ValueContainer.h

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#pragma once

#include <new>

#include <OnixS/CME/ConflatedUDP/Memory.h>
#include <OnixS/CME/ConflatedUDP/Assertion.h>

ONIXS_CONFLATEDUDPFIX_NAMESPACE_BEGIN

/// Container for a value of any supported kinds. 
ONIXS_CONFLATEDUDP_LTWT_CLASS 
ValueContainer
{
    enum 
    { 
        // Capacity of the storage for a value. 
        // 
        // The storage must be capacious enough 
        // to store all integer types, string refs, 
        // time-related typed and the Decimal. 
        Capacity = 16
    };

    Byte bytes_[Capacity];

    // This is to make G++ happy with the 
    // concept of storing value in the array. 
    void* place() 
    {
        return static_cast<void*>(bytes_);
    }

    // This is to make G++ happy with the 
    // concept of storing value in the array. 
    const void* place() const
    {
        return static_cast<const void*>(bytes_);
    }

public:
    /// Initializes the container. 
    ValueContainer()
    {
    }

    /// Provides access to the value stored 
    /// in the container assuming the value 
    /// is of the specified type. 
    template
    <
        typename Value
    >
    Value& get()
    {
        ONIXS_SASSERT_MSG
        (
            sizeof(Value) <= Capacity,
            "Capacity isn't sufficient for "
            "storing values of the given type. "
        );

        return *
            static_cast
            <Value*>
            (place());
    }

    /// Provides access to the value stored 
    /// in the container assuming the value 
    /// is of the specified type. 
    template
    <
        typename Value
    >
    const Value& get() const
    {
        ONIXS_SASSERT_MSG
        (
            sizeof(Value) <= Capacity,
            "Capacity of the storage isn't "
            "sufficient to store values "
            "of the specified type. "
        );

        return *
            static_cast
            <const Value*>
            (place());
    }

    /// Stores the given value in the container. 
    template
    <
        class Value
    >
    ValueContainer&
    assign(
        const Value& value)
    {
        ONIXS_SASSERT_MSG
        (
            sizeof(Value) <= Capacity,
            "Capacity of the storage isn't "
            "sufficient to store values "
            "of the specified type. "
        );

        new (place()) Value(value);

        return *this;
    }
};

ONIXS_CONFLATEDUDPFIX_NAMESPACE_END