Using custom class as a key (QSet)

[daujeroti]

Hello! I have a very simple class, called Node.

Node.h

#ifndef NODE_H
#define NODE_H
 
#include <QSet>
 
class Node
{
 
public:
    Node();
    Node(const uchar &c);
 
    uchar val;
    QSet<Node> childNodes;
 
    bool addChild(const Node& node);
 
    inline bool operator==(const Node &n1, const Node &n2)
    {
        return n1.val == n2.val;
    }
 
    inline uint qHash(const Node &node)
    {
        return qHash(node.val);
    }
 
};
 
#endif // NODE_H

#ifndef NODE_H
#define NODE_H

#include <QSet>

class Node
{

public:
    Node();
    Node(const uchar &c);

    uchar val;
    QSet<Node> childNodes;

    bool addChild(const Node& node);

    inline bool operator==(const Node &n1, const Node &n2)
    {
        return n1.val == n2.val;
    }

    inline uint qHash(const Node &node)
    {
        return qHash(node.val);
    }

};

#endif // NODE_H

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Node.cpp

#include "Node.h"
 
Node::Node()
{
    val = -1;
}
 
Node::Node(const uchar &c)
{
    val = c;
}
 
bool Node::addChild(const Node &node)
{
    if(childNodes.contains(node))
        return false;
 
    childNodes.insert(node);
    return true;
}

#include "Node.h"

Node::Node()
{
    val = -1;
}

Node::Node(const uchar &c)
{
    val = c;
}

bool Node::addChild(const Node &node)
{
    if(childNodes.contains(node))
        return false;

    childNodes.insert(node);
    return true;
}

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I get the following error messages:

• 'bool Node::operator==(const Node&, const Node&)' must take exactly one argument
• no matching function for call to 'qHash(const Node&)'
• no match for 'operator==' in key0==((QHashNode<Node, QHashDummyValue*)this)->QHashNode<Node,QHashDummyValue>::key'

What can be the problem?

Thanks in advance!

[calhal]

The problem is exactly what the compiler says.

First you want to have your == operator more or less like this:

bool	operator== ( const Node & other ) const

bool	operator== ( const Node & other ) const

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because you want to compare object "this" with some "other" object.

The second problem is, I think, that qHash function should be implemented outside the class.

[MarekR22]

Read in documentation of QSet last two paragraphs of Detailed Description.

[daujeroti]

The second problem is, I think, that qHash function should be implemented outside the class.

That's the point! Thank You!

[Fallen_]

this:

return qHash(node.val);

return qHash(node.val);

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should be:

return ::qHash(node.val);

return ::qHash(node.val);

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