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- """
- Error checking functions for GEOS ctypes prototype functions.
- """
- from ctypes import c_void_p, string_at
-
- from django.contrib.gis.geos.error import GEOSException
- from django.contrib.gis.geos.libgeos import GEOSFuncFactory
-
- # Getting the `free` routine used to free the memory allocated for
- # string pointers returned by GEOS.
- free = GEOSFuncFactory('GEOSFree')
- free.argtypes = [c_void_p]
-
-
- def last_arg_byref(args):
- "Return the last C argument's value by reference."
- return args[-1]._obj.value
-
-
- def check_dbl(result, func, cargs):
- "Check the status code and returns the double value passed in by reference."
- # Checking the status code
- if result != 1:
- return None
- # Double passed in by reference, return its value.
- return last_arg_byref(cargs)
-
-
- def check_geom(result, func, cargs):
- "Error checking on routines that return Geometries."
- if not result:
- raise GEOSException('Error encountered checking Geometry returned from GEOS C function "%s".' % func.__name__)
- return result
-
-
- def check_minus_one(result, func, cargs):
- "Error checking on routines that should not return -1."
- if result == -1:
- raise GEOSException('Error encountered in GEOS C function "%s".' % func.__name__)
- else:
- return result
-
-
- def check_predicate(result, func, cargs):
- "Error checking for unary/binary predicate functions."
- if result == 1:
- return True
- elif result == 0:
- return False
- else:
- raise GEOSException('Error encountered on GEOS C predicate function "%s".' % func.__name__)
-
-
- def check_sized_string(result, func, cargs):
- """
- Error checking for routines that return explicitly sized strings.
-
- This frees the memory allocated by GEOS at the result pointer.
- """
- if not result:
- raise GEOSException('Invalid string pointer returned by GEOS C function "%s"' % func.__name__)
- # A c_size_t object is passed in by reference for the second
- # argument on these routines, and its needed to determine the
- # correct size.
- s = string_at(result, last_arg_byref(cargs))
- # Freeing the memory allocated within GEOS
- free(result)
- return s
-
-
- def check_string(result, func, cargs):
- """
- Error checking for routines that return strings.
-
- This frees the memory allocated by GEOS at the result pointer.
- """
- if not result:
- raise GEOSException('Error encountered checking string return value in GEOS C function "%s".' % func.__name__)
- # Getting the string value at the pointer address.
- s = string_at(result)
- # Freeing the memory allocated within GEOS
- free(result)
- return s
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