ValueConverters.h

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// Copyright Onix Solutions Limited [OnixS]. All rights reserved.
//
// This software owned by Onix Solutions Limited [OnixS] and is
// protected by copyright law and international copyright treaties.
//
// Access to and use of the software is governed by the terms of the applicable
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// agreements granting a non-assignable, non-transferable and non-exclusive license
// to use the software for it's own data processing purposes under the terms defined
// in the Agreement.
//
// Except as otherwise granted within the terms of the Agreement, copying or
// reproduction of any part of this source code or associated reference material
// to any other location for further reproduction or redistribution, and any
// amendments to this copyright notice, are expressly prohibited.
//
// Any reproduction or redistribution for sale or hiring of the Software not in
// accordance with the terms of the Agreement is a violation of copyright law.
//

#pragma once

#include <stdexcept>

#include <OnixS/CME/MDH/String.h>
#include <OnixS/CME/MDH/Time.h>

#include <OnixS/CME/MDH/Decimal.h>
#include <OnixS/CME/MDH/Integral.h>
#include <OnixS/CME/MDH/Serialization.h>

#include <OnixS/CME/MDH/FIX/ValueContainer.h>

ONIXS_CMEMDHFIX_NAMESPACE_BEGIN

/// Abstraction gathering operations
/// over a value of a particular type
/// stored as a field in a message.
struct ONIXS_CMEMDH_EXPORTED ValueConverter
{
    /// The name of the type whose values are
    /// manipulated through the given converter.
    virtual const Char* typeName() const = 0;

    /// Outputs the text presentation of the FIX value
    /// stored in the given container into the given string.
    virtual void toStr(std::string&, const ValueContainer&) const {}

    /// Tries to convert the value stored in the given
    /// container into the string reference. The returned
    /// value indicates whether the conversion successful.
    virtual bool convert(StrRef&, const ValueContainer&) const
    {
        return false;
    }

    /// Tries to convert the value stored in the given
    /// container into a character. The returned value
    /// indicates whether the conversion successful.
    virtual bool convert(Char&, const ValueContainer&) const
    {
        return false;
    }

    /// Tries to convert the value stored in the
    /// given container into an integer. The returned
    /// value indicates whether the conversion successful.
    virtual bool convert(Int8&, const ValueContainer&) const
    {
        return false;
    }

    /// Tries to convert the value stored in the
    /// given container into an integer. The returned
    /// value indicates whether the conversion successful.
    virtual bool convert(UInt8&, const ValueContainer&) const
    {
        return false;
    }

    /// Tries to convert the value stored in the
    /// given container into an integer. The returned
    /// value indicates whether the conversion successful.
    virtual bool convert(Int16&, const ValueContainer&) const
    {
        return false;
    }

    /// Tries to convert the value stored in the
    /// given container into an integer. The returned
    /// value indicates whether the conversion successful.
    virtual bool convert(UInt16&, const ValueContainer&) const
    {
        return false;
    }

    /// Tries to convert the value stored in the
    /// given container into an integer. The returned
    /// value indicates whether the conversion successful.
    virtual bool convert(Int32&, const ValueContainer&) const
    {
        return false;
    }

    /// Tries to convert the value stored in the
    /// given container into an integer. The returned
    /// value indicates whether the conversion successful.
    virtual bool convert(UInt32&, const ValueContainer&) const
    {
        return false;
    }

    /// Tries to convert the value stored in the
    /// given container into an integer. The returned
    /// value indicates whether the conversion successful.
    virtual bool convert(Int64&, const ValueContainer&) const
    {
        return false;
    }

    /// Tries to convert the value stored in the
    /// given container into an integer. The returned
    /// value indicates whether the conversion successful.
    virtual bool convert(UInt64&, const ValueContainer&) const
    {
        return false;
    }

    /// Tries to convert the value stored in the
    /// given container into a decimal. The returned
    /// value indicates whether the conversion successful.
    virtual bool convert(Decimal&, const ValueContainer&) const
    {
        return false;
    }

    /// Tries to convert the value stored in the
    /// given container into a timestamp. The returned
    /// value indicates whether the conversion successful.
    virtual bool convert(Timestamp&, const ValueContainer&) const
    {
        return false;
    }

