c ++ unordered_multimap insert hash [英] c++ unordered_multimap insert hash

问题描述

我在这里疯了。我有搜索google找到1单一体面的例子，人们使用unordered_map与枚举类和散列函数没有任何运气。

我试图做以下事情：

面向枚举类 是我的精灵正在查看的方向。

枚举类Action 是我的sprite正在做的动作。

动画 是一个类，用于保存不同的动画，我稍后调用。

像这样：

map

地图中可以有超过1个FACING键，

例如：

  map< ; LEFT，pair< ATTACK，attackAnimation> 
 map< LEFT，pair< IDLE，idleAnimation> 
 map< LEFTUP，pair< IDLE，idleAnimation> 
  

这是一个简化的一切

  #include< iostream> 
 #include< unordered_map> 
 #include< string> 
 #include< memory> 
 
 template< typename T> 
 struct Hash 
 {
 typedef typename std :: underlying_type< T> :: type underlyingType; 
 typedef typename std :: hash< underlyingType> :: result_type resultType; 
 resultType operator（）（const T& arg）const 
 {
 std :: hash< underlyingType>哈希尔
 return hasher（static_cast< underlyingType>（arg））; 
} 
}; 
 
 class动画
 {
 private：
 std :: string str; 
 
 public：
动画（std :: string _string）
 {
 this-> str = _string; 
} 
 
 std :: string& GetString（）
 {
 return this-> str; 
} 
}; 
 
 class Bullshit 
 {
 public：
 enum class Action 
 {
 Attack，
 Move 
}; 
 
枚举类面向
 {
右，
上，
左
}; 
 
 Bullshit（）
 {
 
} 
 
 std :: unordered_multimap< Bullshit :: Facing，std :: pair& ：Action，std :: unique_ptr< Animation>>，Hash< Bullshit :: Facing>>& GetlistAnimation（）
 {
 return this-> listAnimation; 
} 
 
 private：
 std :: unordered_multimap< Bullshit :: Facing，std :: pair< Bullshit :: Action，std :: unique_ptr< Animation>>，Hash< ; Bullshit :: Facing>> listAnimation; 
}; 
 
 
 int main（）
 {
 Bullshit bull; 
 auto myList = bull.GetlistAnimation（）; 
 
 std :: unique_ptr< Animation> anim（new Animation（test））; 
 myList.insert（std :: make_pair（Bullshit :: Facing :: Up，std :: make_pair（Bullshit :: Action :: Attack，std :: move（anim））））; 
 
 std :: cin.get（）; 
 return 0; 
} 
  

错误代码：

< blockquote>

 错误C2248：'std :: unique_ptr< _Ty> :: unique_ptr'：无法访问在'std :: unique_ptr< _Ty& 
 1> with 
 1> [
 1> _Ty = Animation 
 1> ] 
 1> c：\program files（x86）\microsoft visual studio 11.0 \vc\include\ memory（1447）：参见声明'std :: unique_ptr< _Ty> :: unique_ptr'
 1& with 
 1> [
 1> _Ty = Animation 
 1> ] 
 1>该诊断发生在编译器生成的函数'std :: pair< _Ty1，_Ty2> :: pair（const std :: pair< _Ty1，_Ty2>&）'
 1& with 
 1> [
 1> _Ty1 = Bullshit :: Action，
 1> _Ty2 = std :: unique_ptr< Animation> 
 1> ] 
  

解决方案

/ p>

  auto myList = bull.GetlistAnimation（）; 
  

推导出 myList 的类型为 std :: unordered_map< .....> ，也就是说，它不是参考。并且无法创建副本，因为地图包含 unique_ptr 。你的意思是

  auto& myList = bull.GetlistAnimation（）; 
  

或在C ++ 14中，

  decltype（auto）myList = bull.GetlistAnimation（）; 
  

I'm going crazy over here. I have search google to find 1 single decent example where people use a unordered_map together with enum class and a hash function without any luck. Those i manage to find always end up saying "use map instead".

I'm trying to do the following:

Enum class facing is the direction my sprite is looking at.

Enum class Action is the action my sprite is doing.

Animation is a class that holds different animations which i will call later.

The container should look like this:

map

There can be more than 1 FACING in the map as key and there can be more than one ACTION in the pair.

Example:

map<LEFT, pair<ATTACK, attackAnimation>
map<LEFT, pair<IDLE, idleAnimation>
map<LEFTUP, pair<IDLE, idleAnimation>

This is an simplified everything

#include <iostream>
#include <unordered_map>
#include <string>
#include <memory>

template <typename T>
struct Hash
{
    typedef typename std::underlying_type<T>::type underlyingType;
    typedef typename std::hash<underlyingType>::result_type resultType;
    resultType operator()(const T& arg) const
    {
        std::hash<underlyingType> hasher;
        return hasher(static_cast<underlyingType>(arg));
    }
};

class Animation
{
private:
    std::string str;

public:
    Animation(std::string _string)
    {
        this->str = _string;
    }

    std::string& GetString()
    {
        return this->str;
    }
};

class Bullshit
{
public:
    enum class Action
    {
        Attack,
        Move
    };

    enum class Facing
    {
        Right,
        Up,
        Left
    };

    Bullshit()
    {

    }

    std::unordered_multimap<Bullshit::Facing, std::pair<Bullshit::Action, std::unique_ptr<Animation>>,Hash<Bullshit::Facing>>& GetlistAnimation()
    {
        return this->listAnimation;
    }

private:
    std::unordered_multimap<Bullshit::Facing, std::pair<Bullshit::Action, std::unique_ptr<Animation>>,Hash<Bullshit::Facing>> listAnimation;
};


int main()
{
    Bullshit bull;
    auto myList = bull.GetlistAnimation();

    std::unique_ptr<Animation> anim(new Animation("test"));
    myList.insert(std::make_pair(Bullshit::Facing::Up, std::make_pair(Bullshit::Action::Attack, std::move(anim))));

    std::cin.get();
    return 0;
}

Error code:

error C2248: 'std::unique_ptr<_Ty>::unique_ptr' : cannot access private member declared in class 'std::unique_ptr<_Ty>'
1>          with
1>          [
1>              _Ty=Animation
1>          ]
1>          c:\program files (x86)\microsoft visual studio 11.0\vc\include\memory(1447) : see declaration of 'std::unique_ptr<_Ty>::unique_ptr'
1>          with
1>          [
1>              _Ty=Animation
1>          ]
1>          This diagnostic occurred in the compiler generated function 'std::pair<_Ty1,_Ty2>::pair(const std::pair<_Ty1,_Ty2> &)'
1>          with
1>          [
1>              _Ty1=Bullshit::Action,
1>              _Ty2=std::unique_ptr<Animation>
1>          ]

解决方案

Here

auto myList = bull.GetlistAnimation();

the type deduced for myList is std::unordered_map<.....>, that is, it's not a reference. And the copy can't be created because the map contains unique_ptrs. What you meant is

auto& myList = bull.GetlistAnimation();

or in C++14,

decltype(auto) myList = bull.GetlistAnimation();

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