User interface

[Cidree]

Overview

This PR refers to what has been discussed in #92.

I implemented what I explained in this comment, so we can experiment from there.

This is not the definitive approach, as we still need to discuss if this is the best way, and find if there are weaknesses in this method before moving forward.

I will describe the 2-type approach to implement macros.

Simple functions

They just have a 1-to-1 function relationship. For example:

CREATE OR REPLACE MACRO ddbs_is_simple(geom) AS ST_IsSimple(geom);

That will fully integrate ddbs_is_simple().

Complex functions

Those that use one duckspatial function to execute more than 1 DuckDB functions. For example, ddbs_area() uses ST_Area() or ST_Area_Spheroid() depending on the CRS. Therefore, I implemented a macro that will use one or the other depending on the CRS, found in the crs_duckspatial column:

CREATE OR REPLACE MACRO ddbs_area(geom) AS (
      CASE 
        WHEN crs_duckspatial = 'EPSG:4326' THEN ST_Area_Spheroid(ST_FlipCoordinates(geom))
        ELSE ST_Area(geom)
      END
    );

This has an obvious flaw: if the CRS is stored in a different column name, it won't work. However, I wouldn't give so much of impotance to this. When DuckDB v1.5.0 is released, that will be replaced by ST_SRID() or whichever will be the function that returns the CRS.

[Cidree]

By the way, only the last 3 commits are related to this PR.