bslstl_forwarditerator

Macros
#define	bslstl_ForwardIterator   bslstl::ForwardIterator
	This alias is defined for backward compatibility.

Detailed Description

Outline

• Purpose
• Classes
• Description
  • Usage

Purpose

Provide a template to create STL-compliant forward iterators.

Classes

• bslstl::ForwardIterator: forward iterator template

Canonical header: bsl_iterator.h

See also

bslstl_iterator, bslstl_bidirectionaliterator, bslstl_randomaccessiterator

Description

This component provides an iterator adaptor that, given an implementation class defining a core set of iterator functionality, adapts it to provide an STL-compliant forward iterator interface. The set of requirements for a forward iterator is found in "Table 106: Forward iterator requirements", under the tag "[forward.iterators]". (Note that this reference is sourced in N3092, a C++0x working paper; the actual table number may vary in the actual standard.) Include bsl_iterator.h to use this component.

Usage

Given the following "iterator-like" implementation class:

template <class T>
class my_IteratorImp {
  public:
    // CREATORS
    my_IteratorImp();
    my_IteratorImp(const my_IteratorImp&);
    ~my_IteratorImp();
 
    // An additional value-constructor should be supplied that can be
    // called by the unspecified container type, providing access to the
    // container's internal data structure that is to be iterated over.
    // This would typically be called by 'begin' and 'end'.
 
    // MANIPULATORS
    my_IteratorImp& operator=(const my_IteratorImp&);
 
    void operator++();
 
    // ACCESSORS
    T& operator*() const;
};
 
template <class T>
bool operator==(const my_IteratorImp<T>& lhs,
                const my_IteratorImp<T>& rhs);

simply add the following two typedefs to any container class that provides my_IteratorImp<T> access, and the container will have STL-compliant forward iterators:

typedef bslstl::ForwardIterator<T, my_IteratorImp<T> > iterator;
typedef bslstl::ForwardIterator<const T, my_IteratorImp<T> >
                                                            const_iterator;

Note that the implementation for const_iterator is my_IteratorImp<T> and not my_IteratorImp<const T>, rather the const is added to the return value of operator* by way of conversion to the first template argument.

Macro Definition Documentation

bslstl_ForwardIterator

#define bslstl_ForwardIterator   bslstl::ForwardIterator