mapcss should be able to use previous fields in the selector in additional fields

[taylor.smock]

Example:

/* Check for duplicated words in names */
*[/^name/][regexp_test("\\b(\\p{L}+)\\b(?:\\s+\\1\\b)+", tag("{0.key}"), "(?i)")] {
  throwWarning: tr("Possible duplicated words in {0}", "{0.key}");
  assertMatch: "node name=\"Duplicate Duplicate\"";
  assertNoMatch: "node name=\"Nothing to see here\"";
}

instead of

*[/^name/][regexp_test("\\b(\\p{L}+)\\b(?:\\s+\\1\\b)+", tag("name"), "(?i)")] {
  throwWarning: tr("Possible duplicated words in {0}", "{0.key}");
}

Note:

*[/^name/][/^name/=~/(?i)\b(\p{L}+)\b(?:\s+\1\b)+/] {
  throwWarning: tr("Possible duplicated words in {0}", "{0.key}");
}

throws an error on the first +.