    /// Tries to convert the value stored in the
    /// given container into a month-year. The returned
    /// value indicates whether the conversion successful.
    virtual bool convert(MaturityMonthYear&, const ValueContainer&) const
    {
        return false;
    }
};

struct ONIXS_CMEMDH_EXPORTED NullConverter : ValueConverter
{
    const Char* typeName() const ONIXS_CMEMDH_OVERRIDE
    {
        return "Null";
    }

    static const ValueConverter& self();
};

//

/// Implements the value conversion
/// abstraction for the text fields.
struct ONIXS_CMEMDH_EXPORTED StrRefConverter : ValueConverter
{
    const Char* typeName() const ONIXS_CMEMDH_OVERRIDE
    {
        return "String";
    }

    void toStr(std::string& str, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        const StrRef& ref = container.get<StrRef>();

        str.assign(ref.items(), ref.size());
    }

    bool convert(StrRef& ref, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        ref = container.get<StrRef>();

        return true;
    }

    bool convert(Char& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        const StrRef& str = container.get<StrRef>();

        if (1 == str.size())
        {
            value = str[0];

            return true;
        }
        else if (str.empty())
        {
            value = 0;

            return true;
        }

        return false;
    }

    bool convert(Int8& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        const StrRef& str = container.get<StrRef>();

        return fromStr(value, str.items(), str.size());
    }

    bool convert(UInt8& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        const StrRef& str = container.get<StrRef>();

        return fromStr(value, str.items(), str.size());
    }

    bool convert(Int16& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        const StrRef& str = container.get<StrRef>();

        return fromStr(value, str.items(), str.size());
    }

    bool convert(UInt16& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        const StrRef& str = container.get<StrRef>();

        return fromStr(value, str.items(), str.size());
    }

    bool convert(Int32& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        const StrRef& str = container.get<StrRef>();

        return fromStr(value, str.items(), str.size());
    }

    bool convert(UInt32& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        const StrRef& str = container.get<StrRef>();

        return fromStr(value, str.items(), str.size());
    }

    bool convert(Int64& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        const StrRef& str = container.get<StrRef>();

        return fromStr(value, str.items(), str.size());
    }

    bool convert(UInt64& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        const StrRef& str = container.get<StrRef>();

        return fromStr(value, str.items(), str.size());
    }

    bool convert(Decimal& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        const StrRef& str = container.get<StrRef>();

        return fromStr(value, str.items(), str.size());
    }

    bool convert(Timestamp& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        const StrRef& str = container.get<StrRef>();

        return fromStr(value, str.items(), str.size());
    }

    bool convert(MaturityMonthYear&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    static const ValueConverter& self();
};

//

/// Implements the value conversion abstraction for
/// fields whose values represent a single character.
struct ONIXS_CMEMDH_EXPORTED CharConverter : ValueConverter
{
    const Char* typeName() const ONIXS_CMEMDH_OVERRIDE
    {
        return "Char";
    }

    void toStr(std::string& str, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        str.append(1, container.get<Char>());
    }

    bool convert(StrRef& ref, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        ref = StrRef(&container.get<Char>(), 1);

        return true;
    }

    bool convert(Char& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = container.get<Char>();

        return true;
    }

    bool convert(Int8& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        return charToDigit(value, container.get<Char>());
    }

    bool convert(UInt8& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        return charToDigit(value, container.get<Char>());
    }

    bool convert(Int16& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        return charToDigit(value, container.get<Char>());
    }

    bool convert(UInt16& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        return charToDigit(value, container.get<Char>());
    }

    bool convert(Int32& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        return charToDigit(value, container.get<Char>());
    }

    bool convert(UInt32& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        return charToDigit(value, container.get<Char>());
    }

    bool convert(Int64& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        return charToDigit(value, container.get<Char>());
    }

    bool convert(UInt64& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        return charToDigit(value, container.get<Char>());
    }

    bool convert(Decimal& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        Decimal::Mantissa mantissa;

        if (charToDigit(mantissa, container.get<Char>()))
        {
            value = Decimal(mantissa, 0);

            return true;
        }

        return false;
    }

    bool convert(Timestamp&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(MaturityMonthYear&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    static const ValueConverter& self();

private:
    template <class Integer>
    static bool charToDigit(Integer& converted, Char original)
    {
        if ('0' <= original && '9' >= original)
        {
            converted = static_cast<Integer>(original - '0');

            return true;
        }

        return false;
    }
};

