.
    bool operator == (const String& rhs) const
    {
        if (type_ == VAR_STRING)
            return *(reinterpret_cast<const String*>(&value_)) == rhs;
        else
            return false;
    }
    
    /// Test for equality with a buffer. To return true, both the type and value must match.
    bool operator == (const PODVector<unsigned char>& rhs) const
    {
        if (type_ == VAR_BUFFER)
            return *(reinterpret_cast<const PODVector<unsigned char>*>(&value_)) == rhs;
        else
            return false;
    }
    
    /// Test for equality with a pointer. To return true, both the type and value must match.
    bool operator == (void* rhs) const
    {
        if (type_ == VAR_PTR)
            return value_.ptr_ == rhs;
        else
            return false;
    }
    
    /// Test for equality with a resource reference. To return true, both the type and value must match.
    bool operator == (const ResourceRef& rhs) const
    {
        if (type_ == VAR_RESOURCEREF)
            return *(reinterpret_cast<const ResourceRef*>(&value_)) == rhs;
        else
            return false;
    }
    
    /// Test for equality with a resource reference list. To return true, both the type and value must match.
    bool operator == (const ResourceRefList& rhs) const
    {
        if (type_ == VAR_RESOURCEREFLIST)
            return *(reinterpret_cast<const ResourceRefList*>(&value_)) == rhs;
        else
            return false;
    }
    
    /// Test for equality with a variant vector. To return true, both the type and value must match.
    bool operator == (const VariantVector& rhs) const
    {
        if (type_ == VAR_VARIANTVECTOR)
            return *(reinterpret_cast<const VariantVector*>(&value_)) == rhs;
        else
            return false;
    }
    
    /// Test for equality with a variant map. To return true, both the type and value must match.
    bool operator == (const VariantMap& rhs) const
    {
        if (type_ == VAR_VARIANTMAP)
            return *(reinterpret_cast<const VariantMap*>(&value_)) == rhs;
        else
            return false;
    }
    
    /// Test for equality with a StringHash. To return true, both the type and value must match.
    bool operator == (const StringHash& rhs) const
    {
        if (type_ == VAR_INT)
            return (unsigned)value_.int_ == rhs.Value();
        else
            return false;
    }
    
    /// Test for equality with a ShortStringHash. To return true, both the type and value must match.
    bool operator == (const ShortStringHash& rhs) const
    {
        if (type_ == VAR_INT)
            return (unsigned short)value_.int_ == rhs.Value();
        else
            return false;
    }
    
    /// Test for inequality with an integer.
    bool operator != (int rhs) const { return !(*this == rhs); }
    /// Test for inequality with an unsigned integer.
    bool operator != (unsigned rhs) const { return !(*this == rhs); }
    /// Test for inequality with a bool.
    bool operator != (bool rhs) const { return !(*this == rhs); }
    /// Test for inequality with a float.
    bool operator != (float rhs) const { return !(*this == rhs); }
    /// Test for inequality with a Vector2.
    bool operator != (const Vector2& rhs) const { return !(*this == rhs); }
    /// Test for inequality with a Vector3.
    bool operator != (const Vector3& rhs) const { return !(*this == rhs); }
    /// Test for inequality with an Vector4.
    bool operator != (const Vector4& rhs) const { return !(*this == rhs); }
    /// Test for inequality with a Quaternion.
    bool operator != (const Quaternion& rhs) const { return !(*this == rhs); }
    /// Test for inequality with a string.
    bool operator != (const String& rhs) const { return !(*this == rhs); }
    /// Test for inequality with a buffer.
    bool operator != (const PODVector<unsigned char>& rhs) const { return !(*this == rhs); }
    /// Test for inequality with a pointer.
    bool operator != (void* rhs) const { return !(*this == rhs); }
    /// Test for inequality with a resource reference.
    bool operator != (const ResourceRef& rhs) const { return !(*this == rhs); }
    /// Test for inequality with a resource reference list.
    bool operator != (const ResourceRefList& rhs) const { return !(*this == rhs); }
    /// Test for inequality with a variant vector.
    bool operator != (const VariantVector& rhs) const { return !(*this == rhs); }
    /// Test for inequality with a variant map.
    bool operator != (const VariantMap& rhs) const { return !(*this == rhs); }
    /// Test for inequality with a StringHash.
    bool operator != (const StringHash& rhs) const { return !(*this == rhs); }
    /// Test for inequality with a ShortStringHash.
    bool operator != (const ShortStringHash& rhs) const { return !(*this == rhs); }
    
    /// Set from typename and value strings. Pointers will be set to null, and VariantBuffer or VariantMap types are not supported.
    void FromString(const String& type, const String& value);
    /// Set from typename and value strings. Pointers will be set to null, and VariantBuffer or VariantMap types are not supported.
    void FromString(const char* type, const char* value);
    /// Set from type and value string. Pointers will be set to null, and VariantBuffer or VariantMap types are not supported.
    void FromString(VariantType type, const String& value);
    /// Set from type and value string. Pointers will be set to null, and VariantBuffer or VariantMap types are not supported.
    void FromString(VariantType type, const char* value);
    /// Set buffer type from a memory area.
    void SetBuffer(const void* data, unsigned size);
    
    /// Return int or zero on type mismatch.
    int GetInt() const
    {
        if (type_ != VAR_INT)
            return 0;
        return value_.int_;
    }
    
