[Boost-commit] svn:boost r82584 - in trunk: boost/algorithm libs/algorithm/doc libs/algorithm/test

Subject: [Boost-commit] svn:boost r82584 - in trunk: boost/algorithm libs/algorithm/doc libs/algorithm/test
From: marshall_at_[hidden]
Date: 2013-01-21 19:44:54

Author: marshall
Date: 2013-01-21 19:44:53 EST (Mon, 21 Jan 2013)
New Revision: 82584
URL: http://svn.boost.org/trac/boost/changeset/82584

Log:
Add new algorithm 'gather'
Added:
   trunk/boost/algorithm/gather.hpp   (contents, props changed)
   trunk/libs/algorithm/doc/gather.qbk   (contents, props changed)
   trunk/libs/algorithm/test/gather_fail1.cpp   (contents, props changed)
   trunk/libs/algorithm/test/gather_test1.cpp   (contents, props changed)
   trunk/libs/algorithm/test/iterator_test.hpp   (contents, props changed)
Text files modified: 
   trunk/libs/algorithm/doc/algorithm.qbk |     1 +                                       
   trunk/libs/algorithm/test/Jamfile.v2   |     6 +++++-                                  
   2 files changed, 6 insertions(+), 1 deletions(-)

Added: trunk/boost/algorithm/gather.hpp
==============================================================================
--- (empty file)
+++ trunk/boost/algorithm/gather.hpp	2013-01-21 19:44:53 EST (Mon, 21 Jan 2013)
@@ -0,0 +1,122 @@
+/* 
+    Copyright 2008 Adobe Systems Incorporated
+
+   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)
+
+ Revision history:
+   January 2008 mtc Version for Adobe Source Library
+   January 2013 mtc Version for Boost.Algorithm
+
+*/
+
+/**************************************************************************************************/
+
+/*!
+\author Marshall Clow
+\date    January 2008
+*/
+
+#ifndef BOOST_ALGORITHM_GATHER_HPP
+#define ADOBE_ALGORITHM_GATHER_HPP
+
+#include <algorithm>                // for std::stable_partition
+#include <functional>
+
+#include <boost/bind.hpp>           // for boost::bind
+#include <boost/range/begin.hpp>    // for boost::begin(range)
+#include <boost/range/end.hpp>      // for boost::end(range)
+
+
+/**************************************************************************************************/
+/*!
+    \defgroup gather gather
+    \ingroup mutating_algorithm
+
+    \c gather() takes a collection of elements defined by a pair of iterators and moves
+    the ones satisfying a predicate to them to a position (called the pivot) within
+    the sequence. The algorithm is stable. The result is a pair of iterators that
+    contains the items that satisfy the predicate.
+
+    Given an sequence containing:
+    <pre>
+    0 1 2 3 4 5 6 7 8 9
+    </pre>
+
+    a call to gather ( arr, arr + 10, arr + 4, IsEven ()) will result in:
+
+    <pre>
+    1 3 0 2 4 6 8 5 7 9
+        |---|-----|
+      first |  second
+          pivot
+    </pre>
+
+
+    The problem is broken down into two basic steps, namely, moving the items before the pivot
+    and then moving the items from the pivot to the end. These "moves" are done with calls to
+    stable_partition.
+
+    \par Storage Requirements:
+
+    The algorithm uses stable_partition, which will attempt to allocate temporary memory,
+    but will work in-situ if there is none available.
+
+    \par Time Complexity:
+
+    If there is sufficient memory available, the run time is linear in <code>N</code>.
+    If there is not any memory available, then the run time is <code>O(N log N)</code>.
+*/
+
+/**************************************************************************************************/
+
+namespace boost { namespace algorithm {
+
+/**************************************************************************************************/
+
+/*!
+    \ingroup gather
+    \brief iterator-based gather implementation
+*/
+
+template <
+    typename ForwardIterator,  // Iter models ForwardIterator
+    typename Pred>  // Pred models UnaryPredicate
+std::pair<ForwardIterator,ForwardIterator> gather ( ForwardIterator first, ForwardIterator last, ForwardIterator pivot, Pred pred )
+{
+//  The first call partitions everything up to (but not including) the pivot element,
+//  while the second call partitions the rest of the sequence.
+    return std::make_pair (
+        std::stable_partition ( first, pivot, !boost::bind<bool> ( pred, _1 )),
+        std::stable_partition ( pivot, last,   boost::bind<bool> ( pred, _1 )));
+}
+
+/**************************************************************************************************/
+
+/*!
+    \ingroup gather
+    \brief range-based gather implementation
+*/
+
+template <
+    typename ForwardRange,    //
+    typename Pred>                  // Pred models UnaryPredicate
+std::pair<
+    typename boost::range_iterator<ForwardRange>::type,
+    typename boost::range_iterator<ForwardRange>::type>
+gather (
+    ForwardRange &range,
+    typename boost::range_iterator<ForwardRange>::type pivot,
+    Pred pred )
+{
+    return boost::algorithm::gather ( boost::begin ( range ), boost::end ( range ), pivot, pred );
+}
+
+/**************************************************************************************************/
+
+}}  // namespace
+
+/**************************************************************************************************/
+
+#endif
+

