Geometry Boost List: [geometry] [equals] equals(Linestring, Linestring) behavior changed

Subject: [geometry] [equals] equals(Linestring, Linestring) behavior changed
From: Adam Wulkiewicz (adam.wulkiewicz_at_[hidden])
Date: 2014-05-06 13:20:14

Hi,

The equal(Linestring, Linestring) is changed and 
Linestring/MultiLinestring and MultiLinestring/MultiLinestring versions 
are now available.

Previously used trivial-check- and collect_vectors- based approach 
wasn't working correctly for non-simple (OGC conformant) Linear 
geometries. So now, internally relate() is used for L/L versions of 
geometries.
equals() should now return TRUE for geometries occupying the same space.

One remark.

OGC specs defines the DE9IM mask for equals() as: TFFFTFFFT
However in the Wikipedia we may find: T*F**FFF*.

Currently the second one is used (T*F**FFF*). Otherwise the function 
would return FALSE for Linear Geometries Linestrings occupying the same 
space but with non-corresponding boundaries. E.g. consider this pair of 
Linestrings:

LINESTRING(0 0,5 0,5 5,0 5,0 0)
LINESTRING(5 5,0 5,0 0,5 0,5 5,0 5)

The first one is LinearRing (no boundary). The second one has 2-Point 
boundary (and overlapping segments). They occupy the same space though. 
So currently TRUE should be returned in this case. AFAIK this is 
consistent with PostGIS.

Feel free to object.

Regards,
Adam