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01136: change PTV use in pagelists to be more intuitive

Description: Currently there is no way to differentiate between an undefined PTV as opposed to a defined-blank PTV. And the way to select on a blank PTV is the highly unintuitive $:ptv=-?* while the way to select on a non-blank PTV is the only slightly less unintuitive $:ptv=?*.

Suggestion:

• To select by defined and undefined:
  • defined: $:ptv=*
  • undefined: $:ptv=-*
• To select by blank and non-blank:
  • blank: $:ptv=""
  • non-blank: $:ptv=- or $:ptv="-"
    • technically $:ptv=-"" would be clearer, but it doesn't work without changes to ParseArgs which seems too invasive

To accomplish this I offer this modified PageListVariables() function from scripts/pagelist.php below:

function PageListVariables(&$list, &$opt, $pn, &$page) {
  global $PCache;
  switch ($opt['=phase']) {
    case PAGELIST_PRE:
      $varlist = preg_grep('/^\\$/', array_keys($opt));
      if (!$varlist) return 0;
      foreach($varlist as $v) {
        switch ($opt[$v]) {
        case '*':
          $opt['=varexists'][] = preg_replace('/^\$:?/', "", $v);
          break;
        case '-*':
          $opt['=varnoexists'][] = preg_replace('/^\$:?/', "", $v);
          break;
        case '':
          $opt['=varinclp'][$v] = '/^$/';
          break;
        #case '-':  # this case is handled without difficulty below
        default:
          list($inclp, $exclp) = GlobToPCRE($opt[$v]);
          if ($inclp) $opt['=varinclp'][$v] = "/$inclp/i";
          if ($exclp) $opt['=varexclp'][$v] = "/$exclp/i";
        }
      }
      return PAGELIST_ITEM;

    case PAGELIST_ITEM:
      if (@$opt['=varinclp'])
        foreach($opt['=varinclp'] as $v => $pat) 
          if (!preg_match($pat, PageVar($pn, $v))) return 0;
      if (@$opt['=varexclp'])
        foreach($opt['=varexclp'] as $v => $pat) 
           if (preg_match($pat, PageVar($pn, $v))) return 0;
      if (@$opt['=varexists']) {
        PageTextVar($pn, 'x'); // make sure $PCache is primed
        foreach ($opt['=varexists'] as $var)
          if (!isset($PCache[$pn]["=p_$var"])) return 0;
      }
      if (@$opt['=varnoexists']) {
        PageTextVar($pn, 'x'); // make sure $PCache is primed
        foreach ($opt['=varnoexists'] as $var)
          if (isset($PCache[$pn]["=p_$var"])) return 0;
      }
      return 1;
  }
}

NOTE: This would be significantly more usable if there were the capabilities of combining search terms (on the same variable) with "and", but at least this is a step in the right direction.

See also

• 00880 a similar change is suggested, but there was too much else mixed in there.

Can you give an example of where it would really be beneficial to know that a PTV has been set to a blank value, as opposed to not set at all? I'd suggest that in those cases it'd be easier to set the PTV to a false-equivalent value such as '0' instead of setting it completely blank, rather than trying to fix this in the core.

However, I would support making $:ptv=* and $:ptv=-* equivalent of the current $:ptv=?* and $:ptv=-?*, which could be achieved by modifying GlobToPCRE in pmwiki.php, or by changing the first foreach loop in PageListVariables to the following: —Eemeli Aro September 02, 2009, at 06:37 AM

foreach($varlist as $v) {
  list($inclp, $exclp) = str_replace('^.*$', '^.+$', GlobToPCRE($opt[$v]));
  if ($inclp) $opt['=varinclp'][$v] = "/$inclp/i";
  if ($exclp) $opt['=varexclp'][$v] = "/$exclp/i";
}

foreach($varlist as $v) {
  if ($opt[$v]==='') { $opt['=varinclp'][$v] = '/^$/'; continue; }
  list($inclp, $exclp) = GlobToPCRE(preg_replace('/(^|,\s?)[-!][\'"]{2}/', '$1?*', $opt[$v]));
  if ($inclp) $opt['=varinclp'][$v] = "/$inclp/i";
  if ($exclp) $opt['=varexclp'][$v] = "/$exclp/i";
}

I am not sure we want to change the wildcard meaning. In all other places (group=PmWiki??*, name= , etc.) we have '*' equals 'zero or more' characters, and not 'one or more'. It will be counter-intuitive for the wildcard to behave differently for PageTextVariables. Changing it everywhere (GlobToPCRE) will break existing sites.

OTOH, the current subversion release allows disabling a core $PageListFilter function, by setting it to a negative value. This makes it possible to use a custom function instead, without replacing the whole pagelist.php script (which was already possible, for wikis which require the other functionality). --Petko September 02, 2009, at 07:19 AM

Hm. You are probably right. If the search is for a single "*" then it is very likely that the user wanted a PTV that has 'one or more' characters, or they wouldn't bother searching for this PTV. Interesting. --Petko September 02, 2009, at 02:24 PM