WL#10927: Ellipsoidal ST_IsSimple

Affects: Server-8.0 — Status: Complete

Description
Requirements
High Level Architecture
Low Level Design

ST_IsSimple currently only supports computations in Cartesian spatial reference systems (SRSs). This WL extends ST_IsSimple to detect that its parameter is in a geographic (ellipsoidal) SRS and to compute on the ellipsoid.

Projected SRSs and SRID 0 will still return the same result as before. If the SRID refers to a geographic SRS, the result will be different.

The ST_IsSimple function will be implemented as described in SQL/MM Part 3 Spatial (ISO/IEC 13249-3:2015), Sect. 5.1.8.

F-1: ST_IsSimple MUST return NULL if its argument is NULL.
F-2: ST_IsSimple MUST NOT return NULL if its argument is not NULL.
F-3: If the argument is not a syntactically well-formed geometry, ST_IsSimple MUST raise ER_GIS_INVALID_DATA during function evaluation.
F-4: ST_IsSimple MUST return 1 if its argument is an empty geometry.
F-5: If the argument is geometrically simple, ST_IsSimple MUST return 1.
F-6: If the argument is not geometrically simple, ST_IsSimple MUST return 0.
F-7: If the argument is a geometry in a geographic SRS and a longitude value is not in the range (-180,180] (in degrees -- other limits in other units), ST_IsSimple MUST raise ER_LONGITUDE_OUT_OF_RANGE.(*)
F-8: If the argument is a geometry in a geographic SRS and a latitude value is not in the range [-90,90] (in degrees -- other limits in other units), ST_IsSimple MUST raise ER_LATITUDE_OUT_OF_RANGE.(*)

NF-1: The function MUST be non-nullable if the argument is non-nullable.
NF-2: The function MUST be nullable if the argument is nullable.

(*) The exact limits will deviate slightly because of floating point arithmetics.

I-1: No new files.
I-2: No new syntax.
I-3: No new commands.
I-4: No new tools.
I-5: The semantics of interface SQL01 are changed: If the geometry is in a geographic SRS, ST_IsSimple will return a result based on geographical computations. Other computations will remain as they are today.
I-6: No new errors or warnings.

Modify Item_func_issimple and implement the desired behavior in function val_int(). Update function resolve_type() to set maybe_null only if the parameter is nullable.

Create a functor gis::Is_simple and a function gis::is_simple() in sql/gis/is_simple.{h,cc} after the model of gis::distance(), gis::within(), etc., that computes the result using Boost.Geometry.