boost/python/enum.hpp

   1 // Copyright David Abrahams 2002.
   2 // Distributed under the Boost Software License, Version 1.0. (See
   3 // accompanying file LICENSE_1_0.txt or copy at
   4 // http://www.boost.org/LICENSE_1_0.txt)
   5 #ifndef ENUM_DWA200298_HPP
   6 # define ENUM_DWA200298_HPP
   7
   8 # include <boost/python/detail/prefix.hpp>
   9
  10 # include <boost/python/object/enum_base.hpp>
  11 # include <boost/python/converter/rvalue_from_python_data.hpp>
  12 # include <boost/python/converter/registered.hpp>
  13
  14 namespace boost { namespace python {
  15
  16 template <class T>
  17 struct enum_ : public objects::enum_base
  18 {
  19     typedef objects::enum_base base;
  20
  21     // Declare a new enumeration type in the current scope()
  22     enum_(char const* name, char const* doc = 0);
  23
  24     // Add a new enumeration value with the given name and value.
  25     inline enum_<T>& value(char const* name, T);
  26
  27     // Add all of the defined enumeration values to the current scope with the
  28     // same names used here.
  29     inline enum_<T>& export_values();
  30  private:
  31     static PyObject* to_python(void const* x);
  32     static void* convertible_from_python(PyObject* obj);
  33     static void construct(PyObject* obj, converter::rvalue_from_python_stage1_data* data);
  34 };
  35
  36 template <class T>
  37 inline enum_<T>::enum_(char const* name, char const* doc )
  38     : base(
  39         name
  40         , &enum_<T>::to_python
  41         , &enum_<T>::convertible_from_python
  42         , &enum_<T>::construct
  43         , type_id<T>()
  44                 , doc
  45         )
  46 {
  47 }
  48
  49 // This is the conversion function that gets registered for converting
  50 // these enums to Python.
  51 template <class T>
  52 PyObject* enum_<T>::to_python(void const* x)
  53 {
  54     return base::to_python(
  55         converter::registered<T>::converters.m_class_object
  56         , static_cast<long>(*(T const*)x));
  57 }
  58
  59 //
  60 // The following two static functions serve as the elements of an
  61 // rvalue from_python converter for the enumeration type.
  62 //
  63
  64 // This checks that a given Python object can be converted to the
  65 // enumeration type.
  66 template <class T>
  67 void* enum_<T>::convertible_from_python(PyObject* obj)
  68 {
  69     return PyObject_IsInstance(
  70         obj
  71         , upcast<PyObject>(
  72             converter::registered<T>::converters.m_class_object))
  73
  74         ? obj : 0;
  75 }
  76
  77 // Constructs an instance of the enumeration type in the from_python
  78 // data.
  79 template <class T>
  80 void enum_<T>::construct(PyObject* obj, converter::rvalue_from_python_stage1_data* data)
  81 {
  82     T x = static_cast<T>(PyInt_AS_LONG(obj));
  83     void* const storage = ((converter::rvalue_from_python_storage<T>*)data)->storage.bytes;
  84     new (storage) T(x);
  85     data->convertible = storage;
  86 }
  87
  88 template <class T>
  89 inline enum_<T>& enum_<T>::value(char const* name, T x)
  90 {
  91     this->add_value(name, static_cast<long>(x));
  92     return *this;
  93 }
  94
  95 template <class T>
  96 inline enum_<T>& enum_<T>::export_values()
  97 {
  98     this->base::export_values();
  99     return *this;
 100 }
 101
 102 }} // namespace boost::python
 103
 104 #endif // ENUM_DWA200298_HPP