C++ interface to iterable Python objects

[SVN r1524]

include/boost/python/suite/indexing/python_iterator.cpp

@@ -0,0 +1,172 @@
+// -*- mode:c++ -*-
+//
+// Module python_iterator.cpp
+//
+// Copyright (c) 2003 Raoul M. Gough
+//
+// This material is provided "as is", with absolutely no warranty expressed
+// or implied. Any use is at your own risk.
+//
+// Permission to use or copy this material for any purpose is hereby
+// granted without fee, provided the above notices are retained on all
+// copies.  Permission to modify the material and to distribute modified
+// versions is granted, provided the above notices are retained, and a
+// notice that the material was modified is included with the above
+// copyright notice.
+//
+// History
+// =======
+// 2003/ 9/10	rmg	File creation
+//
+// $Id$
+//
+
+#include "python_iterator.hpp"
+
+////////////////////////////////////////////////////////////////////////////
+// python_iterator factory
+///////////////////////////////////////////////////////////////////////////
+
+std::auto_ptr<indexing::python_iterator>
+indexing::make_iterator (boost::python::object temp)
+{
+  std::auto_ptr<python_iterator> result;
+
+  try
+    {
+      result.reset (new python_iter_iterator (temp));
+    }
+
+  catch (boost::python::error_already_set const &)
+    {
+      PyErr_Clear ();
+
+      try
+	{
+	  result.reset (new python_getitem_iterator (temp));
+	}
+
+      catch (boost::python::error_already_set const &)
+	{
+	  PyErr_Clear ();
+	}
+    }
+
+  return result;
+}
+
+////////////////////////////////////////////////////////////////////////////
+// Base class (virtual) destructor
+///////////////////////////////////////////////////////////////////////////
+
+indexing::python_iterator::~python_iterator ()
+{
+}
+
+////////////////////////////////////////////////////////////////////////////
+// python_getitem_iterator constructor
+///////////////////////////////////////////////////////////////////////////
+
+indexing::python_getitem_iterator
+::python_getitem_iterator (boost::python::object obj)
+  : mGetitemMethod (obj.attr ("__getitem__"))
+  , mIndex (0)
+  , mCurrent()
+{
+}
+
+////////////////////////////////////////////////////////////////////////////
+// Get our next item (if any)
+///////////////////////////////////////////////////////////////////////////
+
+bool indexing::python_getitem_iterator::next ()
+{
+  bool result = true; // Assume success
+
+  try
+    {
+      mCurrent = mGetitemMethod (mIndex);
+      ++mIndex;
+    }
+
+  catch (boost::python::error_already_set const &)
+    {
+      if (PyErr_ExceptionMatches (PyExc_IndexError))
+	{
+	  // Eat this exception
+	  PyErr_Clear ();
+	  mCurrent = boost::python::object ();
+	  result = false;
+	}
+
+      else
+	{
+	  // Pass it up the line
+	  throw;
+	}
+    }
+
+  return result;
+}
+
+////////////////////////////////////////////////////////////////////////////
+// Return our current item
+///////////////////////////////////////////////////////////////////////////
+
+boost::python::object indexing::python_getitem_iterator::current () const
+{
+  return mCurrent;
+}
+
+////////////////////////////////////////////////////////////////////////////
+// python_iter_iterator constructor
+///////////////////////////////////////////////////////////////////////////
+
+indexing::python_iter_iterator
+::python_iter_iterator (boost::python::object obj)
+  : mNextMethod (obj.attr ("__iter__")().attr ("next"))
+  , mCurrent()
+{
+}
+
+////////////////////////////////////////////////////////////////////////////
+// Get our next item (if any)
+///////////////////////////////////////////////////////////////////////////
+
+bool indexing::python_iter_iterator::next ()
+{
+  bool result = true; // Assume success
+
+  try
+    {
+      mCurrent = mNextMethod ();
+    }
+
+  catch (boost::python::error_already_set const &)
+    {
+      if (PyErr_ExceptionMatches (PyExc_StopIteration))
+	{
+	  // Eat this exception
+	  PyErr_Clear ();
+	  mCurrent = boost::python::object ();
+	  result = false;
+	}
+
+      else
+	{
+	  // Pass it up the line
+	  throw;
+	}
+    }
+
+  return result;
+}
+
+////////////////////////////////////////////////////////////////////////////
+// Return our current item
+///////////////////////////////////////////////////////////////////////////
+
+boost::python::object indexing::python_iter_iterator::current () const
+{
+  return mCurrent;
+}

include/boost/python/suite/indexing/python_iterator.hpp

@@ -0,0 +1,71 @@
+// -*- mode:c++ -*-
+//
+// Header file python_iterator.hpp
+//
+// Handy Python iterable iterators
+//
+// Copyright (c) 2003 Raoul M. Gough
+//
+// This material is provided "as is", with absolutely no warranty expressed
+// or implied. Any use is at your own risk.
+//
+// Permission to use or copy this material for any purpose is hereby
+// granted without fee, provided the above notices are retained on all
+// copies.  Permission to modify the material and to distribute modified
+// versions is granted, provided the above notices are retained, and a
+// notice that the material was modified is included with the above
+// copyright notice.
+//
+// History
+// =======
+// 2003/ 9/10	rmg	File creation
+//
+// $Id$
+//
+
+#ifndef python_iterator_rmg_20030910_included
+#define python_iterator_rmg_20030910_included
+
+#include <boost/python/object.hpp>
+#include <memory>
+
+namespace indexing {
+  struct python_iterator
+  {
+    virtual ~python_iterator ();
+    virtual bool next () = 0;
+    virtual boost::python::object current() const = 0;
+  };
+
+  std::auto_ptr<python_iterator> make_iterator (boost::python::object);
+  // Returns null auto_ptr if object does not provide __iter__ nor
+  // __getitem__, otherwise a pointer to a suitable implementation of
+  // python_iterator
+
+  struct python_getitem_iterator : public python_iterator
+  {
+  public:
+    python_getitem_iterator (boost::python::object);
+    virtual bool next ();
+    virtual boost::python::object current() const;
+
+  private:
+    boost::python::object mGetitemMethod;
+    int mIndex;
+    boost::python::object mCurrent;
+  };
+
+  struct python_iter_iterator : public python_iterator
+  {
+  public:
+    python_iter_iterator (boost::python::object);
+    virtual bool next ();
+    virtual boost::python::object current() const;
+
+  private:
+    boost::python::object mNextMethod;
+    boost::python::object mCurrent;
+  };
+}
+
+#endif // python_iterator_rmg_20030910_included