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copied!<p>Hey all, this is the OP on an alternative account.</p> <p><strong>THE PURPOSE</strong> To write an universal iterator class family that will be capable of iterating over std::vectors and T[] arrays, where T = byte = unsigned char.</p> <p><strong>THE IDEA BEHIND THE ABSTRACT CLASS</strong></p> <p>The idea was to use the base abstract class for function interfaces so that all functions would have a common type . The following abstract class enforces all children classes to employ the following operators :</p> <p>** I haven't got a compiler with me atm so please forgive any errors my behalf **</p> <pre><code>class iterator { public : virtual iterator & operator -- () = 0; virtual iterator & operator -- (int) = 0; virtual iterator & operator ++ () = 0; virtual iterator & operator ++ (int) = 0; virtual iterator & operator += (int n) = 0; virtual iterator & operator -= (int n) = 0; virtual bool operator == (const iterator & o) = 0; virtual bool operator != (const iterator & o) = 0; }; </code></pre> <p>So an example derived class would look like this :</p> <pre><code>/*! \brief ptr iterator can be used to iterate over classic c-style arrays */ class ptr_iterator : public iterator { public : ptr_iterator() : m_p(NULL) {} ptr_iterator(byte * b) : m_p(b) {} iterator & operator = (const ptr_iterator &o) { m_p = o.m_p; return *this; } iterator & operator = (byte * b) { m_p = b; return *this; } virtual iterator & operator -- () { --m_p; return *this; } virtual iterator & operator -- (int) { m_p--; return *this; } virtual iterator & operator ++ () { ++m_p; return *this; } virtual iterator & operator ++ () { m_p++; return *this; } virtual iterator & operator += (int n) { m_p += n; return *this; } virtual iterator & operator -= (int n) { m_p -= n; return *this; } virtual bool operator == (const iterator & o) { return ((ptr_iterator*)&o)->m_p == m_p; } virtual bool operator != (const iterator & o) { return ((ptr_iterator*)&o)->m_p != m_p; } private : byte * m_p; }; </code></pre> <p>Apart the forementioned iterator we can have an iterator that will iterate over an std::vector</p> <p>template class std_iterator : public iterator { typedef typename C::iterator c_iterator; public : iterator & operator = (const c_iterator & i) { m_it = i; return *this; } iterator & operator = (const std_iterator & o) { m_it = o.m_it; return *this; }</p> <pre><code>virtual iterator & operator ++ () { ++m_it; return *this; } virtual iterator & operator ++ (int) { m_it++; return *this; } virtual iterator & operator -- () { --m_it; return *this; } virtual iterator & operator -- (int) { m_it--; return *this; } virtual iterator & operator += (int n) { m_it += n; return *this; } virtual iterator & operator -= (int n) { m_it -= n; return *this; } virtual bool operator == (const iterator &o) { return ((std_iterator*)&o)->m_it == m_it; } virtual bool operator != (const iterator &o) { return ((std_iterator*)&o)->m_it != m_it; } bool operator == (const c_iterator &i) { return m_it == i; } bool operator != (const c_iterator &i) { return m_it != i; } </code></pre> <p>private :</p> <pre><code>c_iterator m_it; </code></pre> <p>};</p> <p>Ok, so basically the forementioned iterators are capable of iterating over an array or a vector. </p> <p>if we were to use a function that has the following interface :</p> <pre><code>int DoStuff(iterator &it); </code></pre> <p>All kinds of iterators would be capable of calling it - and that is the general idea. Let's say that I'm dealing with data coming in a variety of forms - ranging from arrays to vectors :)</p> <p>Thing is, I need the following functionality :</p> <p>std_iterator> it = my_vector.begin(); // THIS ONE WORKS std_iterator> other = it; // THIS ONE WORKS TOO</p> <p>If I were inside the forementioned function</p> <pre><code>int DoStuff(iterator &it) { iterator a = it + 2; // THIS IS ILLEGAL DUE TO ABSTRACT-NESS OF THE BASE CLASS // YET I STILL NEED THIS TO WORK. HOW DO I ACHIEVE THAT ? // DO I SACRIFICE THE ABSTRACT-NESS OF THE BASE CLASS ? // AT THIS POINT I WAS SERIOUSLY CONSIDERING AN OVERLOAD OF THE // + OPERATOR BUT HAVE NO IDEA HOW TO DO IT WITH AN ABSTRACT // CLASS // (...) return 0; } </code></pre>

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