//

/// Implements the value conversion
/// abstraction for the integer fields.
template <class Integer, class Descendant>
class IntegerConverter : public ValueConverter
{
    template <class Integral, bool IsSigned>
    struct FitsToChar
    {
        bool operator()(Integral value) const
        {
            return (0 <= value && value < 10);
        }
    };

    template <class Integral>
    struct FitsToChar<Integral, false>
    {
        bool operator()(Integral value) const
        {
            return (value < 10);
        }
    };

    typedef FitsToChar<Integer, !(static_cast<Integer>(-1) > static_cast<Integer>(0))> CanFitToChar;

public:
    void toStr(std::string& str, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        OnixS::CME::MDH::toStr(str, container.get<Integer>());
    }

    bool convert(Char& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        const Integer actual = container.get<Integer>();

        if (CanFitToChar()(actual))
        {
            value = static_cast<Char>('0' + actual);

            return true;
        }

        return false;
    }

    bool convert(Int8& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = static_cast<Int8>(container.get<Integer>());

        return true;
    }

    bool convert(UInt8& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = static_cast<UInt8>(container.get<Integer>());

        return true;
    }

    bool convert(Int16& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = static_cast<Int16>(container.get<Integer>());

        return true;
    }

    bool convert(UInt16& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = static_cast<UInt16>(container.get<Integer>());

        return true;
    }

    bool convert(Int32& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = static_cast<Int32>(container.get<Integer>());

        return true;
    }

    bool convert(UInt32& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = static_cast<UInt32>(container.get<Integer>());

        return true;
    }

    bool convert(Int64& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = static_cast<Int64>(container.get<Integer>());

        return true;
    }

    bool convert(UInt64& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = static_cast<UInt64>(container.get<Integer>());

        return true;
    }

    bool convert(Decimal& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = Decimal(static_cast<Decimal::Mantissa>(container.get<Integer>()), 0);

        return true;
    }

    bool convert(StrRef&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Timestamp&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(MaturityMonthYear&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }
};

/// Implements the value conversion
/// abstraction for the integer fields.
struct ONIXS_CMEMDH_EXPORTED Int8Converter : IntegerConverter<Int8, Int8Converter>
{
    const Char* typeName() const ONIXS_CMEMDH_OVERRIDE
    {
        return "Int8";
    }

    static const ValueConverter& self();
};

/// Implements the value conversion
/// abstraction for the integer fields.
struct ONIXS_CMEMDH_EXPORTED UInt8Converter : IntegerConverter<UInt8, UInt8Converter>
{
    const Char* typeName() const ONIXS_CMEMDH_OVERRIDE
    {
        return "UInt8";
    }

    static const ValueConverter& self();
};

/// Implements the value conversion
/// abstraction for the integer fields.
struct ONIXS_CMEMDH_EXPORTED Int16Converter : IntegerConverter<Int16, Int16Converter>
{
    const Char* typeName() const ONIXS_CMEMDH_OVERRIDE
    {
        return "Int16";
    }

    static const ValueConverter& self();
};

/// Implements the value conversion
/// abstraction for the integer fields.
struct ONIXS_CMEMDH_EXPORTED UInt16Converter : IntegerConverter<UInt16, UInt16Converter>
{
    const Char* typeName() const ONIXS_CMEMDH_OVERRIDE
    {
        return "UInt16";
    }

    static const ValueConverter& self();
};

/// Implements the value conversion
/// abstraction for the integer fields.
struct ONIXS_CMEMDH_EXPORTED Int32Converter : IntegerConverter<Int32, Int32Converter>
{
    const Char* typeName() const ONIXS_CMEMDH_OVERRIDE
    {
        return "Int32";
    }

    static const ValueConverter& self();
};

/// Implements the value conversion
/// abstraction for the integer fields.
struct ONIXS_CMEMDH_EXPORTED UInt32Converter : IntegerConverter<UInt32, UInt32Converter>
{
    const Char* typeName() const ONIXS_CMEMDH_OVERRIDE
    {
        return "UInt32";
    }

    static const ValueConverter& self();
};

