initial import

git-svn-id: http://svn.osgeo.org/postgis/trunk@1205 b70326c6-7e19-0410-871a-916f4a2858ee

diff --git a/lwgeom/BBOXCACHE_BEHAVIOURS b/lwgeom/BBOXCACHE_BEHAVIOURS
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+Possible strategies:
+
+       1) compute bbox if geometry is complex. 
+
+       2) compute bbox if it's a simple operation (some combination
+          of input bboxes - iff all available)
+
+       3) compute bbox if any input geoms have one
+
+       4) never compute bbox
+
+       5) always compute bbox
+
+We can express the strategies with these labels:
+
+COMPUTE_BBOX:
+        1) FOR_COMPLEX_GEOMS,
+        2) WHEN_SIMPLE,
+        3) TAINTING,
+        4) ALWAYS,
+        5) NEVER
+
+Here is a list of geometry-returning functions with the bbox cache
+strategy they use. Note that current condition matching
+FOR_COMPLEX_GEOMS is that geometrytype(geom) != POINTTYPE.
+
+[ explicit control ]
+       addBBOX(geometry) 
+       dropBBOX(geometry) 
+
+[ AUTOCACHE_BBOX==1 ? FOR_COMPLEX_GEOMS : NEVER ]
+       geometry_in(cstring)
+       geometry_recv(internal)
+       geometry(text)
+       geometry(bytea)
+       GeometryFromText(geometry, SRID)
+       GeomFromWKB(bytea, SRID)
+       GeomFromEWKB(bytea)
+       GeomFromEWKT(text)
+       noop(geometry)
+       polygonize_garray (geometry[])
+       -- GEOS
+       intersection(geometry,geometry)
+       buffer(geometry,float8,[integer])
+       difference(geometry,geometry)
+       boundary(geometry) 
+       symdifference(geometry,geometry)
+       symmetricdifference(geometry,geometry)
+       GeomUnion(geometry,geometry)
+       unite_garray (geometry[])
+       GEOSnoop(geometry)
+       Centroid(geometry)
+       PointOnSurface(geometry)
+
+[ TAINING ]
+       GeometryN(geometry,integer)
+
+       #### could use WHEN_SIMPLE
+       #### translating and transforming an eventually present
+       #### bbox cache in input
+       translate(geometry,float8,float8,[float8])
+       transform(geometry,integer)
+
+       InteriorRingN(geometry,integer) 
+       simplify(geometry, float8)
+
+[ WHEN_SIMPLE (use input bbox if present) ]
+       ExteriorRing(geometry)
+       SetSRID(geometry,int4) 
+       force_2d(geometry) 
+       force_3dz(geometry) 
+       force_3d(geometry) 
+       force_3dm(geometry) 
+       force_4d(geometry) 
+       force_collection(geometry) 
+       multi(geometry) 
+       envelope(geometry)
+       reverse(geometry)
+       ForceRHR(geometry)
+       segmentize(geometry, float8)
+       convexhull(geometry) #### uses FOR_COMPLEX_GEOMS with AUTOCACHE_BBOX=1
+
+[ NEVER ]
+       PointN(geometry,integer)
+       StartPoint(geometry) 
+       EndPoint(geometry) 
+
+       ### could use WHEN_SIMPLE computing union of
+       ### input bbox (if available or SIMPLE to compute: points)
+       collector(geometry, geometry) 
+       collect(geometry, geometry) 
+       collect_garray (geometry[]) 
+       
+       makePoint(float8, float8, [float8], [float8])
+       makePointM(float8, float8, float8)
+       makeline_garray (geometry[])
+       LineFromMultiPoint(geometry)
+       MakeLine(geometry, geometry)
+       AddPoint(geometry, geometry, [integer])
+       geometry(box2d)
+       geometry(box3d)
+       geometry(chip)
+       line_interpolate_point(geometry, float8)
+       Centroid(geometry) [the version w/out GEOS]
+
+[ ALWAYS ]
+       expand(geometry,float8)
+