Modified: trunk/libs/algorithm/doc/algorithm.qbk
==============================================================================
--- trunk/libs/algorithm/doc/algorithm.qbk	(original)
+++ trunk/libs/algorithm/doc/algorithm.qbk	2013-01-21 19:44:53 EST (Mon, 21 Jan 2013)
@@ -58,6 +58,7 @@
 
 [section:Misc Other Algorithms]
 [include clamp-hpp.qbk]
+[include gather.qbk]
 [include hex.qbk]
 [endsect]
 

Added: trunk/libs/algorithm/doc/gather.qbk
==============================================================================
--- (empty file)
+++ trunk/libs/algorithm/doc/gather.qbk	2013-01-21 19:44:53 EST (Mon, 21 Jan 2013)
@@ -0,0 +1,79 @@
+[/ File gather.qbk]
+
+[section:gather gather]
+
+[/license
+Copyright (c) 2013 Marshall Clow
+
+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)
+]
+
+The header file 'boost/algorithm/gather.hpp' contains two variants of a single algorithm, `gather`. 
+
+`gather()` takes a collection of elements defined by a pair of iterators and moves the ones satisfying a predicate to them to a position (called the pivot) within the sequence. The algorithm is stable. The result is a pair of iterators that contains the items that satisfy the predicate.
+
+[heading Interface]
+
+The function `gather` returns a `std::pair` of iterators that denote the elements that satisfy the predicate.  
+
+There are two versions; one takes two iterators, and the other takes a range.
+
+``
+namespace boost { namespace algorithm {
+
+template <typename ForwardIterator, typename Pred>
+std::pair<ForwardIterator,ForwardIterator> 
+gather ( ForwardIterator first, ForwardIterator last, ForwardIterator pivot, Pred pred );
+
+template <typename ForwardRange, typename Pred>
+std::pair<typename boost::range_iterator<ForwardRange>::type, typename boost::range_iterator<ForwardRange>::type>
+gather ( ForwardRange &range, typename boost::range_iterator<ForwardRange>::type pivot, Pred pred );
+
+}}
+``
+
+[heading Examples]
+
+Given an sequence containing:
+``
+0 1 2 3 4 5 6 7 8 9
+``
+
+a call to gather ( arr, arr + 10, arr + 4, IsEven ) will result in:
+
+``
[phone]
+    |---|-----|
+  first |  second
+      pivot
+``
+where `first` and `second` are the fields of the pair that is returned by the call.
+
+
+[heading Iterator Requirements]
+
+`gather` work on all iterators except input or output iterators.
+
+[heading Storage Requirements]
+
+`gather` uses stable_partition, which will attempt to allocate temporary memory, but will work in-situ if there is none available.
+
+[heading Complexity]
+
+If there is sufficient memory available, the run time is linear: `O(N)`
+
+If there is not any memory available, then the run time is `O(N log N)`.
+
+[heading Exception Safety]
+
+[heading Notes]
+
+[endsect]
+
+[/ File gather.qbk
+Copyright 2013 Marshall Clow
+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).
+]
+

Modified: trunk/libs/algorithm/test/Jamfile.v2
==============================================================================
--- trunk/libs/algorithm/test/Jamfile.v2	(original)
+++ trunk/libs/algorithm/test/Jamfile.v2	2013-01-21 19:44:53 EST (Mon, 21 Jan 2013)
@@ -46,10 +46,14 @@
      [ run hex_test2.cpp        : : : : hex_test2 ]
      [ run hex_test3.cpp        : : : : hex_test3 ]
      [ run hex_test4.cpp        : : : : hex_test4 ]
-	 [ compile-fail hex_fail1.cpp ]
+     [ compile-fail hex_fail1.cpp ]
 
