add initial "proxy" interior rings implementation

include/mapnik/polygon_interior.hpp

@@ -0,0 +1,79 @@
+/*****************************************************************************
+ *
+ * This file is part of Mapnik (c++ mapping toolkit)
+ *
+ * Copyright (C) 2016 Artem Pavlenko
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ *****************************************************************************/
+
+#ifndef MAPNIK_POLYGON_INTERIOR_HPP
+#define MAPNIK_POLYGON_INTERIOR_HPP
+
+#include <mapnik/geometry/polygon.hpp>
+
+
+namespace mapnik { namespace detail {
+
+template <typename T>
+struct polygon_interior
+{
+    using coordinate_type = T;
+    using iterator = typename geometry::polygon<coordinate_type>::iterator;
+    using const_iterator = typename geometry::polygon<coordinate_type>::const_iterator;
+    using value_type = typename geometry::polygon<coordinate_type>::value_type;
+
+    polygon_interior(geometry::polygon<coordinate_type> & poly)
+        : poly_(poly) {}
+
+    iterator begin()
+    {
+        auto itr = poly_.begin();
+        std::advance(itr, 1);
+        return itr;
+    }
+
+    iterator end() { return poly_.end();}
+    const_iterator begin() const
+    {
+        auto itr = poly_.begin();
+        std::advance(itr, 1);
+        return itr;
+    }
+    const_iterator end() const { return poly_.end();}
+
+    void clear()
+    {
+        poly_.resize(1);
+    }
+    void resize(std::size_t size)
+    {
+        poly_.resize(size + 1);
+    }
+
+    std::size_t size() const
+    {
+        return poly_.empty() ? 0 : poly_.size() - 1;
+    }
+
+    value_type& back() { return poly_.back(); }
+    value_type const& back()  const { return poly_.back(); }
+    geometry::polygon<coordinate_type> & poly_;
+};
+
+}}
+
+#endif // MAPNIK_POLYGON_INTERIOR_HPP