python/object/py_function.hpp

0001 // Copyright David Abrahams 2002.
0002 // Distributed under the Boost Software License, Version 1.0. (See
0003 // accompanying file LICENSE_1_0.txt or copy at
0004 // http://www.boost.org/LICENSE_1_0.txt)
0005 #ifndef PY_FUNCTION_DWA200286_HPP
0006 # define PY_FUNCTION_DWA200286_HPP
0007
0008 # include <boost/python/detail/signature.hpp>
0009 # include <boost/detail/workaround.hpp>
0010 # include <boost/mpl/size.hpp>
0011 # include <memory>
0012
0013 namespace boost { namespace python { namespace objects {
0014
0015 // This type is used as a "generalized Python callback", wrapping the
0016 // function signature:
0017 //
0018 //      PyObject* (PyObject* args, PyObject* keywords)
0019
0020 struct BOOST_PYTHON_DECL py_function_impl_base
0021 {
0022     virtual ~py_function_impl_base();
0023     virtual PyObject* operator()(PyObject*, PyObject*) = 0;
0024     virtual unsigned min_arity() const = 0;
0025     virtual unsigned max_arity() const;
0026     virtual python::detail::py_func_sig_info signature() const = 0;
0027 };
0028
0029 template <class Caller>
0030 struct caller_py_function_impl : py_function_impl_base
0031 {
0032     caller_py_function_impl(Caller const& caller)
0033         : m_caller(caller)
0034     {}
0035
0036     PyObject* operator()(PyObject* args, PyObject* kw)
0037     {
0038         return m_caller(args, kw);
0039     }
0040
0041     virtual unsigned min_arity() const
0042     {
0043         return m_caller.min_arity();
0044     }
0045
0046     virtual python::detail::py_func_sig_info signature() const
0047     {
0048         return m_caller.signature();
0049     }
0050
0051  private:
0052     Caller m_caller;
0053 };
0054
0055 template <class Caller, class Sig>
0056 struct signature_py_function_impl : py_function_impl_base
0057 {
0058     signature_py_function_impl(Caller const& caller)
0059         : m_caller(caller)
0060     {}
0061
0062     PyObject* operator()(PyObject* args, PyObject* kw)
0063     {
0064         return m_caller(args, kw);
0065     }
0066
0067     virtual unsigned min_arity() const
0068     {
0069         return mpl::size<Sig>::value - 1;
0070     }
0071
0072     virtual python::detail::py_func_sig_info signature() const
0073     {
0074         python::detail::signature_element const* sig = python::detail::signature<Sig>::elements();
0075         python::detail::py_func_sig_info res = {sig, sig};
0076         return  res;
0077     }
0078
0079  private:
0080     Caller m_caller;
0081 };
0082
0083 template <class Caller, class Sig>
0084 struct full_py_function_impl : py_function_impl_base
0085 {
0086     full_py_function_impl(Caller const& caller, unsigned min_arity, unsigned max_arity)
0087       : m_caller(caller)
0088       , m_min_arity(min_arity)
0089       , m_max_arity(max_arity > min_arity ? max_arity : min_arity)
0090     {}
0091
0092     PyObject* operator()(PyObject* args, PyObject* kw)
0093     {
0094         return m_caller(args, kw);
0095     }
0096
0097     virtual unsigned min_arity() const
0098     {
0099         return m_min_arity;
0100     }
0101
0102     virtual unsigned max_arity() const
0103     {
0104         return m_max_arity;
0105     }
0106
0107     virtual python::detail::py_func_sig_info signature() const
0108     {
0109         python::detail::signature_element const* sig = python::detail::signature<Sig>::elements();
0110         python::detail::py_func_sig_info res = {sig, sig};
0111         return  res;
0112     }
0113
0114  private:
0115     Caller m_caller;
0116     unsigned m_min_arity;
0117     unsigned m_max_arity;
0118 };
0119
0120 struct py_function
0121 {
0122     template <class Caller>
0123     py_function(Caller const& caller)
0124         : m_impl(new caller_py_function_impl<Caller>(caller))
0125     {}
0126
0127     template <class Caller, class Sig>
0128     py_function(Caller const& caller, Sig)
0129       : m_impl(new signature_py_function_impl<Caller, Sig>(caller))
0130     {}
0131
0132     template <class Caller, class Sig>
0133     py_function(Caller const& caller, Sig, int min_arity, int max_arity = 0)
0134       : m_impl(new full_py_function_impl<Caller, Sig>(caller, min_arity, max_arity))
0135     {}
0136
0137     py_function(py_function const& rhs)
0138 #if defined(BOOST_NO_CXX11_SMART_PTR)
0139       : m_impl(rhs.m_impl)
0140 #else
0141       : m_impl(std::move(rhs.m_impl))
0142 #endif
0143     {}
0144
0145     PyObject* operator()(PyObject* args, PyObject* kw) const
0146     {
0147         return (*m_impl)(args, kw);
0148     }
0149
0150     unsigned min_arity() const
0151     {
0152         return m_impl->min_arity();
0153     }
0154
0155     unsigned max_arity() const
0156     {
0157         return m_impl->max_arity();
0158     }
0159
0160     python::detail::signature_element const* signature() const
0161     {
0162         return m_impl->signature().signature;
0163     }
0164
0165     python::detail::signature_element const& get_return_type() const
0166     {
0167         return *m_impl->signature().ret;
0168     }
0169
0170  private:
0171 #if defined(BOOST_NO_CXX11_SMART_PTR)
0172     mutable std::auto_ptr<py_function_impl_base> m_impl;
0173 #else
0174     mutable std::unique_ptr<py_function_impl_base> m_impl;
0175 #endif
0176 };
0177
0178 }}} // namespace boost::python::objects
0179
0180 #endif // PY_FUNCTION_DWA200286_HPP