 # Wrapper tests
      [ run wrapper_test1.cpp        : : : : wrapper_test1 ]
+
+# Gather tests
+     [ run gather_test1.cpp        : : : : gather_test1 ]
+     [ compile-fail gather_fail1.cpp ]
    ;
 }
 

Added: trunk/libs/algorithm/test/gather_fail1.cpp
==============================================================================
--- (empty file)
+++ trunk/libs/algorithm/test/gather_fail1.cpp	2013-01-21 19:44:53 EST (Mon, 21 Jan 2013)
@@ -0,0 +1,39 @@
+/* 
+   Copyright (c) Marshall Clow 2011-2012.
+
+   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)
+
+    For more information, see http://www.boost.org
+*/
+
+#include <iostream>
+
+#include <boost/config.hpp>
+#include <boost/algorithm/gather.hpp>
+#include <boost/test/included/test_exec_monitor.hpp>
+
+#include <string>
+#include <vector>
+#include <list>
+
+#include "iterator_test.hpp"
+
+namespace ba = boost::algorithm;
+
+bool is_ten  ( int i ) { return i == 10; }
+
+void test_sequence1 () {
+    std::vector<int> v;
+    typedef input_iterator<std::vector<int>::iterator> II;    
+
+//  This should fail to compile, since gather doesn't work with input iterators
+    (void) ba::gather ( II( v.begin ()), II( v.end ()), II( v.begin ()), is_even );
+    }
+
+
+int test_main( int , char* [] )
+{
+  test_sequence1 ();
+  return 0;
+}

