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// Copyright David Abrahams 2002.
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#include <boost/python/converter/from_python.hpp>
#include <boost/python/converter/registrations.hpp>
#include <boost/python/converter/rvalue_from_python_data.hpp>
#include <boost/python/object/find_instance.hpp>
#include <boost/python/handle.hpp>
#include <boost/python/detail/raw_pyobject.hpp>
#include <boost/python/cast.hpp>
#include <vector>
#include <algorithm>
namespace boost { namespace python { namespace converter {
// rvalue_from_python_stage1 -- do the first stage of a conversion
// from a Python object to a C++ rvalue.
//
// source - the Python object to be converted
// converters - the registry entry for the target type T
//
// Postcondition: where x is the result, one of:
//
// 1. x.convertible == 0, indicating failure
//
// 2. x.construct == 0, x.convertible is the address of an object of
// type T. Indicates a successful lvalue conversion
//
// 3. where y is of type rvalue_from_python_data<T>,
// x.construct(source, y) constructs an object of type T
// in y.storage.bytes and then sets y.convertible == y.storage.bytes,
// or else throws an exception and has no effect.
BOOST_PYTHON_DECL rvalue_from_python_stage1_data rvalue_from_python_stage1(
PyObject* source
, registration const& converters)
{
rvalue_from_python_stage1_data data;
// First check to see if it's embedded in an extension class
// instance, as a special case.
data.convertible = objects::find_instance_impl(source, converters.target_type, converters.is_shared_ptr);
data.construct = 0;
if (!data.convertible)
{
for (rvalue_from_python_chain const* chain = converters.rvalue_chain;
chain != 0;
chain = chain->next)
{
void* r = chain->convertible(source);
if (r != 0)
{
data.convertible = r;
data.construct = chain->construct;
break;
}
}
}
return data;
}
// rvalue_result_from_python -- return the address of a C++ object which
// can be used as the result of calling a Python function.
//
// src - the Python object to be converted
//
// data - a reference to the base part of a
// rvalue_from_python_data<T> object, where T is the
// target type of the conversion.
//
// Requires: data.convertible == ®istered<T>::converters
//
BOOST_PYTHON_DECL void* rvalue_result_from_python(
PyObject* src, rvalue_from_python_stage1_data& data)
{
// Retrieve the registration
// Cast in two steps for less-capable compilers
void const* converters_ = data.convertible;
registration const& converters = *static_cast<registration const*>(converters_);
// Look for an eligible converter
data = rvalue_from_python_stage1(src, converters);
return rvalue_from_python_stage2(src, data, converters);
}
BOOST_PYTHON_DECL void* rvalue_from_python_stage2(
PyObject* source, rvalue_from_python_stage1_data& data, registration const& converters)
{
if (!data.convertible)
{
handle<> msg(
#if PY_VERSION_HEX >= 0x03000000
::PyUnicode_FromFormat
#else
::PyString_FromFormat
#endif
(
"No registered converter was able to produce a C++ rvalue of type %s from this Python object of type %s"
, converters.target_type.name()
, source->ob_type->tp_name
));
PyErr_SetObject(PyExc_TypeError, msg.get());
throw_error_already_set();
}
// If a construct function was registered (i.e. we found an
// rvalue conversion), call it now.
if (data.construct != 0)
data.construct(source, &data);
// Return the address of the resulting C++ object
return data.convertible;
}
BOOST_PYTHON_DECL void* get_lvalue_from_python(
PyObject* source
, registration const& converters)
{
// Check to see if it's embedded in a class instance
void* x = objects::find_instance_impl(source, converters.target_type);
if (x)
return x;
lvalue_from_python_chain const* chain = converters.lvalue_chain;
for (;chain != 0; chain = chain->next)
{
void* r = chain->convert(source);
if (r != 0)
return r;
}
return 0;
}
namespace
{
// Prevent looping in implicit conversions. This could/should be
// much more efficient, but will work for now.
typedef std::vector<rvalue_from_python_chain const*> visited_t;
static visited_t visited;
inline bool visit(rvalue_from_python_chain const* chain)
{
visited_t::iterator const p = std::lower_bound(visited.begin(), visited.end(), chain);
if (p != visited.end() && *p == chain)
return false;
visited.insert(p, chain);
return true;
}
// RAII class for managing global visited marks.
struct unvisit
{
unvisit(rvalue_from_python_chain const* chain)
: chain(chain) {}
~unvisit()
{
visited_t::iterator const p = std::lower_bound(visited.begin(), visited.end(), chain);
assert(p != visited.end());
visited.erase(p);
}
private:
rvalue_from_python_chain const* chain;
};
}
BOOST_PYTHON_DECL bool implicit_rvalue_convertible_from_python(
PyObject* source
, registration const& converters)
{
if (objects::find_instance_impl(source, converters.target_type))
return true;
rvalue_from_python_chain const* chain = converters.rvalue_chain;
if (!visit(chain))
return false;
unvisit protect(chain);
for (;chain != 0; chain = chain->next)
{
if (chain->convertible(source))
return true;
}
return false;
}
namespace
{
void throw_no_lvalue_from_python(PyObject* source, registration const& converters, char const* ref_type)
{
handle<> msg(
#if PY_VERSION_HEX >= 0x03000000
::PyUnicode_FromFormat
#else
::PyString_FromFormat
#endif
(
"No registered converter was able to extract a C++ %s to type %s"
" from this Python object of type %s"
, ref_type
, converters.target_type.name()
, source->ob_type->tp_name
));
PyErr_SetObject(PyExc_TypeError, msg.get());
throw_error_already_set();
}
void* lvalue_result_from_python(
PyObject* source
, registration const& converters
, char const* ref_type)
{
handle<> holder(source);
if (source->ob_refcnt <= 1)
{
handle<> msg(
#if PY_VERSION_HEX >= 0x3000000
::PyUnicode_FromFormat
#else
::PyString_FromFormat
#endif
(
"Attempt to return dangling %s to object of type: %s"
, ref_type
, converters.target_type.name()));
PyErr_SetObject(PyExc_ReferenceError, msg.get());
throw_error_already_set();
}
void* result = get_lvalue_from_python(source, converters);
if (!result)
(throw_no_lvalue_from_python)(source, converters, ref_type);
return result;
}
}
BOOST_PYTHON_DECL void throw_no_pointer_from_python(PyObject* source, registration const& converters)
{
(throw_no_lvalue_from_python)(source, converters, "pointer");
}
BOOST_PYTHON_DECL void throw_no_reference_from_python(PyObject* source, registration const& converters)
{
(throw_no_lvalue_from_python)(source, converters, "reference");
}
BOOST_PYTHON_DECL void* reference_result_from_python(
PyObject* source
, registration const& converters)
{
return (lvalue_result_from_python)(source, converters, "reference");
}
BOOST_PYTHON_DECL void* pointer_result_from_python(
PyObject* source
, registration const& converters)
{
if (source == Py_None)
{
Py_DECREF(source);
return 0;
}
return (lvalue_result_from_python)(source, converters, "pointer");
}
BOOST_PYTHON_DECL void void_result_from_python(PyObject* o)
{
Py_DECREF(expect_non_null(o));
}
} // namespace boost::python::converter
BOOST_PYTHON_DECL PyObject*
pytype_check(PyTypeObject* type_, PyObject* source)
{
if (!PyObject_IsInstance(source, python::upcast<PyObject>(type_)))
{
::PyErr_Format(
PyExc_TypeError
, "Expecting an object of type %s; got an object of type %s instead"
, type_->tp_name
, source->ob_type->tp_name
);
throw_error_already_set();
}
return source;
}
}} // namespace boost::python