VS 2008 中的 C++ 0x 错误

Question

首先感谢论坛在将一个用C++ 0x函数编写的函数转换为C++03时提供的支持。我还有几行要转换。在完成任务之前，我有一个主要的编译错误(在 VS 2008 中)需要在以下代码中修复。

(错误读作“模板声明只允许在全局、命名空间或类范围内使用”)

#include "stdafx.h"

#define EMPTY(x, func)
#define ACTION(x, func) func(x)
#define IFRETURN(x, func) if (!func(x)) { return; }

#define  BIN_TREE_TRAVERSAL(NAME, PRE, IN, POST) \
  template <typename node_t, typename func_t>      \
  void NAME (node_t* proot, func_t const& func)    \
  {                                                \
   if (proot)                                      \
   {                                               \
    PRE(proot, func);                              \
    NAME(proot->left (), func);                    \
    IN(proot, func);                               \
    NAME(proot->right(), func);                    \
    POST(proot, func);                             \
   }                                               \
  }

   BIN_TREE_TRAVERSAL(inorder, EMPTY, ACTION, EMPTY)
   BIN_TREE_TRAVERSAL(preorder, ACTION, EMPTY, EMPTY)
   BIN_TREE_TRAVERSAL(postorder, EMPTY, EMPTY, ACTION)

#define LEFT  left
#define RIGHT right

#define  BIN_TREE_FIRST(NAME, CONTAINER, NEXT, ACT, L, R) \
  template <typename node_t, typename func_t>               \
  void NAME (node_t* proot, func_t const& func)             \
  {                                                         \
   CONTAINER<node_t*> tovisit;                              \
   std::vector<node_t*> visited;                            \
   tovisit.push(proot);                                     \
   while (!tovisit.empty())                                 \
   {                                                        \
    node_t* pnode = tovisit.NEXT(); tovisit.pop();          \
    if (std::find(visited.begin(), visited.end(), pnode)    \
      == visited.end())                                     \
    {                                                       \
     visited.push_back(pnode);                              \
     ACT(pnode, func);                                      \
     if (pnode->L()) { tovisit.push(pnode->L()); }          \
     if (pnode->R()) { tovisit.push(pnode->R()); }          \
    }                                                       \
   }                                                        \
  }

   BIN_TREE_FIRST(width_first   , std::queue, front, ACTION, LEFT, RIGHT)
   BIN_TREE_FIRST(width_first_if, std::queue, front, IFRETURN, LEFT, RIGHT)

   BIN_TREE_FIRST(depth_first   , std::stack, top, ACTION, RIGHT, LEFT)
   BIN_TREE_FIRST(depth_first_if, std::stack, top, IFRETURN, RIGHT, LEFT)

#define BASETREEE_TRAVERSAL(NAME)                                   \
  template <typename func_t> void NAME (func_t const& f)         \
  {  bintree::NAME (m_root, [&f] (node_t* x) { f(x->n); } ); } \
  template <typename func_t> void NAME (func_t const& f) const   \
  { bintree::NAME (m_root, [&f] (node_t const* x) { f(x->n); } ); }

#define BASETREEE_TRAVERSAL_IF(NAME)                                       \
  template <typename func_t> void NAME (func_t const& f)                \
  { bintree::NAME (m_root, [&f] (node_t* x) { return f(x->n); } ); } \
  template <typename func_t> void NAME (func_t const& f) const          \
  { bintree::NAME (m_root, [&f] (node_t const* x) { return f(x->n); } ); }

int _tmain(int argc, _TCHAR* argv[])
{
    BASETREEE_TRAVERSAL(preorder)
  BASETREEE_TRAVERSAL(inorder)
  BASETREEE_TRAVERSAL(postorder)
  BASETREEE_TRAVERSAL(width_first)
  BASETREEE_TRAVERSAL(depth_first)


  BASETREEE_TRAVERSAL_IF(width_first_if)
  BASETREEE_TRAVERSAL_IF(depth_first_if)
  return 0;
}

如何修复错误。

Answer 1

尝试将宏调用移到 main 之外。

不过，在某些时候，您将不得不使用 C++03 语法将所有 lambda 替换为仿函数对象。