Added: trunk/libs/algorithm/test/gather_test1.cpp
==============================================================================
--- (empty file)
+++ trunk/libs/algorithm/test/gather_test1.cpp	2013-01-21 19:44:53 EST (Mon, 21 Jan 2013)
@@ -0,0 +1,139 @@
+/* 
+   Copyright (c) Marshall Clow 2011-2012.
+
+   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)
+
+    For more information, see http://www.boost.org
+*/
+
+#include <iostream>
+
+#include <boost/config.hpp>
+#include <boost/algorithm/gather.hpp>
+#include <boost/test/included/test_exec_monitor.hpp>
+
+#include <string>
+#include <vector>
+#include <list>
+
+#include "iterator_test.hpp"
+
+namespace ba = boost::algorithm;
+
+template <typename Container>
+void print ( const char *prompt, const Container &c ) {
+    std::cout << prompt << " { ";
+    std::copy ( c.begin (), c.end (), std::ostream_iterator<typename Container::value_type>(std::cout, " "));
+    std::cout << std::endl;
+    }
+
+template <typename Iterator, typename Predicate>
+void test_iterators ( Iterator first, Iterator last, Predicate comp, std::size_t offset ) {
+//  Create the pivot point
+    Iterator off = first;
+    std::advance(off, offset);
+        
+//  Gather the elements
+    std::pair<Iterator, Iterator> res = ba::gather ( first, last, off, comp );
+
+//  We should now have three sequences, any of which may be empty:
+//      * [begin .. result.first)         - items that do not satisfy the predicate
+//      * [result.first .. result.second) - items that do satisfy the predicate
+//      * [result.second .. end)          - items that do not satisfy the predicate
+    Iterator iter = first;
+    for ( ; iter != res.first; ++iter )
+        BOOST_CHECK ( !comp ( *iter ));
+    for ( ; iter != res.second; ++iter)
+        BOOST_CHECK ( comp ( *iter ));
+    for ( ; iter != last; ++iter )
+        BOOST_CHECK ( !comp ( *iter ));
+    }
+
+template <typename Container, typename Predicate>
+void test_iterator_types ( const Container &c, Predicate comp, std::size_t offset ) {
+    typedef std::vector<typename Container::value_type> vec;
+    typedef forward_iterator<typename vec::iterator> FI;
+    typedef bidirectional_iterator<typename vec::iterator> BDI;
+    typedef random_access_iterator<typename vec::iterator> RAI;
+    
+    vec v;
+    v.assign ( c.begin (), c.end ());
+    test_iterators ( FI  ( v.begin ()), FI  ( v.end ()), comp, offset );
+    v.assign ( c.begin (), c.end ());
+    test_iterators ( BDI ( v.begin ()), BDI ( v.end ()), comp, offset );
+    v.assign ( c.begin (), c.end ());
+    test_iterators ( RAI ( v.begin ()), RAI ( v.end ()), comp, offset );
+    }
+
+
+template <typename T>
+struct less_than {
+public:
+//    typedef T argument_type;
+//    typedef bool result_type;
+
+    less_than ( T foo ) : val ( foo ) {}
+    less_than ( const less_than &rhs ) : val ( rhs.val ) {}
+
+    bool operator () ( const T &v ) const { return v < val; }
+private:
+    less_than ();
+    less_than operator = ( const less_than &rhs );
+    T val;
+    };
+
+bool is_even ( int i ) { return i % 2 == 0; }
+bool is_ten  ( int i ) { return i == 10; }
+
+void test_sequence1 () {
+    std::vector<int> v;
+    
+    for ( int i = 5; i < 15; ++i )
+        v.push_back ( i );
+    test_iterator_types ( v, less_than<int>(10),  0 );                  // at beginning
+    test_iterator_types ( v, less_than<int>(10),  5 );
+    test_iterator_types ( v, less_than<int>(10), v.size () - 1 );       // at end
+
+    test_iterator_types ( v, is_even, 0 );
+    test_iterator_types ( v, is_even, 5 );
+    test_iterator_types ( v, is_even, v.size () - 1 );
+
+//  Exactly one element in the sequence matches
+    test_iterator_types ( v, is_ten, 0 );
+    test_iterator_types ( v, is_ten, 5 );
+    test_iterator_types ( v, is_ten, v.size () - 1 );
+
+//  Everything in the sequence matches
+    test_iterator_types ( v, less_than<int>(99),  0 );
+    test_iterator_types ( v, less_than<int>(99),  5 );
+    test_iterator_types ( v, less_than<int>(99), v.size () - 1 );
+    
+//  Nothing in the sequence matches
+    test_iterator_types ( v, less_than<int>(0),  0 );
+    test_iterator_types ( v, less_than<int>(0),  5 );
+    test_iterator_types ( v, less_than<int>(0), v.size () - 1 );
+    
+//  All the elements in the sequence are the same
+    v.clear ();
+    for ( int i = 0; i < 11; ++i )
+        v.push_back ( 10 );
+    
+//  Everything in the sequence matches
+    test_iterator_types ( v, is_ten, 0 );
+    test_iterator_types ( v, is_ten, 5 );
+    test_iterator_types ( v, is_ten, v.size () - 1 );
+
+//  Nothing in the sequence matches
+    test_iterator_types ( v, less_than<int>(5),  0 );
+    test_iterator_types ( v, less_than<int>(5),  5 );
+    test_iterator_types ( v, less_than<int>(5), v.size () - 1 );
+
+    }
+
+
+int test_main( int , char* [] )
+{
+  test_sequence1 ();
+  return 0;
+}