/// Implements the value conversion
/// abstraction for the integer fields.
struct ONIXS_CMEMDH_EXPORTED Int64Converter : IntegerConverter<Int64, Int64Converter>
{
    const Char* typeName() const ONIXS_CMEMDH_OVERRIDE
    {
        return "Int64";
    }

    static const ValueConverter& self();
};

/// Implements the value conversion
/// abstraction for the integer fields.
struct ONIXS_CMEMDH_EXPORTED UInt64Converter : IntegerConverter<UInt64, UInt64Converter>
{
    const Char* typeName() const ONIXS_CMEMDH_OVERRIDE
    {
        return "UInt64";
    }

    static const ValueConverter& self();
};

//

/// Implements the value conversion
/// abstraction for the decimal fields.
struct ONIXS_CMEMDH_EXPORTED DecimalConverter : ValueConverter
{
    const Char* typeName() const ONIXS_CMEMDH_OVERRIDE
    {
        return "Decimal";
    }

    void toStr(std::string& str, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        OnixS::CME::MDH::toStr(str, container.get<Decimal>());
    }

    bool convert(Decimal& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = container.get<Decimal>();

        return true;
    }

    bool convert(StrRef&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Char&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Int8&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(UInt8&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Int16&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(UInt16&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Int32&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(UInt32&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Int64&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(UInt64&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Timestamp&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(MaturityMonthYear&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    static const ValueConverter& self();
};

//

/// Implements the value conversion
/// abstraction for the timestamp fields.
struct ONIXS_CMEMDH_EXPORTED TimestampConverter : ValueConverter
{
    const Char* typeName() const ONIXS_CMEMDH_OVERRIDE
    {
        return "Timestamp";
    }

    void toStr(std::string& str, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        OnixS::CME::MDH::toStr(str, container.get<Timestamp>());
    }

    bool convert(Int64& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = static_cast<Int64>(container.get<Timestamp>().sinceEpoch());

        return true;
    }

    bool convert(UInt64& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = container.get<Timestamp>().sinceEpoch();

        return true;
    }

    bool convert(Timestamp& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = container.get<Timestamp>();

        return true;
    }

    bool convert(StrRef&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Char&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Int8&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(UInt8&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Int16&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(UInt16&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Int32&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(UInt32&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Decimal&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(MaturityMonthYear&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    static const ValueConverter& self();
};

//

/// Implements the value conversion
/// abstraction for the month-year fields.
struct ONIXS_CMEMDH_EXPORTED MaturityMonthYearConverter : ValueConverter
{
    const Char* typeName() const ONIXS_CMEMDH_OVERRIDE
    {
        return "MaturityMonthYear";
    }

    void toStr(std::string& str, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        OnixS::CME::MDH::toStr(str, container.get<MaturityMonthYear>());
    }

    bool convert(MaturityMonthYear& value, const ValueContainer& container) const ONIXS_CMEMDH_OVERRIDE
    {
        value = container.get<MaturityMonthYear>();

        return true;
    }

    bool convert(StrRef&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Char&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Int8&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(UInt8&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Int16&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(UInt16&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Int32&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(UInt32&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Int64&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(UInt64&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Decimal&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    bool convert(Timestamp&, const ValueContainer&) const ONIXS_CMEMDH_OVERRIDE
    {
        return false;
    }

    static const ValueConverter& self();
};

//

inline void throwBadConversion(const Char* typeName)
{
    std::string issue;

    issue += "Cannot transform ";

    issue += typeName ? typeName : "Unknown type";

    issue += " value to the value of the requested "
             "type because either conversion between "
             "types does not exist or the value cannot "
             "be fit to the value of the target type. ";

    throw std::domain_error(issue);
}

//

/// Identifies kinds of FIX field values.
struct ValueKinds
{
    /// Identifies kinds of FIX field values.
    enum Enum
    {
        Ordinary,
        Enumeration,
        Bits
    };
};

