Q3ValueStack Class Reference

Detailed Description

The Q3ValueStack class is a value-based template class that provides a stack.

Define a template instance Q3ValueStack<X> to create a stack of values that all have the class X.

Note that Q3ValueStack does not store pointers to the members of the stack; it holds a copy of every member. That is why these kinds of classes are called "value based"; Q3PtrStack, Q3PtrList, Q3Dict, etc., are "pointer based".

A stack is a last in, first out (LIFO) structure. Items are added to the top of the stack with push() and retrieved from the top with pop(). The top() function provides access to the topmost item without removing it.

Example:

 Q3ValueStack<int> stack;
 stack.push( 1 );
 stack.push( 2 );
 stack.push( 3 );
 while ( ! stack.isEmpty() )
     cout << "Item: " << stack.pop() << endl;

 // Output:
 //      Item: 3
 //      Item: 2
 //      Item: 1

Q3ValueStack is a specialized Q3ValueList provided for convenience. All of Q3ValueList's functionality also applies to Q3PtrStack, for example the facility to iterate over all elements using Q3ValueStack<T>::Iterator. See Q3ValueListIterator for further details.

Some classes cannot be used within a Q3ValueStack, for example everything derived from QObject and thus all classes that implement widgets. Only values can be used in a Q3ValueStack. To qualify as a value, the class must provide

• a copy constructor;
• an assignment operator;
• a default constructor, i.e. a constructor that does not take any arguments.

Note that C++ defaults to field-by-field assignment operators and copy constructors if no explicit version is supplied. In many cases this is sufficient.