Enhancing geosop with an option for printing the reason behind each TopologyValidationError

[swiss-knight]

Hi,

It would be of great help if one can check TopologyValidationError reason messages using the geosop CLI tool.
I'm thinking of these messages.

Indeed, currently it only has those abilities regarding validation (from geosop --help):

  Validity  ------------------
   A    isSimple > B - test if geometry is simple
   A    isValid > B - test if geometry is valid
   A    fixInvalid > G - fix invalid geometry to be valid
   A    makeValid > G - make geometry valid (original algorithm)

I'd love seeing a new option which can print the reason why a geometry is valid or invalid, e.g. isValidReason:

  Validity  ------------------
   A    isSimple > B - test if geometry is simple
   A    isValid > B - test if geometry is valid
   A    isValidReason > B - return the topology validation error message
   A    fixInvalid > G - fix invalid geometry to be valid
   A    makeValid > G - make geometry valid (original algorithm)

Of course, one can also imagine exposing the location where the validity issue was met.

This is especially "frustrating" because such underlying messages are shown by GDAL/OGR when meeting an invalid geometry using the SQLITE ST_IsValid() function:

ogrinfo :memory: -sql "SELECT ST_IsValid(GeomFromText(\"POLYGON ((0 0, 1 0, 1 1, 0 1, 0 0), (2 2, 3 2, 3 3, 2 3, 2 2))\")) AS Err" -dialect SQLITE -q
GEOS warning: Hole lies outside shell at or near point 2 2

Layer name: SELECT
OGRFeature(SELECT):0
  Err (Integer) = 0

and I would very much like to receive these messages, independently of GDAL, with geosop as well.

Thanks!