/// Traits class used identify a field value kind.
template <class Value>
class ValueKind
{
    typedef char Ordinary[1];

    typedef char Enumeration[2];

    typedef char Bits[3];

    template <class Other>
    static Bits& kind(typename Other::Bits*);

    template <class Other>
    static Enumeration& kind(typename Other::Enum*);

    template <class Other>
    static Ordinary& kind(...);

public:
    enum
    {
        /// The kind of the given field value by its type.
        Kind =
            (sizeof(Bits) == sizeof(kind<Value>(ONIXS_CMEMDH_NULLPTR))
                 ? ValueKinds::Bits
                 : (sizeof(Enumeration) == sizeof(kind<Value>(ONIXS_CMEMDH_NULLPTR)) ? ValueKinds::Enumeration : ValueKinds::Ordinary))
    };
};

/// The field value traits used in
/// conversion related operations.
template <class Value, int>
struct ValueConversionTraits
{
    /// Type of the conversion output.
    typedef Value Result;

    /// Converters the given value by using the
    /// specified value converter and returns the
    /// result of conversion. Throws an exception
    /// in case of conversion failure.
    static Result convert(const ValueConverter& converter, const ValueContainer& container)
    {
        Result result;

        if (!converter.convert(result, container))
        {
            throwBadConversion(converter.typeName());
        }

        return result;
    }

    /// Tries to convert the given value using
    /// the given value converter and puts the
    /// result of the conversion into the given
    /// variable. Returns conversion status.
    static bool convert(Result& result, const ValueConverter& converter, const ValueContainer& container)
    {
        return converter.convert(result, container);
    }
};

/// The field value traits used in
/// conversion related operations.
///
/// Specialization for enumerations.
template <class Enumeration>
struct ValueConversionTraits<Enumeration, ValueKinds::Enumeration>
{
    /// Type of the conversion output.
    typedef typename Enumeration::Enum Result;

    /// Converters the given value by using the
    /// specified value converter and returns the
    /// result of conversion. Throws an exception
    /// in case of conversion failure.
    static Result convert(const ValueConverter& converter, const ValueContainer& container)
    {
        typename Enumeration::Base result;

        if (!converter.convert(result, container))
        {
            throwBadConversion(converter.typeName());
        }

        return static_cast<Result>(result);
    }

    /// Tries to convert the given value using
    /// the given value converter and puts the
    /// result of the conversion into the given
    /// variable. Returns conversion status.
    static bool convert(Result& result, const ValueConverter& converter, const ValueContainer& container)
    {
        typename Enumeration::Base base;

        if (converter.convert(base, container))
        {
            result = static_cast<Result>(base);

            return true;
        }

        return false;
    }
};

/// The field value traits used in
/// conversion related operations.
///
/// Specialization for bit sets.
template <class BitSet>
struct ValueConversionTraits<BitSet, ValueKinds::Bits>
{
    /// Type of the conversion output.
    typedef BitSet Result;

    /// Converters the given value by using the
    /// specified value converter and returns the
    /// result of conversion. Throws an exception
    /// in case of conversion failure.
    static BitSet convert(const ValueConverter& converter, const ValueContainer& container)
    {
        typename BitSet::Bits bits;

        if (!converter.convert(bits, container))
        {
            throwBadConversion(converter.typeName());
        }

        return BitSet(bits);
    }

    /// Tries to convert the given value using
    /// the given value converter and puts the
    /// result of the conversion into the given
    /// variable. Returns conversion status.
    static bool convert(BitSet& result, const ValueConverter& converter, const ValueContainer& container)
    {
        typename BitSet::Bits bits;

        if (converter.convert(bits, container))
        {
            result = BitSet(bits);

            return true;
        }

        return false;
    }
};

/// Implements value conversion operations
/// through value conversion traits.
template <class Value>
struct ValueConversion
{
    /// Conversion traits.
    typedef ValueConversionTraits<Value, ValueKind<Value>::Kind> Traits;

    /// Conversion output type.
    typedef typename Traits::Result Result;

    /// Converts the given value into a value of target
    /// type. Throws an exception in case of failure.
    typename Traits::Result operator()(const ValueConverter& converter, const ValueContainer& container) const
    {
        return Traits::convert(converter, container);
    }

    /// Converts the given value into a value
    /// of target type. Returns conversion status.
    bool
    operator()(typename Traits::Result& result, const ValueConverter& converter, const ValueContainer& container) const
    {
        return Traits::convert(result, converter, container);
    }
};

ONIXS_CMEMDHFIX_NAMESPACE_END