Question

我刚刚开始使用加固多功能指数,迄今为止,有一个集装箱,装配了有序的类型和混合的关键未定的斜体。

我想做的是,如果集装箱是 st的:ctor子或 st子:list子,那么它就能够进入。通过这一方式,采用<代码>size_t index。

我的守则如下:

// tags
struct linear { };
struct semantic { };
struct semantic_and_index { };

// typedefs for multi_index
typedef boost::multi_index::sequenced< 
    boost::multi_index::tag<linear>
> LinearIndex;

typedef boost::multi_index::composite_key<
    CVertexElement,
    boost::multi_index::const_mem_fun<CVertexElement, Buffer::VertexSemantic, &CVertexElement::GetVertexSemantic>,
    boost::multi_index::const_mem_fun<CVertexElement, UInt, &CVertexElement::GetSemanticIndex> 
> CompositeSemanticIndex;

typedef boost::multi_index::hashed_non_unique<
    boost::multi_index::tag<semantic_and_index>,
    CompositeSemanticIndex
> SemanticAndIDIndex;

typedef boost::multi_index::hashed_non_unique<
    boost::multi_index::tag<semantic>,
    boost::multi_index::const_mem_fun<CVertexElement, Buffer::VertexSemantic, &CVertexElement::GetVertexSemantic> 
> SemanticIndex;

class CVertexFormat
{
public:
    typedef boost::multi_index::multi_index_container <
        CVertexElementPtr,
        boost::multi_index::indexed_by <
            LinearIndex,
            SemanticAndIDIndex,
            SemanticIndex
        > // index_by
    > ElementContainer; 

      // etc...

protected:
    ElementContainer m_elements;
};

我指的是:

// this function fails! :(
CVertexElementPtr CVertexFormat::GetElement(size_t index) const 
{
    //sequenced_index.
    typedef ElementContainer::index<linear>::type element_by_linear;
    const element_by_linear& index_type = m_elements.get<linear>();

    if ( index < index_type.size() )
    {
        auto itor = index_type.begin();
        for (UInt i = 0; i < index_type.size(); ++i)
            ++itor;

        const CVertexElementPtr& pElement = (*itor);        
        return pElement;
    }
    else
    {
        assert(!"Invalid index called for GetElement");
        return CVertexElementPtr();
    }
}

• 对2010年(右边看望窗):

高度喷雾管

Answer 1

问题通过修改以下功能得到解决:。

正确的职能是:

CVertexElementPtr CVertexFormat::GetElement(size_t index) const
{
    //sequenced_index.
    typedef ElementContainer::index<linear>::type element_by_linear;
    const element_by_linear& index_type = m_elements.get<linear>();

    size_t size = index_type.size();
    if ( index < size )
    {
        auto itor = index_type.begin();
        for (UInt i = 0; i < index; ++i)
            ++itor;

        const CVertexElementPtr& pElement = (*itor);        
        return pElement;
    }
    else
    {
        assert( false && ieS("Invalid index called for GetElement") );
        return CVertexElementPtr();
    }
}

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