On Apr 11, 2006, at 11:56 AM, Doug Cutting wrote:
Erik Hatcher wrote:
I have a potential need for a SpanNearQuery with an exact non-
zero gap specified
Ironically, you can now easily specify this with PhraseQuery, but
not with SpanNearQuery. You can construct a phrase query with
explicit positions, e.g.:
PhraseQuery pq = new PhraseQuery();
pq.add(new Term("f", "x"), 0);
pq.add(new Term("f", "y"), 2);
This will match instances of "x" and "y" with exactly one word
between them in field "f".
Unfortunately one cannot (yet) construct a SpanNearQuery with
explicit positions. I think that would be useful, and not too hard
to add. Internally all the computation is in terms of positions, so
adding this is mostly a matter of exposing this in the public API.
Would this be as easy as modifying SpanNearQuery to have a
minimum and maximum slop feature, and modifying
NearSpans.checkSlop() to add a condition that the difference is
>= the minimum slop? At first glance it seems so, but I want to
be sure I'm not missing something.
If you want to match something like "a ? b ? ? c", where "?"
matches any word, then slop is not sufficient, you really need
explicit positions, or else you'll match things like "a ? ? b ? c".
In my case, I was thinking of joining two zero-slopped SpanNearQuerys
within an outer SpanNearQuery with a slop of _exactly_ one, so it'd
be like this: (a b) ? (c d)
I'll dig into this further when the project demands, and am glad to
confirm that it won't be too difficult to implement if/when the need
arises.
Erik
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