    /// Return unsigned int or zero on type mismatch.
    int GetUInt() const
    {
        if (type_ != VAR_INT)
            return 0;
        return (unsigned)value_.int_;
    }
    
    /// Return StringHash or zero on type mismatch.
    StringHash GetStringHash() const
    {
        if (type_ != VAR_INT)
            return StringHash::ZERO;
        return StringHash(value_.int_);
    }
    
    /// Return ShortStringHash or zero on type mismatch.
    ShortStringHash GetShortStringHash() const
    {
        if (type_ != VAR_INT)
            return ShortStringHash::ZERO;
        return ShortStringHash(value_.int_);
    }
    
    /// Return bool or false on type mismatch.
    bool GetBool() const
    {
        if (type_ != VAR_BOOL)
            return false;
        return value_.bool_;
    }
    
    /// Return float or zero on type mismatch.
    float GetFloat() const
    {
        if (type_ != VAR_FLOAT)
            return 0.0f;
        return value_.float_;
    }
    
    /// Return Vector2 or zero on type mismatch.
    const Vector2& GetVector2() const
    {
        if (type_ != VAR_VECTOR2)
            return Vector2::ZERO;
        return *reinterpret_cast<const Vector2*>(&value_);
    }
    
    /// Return Vector3 or zero on type mismatch.
    const Vector3& GetVector3() const
    {
        if (type_ != VAR_VECTOR3)
            return Vector3::ZERO;
        return *reinterpret_cast<const Vector3*>(&value_);
    }
    
    /// Return Vector4 or zero on type mismatch.
    const Vector4& GetVector4() const
    {
        if (type_ != VAR_VECTOR4)
            return Vector4::ZERO;
        return *reinterpret_cast<const Vector4*>(&value_);
    }
    
    /// Return quaternion or identity on type mismatch.
    const Quaternion& GetQuaternion() const
    {
        if (type_ != VAR_QUATERNION)
            return Quaternion::IDENTITY;
        return *reinterpret_cast<const Quaternion*>(&value_);
    }
    
    /// Return color or default on type mismatch.
    const Color& GetColor() const
    {
        if (type_ != VAR_COLOR)
            return Color::WHITE;
        return *reinterpret_cast<const Color*>(&value_);
    }
    
    /// Return string or empty on type mismatch.
    const String& GetString() const
    {
        if (type_ != VAR_STRING)
            return String::EMPTY;
        return *reinterpret_cast<const String*>(&value_);
    }
    
    /// Return buffer or empty on type mismatch.
    const PODVector<unsigned char>& GetBuffer() const
    {
        if (type_ != VAR_BUFFER)
            return emptyBuffer;
        return *reinterpret_cast<const PODVector<unsigned char>*>(&value_);
    }
    
    /// Return pointer or null on type mismatch.
    void* GetPtr() const
    {
        if (type_ != VAR_PTR)
            return 0;
        return value_.ptr_;
    }
    
    /// Return a resource reference or empty on type mismatch.
    const ResourceRef& GetResourceRef() const
    {
        if (type_ != VAR_RESOURCEREF)
            return emptyResourceRef;
        return *reinterpret_cast<const ResourceRef*>(&value_);
    }
    
    /// Return a resource reference list or empty on type mismatch.
    const ResourceRefList& GetResourceRefList() const
    {
        if (type_ != VAR_RESOURCEREFLIST)
            return emptyResourceRefList;
        return *reinterpret_cast<const ResourceRefList*>(&value_);
    }
    
    /// Return a variant vector or empty on type mismatch.
    const VariantVector& GetVariantVector() const
    {
        if (type_ != VAR_VARIANTVECTOR)
            return emptyVariantVector;
        return *reinterpret_cast<const VariantVector*>(&value_);
    }
    
    /// Return a variant map or empty on type mismatch
    const VariantMap& GetVariantMap() const
    {
        if (type_ != VAR_VARIANTMAP)
            return emptyVariantMap;
        return *reinterpret_cast<const VariantMap*>(&value_);
    }

    /// Return the value, template version.
    template <class T> T Get() const;
    /// Return value's type.
    VariantType GetType() const { return type_; }
    /// Return value's type name.
    const String& GetTypeName() const;
    /// Convert value to string. Pointers are returned as null, and VariantBuffer or VariantMap are not supported and return empty.
    String ToString() const;
    
    /// Return name for variant type.
    static const String& GetTypeName(VariantType type);
    /// Return variant type from type name.
    static VariantType GetTypeFromName(const String& typeName);
    /// Return variant type from type name.
    static VariantType GetTypeFromName(const char* typeName);
    
    /// Empty variant.
    static const Variant EMPTY;
    
private:
    /// Set new type and allocate/deallocate memory as necessary.
    void SetType(VariantType newType);
    
    /// Variant type.
    VariantType type_;
    /// Variant value.
    VariantValue value_;
    
    /// Empty buffer.
    static const PODVector<unsigned char> emptyBuffer;
    /// Empty resource reference.
    static const ResourceRef emptyResourceRef;
    /// Empty resource reference list.
    static const ResourceRefList emptyResourceRefList;
    /// Empty variant map.
    static const VariantMap emptyVariantMap;
    /// Empty variant vector.
    static const VariantVector emptyVariantVector;
};

}