C ++循环依赖混淆与邻接表的表示 [英] C++ cyclic dependency confusion with adjacency list representation

问题描述

对不起，因为我没有经验C ++，但我花了一段时间安静一段时间解决循环依赖问题，因此构成这个。

Sorry for my inexperience with C++, but I spent quiet some time with solving a cyclic dependency issue and hence posing this.

我试图代表邻接列表在C ++中。

I am trying to represent a Adjacency List in C++.

我有struct Node ，

struct Node{

    int data;
    unordered_set<Node, Hash> links;

    bool operator == (Node const& other) const{
        return (data == other.data);
    }

    Node(){
    }

    Node(int data){
        this->data = data;
    }
};

我有我的 Hash p>

and I have my Hash functor

struct Hash {
    size_t operator()(const Node &node) const {
        return node.data;
    };
};

我注意到 Hash 使用 Node 和节点使用 Hash

这个练习的目的我想在一个文件中声明一切，我应该首先声明。

I noticed that Hash uses Node and Node uses Hash
If for the purpose of this exercise I want to declare everything in a single file, which one should I declare first.

我试着向前声明 Hash 和节点，首先定义它们，但没有编译。

I tried forward declaration of both Hash and Node with defining either of them first, but none of them compiled.

PS：这不是家庭作业，我想在线解决图形算法谜题

PS: This is not homework, I'm trying to solve graph algorithm puzzles online

推荐答案

延迟定义 Hash :: operator（），直到定义节点，并声明节点之前 Hash 。

Delay defining Hash::operator() until after defining Node and declare Node before Hash. You can have a reference to an incomplete type as long as you don't do anything with it.

class Node;

class Hash{
    public:
        size_t operator()(const Node &node) const;
};

class Node{
    public:
        int data;
        unordered_set<Node, Hash> links;
};

inline size_t Hash::operator()(const Node &node) const{
    return node.data;
}

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