Added: trunk/libs/algorithm/test/iterator_test.hpp
==============================================================================
--- (empty file)
+++ trunk/libs/algorithm/test/iterator_test.hpp	2013-01-21 19:44:53 EST (Mon, 21 Jan 2013)
@@ -0,0 +1,296 @@
+#ifndef ITERATOR_TEST_H
+#define ITERATOR_TEST_H
+
+/* 
+	A set of iterator adapters for constructing test cases
+	From an iterator (or a pointer), you can make any class of iterator.
+	Assuming you want to degrade the capabilities.
+	
+	Modeled closely on work that Howard Hinnant did for libc++.
+*/
+
+#include <iterator>
+
+// == Input Iterator ==
+template <typename It>
+class input_iterator {
+public:
+    typedef          std::input_iterator_tag                   iterator_category;
+    typedef typename std::iterator_traits<It>::value_type      value_type;
+    typedef typename std::iterator_traits<It>::difference_type difference_type;
+    typedef It                                                 pointer;
+    typedef typename std::iterator_traits<It>::reference       reference;
+
+    It base() const {return it_;}
+
+    input_iterator() : it_() {}
+    explicit input_iterator(It it) : it_(it) {}
+
+    template <typename U>
+    input_iterator(const input_iterator<U>& u) :it_(u.it_) {}
+
+    reference operator*() const {return *it_;}
+    pointer  operator->() const {return  it_;}
+
+    input_iterator& operator++()    {++it_; return *this;}
+    input_iterator  operator++(int) {input_iterator tmp(*this); ++(*this); return tmp;}
+
+    friend bool operator==(const input_iterator& x, const input_iterator& y)
+        {return x.it_ == y.it_;}
+    friend bool operator!=(const input_iterator& x, const input_iterator& y)
+        {return !(x == y);}
+
+private:
+    It it_;
+    template <typename U> friend class input_iterator;
+};
+
+template <typename T, typename U>
+inline bool
+operator==(const input_iterator<T>& x, const input_iterator<U>& y)
+{
+    return x.base() == y.base();
+}
+
+template <typename T, typename U>
+inline bool
+operator!=(const input_iterator<T>& x, const input_iterator<U>& y)
+{
+    return !(x == y);
+}
+
+
+// == Forward Iterator ==
+template <typename It>
+class forward_iterator {
+public:
+    typedef          std::forward_iterator_tag                 iterator_category;
+    typedef typename std::iterator_traits<It>::value_type      value_type;
+    typedef typename std::iterator_traits<It>::difference_type difference_type;
+    typedef It                                                 pointer;
+    typedef typename std::iterator_traits<It>::reference       reference;
+
+    It base() const {return it_;}
+
+    forward_iterator() : it_() {}
+    explicit forward_iterator(It it) : it_(it) {}
+    template <typename U>
+    forward_iterator(const forward_iterator<U>& u) :it_(u.it_) {}
+
+    reference operator*() const {return *it_;}
+    pointer  operator->() const {return  it_;}
+
+    forward_iterator& operator++()    {++it_; return *this;}
+    forward_iterator  operator++(int) {forward_iterator tmp(*this); ++(*this); return tmp;}
+
+    friend bool operator==(const forward_iterator& x, const forward_iterator& y)
+        {return x.it_ == y.it_;}
+    friend bool operator!=(const forward_iterator& x, const forward_iterator& y)
+        {return !(x == y);}
+private:
+    It it_;
+
+    template <typename U> friend class forward_iterator;
+};
+
+template <typename T, typename U>
+inline bool
+operator==(const forward_iterator<T>& x, const forward_iterator<U>& y)
+{
+    return x.base() == y.base();
+}
+
+template <typename T, typename U>
+inline bool
+operator!=(const forward_iterator<T>& x, const forward_iterator<U>& y)
+{
+    return !(x == y);
+}
+
+// == Bidirectional Iterator ==
+template <typename It>
+class bidirectional_iterator
+{
+public:
+    typedef          std::bidirectional_iterator_tag           iterator_category;
+    typedef typename std::iterator_traits<It>::value_type      value_type;
+    typedef typename std::iterator_traits<It>::difference_type difference_type;
+    typedef It                                                 pointer;
+    typedef typename std::iterator_traits<It>::reference       reference;
+
+    It base() const {return it_;}
+
+    bidirectional_iterator() : it_() {}
+    explicit bidirectional_iterator(It it) : it_(it) {}
+    template <typename U>
+    bidirectional_iterator(const bidirectional_iterator<U>& u) :it_(u.it_) {}
+
+    reference operator*() const {return *it_;}
+    pointer  operator->() const {return  it_;}
+
+    bidirectional_iterator& operator++()    {++it_; return *this;}
+    bidirectional_iterator  operator++(int) {bidirectional_iterator tmp(*this); ++(*this); return tmp;}
+
+    bidirectional_iterator& operator--()    {--it_; return *this;}
+    bidirectional_iterator  operator--(int) {bidirectional_iterator tmp(*this); --(*this); return tmp;}
+private:
+    It it_;
+    template <typename U> friend class bidirectional_iterator;
+};
+
+template <typename T, typename U>
+inline bool
