[RFC PATCH] Check if a pref could be converted to a color instead of a string

[taylor.smock]

Example mapcss code:

way[regexp_test(concat("^(", JOSM_pref("mapwithai.mappaint.sources", "microsoft|digitalglobe"), ")$"), tag("source"))][setting("show_new")]:new {
    set .mapwithai;
    set_color: JOSM_pref(concat("mapwithai.mappaint.", tag("source"), "_new"), #FF00FF);
}
way[regexp_test(concat("^(", JOSM_pref("mapwithai.mappaint.sources", "microsoft|digitalglobe"), ")$"), tag("source"))][setting("show_old")]!:new!:modified {
    set .mapwithai;
    set_color: JOSM_pref(concat("mapwithai.mappaint.", tag("source"), "_old"), #FF00FF);
}
way[regexp_test(concat("^(", JOSM_pref("mapwithai.mappaint.sources", "microsoft|digitalglobe"), ")$"), tag("source"))][setting("show_modified")]:modified {
    set .mapwithai;
    set_color: JOSM_pref(concat("mapwithai.mappaint.", tag("source"), "_modified"), #FF00FF);
}

way.mapwithai {
    color: prop("set_color");
}

I would have preferred to do something like the following:

way[regexp_test(concat("^(", JOSM_pref("mapwithai.mappaint.sources", "microsoft|digitalglobe"), ")$"), tag("source"))][setting("show_new")]:new {
    set .mapwithai;
    set_color: concat("sources", "_new");
}
way[regexp_test(concat("^(", JOSM_pref("mapwithai.mappaint.sources", "microsoft|digitalglobe"), ")$"), tag("source"))][setting("show_old")]!:new!:modified {
    set .mapwithai;
    set_color: concat("sources", "_old");
}
way[regexp_test(concat("^(", JOSM_pref("mapwithai.mappaint.sources", "microsoft|digitalglobe"), ")$"), tag("source"))][setting("show_modified")]:modified {
    set .mapwithai;
    set_color: concat("sources", "_modified");
}

way.mapwithai {
    color: prop("set_color")#FF00FF;
}

Unfortunately, the latter doesn't work well (I've also tried wrapping prop in an eval expression, just in case there was special handling). I tried figuring out if there was a way for me to attempt to evaluate a color expression, when there is a default. I haven't seen one. :(

I am unable to hardcode all of the possible MapWithAI sources (you can add any third-party OSM-XML server source).

[taylor.smock]

Probably needs some work around NamedColorProperty

[simon04]

Unit tests would be very welcome for JOSM_pref/getPreferenceCached.

You might want to use org.openstreetmap.josm.tools.ColorHelper#color2html(java.awt.Color)

[taylor.smock]

Use ColorHelper. No tests implemented.

[simon04]

In 16583/josm:

see #19197 - Add FunctionsTest.testPref

[taylor.smock]

Add tests (extends FunctionsTest.testPref, and abstracts the base code for testing preferences)

[simon04]

In 16590/josm:

fix #19197 - MapCSS JOSM_pref: check if a pref could be converted to a color instead of a string (patch by taylor.smock, modified)

[simon04]

Thanks. I've refactored/split the test function since I found hard to see what was actually being tested.

Help/Styles/MapCSSImplementation needs to be updated.

[taylor.smock]

I've updated the JOSM_pref section of the help page. I specified the change, and what it now allows.