Question

我尝试定义自己的boost::intrusive::slist 另外，我想在类中有另一个静态方法。（copy_buffer_from_list）获取列表＆amp;和迭代器＆amp;作为参数。
问题是一些定义是循环的，我无法做到正确这是当前的代码：

#include <boost/intrusive/slist.hpp>

typedef boost::intrusive::slist_base_hook<> InputBufferSglHook;

class InputBufferSglNode;

// list
typedef boost::intrusive::slist<InputBufferSglNode, boost::intrusive::cache_last<true>> InputBufferSglList;
typedef InputBufferSglList::iterator InputBufferSglIterator;

class InputBufferSglNode : public InputBufferSglHook
{
public :

    InputBufferSglNode(const void* buffer, size_t size); 

    ~InputBufferSglNode() {};

    // copy 'size_t' bytes from list to target, if list doesn't have enough space, method shall return false
    static bool copy_buffer_from_list(InputBufferSglList &list, InputBufferSglIterator &iter, size_t &offset_in_node, const InputBufferSglIterator& end, uint8_t *target, size_t size);

    void reset();

public:
    const void *m_buffer;
    size_t m_size;
};

// empty list
const InputBufferSglList s_EMPTY_INPUT_BUFF_SGL = InputBufferSglList();

InputBufferSglNode::InputBufferSglNode(const void* buffer, size_t size) :
    InputBufferSglHook(),
    m_buffer(buffer),
    m_size(size)
{
    // empty
}

void InputBufferSglNode::reset()
{
    m_buffer = nullptr;
    m_size = 0;
}

static bool InputBufferSglNode::copy_buffer_from_list(InputBufferSglList &list, InputBufferSglIterator &iter, size_t &offset_in_node, const InputBufferSglIterator& end, uint8_t *target, size_t size)
{
    // implementation
}

注意我试图转发声明InputBufferSglNode，但在编译时遇到以下错误：

error: incomplete type 'InputBufferSglNode' named in nested name specifier
note: in instantiation of template class 'boost::intrusive::slist<InputBufferSglNode, boost::intrusive::cache_last<true>, void, void, void, void>' requested here
typedef InputBufferSglList::iterator InputBufferSglIterator;
        ^
note: forward declaration of 'InputBufferSglNode'
class InputBufferSglNode;
      ^

Answer 1

类型不完整，就像它说的那样。这不合法（侵入式容器需要知道实现细节 - 基础，大小等 - 在实例化时）。

文档特别提到在进行这种“嵌套”使用时应避免推断钩子类型。

鉴于此，有几种方法可以解决它：

你可以随意改变： Live On Coliru 。
如果您真的希望InputBufferSglList成为全局typedef，当然，您可以使用别名： Live On Coliru

更新对于评论，您似乎真的坚持要将此作为前向声明的列表类型，您可以按照in the documentation所述：

typedef boost::intrusive::slist_base_hook<> InputBufferSglHook;
class InputBufferSglNode;

// list
typedef boost::intrusive::slist<
        InputBufferSglNode,
        boost::intrusive::base_hook<InputBufferSglHook>,
        boost::intrusive::cache_last<true> 
    > InputBufferSglList;

typedef InputBufferSglList::iterator InputBufferSglIterator;

工作完成。见 Live On Coliru 。

完整演示

完整的第三个版本，供将来参考：

#include <boost/intrusive/slist.hpp>

typedef boost::intrusive::slist_base_hook<> InputBufferSglHook;
class InputBufferSglNode;

// list
typedef boost::intrusive::slist<
        InputBufferSglNode,
        boost::intrusive::base_hook<InputBufferSglHook>,
        boost::intrusive::cache_last<true> 
    > InputBufferSglList;

typedef InputBufferSglList::iterator InputBufferSglIterator;

class InputBufferSglNode : public InputBufferSglHook
{
  public:

    InputBufferSglNode(const void* buffer, size_t size); 

    ~InputBufferSglNode() {};

    // copy 'size_t' bytes from list to target, if list doesn't have enough space, method shall return false
    static bool copy_buffer_from_list(InputBufferSglList &list, InputBufferSglIterator &iter, size_t &offset_in_node, const InputBufferSglIterator& end, uint8_t *target, size_t size);

    void reset();

  public:
    const void *m_buffer;
    size_t m_size;
};

// empty list
const InputBufferSglList s_EMPTY_INPUT_BUFF_SGL = InputBufferSglList();

InputBufferSglNode::InputBufferSglNode(const void* buffer, size_t size) :
    InputBufferSglHook(),
    m_buffer(buffer),
    m_size(size)
{
    // empty
}

void InputBufferSglNode::reset()
{
    m_buffer = nullptr;
    m_size = 0;
}

bool InputBufferSglNode::copy_buffer_from_list(InputBufferSglList &list, InputBufferSglIterator &iter, size_t &offset_in_node, const InputBufferSglIterator& end, uint8_t *target, size_t size)
{
    // implementation
}

int main() {
}

错误：类型不完整＆＃39; typename＆＃39;以嵌套名称说明符命名

1 个答案:

完整演示