mapcss [functionresult() <= functionresult()] gives bad results with numbers

[Famlam]

way 680531945 has the following tags

building:levels=11 
building:min_level=9
building:part=yes

Having the following mapcss selector from combinations.mapcss in JOSM (where you can temporarily replace area by way until that PR has been merged)

area[/^(building\|building:part)$/][height =~ /^[0-9]+(\.[0-9]+)?( m)?$/][min_height =~ /^[0-9]+(\.[0-9]+)?( m)?$/][get(split(" ", tag(height)), 0) <= get(split(" ", tag(min_height)), 0)],
area[/^(building\|building:part)$/][building:levels][building:min_level][tag("building:levels") <= tag("building:min_level")] {
throwWarning: tr("{0} is lower or equal to {1} on {2}", "{1.key}", "{2.key}", "{0.key}");
group: tr("suspicious tag combination");
}

JOSM will not warn.
Osmose will show the following message:

building:levels is lower or equal to building:min_level on building:part

So apparently JOSM does a numeric comparison (11 > 9), while Osmose does a string ("11" < "9") comparison for [tag("building:levels") <= tag("building:min_level")]

Similar for way 680531956 with height = 104 and min_height = 96.

Maybe we'll have to do some checks with "value".isdecimal() or similar in the redefinition of <= (etcetera) in mapcss_lib.py.

[Famlam]

It seems that the following mapcss passes all tests in JOSM:

node[a][b][tag("a") > tag("b")] {
  throwError: tr("{0}-{1}", "{0.tag}", "{1.tag}");
  assertNoMatch: "node a=3  b=6";
  assertNoMatch: "node a=X  b=Y";
  assertNoMatch: "node a=3a b=6a";
  assertNoMatch: "node a=3a b=6";
  assertNoMatch: "node a=3  b=6a";
  assertMatch:   "node b=3  a=6";
  assertMatch:   "node b=3  a=12"; /* Fails in Osmose */
  assertNoMatch: "node b=X  a=Y"; /* Fails in Osmose */
  assertNoMatch: "node b=3a a=6a"; /* Fails in Osmose */
  assertNoMatch: "node b=3a a=6"; /* Fails in Osmose */
  assertNoMatch: "node b=3  a=6a"; /* Fails in Osmose */
}

node[a > 2] {
  throwError: tr("{0}", "{0.tag}");
  assertMatch: "node a=3";
  assertNoMatch: "node a=X";
  assertNoMatch: "node a=1";
}

Which seems to imply that the way to interpret >, <, >=, <= in mapcss context is to just try to convert both left and right operands to numbers, and if it fails, just abort. (I.e. never compare strings).

(Technically it's also what the wiki says: "Comparison for numeric values.")

This is already implemented as such for selectors like [a > 2], but when the right hand side value isn't a number it currently falls back to string comparison.

[frodrigo]

Ok. It should not be hard to change that.

[Famlam]

Agree, it's on my planning for tonight :)
(Unless you're faster ;) )