[postgis-devel] WKT Parser changes for Curve support

[Mark Leslie]

I've cobbled together a quick RFC describing some changes I'd like to 
impose upon the parser in order to support the CompoundCurve and 
CurvePolygon properly.  I've committed it to trunk: 
http://svn.refractions.net/postgis/trunk/doc/rfc/postgis_rfc_04.txt

The short summary is that our practise of using global variables to 
define constraints such as minimum number of points or ring closure no 
longer work once we start dealing with nesting of multiple geometry 
types and constraints between sub-geometries, such as checking the 
continuity of a compound curve.

My proposed change moves the validation to the level of a complete 
geometry, instead of validating each point array on completion.  The 
down sides are that it will need to traverse the list of tuples to 
properly validate which can only degrade performance, and it will no 
longer report which point array is in violation of a given constraint, 
only which geometry.

Please have a look at the rfc and share any comments you have.

-- 
Mark Leslie
Geospatial Software Architect
LISAsoft

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