--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/django/contrib/gis/geos/prototypes/topology.py	Tue Oct 14 16:00:59 2008 +0000
@@ -0,0 +1,35 @@
+"""
+ This module houses the GEOS ctypes prototype functions for the 
+ topological operations on geometries.
+"""
+from ctypes import c_char_p, c_double, c_int
+from django.contrib.gis.geos.libgeos import lgeos, GEOM_PTR
+from django.contrib.gis.geos.prototypes.errcheck import check_geom, check_string
+
+def topology(func, *args):
+    "For GEOS unary topology functions."
+    argtypes = [GEOM_PTR]
+    if args: argtypes += args
+    func.argtypes = argtypes
+    func.restype = GEOM_PTR
+    func.errcheck = check_geom
+    return func
+
+### Topology Routines ###
+geos_boundary = topology(lgeos.GEOSBoundary)
+geos_buffer = topology(lgeos.GEOSBuffer, c_double, c_int)
+geos_centroid = topology(lgeos.GEOSGetCentroid)
+geos_convexhull = topology(lgeos.GEOSConvexHull)
+geos_difference = topology(lgeos.GEOSDifference, GEOM_PTR)
+geos_envelope = topology(lgeos.GEOSEnvelope)
+geos_intersection = topology(lgeos.GEOSIntersection, GEOM_PTR)
+geos_pointonsurface = topology(lgeos.GEOSPointOnSurface)
+geos_preservesimplify = topology(lgeos.GEOSTopologyPreserveSimplify, c_double)
+geos_simplify = topology(lgeos.GEOSSimplify, c_double)
+geos_symdifference = topology(lgeos.GEOSSymDifference, GEOM_PTR)
+geos_union = topology(lgeos.GEOSUnion, GEOM_PTR)
+
+# GEOSRelate returns a string, not a geometry.
+geos_relate = lgeos.GEOSRelate
+geos_relate.argtypes = [GEOM_PTR, GEOM_PTR]
+geos_relate.errcheck = check_string