Merge pull request #24 from morinmorin/add_advance_and_distance

Add boost::advance and boost::distance

include/boost/iterator/advance.hpp

@@ -0,0 +1,85 @@
+// Copyright (C) 2017 Michel Morin.
+//
+// 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)
+
+#ifndef BOOST_ITERATOR_ADVANCE_HPP
+#define BOOST_ITERATOR_ADVANCE_HPP
+
+#include <boost/config.hpp>
+#include <boost/iterator/iterator_categories.hpp>
+#include <boost/iterator/iterator_traits.hpp>
+
+namespace boost {
+namespace iterators {
+
+    namespace detail {
+        template <typename InputIterator>
+        inline BOOST_CXX14_CONSTEXPR void
+        advance_impl(
+            InputIterator& it
+          , typename iterator_difference<InputIterator>::type n
+          , incrementable_traversal_tag
+        )
+        {
+            while (n > 0) {
+                ++it;
+                --n;
+            }
+        }
+
+        template <typename BidirectionalIterator>
+        inline BOOST_CXX14_CONSTEXPR void
+        advance_impl(
+            BidirectionalIterator& it
+          , typename iterator_difference<BidirectionalIterator>::type n
+          , bidirectional_traversal_tag
+        )
+        {
+            if (n >= 0) {
+                while (n > 0) {
+                    ++it;
+                    --n;
+                }
+            }
+            else {
+                while (n < 0) {
+                    --it;
+                    ++n;
+                }
+            }
+        }
+
+        template <typename RandomAccessIterator>
+        inline BOOST_CXX14_CONSTEXPR void
+        advance_impl(
+            RandomAccessIterator& it
+          , typename iterator_difference<RandomAccessIterator>::type n
+          , random_access_traversal_tag
+        )
+        {
+            it += n;
+        }
+    }
+
+    namespace advance_adl_barrier {
+        template <typename InputIterator>
+        inline BOOST_CXX14_CONSTEXPR void
+        advance(InputIterator& it, typename iterator_difference<InputIterator>::type n)
+        {
+            detail::advance_impl(
+                it, n, typename iterator_traversal<InputIterator>::type()
+            );
+        }
+    }
+
+    using namespace advance_adl_barrier;
+
+} // namespace iterators
+
+using iterators::advance;
+
+} // namespace boost
+
+#endif

include/boost/iterator/distance.hpp

@@ -0,0 +1,65 @@
+// Copyright (C) 2017 Michel Morin.
+//
+// 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)
+
+#ifndef BOOST_ITERATOR_DISTANCE_HPP
+#define BOOST_ITERATOR_DISTANCE_HPP
+
+#include <boost/config.hpp>
+#include <boost/iterator/iterator_categories.hpp>
+#include <boost/iterator/iterator_traits.hpp>
+
+namespace boost {
+namespace iterators {
+
+    namespace detail {
+        template <typename SinglePassIterator>
+        inline BOOST_CXX14_CONSTEXPR typename iterator_difference<SinglePassIterator>::type
+        distance_impl(
+            SinglePassIterator first
+          , SinglePassIterator last
+          , single_pass_traversal_tag
+        )
+        {
+            typename iterator_difference<SinglePassIterator>::type n = 0;
+            while (first != last) {
+                ++first;
+                ++n;
+            }
+            return n;
+        }
+
+        template <typename RandomAccessIterator>
+        inline BOOST_CXX14_CONSTEXPR typename iterator_difference<RandomAccessIterator>::type
+        distance_impl(
+            RandomAccessIterator first
+          , RandomAccessIterator last
+          , random_access_traversal_tag
+        )
+        {
+            return last - first;
+        }
+    }
+
+    namespace distance_adl_barrier {
+        template <typename SinglePassIterator>
+        inline BOOST_CXX14_CONSTEXPR typename iterator_difference<SinglePassIterator>::type
+        distance(SinglePassIterator first, SinglePassIterator last)
+        {
+            return detail::distance_impl(
+                first, last, typename iterator_traversal<SinglePassIterator>::type()
+            );
+        }
+    }
+
+    using namespace distance_adl_barrier;
+
+} // namespace iterators
+
+using iterators::distance;
+
+} // namespace boost
+
+#endif

