cpython/Include/cStringIO.h

#ifndef CSTRINGIO_INCLUDED
#define CSTRINGIO_INCLUDED
#ifdef __cplusplus
extern "C" {
#endif
/*

  This header provides access to cStringIO objects from C.
  Functions are provided for calling cStringIO objects and
  macros are provided for testing whether you have cStringIO 
  objects.

  Before calling any of the functions or macros, you must initialize
  the routines with:

    PycString_IMPORT

  This would typically be done in your init function.

*/

/* Basic functions to manipulate cStringIO objects from C */

static struct PycStringIO_CAPI {
  
  /* Read a string.  If the last argument is -1, the remainder will be read. */
  int(*cread)(PyObject *, char **, int);

  /* Read a line */
  int(*creadline)(PyObject *, char **);

  /* Write a string */
  int(*cwrite)(PyObject *, char *, int);

  /* Get the cStringIO object as a Python string */
  PyObject *(*cgetvalue)(PyObject *);

  /* Create a new output object */
  PyObject *(*NewOutput)(int);

  /* Create an input object from a Python string */
  PyObject *(*NewInput)(PyObject *);

  /* The Python types for cStringIO input and output objects.
     Note that you can do input on an output object.
     */
  PyTypeObject *InputType, *OutputType;

} * PycStringIO = NULL;

/* These can be used to test if you have one */
#define PycStringIO_InputCheck(O) \
  ((O)->ob_type==PycStringIO->InputType)
#define PycStringIO_OutputCheck(O) \
  ((O)->ob_type==PycStringIO->OutputType)

static void *
xxxPyCObject_Import(char *module_name, char *name)
{
  PyObject *m, *c;
  void *r=NULL;
  
  if((m=PyImport_ImportModule(module_name)))
    {
      if((c=PyObject_GetAttrString(m,name)))
	{
	  r=PyCObject_AsVoidPtr(c);
	  Py_DECREF(c);
	}
      Py_DECREF(m);
    }

  return r;
}

#define PycString_IMPORT \
  PycStringIO=(struct PycStringIO_CAPI*)xxxPyCObject_Import("cStringIO", "cStringIO_CAPI")

#ifdef __cplusplus
}
#endif
#endif /* CSTRINGIO_INCLUDED */