Singly linked list - Segmentation fault - c++

Question

First, sorry for the long code. I did my best to trim it as small as possible.
I'm getting segmentation fault when i want to add a new element (void SLList::pushBack(const Data &rDATA)) to my singly linked list (in SLList.hxx). The segmentation fault caused by 0xbaadf00d value.
........................................................................................................
IniFile.h
#include "Section.h"
class IniFile
{
public:
IniFile() :
void addSection();
private:
SLList<Section> mContent;
};
IniFile.cpp
#include "IniFile.h"
IniFile::IniFile() :
mContent() {}
void IniFile::addSection() // This is the only one method what i call
{
mContent.pushBack(Section());
}
Section.h
#include "Pair.hxx"
#include "SLList.hxx"
class Section
{
public:
Section();
private:
SLList<Pair<std::string, std::string>> mKeyValuePairs;
};
Section.cpp
#include "Section.h"
Section::Section() :
mKeyValuePairs() {}
SLList.hxx
template <typename Data>
class SLList
{
public:
class Node
{
public:
Node(const Data &rDATA, Node *const pNEXT = nullptr) :
mData(rDATA),
mNext(pNEXT) {}
Node(const Node &rRHS)
{
mData = rRHS.mData;
*mNext = *rRHS.mNext;
}
~Node()
{
delete mNext;
}
Node &operator=(const Node &rRHS)
{
if (&rRHS == this)
return *this;
mData = rRHS.mData;
*mNext = *rRHS.mNext;
return *this;
}
private:
void setNext(Node *const pNext)
{
mNext = pNext;
}
friend void SLList<Data>::pushBack(const Data &rDATA);
private:
Data mData;
Node *mNext;
};
SLList() :
mHead(nullptr),
mTail(nullptr) {}
SLList(const SLList &rRHS)
{
*mHead = *rRHS.mHead;
*mTail = *rRHS.mTail;
}
SLList &operator=(const SLList &rRHS)
{
if (&rRHS == this)
return *this;
*mHead = *rRHS.mHead;
*mTail = *rRHS.mTail;
return *this;
}
~SLList()
{
clear();
}
void clear()
{
delete mHead;
}
void pushBack(const Data &rDATA)
{
Node *pNode = new Node(rDATA, nullptr); // I get segmentation fault at this point
if (!mTail)
{
mHead = pNode;
mTail = pNode;
}
else
{
mTail->setNext(pNode);
mTail = pNode;
}
}
private:
Node *mHead;
Node *mTail;
};
Pair.hxx
template <typename T1, typename T2>
class Pair
{
public:
Pair(const T1 &rFIRST, const T2 &rSECOND) :
mFirst(rFIRST),
mSecond(rSECOND) {}
private:
T1 mFirst;
T2 mSecond;
};

Answer 1

SLList's copy constructor and assignment operator are wrong in terms of Node* pointer management.
Also, Node's destructor shouldn't destroy the next Node object in the list. Not only is a recursive destructor bad for long lists, but also think of in the future if you ever want to remove a single Node without clearing the whole list. Your clear() method should directly iterate the list deleting Node objects one at a time without using recursion.
Try something more like this:
#include <utility>
template <typename Data>
class SLList
{
public:
class Node
{
public:
Node(const Data &rDATA, Node *const pNEXT = nullptr)
: mData(rDATA), mNext(pNEXT)
{
}
Node(const Node &rSRC)
: mData(rSRC.mData), mNext(nullptr)
{
}
Node &operator=(const Node &rRHS)
{
if (&rRHS != this)
mData = rRHS.mData;
return *this;
}
private:
Data mData;
Node *mNext;
friend class SLList<Data>;
};
SLList()
: mHead(nullptr), mTail(nullptr)
{
}
SLList(const SLList &rSRC)
: mHead(nullptr), mTail(nullptr)
{
Node *pNode = rSRC.mHead;
while (pNode)
{
pushBack(pNode->mData);
pNode = pNode->mNext;
}
}
SLList &operator=(const SLList &rRHS)
{
if (&rRHS != this)
{
SLList temp(rRHS);
std::swap(mHead, temp.mHead);
std::swap(mTail, temp.mTail);
}
return *this;
}
~SLList()
{
clear();
}
void clear()
{
Node *pNode = mHead;
mHead = mTail = nullptr;
while (pNode)
{
Node *pNext = pNode->mNext;
delete pNode;
pNode = pNext;
}
}
void pushBack(const Data &rDATA)
{
Node *pNode = new Node(rDATA);
if (!mHead) mHead = pNode;
if (mTail) mTail->mNext = pNode;
mTail = pNode;
}
private:
Node *mHead;
Node *mTail;
};
With that said, what you really should do is use std::list (or std::forward_list) and std::pair instead. There is no benefit to "reinventing the wheel" at all:
#include "Section.h"
#include <list>
class IniFile
{
public:
void addSection();
private:
std::list<Section> mContent;
};
#include "IniFile.h"
void IniFile::addSection()
{
mContent.push_back(Section());
}
#include <pair>
#include <list>
#include <string>
class Section
{
private:
std::list<std::pair<std::string, std::string>> mKeyValuePairs;
};
#include <list>
template <typename Data>
class SLList
{
public:
void clear()
{
mList.clear();
}
void pushBack(const Data &rDATA)
{
mList.push_back(rDATA);
}
private:
std::list<Data> mList;
};