util: add IteratorRange utility

This is a utility class meant to provide a helper which permits returning a
range for iteration via a named pair of iterators.  It serves as an adapter
for creating a C++11 friendly interface for iteration.

paludis/util/files.m4

@@ -42,6 +42,7 @@ add(`fs_stat',                           `hh', `cc', `fwd', `gtest', `testscript
 add(`graph',                             `hh', `cc', `fwd', `impl', `gtest')
 add(`hashes',                            `hh', `cc', `gtest')
 add(`iterator_funcs',                    `hh', `gtest')
+add(`iterator_range',                    `hh')
 add(`indirect_iterator',                 `hh', `fwd', `impl', `gtest')
 add(`is_file_with_extension',            `hh', `cc', `se', `gtest', `testscript')
 add(`join',                              `hh', `gtest')

paludis/util/iterator_range.hh

@@ -0,0 +1,78 @@
+/* vim: set sw=4 sts=4 et foldmethod=syntax : */
+/*
+ * Copyright (c) 2014 Saleem Abdulrasool
+ *
+ * This file is part of the Paludis package manager. Paludis is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU General
+ * Public License version 2, as published by the Free Software Foundation.
+ *
+ * Paludis is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef PALUDIS_GUARD_PALUDIS_UTIL_ITERATOR_RANGE_HH
+#define PALUDIS_GUARD_PALUDIS_UTIL_ITERATOR_RANGE_HH 1
+
+#include <iterator>
+#include <utility>
+
+namespace paludis
+{
+    template <typename Iterator_>
+    class IteratorRange
+    {
+        private:
+            Iterator_ _begin, _end;
+
+        public:
+            // TODO(compnerd) use SFINAE to ensure that the container's
+            // iterators match the range's iterator
+            template <typename Container_>
+            IteratorRange(Container_ && container)
+                : _begin(std::begin(container)), _end(std::end(container))
+            {
+            }
+
+            IteratorRange(Iterator_ begin, Iterator_ end)
+                : _begin(std::move(begin)), _end(std::move(end))
+            {
+            }
+
+            Iterator_ begin() const
+            {
+                return _begin;
+            }
+
+            Iterator_ end() const
+            {
+                return _end;
+            }
+
+            size_t size() const
+            {
+                return std::distance(_end, _begin);
+            }
+    };
+
+    template <typename Iterator_>
+    IteratorRange<Iterator_> make_range(Iterator_ begin, Iterator_ end)
+    {
+        return IteratorRange<Iterator_>(std::move(begin), std::move(end));
+    }
+
+    template <typename Iterator_>
+    IteratorRange<Iterator_> make_range(std::pair<Iterator_, Iterator_> range)
+    {
+        return IteratorRange<Iterator_>(std::move(range.first),
+                                        std::move(range.second));
+    }
+}
+
+#endif
+