funcWrapper.h

// This file is part of Cantera. See License.txt in the top-level directory or
// at https://cantera.org/license.txt for license and copyright information.
 
#ifndef CT_CYTHON_FUNC_WRAPPER
#define CT_CYTHON_FUNC_WRAPPER
 
#include "cantera/numerics/Func1.h"
#include "cantera/base/ctexceptions.h"
#include <stdexcept>
 
#define CANTERA_USE_INTERNAL
#include "cantera/clib/clib_defs.h"
#include "Python.h"
 
typedef double(*callback_wrapper)(double, void*, void**);
 
// A C++ exception that holds a Python exception so that it can be re-raised
// by translate_exception()
class CallbackError : public Cantera::CanteraError
{
public:
    CallbackError(void* type, void* value) :
        CanteraError("Python callback function"),
        m_type((PyObject*) type),
        m_value((PyObject*) value)
    {
    }
    std::string getMessage() const {
        std::string msg;
 
        PyObject* name = PyObject_GetAttrString(m_type, "__name__");
        PyObject* value_str = PyObject_Str(m_value);
 
        #if PY_MAJOR_VERSION > 2
        PyObject* name_bytes = PyUnicode_AsASCIIString(name);
        PyObject* value_bytes = PyUnicode_AsASCIIString(value_str);
        #else
        PyObject* name_bytes = PyObject_Bytes(name);
        PyObject* value_bytes = PyObject_Bytes(value_str);
        #endif
 
        if (name_bytes) {
            msg += PyBytes_AsString(name_bytes);
            Py_DECREF(name_bytes);
        } else {
            msg += "<error determining exception type>";
        }
 
        msg += ": ";
 
        if (value_bytes) {
            msg += PyBytes_AsString(value_bytes);
            Py_DECREF(value_bytes);
        } else {
            msg += "<error determining exception message>";
        }
 
        Py_XDECREF(name);
        Py_XDECREF(value_str);
        return msg;
    }
 
    virtual std::string getClass() const {
        return "Exception";
    }
 
    PyObject* m_type;
    PyObject* m_value;
};
 
 
// A function of one variable implemented as a callable Python object
class Func1Py : public Cantera::Func1
{
public:
    Func1Py(callback_wrapper callback, void* pyobj) :
        m_callback(callback),
        m_pyobj(pyobj) {
    }
 
    double eval(double t) const {
        void* err[2] = {0, 0};
        double y = m_callback(t, m_pyobj, err);
        if (err[0]) {
            throw CallbackError(err[0], err[1]);
        }
        return y;
    }
 
private:
    callback_wrapper m_callback;
    void* m_pyobj;
};
 
extern "C" {
    CANTERA_CAPI PyObject* pyCanteraError;
}
 
// Translate C++ Exceptions generated by Cantera to appropriate Python
// exceptions. Used with Cython function declarations, e.g:
//     cdef double eval(double) except +translate_exception
inline int translate_exception()
{
    try {
        if (!PyErr_Occurred()) {
            // Let the latest Python exception pass through and ignore the
            // current one.
            throw;
        }
    } catch (const CallbackError& exn) {
        // Re-raise a Python exception generated in a callback
        PyErr_SetObject(exn.m_type, exn.m_value);
    } catch (const std::out_of_range& exn) {
        PyErr_SetString(PyExc_IndexError, exn.what());
    } catch (const Cantera::CanteraError& exn) {
        PyErr_SetString(pyCanteraError, exn.what());
    } catch (const std::exception& exn) {
        PyErr_SetString(PyExc_RuntimeError, exn.what());
    } catch (...) {
        PyErr_SetString(PyExc_Exception, "Unknown exception");
    }
    return 0;
}
 
#endif