vertex iterator implementation (forward traversal)

include/mapnik/util/vertex_iterator.hpp

@@ -0,0 +1,86 @@
+/*****************************************************************************
+ * 
+ * This file is part of Mapnik (c++ mapping toolkit)
+ *
+ * Copyright (C) 2011 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
+ *
+ *****************************************************************************/
+
+//$Id$
+
+#ifndef MAPNIK_VERTEX_ITERATOR_HPP
+#define MAPNIK_VERTEX_ITERATOR_HPP
+
+// mapnik
+#include <mapnik/global.hpp>
+#include <mapnik/geometry.hpp>
+
+// boost
+#include <boost/tuple/tuple.hpp>
+#include <boost/iterator/iterator_facade.hpp>
+
+namespace mapnik { namespace util {
+
+typedef boost::tuple<unsigned,double,double> vertex_type;
+
+class vertex_iterator
+    : public boost::iterator_facade<vertex_iterator,
+                                    vertex_type const,                                   
+                                    boost::forward_traversal_tag,
+                                    vertex_type const&
+                                    >
+{
+
+public:
+    
+    vertex_iterator()
+        : geom_(0),
+          v_(SEG_END,0,0) {}
+    
+    explicit vertex_iterator(geometry_type const& geom)
+        : geom_(&geom),
+          v_(SEG_END,0,0) 
+    {
+        increment();
+    }
+    
+private:
+    friend class boost::iterator_core_access;
+
+    void increment() 
+    {
+        v_.get<0>() = geom_->vertex(&v_.get<1>(),&v_.get<2>());
+    }
+    
+    bool equal( vertex_iterator const& other) const
+    {
+        return v_.get<0>() == other.v_.get<0>();
+    }
+    
+    vertex_type const& dereference() const
+    {
+        return v_; 
+    }
+    
+    geometry_type const *geom_;
+    vertex_type v_;
+};
+                                     
+}}
+
+
+#endif // MAPNIK_VERTEX_ITERATOR_HPP