MapCSS: implement "set"

[Don-vip]

From our very own implementation:

• set is not supported, instead of

  way[highway=footway] { set path; color: #FF6644; width: 2; }
  way[highway=path]    { set path; color: brown; width: 2; }
  way.path { text:auto; text-color: green; text-position: line; text-offset: 5; }
  

  you can write

  way[highway=footway] { path-set : true; color: #FF6644; width: 2; }
  way[highway=path]    { path-set : true; color: brown; width: 2; }
  way[eval(prop(path-set))] { text:auto; text-color: green; text-position: line; text-offset: 5; }
  

I'd like to use this syntax in MapCSS-Tagchecker, we should support it.

[simon04]

What should be the effect of a set statement?

[Don-vip]

As I understand the ​specification, it should allow us to define classes we can then use as selectors.

Examples I have in mind for #9379 and #9380:

way[highway=~/(motorway|trunk|primary|secondary|tertiary)(_link)?/] {
  set major_road;
}
way[highway=~/unclassified|residential|living_street|service/] {
  set minor_road;
}
way.major_road[motor_vehicle=yes] {
  throwWarning("unnecessary ...");
}
way.major_road[foot=yes] {
  throwWarning("replace by sidewalk...");
}

[simon04]

Okay, thanks. I got the idea now.

I found an implementation in dart-mapcss: ​https://github.com/Gubaer/dart-mapcss/blob/master/grammar/MapCSS.g#L413-L416 Here, only identifiers are allowed (no evaluation of complex expression is performed).

[simon04]

In 6560/josm:

see #9485 - MapCSS: add support for set class_name instruction and .class_name condition (which is specified in the MapCSS specification)

[simon04]

In 6561/josm:

see #9485 - MapCSS: add support for set .class_name instruction (with optional . before class), define Range.ZERO_TO_INFINITY

[simon04]

In 6601/josm:

see #9414 fix #9485 - MapCSSTagChecker: add support for set class_name instruction and .class_name condition