test/Jamfile.v2

@@ -55,4 +55,7 @@ test-suite iterator
 
     [ run minimum_category.cpp ]
     [ compile-fail minimum_category_compile_fail.cpp ]
+
+    [ run advance_test.cpp ]
+    [ run distance_test.cpp ]
 ;

test/advance_test.cpp

@@ -0,0 +1,65 @@
+// Copyright (C) 2017 Michel Morin.
+//
+// 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)
+
+#include <vector>
+#include <list>
+#include <boost/container/slist.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/iterator/advance.hpp>
+#include <boost/iterator/transform_iterator.hpp>
+
+int twice(int x) { return x + x; }
+
+template <typename Iterator>
+void test_advance(Iterator it_from, Iterator it_to, int n)
+{
+    boost::advance(it_from,  n);
+    BOOST_TEST(it_from == it_to);
+}
+
+int main()
+{
+    int array[3] = {1, 2, 3};
+    int* ptr1 = array;
+    int* ptr2 = array + 3;
+
+    {
+        test_advance(ptr1, ptr2,  3);
+        test_advance(ptr2, ptr1, -3);
+    }
+
+    {
+        std::vector<int> ints(ptr1, ptr2);
+        test_advance(ints.begin(), ints.end(),  3);
+        test_advance(ints.end(), ints.begin(), -3);
+    }
+
+    {
+        test_advance(
+            boost::make_transform_iterator(ptr1, twice)
+          , boost::make_transform_iterator(ptr2, twice)
+          , 3
+        );
+        test_advance(
+            boost::make_transform_iterator(ptr2, twice)
+          , boost::make_transform_iterator(ptr1, twice)
+          , -3
+        );
+    }
+
+    {
+        std::list<int> ints(ptr1, ptr2);
+        test_advance(ints.begin(), ints.end(),  3);
+        test_advance(ints.end(), ints.begin(), -3);
+    }
+
+    {
+        boost::container::slist<int> ints(ptr1, ptr2);
+        test_advance(ints.begin(), ints.end(),  3);
+    }
+
+    return boost::report_errors();
+}

test/distance_test.cpp

@@ -0,0 +1,63 @@
+// Copyright (C) 2017 Michel Morin.
+//
+// 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)
+
+#include <vector>
+#include <list>
+#include <boost/container/slist.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/iterator/distance.hpp>
+#include <boost/iterator/transform_iterator.hpp>
+
+int twice(int x) { return x + x; }
+
+template <typename Iterator>
+void test_distance(Iterator it_from, Iterator it_to, int n)
+{
+    BOOST_TEST(boost::distance(it_from, it_to) == n);
+}
+
+int main()
+{
+    int array[3] = {1, 2, 3};
+    int* ptr1 = array;
+    int* ptr2 = array + 3;
+
+    {
+        test_distance(ptr1, ptr2,  3);
+        test_distance(ptr2, ptr1, -3);
+    }
+
+    {
+        std::vector<int> ints(ptr1, ptr2);
+        test_distance(ints.begin(), ints.end(),  3);
+        test_distance(ints.end(), ints.begin(), -3);
+    }
+
+    {
+        test_distance(
+            boost::make_transform_iterator(ptr1, twice)
+          , boost::make_transform_iterator(ptr2, twice)
+          , 3
+        );
+        test_distance(
+            boost::make_transform_iterator(ptr2, twice)
+          , boost::make_transform_iterator(ptr1, twice)
+          , -3
+        );
+    }
+
+    {
+        std::list<int> ints(ptr1, ptr2);
+        test_distance(ints.begin(), ints.end(),  3);
+    }
+
+    {
+        boost::container::slist<int> ints(ptr1, ptr2);
+        test_distance(ints.begin(), ints.end(),  3);
+    }
+
+    return boost::report_errors();
+}