# Iterator Concepts

Author: | David Abrahams, Jeremy Siek, Thomas Witt
Contact: | dave@boost-consulting.com, jsiek@osl.iu.edu, witt@styleadvisor.com
Organization: | Boost Consulting, Indiana University Open Systems Lab, Zephyr Associates, Inc.
Date: | 2004-11-01
Copyright: | Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2004.

abstract: | The iterator concept checking classes provide a mechanism for a template to report better error messages when a user instantiates the template with a type that does not meet the requirements of the template.

For an introduction to using concept checking classes, see the documentation for the `boost::concept_check` library.

# Reference

## Iterator Access Concepts

- Readable Iterator
- Writable Iterator
- Swappable Iterator
- Lvalue Iterator

## Iterator Traversal Concepts

- Incrementable Iterator
- Single Pass Iterator
- Forward Traversal
- Bidirectional Traversal
- Random Access Traversal

## `iterator_concepts.hpp` Synopsis

    namespace boost_concepts {

        // Iterator Access Concepts

        template <typename Iterator>
        class ReadableIteratorConcept;

        template <
            typename Iterator
          , typename ValueType = std::iterator_traits<Iterator>::value_type
        >
        class WritableIteratorConcept;

        template <typename Iterator>
        class SwappableIteratorConcept;

        template <typename Iterator>
        class LvalueIteratorConcept;

        // Iterator Traversal Concepts

        template <typename Iterator>
        class IncrementableIteratorConcept;

        template <typename Iterator>
        class SinglePassIteratorConcept;

        template <typename Iterator>
        class ForwardTraversalConcept;

        template <typename Iterator>
        class BidirectionalTraversalConcept;

        template <typename Iterator>
        class RandomAccessTraversalConcept;

        // Interoperability

        template <typename Iterator, typename ConstIterator>
        class InteroperableIteratorConcept;

    }