TypeWrapper for Python slice objects

[SVN r1525]

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

@@ -0,0 +1,93 @@
+// -*- mode:c++ -*-
+//
+// Module slice.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 "slice.hpp"
+
+/////////////////////////////////////////////////////////////////////////////
+// Check that setLength has been called, and throw otherwise
+/////////////////////////////////////////////////////////////////////////////
+
+void indexing::slice::validate () const
+{
+  if (mDirection == 0)
+    {
+      PyErr_SetString (PyExc_RuntimeError
+		       , "slice access attempted before setLength called");
+      boost::python::throw_error_already_set();
+    }
+}
+
+/////////////////////////////////////////////////////////////////////////////
+// Slice constructor
+/////////////////////////////////////////////////////////////////////////////
+
+indexing::slice::slice (boost::python::detail::borrowed_reference ref)
+  : boost::python::object (ref)
+  , mStart (0)
+  , mStep (0)
+  , mStop (0)
+  , mDirection (0)
+{
+  if (!PySlice_Check (this->ptr()))
+    {
+      PyErr_SetString (PyExc_TypeError
+		       , "slice constructor: passed a non-slice object");
+
+      boost::python::throw_error_already_set();
+    }
+
+  // This slice object is useless until setLength is called
+}
+
+/////////////////////////////////////////////////////////////////////////////
+// Set up our member variables for a sequence of a given length
+/////////////////////////////////////////////////////////////////////////////
+
+void indexing::slice::setLength (int sequenceLength)
+{
+  PySlice_GetIndices ((PySliceObject *) this->ptr()
+		      , sequenceLength
+		      , &mStart
+		      , &mStop
+		      , &mStep);
+
+  if (mStep == 0)
+    {
+      // Can happen with Python prior to 2.3
+      PyErr_SetString (PyExc_ValueError, "slice step cannot be zero");
+      boost::python::throw_error_already_set ();
+    }
+
+  mStart = std::max (0, std::min (sequenceLength, mStart));
+  mStop = std::max (0, std::min (sequenceLength, mStop));
+  mDirection = (mStep > 0) ? 1 : -1;
+}
+
+/////////////////////////////////////////////////////////////////////////////
+// Check if an index is within the range of this slice
+/////////////////////////////////////////////////////////////////////////////
+
+bool indexing::slice::inRange (int index)
+{
+  return ((mStop - index) * mDirection) > 0;
+}

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

@@ -0,0 +1,71 @@
+// -*- mode:c++ -*-
+//
+// Header file slice.hpp
+//
+// 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 slice_rmg_20030910_included
+#define slice_rmg_20030910_included
+
+#include <Python.h>
+#include <boost/python/object.hpp>
+#include <boost/python/converter/pytype_object_mgr_traits.hpp>
+
+namespace indexing
+{
+  struct slice : public boost::python::object
+  {
+    //
+    // *** WARNING ***
+    //
+    // A newly constructed slice object is useless until setLength is called
+    //
+
+    slice (boost::python::detail::borrowed_reference ref);
+    void setLength (int sequenceLength);
+
+    int start() const { validate(); return mStart; }
+    int step() const  { validate(); return mStep; }
+    int stop() const  { validate(); return mStop; }
+
+    int size() const { validate(); return (mStop - mStart) / mStep; }
+
+    bool inRange (int index);
+
+  private:
+    void validate () const; // throws unless setLength has been called
+
+    int mStart;
+    int mStep;
+    int mStop;
+    int mDirection;
+  };
+}
+
+namespace boost { namespace python { namespace converter {
+  // Specialized converter to handle PySlice_Type objects
+  template<>
+  struct object_manager_traits<indexing::slice>
+    : pytype_object_manager_traits<&PySlice_Type, ::indexing::slice>
+  {
+  };
+}}}
+
+#endif // slice_rmg_20030910_included