python/src/pygeos/c_api.h

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

/************************************************************************
 * PyGEOS C API
 *
 * This file wraps internal PyGEOS C extension functions for use in other
 * extensions.  These are specifically wrapped to enable dynamic loading
 * after Python initialization.
 *
 * Each function must provide 3 defines for use in the dynamic loading process:
 * NUM: the index in function pointer array
 * RETURN: the return type
 * PROTO: function prototype
 *
 * IMPORTANT: each function must provide 2 sets of defines below and
 * provide an entry into PyGEOS_API in lib.c module declaration block.
 *
 ***********************************************************************/

#ifndef _PYGEOS_API_H
#define _PYGEOS_API_H

#include <Python.h>

#include "../geos_c_dyn.h"

/* PyObject* PyGEOS_CreateGeometry(GEOSGeometry *ptr, GEOSContextHandle_t ctx)
 */
#define PyGEOS_CreateGeometry_NUM 0
#define PyGEOS_CreateGeometry_RETURN PyObject *
#define PyGEOS_CreateGeometry_PROTO \
  (GEOSGeometry * ptr, GEOSContextHandle_t ctx)

/* char PyGEOS_GetGEOSGeometry(GeometryObject *obj, GEOSGeometry **out) */
#define PyGEOS_GetGEOSGeometry_NUM 1
#define PyGEOS_GetGEOSGeometry_RETURN char
#define PyGEOS_GetGEOSGeometry_PROTO (PyObject * obj, GEOSGeometry * *out)

/* GEOSCoordSequence* PyGEOS_CoordSeq_FromBuffer(GEOSContextHandle_t ctx, const
   double* buf, unsigned int size, unsigned int dims, char ring_closure)*/
#define PyGEOS_CoordSeq_FromBuffer_NUM 2
#define PyGEOS_CoordSeq_FromBuffer_RETURN GEOSCoordSequence *
#define PyGEOS_CoordSeq_FromBuffer_PROTO                          \
  (GEOSContextHandle_t ctx, const double *buf, unsigned int size, \
   unsigned int dims, char ring_closure)

/* Total number of C API pointers */
#define PyGEOS_API_num_pointers 3

#ifdef PyGEOS_API_Module
/* This section is used when compiling shapely.lib C extension.
 * Each API function needs to provide a corresponding *_PROTO here.
 */

extern PyGEOS_CreateGeometry_RETURN PyGEOS_CreateGeometry
    PyGEOS_CreateGeometry_PROTO;
extern PyGEOS_GetGEOSGeometry_RETURN PyGEOS_GetGEOSGeometry
    PyGEOS_GetGEOSGeometry_PROTO;
extern PyGEOS_CoordSeq_FromBuffer_RETURN PyGEOS_CoordSeq_FromBuffer
    PyGEOS_CoordSeq_FromBuffer_PROTO;

#else
/* This section is used in modules that use the PyGEOS C API
 * Each API function needs to provide the lookup into PyGEOS_API as a
 * define statement.
 */

static void **PyGEOS_API;

#define PyGEOS_CreateGeometry        \
  (*(PyGEOS_CreateGeometry_RETURN(*) \
         PyGEOS_CreateGeometry_PROTO)PyGEOS_API[PyGEOS_CreateGeometry_NUM])

#define PyGEOS_GetGEOSGeometry        \
  (*(PyGEOS_GetGEOSGeometry_RETURN(*) \
         PyGEOS_GetGEOSGeometry_PROTO)PyGEOS_API[PyGEOS_GetGEOSGeometry_NUM])

#define PyGEOS_CoordSeq_FromBuffer                                          \
  (*(PyGEOS_CoordSeq_FromBuffer_RETURN(*) PyGEOS_CoordSeq_FromBuffer_PROTO) \
       PyGEOS_API[PyGEOS_CoordSeq_FromBuffer_NUM])

/* Dynamically load C API from PyCapsule.
 * This MUST be called prior to using C API functions in other modules;
 * otherwise segfaults will occur when the PyGEOS C API functions are called.
 *
 * Returns 0 on success, -1 if error.
 * PyCapsule_Import will set an exception on error.
 */
static int import_shapely_c_api(void) {
  PyGEOS_API = (void **)PyCapsule_Import("shapely.lib._C_API", 0);
  return (PyGEOS_API == NULL) ? -1 : 0;
}

#endif

#endif /* !defined(_PYGEOS_API_H) */