2004-01-29 05:55:26 +00:00
<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
< html xmlns = "http://www.w3.org/1999/xhtml" xml:lang = "en" lang = "en" >
< head >
< meta http-equiv = "Content-Type" content = "text/html; charset=utf-8" / >
2007-11-03 03:25:13 +00:00
< meta name = "generator" content = "Docutils 0.5: http://docutils.sourceforge.net/" / >
2004-01-29 05:55:26 +00:00
< title > Iterator Traits< / title >
< meta name = "author" content = "David Abrahams" / >
< meta name = "organization" content = "Boost Consulting" / >
2007-11-03 03:25:13 +00:00
< meta name = "date" content = "2006-09-11" / >
2004-11-02 14:31:27 +00:00
< meta name = "copyright" content = "Copyright David Abrahams 2004." / >
2007-11-03 03:25:13 +00:00
< link rel = "stylesheet" href = "../../../rst.css" type = "text/css" / >
2004-01-29 05:55:26 +00:00
< / head >
< body >
2005-05-20 15:32:55 +00:00
< div class = "document" id = "iterator-traits" >
2004-01-29 05:55:26 +00:00
< h1 class = "title" > Iterator Traits< / h1 >
< table class = "docinfo" frame = "void" rules = "none" >
< col class = "docinfo-name" / >
< col class = "docinfo-content" / >
< tbody valign = "top" >
< tr > < th class = "docinfo-name" > Author:< / th >
< td > David Abrahams< / td > < / tr >
< tr > < th class = "docinfo-name" > Contact:< / th >
2007-11-03 03:25:13 +00:00
< td > < a class = "first last reference external" href = "mailto:dave@boost-consulting.com" > dave@ boost-consulting.com< / a > < / td > < / tr >
2004-01-29 05:55:26 +00:00
< tr > < th class = "docinfo-name" > Organization:< / th >
2007-11-03 03:25:13 +00:00
< td > < a class = "first last reference external" href = "http://www.boost-consulting.com" > Boost Consulting< / a > < / td > < / tr >
2004-01-29 05:55:26 +00:00
< tr > < th class = "docinfo-name" > Date:< / th >
2007-11-03 03:25:13 +00:00
< td > 2006-09-11< / td > < / tr >
2004-01-29 05:55:26 +00:00
< tr > < th class = "docinfo-name" > Copyright:< / th >
2004-11-02 14:31:27 +00:00
< td > Copyright David Abrahams 2004.< / td > < / tr >
2004-01-29 05:55:26 +00:00
< / tbody >
< / table >
2006-09-11 22:08:18 +00:00
<!-- Distributed under the Boost -->
<!-- Software License, Version 1.0. (See accompanying -->
<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) -->
2005-05-20 15:32:55 +00:00
< table class = "docutils field-list" frame = "void" rules = "none" >
2004-01-29 05:55:26 +00:00
< col class = "field-name" / >
< col class = "field-body" / >
< tbody valign = "top" >
2005-05-20 15:32:55 +00:00
< tr class = "field" > < th class = "field-name" > abstract:< / th > < td class = "field-body" > Header < tt class = "docutils literal" > < span class = "pre" > < boost/iterator/iterator_traits.hpp> < / span > < / tt > provides
2004-01-29 05:55:26 +00:00
the ability to access an iterator's associated types using
2007-11-03 03:25:13 +00:00
MPL-compatible < a class = "reference external" href = "../../mpl/doc/index.html#metafunctions" > metafunctions< / a > .< / td >
2004-01-29 05:55:26 +00:00
< / tr >
< / tbody >
< / table >
2007-11-03 03:25:13 +00:00
< div class = "section" id = "overview" >
< h1 > Overview< / h1 >
2005-05-20 15:32:55 +00:00
< p > < tt class = "docutils literal" > < span class = "pre" > std::iterator_traits< / span > < / tt > provides access to five associated types
of any iterator: its < tt class = "docutils literal" > < span class = "pre" > value_type< / span > < / tt > , < tt class = "docutils literal" > < span class = "pre" > reference< / span > < / tt > , < tt class = "docutils literal" > < span class = "pre" > pointer< / span > < / tt > ,
< tt class = "docutils literal" > < span class = "pre" > iterator_category< / span > < / tt > , and < tt class = "docutils literal" > < span class = "pre" > difference_type< / span > < / tt > . Unfortunately,