+operator==(const bidirectional_iterator<T>& x, const bidirectional_iterator<U>& y)
+{
+    return x.base() == y.base();
+}
+
+template <typename T, typename U>
+inline bool
+operator!=(const bidirectional_iterator<T>& x, const bidirectional_iterator<U>& y)
+{
+    return !(x == y);
+}
+
+
+// == Random Access Iterator ==
+template <typename It>
+class random_access_iterator {
+public:
+    typedef          std::random_access_iterator_tag           iterator_category;
+    typedef typename std::iterator_traits<It>::value_type      value_type;
+    typedef typename std::iterator_traits<It>::difference_type difference_type;
+    typedef It                                                 pointer;
+    typedef typename std::iterator_traits<It>::reference       reference;
+
+    It base() const {return it_;}
+
+    random_access_iterator() : it_() {}
+    explicit random_access_iterator(It it) : it_(it) {}
+    template <typename U>
+    random_access_iterator(const random_access_iterator<U>& u) :it_(u.it_) {}
+
+    reference operator*() const {return *it_;}
+    pointer  operator->() const {return  it_;}
+
+    random_access_iterator& operator++()    {++it_; return *this;}
+    random_access_iterator  operator++(int) {random_access_iterator tmp(*this); ++(*this); return tmp;}
+
+    random_access_iterator& operator--()    {--it_; return *this;}
+    random_access_iterator  operator--(int) {random_access_iterator tmp(*this); --(*this); return tmp;}
+
+    random_access_iterator& operator+=(difference_type n)       {it_ += n; return *this;}
+    random_access_iterator  operator+ (difference_type n) const {random_access_iterator tmp(*this); tmp += n; return tmp;}
+    friend random_access_iterator operator+(difference_type n, random_access_iterator x) {x += n; return x;}
+
+    random_access_iterator& operator-=(difference_type n)       {return *this += -n;}
+    random_access_iterator  operator- (difference_type n) const {random_access_iterator tmp(*this); tmp -= n; return tmp;}
+
+    reference operator[](difference_type n) const {return it_[n];}
+private:
+    It it_;
+
+    template <typename U> friend class random_access_iterator;
+};
+
+template <typename T, typename U>
+inline bool
+operator==(const random_access_iterator<T>& x, const random_access_iterator<U>& y)
+{
+    return x.base() == y.base();
+}
+
+template <typename T, typename U>
+inline bool
+operator!=(const random_access_iterator<T>& x, const random_access_iterator<U>& y)
+{
+    return !(x == y);
+}
+
+template <typename T, typename U>
+inline bool
+operator<(const random_access_iterator<T>& x, const random_access_iterator<U>& y)
+{
+    return x.base() < y.base();
+}
+
+template <typename T, typename U>
+inline bool
+operator<=(const random_access_iterator<T>& x, const random_access_iterator<U>& y)
+{
+    return !(y < x);
+}
+
+template <typename T, typename U>
+inline bool
+operator>(const random_access_iterator<T>& x, const random_access_iterator<U>& y)
+{
+    return y < x;
+}
+
+template <typename T, typename U>
+inline bool
+operator>=(const random_access_iterator<T>& x, const random_access_iterator<U>& y)
+{
+    return !(x < y);
+}
+
+template <typename T, typename U>
+inline typename std::iterator_traits<T>::difference_type
+operator-(const random_access_iterator<T>& x, const random_access_iterator<U>& y)
+{
+    return x.base() - y.base();
+}
+
+
+// == Output Iterator ==
+template <typename It>
+class output_iterator {
+public:
+    typedef          std::output_iterator_tag                  iterator_category;
+    typedef void                                               value_type;
+    typedef typename std::iterator_traits<It>::difference_type difference_type;
+    typedef It                                                 pointer;
+    typedef typename std::iterator_traits<It>::reference       reference;
+
+    It base() const {return it_;}
+
+    output_iterator () {}
+    explicit output_iterator(It it) : it_(it) {}
+
+    template <typename U>
+    output_iterator(const output_iterator<U>& u) :it_(u.it_) {}
+
+    reference operator*() const {return *it_;}
+
+    output_iterator& operator++()    {++it_; return *this;}
+    output_iterator  operator++(int) {output_iterator tmp(*this); ++(*this); return tmp;}
+
+private:
+    It it_;
+    template <typename U> friend class output_iterator;
+	};
+	
+//	No comparison operators for output iterators
+	
+
+// == Get the base of an iterator; used for comparisons ==
+template <typename Iter>
+inline Iter base(output_iterator<Iter> i) { return i.base(); }
+
+template <typename Iter>
+inline Iter base(input_iterator<Iter> i) { return i.base(); }
+
+template <typename Iter>
+inline Iter base(forward_iterator<Iter> i) { return i.base(); }
+
+template <typename Iter>
+inline Iter base(bidirectional_iterator<Iter> i) { return i.base(); }
+
+template <typename Iter>
+inline Iter base(random_access_iterator<Iter> i) { return i.base(); }
+
+template <typename Iter>	// everything else
+inline Iter base(Iter i) { return i; }
+
+#endif  // ITERATORS_H