* Markus Krötzsch <[EMAIL PROTECTED]> [2008-01-02 08:37]: > On Sonntag, 30. Dezember 2007, Thomas Bleher wrote: > > * Markus Krötzsch <[EMAIL PROTECTED]> [2007-12-30 22:10]: > > > OK, my conclusion now was to support the following syntax: > > > > > > [[property% *subs?r*]] > > > > > > where ? and * represent _ and % in SQL. > > > > I think this is fine generally, but now you cannot query for a literal * or > > ? anymore, AFAIK. > > I would not consider this to be a major issue, given that those characters > are > not too common in typical application strings, and given the fact that > using "?" still queries for "some symbol" in that place -- it seems to be > very unlikely that too strings differ only in one position where the query > string has a "?". So in most cases it will have the same hits anyway (yes, > there are some cases that could be problematic [1] ;).
Agreed.
> Anyway, I will leave this issue at rest until any user actually complains
> about this limitation.
Here I have to respectfully disagree.
It seems unwise to wait until someone complains, when there is already a
patch resolving the issue. Why spend more time later on when the issue
can just be fixed right now?
OK, the regexes where not very readable, but it doesn't really make the
code more complicated.
FWIW, the regexes where so ugly only because backslashes have to be escaped
twice for PHPs preg_replace (so a single \ becomes \\\\).
If we used ! as an escape sequence instead of \, the regexes would look
like this (untested):
$value = str_replace(array('%', '_'), array('!%', '!_'), $value);
$value = preg_replace('/(?<!!)((?:!!)*)\*/', '$1%', $value); // if there's an
even number of \, change * to %
$value = preg_replace('/(?<!!)((?:!!)*)\?/', '$1_', $value); // ditto for ?
and _
$value = preg_replace('/(?<!!)((?:!!)*)!\*/', '$1*', $value); // if there's an
odd number, * was escaped and should stay as is; but the last \ is removed
$value = preg_replace('/(?<!!)((?:!!)*)!\?/', '$1?', $value); // ditto for ?
(?: ) is a subexpression for grouping, not capturing,
(?<! ) is zero-width negative look-behind (i.e. we make sure that the
character before our match is not !).
Regards,
Thomas
> [1] http://de.wikipedia.org/wiki/Die_drei_%3F%3F%3F
>
> >
> > Not a huge deal, but before, "a_b" searched for "a, followed by any char,
> > followed by b", while "a\_b" searched for "exactly a_b".
> >
> > Properly escaping everything gets messy rather quickly, as \ can also be
> > escaped to query for a literal \, so you need translations like:
> >
> > ? => _
> > \? => ?
> > \\? => \\_
> > \\\? => \\?
> >
> > The following regular expressions work fine for me, but unfortunately they
> > are quite ugly:
> >
> > $value = str_replace(array('%', '_'), array('\%', '\_'), $value); // escape
> > % and _ $value = preg_replace('/(?<!\\\\)((?:\\\\\\\\)*)\*/', '$1%',
> > $value); // if there's an even number of \, change * to % $value =
> > preg_replace('/(?<!\\\\)((?:\\\\\\\\)*)\?/', '$1_', $value); // ditto for ?
> > and _ $value = preg_replace('/(?<!\\\\)((?:\\\\\\\\)*)\\\\\*/', '$1*',
> > $value); // if there's an odd number, * was escaped and should stay as is;
> > but the last \ is removed $value =
> > preg_replace('/(?<!\\\\)((?:\\\\\\\\)*)\\\\\?/', '$1?', $value); // ditto
> > for ?
> >
> > I think these should be added to SMW, so all characters can be queried.
> >
> > Regards,
> > Thomas
>
>
>
> --
> Markus Krötzsch
> Institut AIFB, Universät Karlsruhe (TH), 76128 Karlsruhe
> phone +49 (0)721 608 7362 fax +49 (0)721 608 5998
> [EMAIL PROTECTED] www http://korrekt.org
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