2004-01-29 05:55:26 +00:00
such a " multi-valued" traits template can be difficult to use in a
2005-05-20 15:32:55 +00:00
metaprogramming context. < tt class = "docutils literal" > < span class = "pre" > < boost/iterator/iterator_traits.hpp> < / span > < / tt >
2007-11-03 03:25:13 +00:00
provides access to these types using a standard < a class = "reference external" href = "../../mpl/doc/index.html#metafunctions" > metafunctions< / a > .< / p >
2004-01-29 05:55:26 +00:00
< / div >
2007-11-03 03:25:13 +00:00
< div class = "section" id = "summary" >
< h1 > Summary< / h1 >
2005-05-20 15:32:55 +00:00
< p > Header < tt class = "docutils literal" > < span class = "pre" > < boost/iterator/iterator_traits.hpp> < / span > < / tt > :< / p >
2004-01-29 05:55:26 +00:00
< pre class = "literal-block" >
template < class Iterator>
struct iterator_value
{
2006-09-11 22:08:18 +00:00
typedef typename
std::iterator_traits< Iterator> ::value_type
2004-01-29 05:55:26 +00:00
type;
};
template < class Iterator>
struct iterator_reference
{
2006-09-11 22:08:18 +00:00
typedef typename
2004-01-29 05:55:26 +00:00
std::iterator_traits< Iterator> ::reference
type;
};
template < class Iterator>
struct iterator_pointer
{
2006-09-11 22:08:18 +00:00
typedef typename
std::iterator_traits< Iterator> ::pointer
2004-01-29 05:55:26 +00:00
type;
};
template < class Iterator>
struct iterator_difference
{
typedef typename
detail::iterator_traits< Iterator> ::difference_type
type;
};
template < class Iterator>
struct iterator_category
{
typedef typename
detail::iterator_traits< Iterator> ::iterator_category
type;
};
< / pre >
< / div >
2007-11-03 03:25:13 +00:00
< div class = "section" id = "broken-compiler-notes" >
< h1 > Broken Compiler Notes< / h1 >
2004-01-29 05:55:26 +00:00
< p > Because of workarounds in Boost, you may find that these
2007-11-03 03:25:13 +00:00
< a class = "reference external" href = "../../mpl/doc/index.html#metafunctions" > metafunctions< / a > actually work better than the facilities provided by
2004-01-29 05:55:26 +00:00
your compiler's standard library.< / p >
< p > On compilers that don't support partial specialization, such as
Microsoft Visual C++ 6.0 or 7.0, you may need to manually invoke
2007-11-03 03:25:13 +00:00
< a class = "reference external" href = "../../type_traits/index.html#transformations" > BOOST_BROKEN_COMPILER_TYPE_TRAITS_SPECIALIZATION< / a > on the
2005-05-20 15:32:55 +00:00
< tt class = "docutils literal" > < span class = "pre" > value_type< / span > < / tt > of pointers that are passed to these metafunctions.< / p >
2004-01-29 05:55:26 +00:00
< p > Because of bugs in the implementation of GCC-2.9x, the name of
2005-05-20 15:32:55 +00:00
< tt class = "docutils literal" > < span class = "pre" > iterator_category< / span > < / tt > is changed to < tt class = "docutils literal" > < span class = "pre" > iterator_category_< / span > < / tt > on that
compiler. A macro, < tt class = "docutils literal" > < span class = "pre" > BOOST_ITERATOR_CATEGORY< / span > < / tt > , that expands to
either < tt class = "docutils literal" > < span class = "pre" > iterator_category< / span > < / tt > or < tt class = "docutils literal" > < span class = "pre" > iterator_category_< / span > < / tt > , as
2004-01-29 05:55:26 +00:00
appropriate to the platform, is provided for portability.< / p >
< / div >
2007-11-03 03:25:13 +00:00
< / div >
< div class = "footer" >
< hr class = "footer" / >
< a class = "reference external" href = "iterator_traits.rst" > View document source< / a > .
Generated by < a class = "reference external" href = "http://docutils.sourceforge.net/" > Docutils< / a > from < a class = "reference external" href = "http://docutils.sourceforge.net/rst.html" > reStructuredText< / a > source.
2004-01-29 05:55:26 +00:00
< / div >
< / body >
< / html >
