add boost::generator_iterator_policies and convenience classes

[SVN r11725]

include/boost/generator_iterator.hpp

@@ -0,0 +1,73 @@
+// (C) Copyright Jens Maurer 2001. Permission to copy, use,
+// modify, sell and distribute this software is granted provided this
+// copyright notice appears in all copies. This software is provided
+// "as is" without express or implied warranty, and with no claim as
+// to its suitability for any purpose.
+//
+// Revision History:
+
+// 15 Nov 2001   Jens Maurer
+//      created.
+
+#ifndef BOOST_ITERATOR_ADAPTOR_GENERATOR_ITERATOR_HPP
+#define BOOST_ITERATOR_ADAPTOR_GENERATOR_ITERATOR_HPP
+
+#include <boost/iterator_adaptors.hpp>
+#include <boost/ref.hpp>
+
+namespace boost {
+
+template<class Generator>
+class generator_iterator_policies
+{
+public:
+    generator_iterator_policies() { }
+
+    template<class Base>
+    void initialize(Base& base) {
+      m_value = (*base)();
+    }
+
+    // The Iter template argument is necessary for compatibility with a MWCW
+    // bug workaround
+    template <class IteratorAdaptor>
+    void increment(IteratorAdaptor& iter) {
+      m_value = (*iter.base())();
+    }
+
+    template <class IteratorAdaptor>
+    const typename Generator::result_type&
+    dereference(const IteratorAdaptor&) const
+        { return m_value; }
+
+    template <class IteratorAdaptor1, class IteratorAdaptor2>
+    bool equal(const IteratorAdaptor1& x, const IteratorAdaptor2& y) const
+        { return x.base() == y.base() &&
+            x.policies().m_value == y.policies().m_value; }
+
+private:
+  typename Generator::result_type m_value;
+};
+
+template<class Generator>
+struct generator_iterator_generator
+{
+  typedef iterator_adaptor<Generator*, generator_iterator_policies<Generator>,
+    typename Generator::result_type, const typename Generator::result_type&,
+    const typename Generator::result_type*, std::input_iterator_tag,
+    long>       type;
+};
+
+template <class Generator>
+inline typename generator_iterator_generator<Generator>::type
+make_generator_iterator(Generator & gen)
+{
+  typedef typename generator_iterator_generator<Generator>::type result_t;
+  return result_t(&gen);
+}
+
+} // namespace boost
+
+
+#endif // BOOST_ITERATOR_ADAPTOR_GENERATOR_ITERATOR_HPP
+