Squashed 'third_party/boostorg/iterator/' content from commit b2adecb
Change-Id: I284a73816f9cc846742923879275b84c6e0c915c
git-subtree-dir: third_party/boostorg/iterator
git-subtree-split: b2adecb951af025698618f19a3c838bd314966dc
diff --git a/include/boost/iterator/advance.hpp b/include/boost/iterator/advance.hpp
new file mode 100644
index 0000000..6f81cdb
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+++ b/include/boost/iterator/advance.hpp
@@ -0,0 +1,84 @@
+// 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>
+
+namespace boost {
+namespace iterators {
+
+ namespace detail {
+ template <typename InputIterator, typename Distance>
+ inline BOOST_CXX14_CONSTEXPR void
+ advance_impl(
+ InputIterator& it
+ , Distance n
+ , incrementable_traversal_tag
+ )
+ {
+ while (n > 0) {
+ ++it;
+ --n;
+ }
+ }
+
+ template <typename BidirectionalIterator, typename Distance>
+ inline BOOST_CXX14_CONSTEXPR void
+ advance_impl(
+ BidirectionalIterator& it
+ , Distance n
+ , bidirectional_traversal_tag
+ )
+ {
+ if (n >= 0) {
+ while (n > 0) {
+ ++it;
+ --n;
+ }
+ }
+ else {
+ while (n < 0) {
+ --it;
+ ++n;
+ }
+ }
+ }
+
+ template <typename RandomAccessIterator, typename Distance>
+ inline BOOST_CXX14_CONSTEXPR void
+ advance_impl(
+ RandomAccessIterator& it
+ , Distance n
+ , random_access_traversal_tag
+ )
+ {
+ it += n;
+ }
+ }
+
+ namespace advance_adl_barrier {
+ template <typename InputIterator, typename Distance>
+ inline BOOST_CXX14_CONSTEXPR void
+ advance(InputIterator& it, Distance n)
+ {
+ detail::advance_impl(
+ it, n, typename iterator_traversal<InputIterator>::type()
+ );
+ }
+ }
+
+ using namespace advance_adl_barrier;
+
+} // namespace iterators
+
+using iterators::advance;
+
+} // namespace boost
+
+#endif