无序图：自有值类型问题

Question

我有一个用户定义的类，它应该是unsorted_map的值类型。我的问题是，插入不工作（用gcc 4.7编译时已经是一个静态错误）。

我的类：以创建地图并插入

class bk_tree { 

public: 
    bk_point *root; 
    DISTANCE_FUN metric; 
    int max_depth; 

    //assume words not empty 
    bk_tree() {metric=NULL; root=NULL; max_depth = 0;} 

    //rule of three 
    bk_tree(const bk_tree& copy_this) {metric=copy_this.metric; root=copy_this.root; max_depth = copy_this.max_depth;} 
    bk_tree& operator=(const bk_tree& copy_this) { metric=copy_this.metric; root=copy_this.root; max_depth = copy_this.max_depth; return *this; } 
    ~bk_tree() { delete root; } 

    bk_tree(unordered_set<string> *words, DISTANCE_FUN _metric); 
    bk_tree(DISTANCE_FUN _metric) { metric = _metric; root = NULL; max_depth = 0;   
}; 

代码：

#include<tr/unordered_map> 
using namespace std; 
using namespace std::tr1; 

unordered_map<DocID, sigmod::bk_tree> *my_map = new unordered_map<DocID, sigmod::bk_tree>; 
sigmod::bk_tree my_value = sigmod::bk_tree(&words, sigmod::hamming_distance_metric); 
doc_bk_hamming->insert(make_pair(my_key, my_value)); 

汇编（克++ -O3 -std = C++ 11 -fopenmp -fPIC -Wall - 克-I -I./include -c -o ref_impl/core.o）错误：

ref_impl/core.cpp 
In file included from /usr/include/c++/4.7/bits/move.h:57:0, 
       from /usr/include/c++/4.7/bits/stl_pair.h:61, 
       from /usr/include/c++/4.7/bits/stl_algobase.h:65, 
       from /usr/include/c++/4.7/bits/char_traits.h:41, 
       from /usr/include/c++/4.7/string:42, 
       from ref_impl/../include/metric.h:5, 
       from ref_impl/core.cpp:29: 
/usr/include/c++/4.7/type_traits: In instantiation of ‘struct std::is_convertible<const std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>&, std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false> >’: 
/usr/include/c++/4.7/type_traits:116:12: required from ‘struct std::__and_<std::is_convertible<const std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>&, std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false> >, std::is_convertible<const bool&, bool> >’ 
/usr/include/c++/4.7/bits/stl_pair.h:113:38: required from here 
/usr/include/c++/4.7/type_traits:1263:12: error: the value of ‘std::__is_convertible_helper<const std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>&, std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>, false>::value’ is not usable in a constant expression 
/usr/include/c++/4.7/type_traits:1258:70: note: ‘std::__is_convertible_helper<const std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>&, std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>, false>::value’ used in its own initializer 
/usr/include/c++/4.7/type_traits:1263:12: note: in template argument for type ‘bool’ 
/usr/include/c++/4.7/type_traits: In instantiation of ‘struct std::__and_<std::is_convertible<const std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>&, std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false> >, std::is_convertible<const bool&, bool> >’: 
/usr/include/c++/4.7/bits/stl_pair.h:113:38: required from here 
/usr/include/c++/4.7/type_traits:116:12: error: ‘value’ is not a member of ‘std::is_convertible<const std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>&, std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false> >’ 

Answer 1

是对的DocID类型可哈希？这对于unordered_map的键类型是必需的，这是compailer所抱怨的。另一方面，DocID听起来像支持一个命令，为什么不使用一个映射，它被实现为二叉搜索树？

此外，您的副本构造函数和复制赋值运算符已损坏。他们复制指针，然后原始对象和副本都认为他们拥有资源。如果其中一个被破坏，则该资源被删除，导致在另一个对象被破坏时产生双重空闲。

Answer 2

有很多遗漏的信息，阻止我们给你一个正确的答案。例如，什么是doc_bk_hamming？您分配和unordered_map并将其地址分配给指针my_map。但是，您将(my_key, my_value)对插入我们看不到的doc_bk_hamming所指的地图中。