I'm following this tutorial to create a simple iterator, although they are iterating primitive int, I'm iterating an object type SpamValue.
I have class called SpamValue and another called SpamValueStackIter and they are tightly coupled, because I didn't want to expose a lot of getters, so I made one class SpamValueStackIter a "friend class" in SpamValue header.
#ifndef SPAMSTACK_H
#define SPAMSTACK_H
#include <iostream>
#include "SpamValue.h"
using namespace std;
class SpamStack
{
public:
friend class SpamValueStackIter;
SpamStack(SpamValue** SpamValueItems, int size)
{
_position =-1;
_total_size = size;
_SpamValueItems = new SpamValue*[_total_size];
int i=0;
for (; i<_total_size; i++)
{
this->_SpamValueItems[i] = SpamValueItems[i];
}
}
~SpamStack()
{
if (NULL!=_SpamValueItems)
{
/*delete each*/
int i =0;
for (; i<_total_size; i++)
{
if (NULL!=_SpamValueItems[i])
{
delete _SpamValueItems[i];
}
}
/*delete the array*/
delete [] _SpamValueItems;
}
}
/*push*/
void push(SpamValue* SpamValue)
{
_SpamValueItems[++_position];
}
/*pop*/
SpamValue* pop()
{
return _SpamValueItems[_position--];
}
/*isEmpty*/
bool isEmpty()
{
return (_position == -1);
}
/*getters*/
SpamValue** getSpamValueItems()
{
return this->_SpamValueItems;
}
int getTotalSize()
{
return _total_size;
}
SpamValueStackIter* createIterator()const;
private:
SpamValue** _SpamValueItems;
int _total_size;
int _position;
};
class SpamValueStackIter
{
const SpamStack* _stack;
int _index;
public:
SpamValueStackIter(const SpamStack *s)
{
_stack = s;
}
/*set index position to first item*/
void first()
{
_index = 0;
}
/*set index position to the next item in the iterator*/
void next()
{
_index++;
}
/*is the iteration completed */
bool isDone()
{
return _index == _stack->_position + 1;
}
/* return the current item */
SpamValue* currentItem()
{
return _stack->_SpamValueItems[index];
}
/*create a new iterator*/
SpamValueStackIter* SpamStack::createIterator()const
{
return new SpamValueStackIter(this);
}
};
#endif /* SPAMSTACK_H*/
In the SpamStack.h:, Im getting this error:
SpamStack.h:77:6: error: ‘SpamValueStackIter’ does not name a type
SpamValueStackIter* createIterator()const;
And also:
SpamStack.h:121:52: error: cannot define member function ‘SpamStack::createIterator tor’ within ‘SpamValueStackIter’
SpamValueStackIter* SpamStack::createIterator()const
Why can't SpamStack resolve the "friend class" that's defined in the same header?
After forward declaration, as suggested by others:
#ifndef SPAMSTACK_H
#define SPAMSTACK_H
#include <iostream>
#include "SpamValue.h"
using namespace std;
/*forward declare*/
class SpamValueStackIter;
class SpamStack
{
public:
friend class SpamValueStackIter;
SpamStack(SpamValue** SpamValueItems, int size)
{
_position =-1;
_total_size = size;
_SpamValueItems = new SpamValue*[_total_size];
int i=0;
for (; i<_total_size; i++)
{
this->_SpamValueItems[i] = SpamValueItems[i];
}
}
~SpamStack()
{
if (NULL!=_SpamValueItems)
{
/*delete each*/
int i =0;
for (; i<_total_size; i++)
{
if (NULL!=_SpamValueItems[i])
{
delete _SpamValueItems[i];
}
}
/*delete the array*/
delete [] _SpamValueItems;
}
}
/*push*/
void push(SpamValue* SpamValue)
{
_SpamValueItems[++_position];
}
/*pop*/
SpamValue* pop()
{
return _SpamValueItems[_position--];
}
/*isEmpty*/
bool isEmpty()
{
return (_position == -1);
}
/*getters*/
SpamValue** getSpamValueItems()
{
return this->_SpamValueItems;
}
int getTotalSize()
{
return _total_size;
}
SpamValueStackIter* createIterator()const;
private:
SpamValue** _SpamValueItems;
int _total_size;
int _position;
};
class SpamValueStackIter
{
public:
SpamValueStackIter(const SpamStack *s)
{
_stack = s;
}
/*set index position to first item*/
void first()
{
_index = 0;
}
/*set index position to the next item in the iterator*/
void next()
{
_index++;
}
/*is the iteration completed */
bool isDone()
{
return _index == _stack->_position + 1;
}
/* return the current item */
SpamValue* currentItem()
{
return _stack->_SpamValueItems[index];
}
private:
const SpamStack* _stack;
int _index;
};
/create a new iterator/ SpamValueStackIter* SpamStack::createIterator()const { return new SpamValueStackIter(this); }
#endif /* SPAMSTACK_H */
In getting this error now:
SpamStack.h:117:45: error: invalid types ‘SpamValue** const[<unresolved overloaded function type>]’ for array subscript
return _stack->_SpamValueItems[index];
