Xapian discuss - Jan 2012 - [issue] The difference between QueryParser::FLAG_AUTO_SYNONYMS and QueryParser::FLAG_AUTO_MULTIWORD_SYNONYMS

I don't know whether this is a BUG or for special purpose...

According to the definition of "xapian/queryparser.h",
FLAG_AUTO_MULTIWORD_SYNONYMS contains bit of
FLAG_AUTO_SYNONYMS .

Therefore, long as I set the parse flag with FLAG_AUTO_SYNONYMS, the query
parser will automatically activate
the function of FLAG_AUTO_MULTIWORD_SYNONYMS. See the below source code part
from "queryparser.lemon"

...
1358     subqs.reserve(terms.size());
1359     if (state->flags & QueryParser::FLAG_AUTO_MULTIWORD_SYNONYMS) {
1360         // Check for multi-word synonyms.
1361         Database db = state->get_database();
...

On 4 January 2012 07:53, hightman <hightman at zuaa.zju.edu.cn>
wrote:
> I don't know whether this is a BUG or for special purpose...
>
> According to the definition of "xapian/queryparser.h",
FLAG_AUTO_MULTIWORD_SYNONYMS contains bit of
> FLAG_AUTO_SYNONYMS .
This is deliberate; the idea is that setting
FLAG_AUTO_MULTIWORD_SYNONYMS should imply FLAG_AUTO_SYNONYMS.
> Therefore, long as I set the parse flag with FLAG_AUTO_SYNONYMS, the query
parser will automatically activate
> the function of FLAG_AUTO_MULTIWORD_SYNONYMS. See the below source code
part from "queryparser.lemon"
>
> ...
> 1358 ? ? subqs.reserve(terms.size());
> 1359 ? ? if (state->flags &
QueryParser::FLAG_AUTO_MULTIWORD_SYNONYMS) {
> 1360 ? ? ? ? // Check for multi-word synonyms.
> 1361 ? ? ? ? Database db = state->get_database();
This is a bug, I think.  As you observe, this "if" clause evaluates to
true if flags is set to FLAG_AUTO_SYNONYMS.  I think this could be
fixed by changing line 1359 (above) to

if (state->flags & 1024) {

but this isn't very clean.  We should probably be defining an
appropriate constant in queryparser.h and using that here.

-- 
Richard

On Wed, Jan 04, 2012 at 03:53:15PM +0800, hightman
wrote:
> Therefore, long as I set the parse flag with FLAG_AUTO_SYNONYMS, the
> query parser will automatically activate the function of
> FLAG_AUTO_MULTIWORD_SYNONYMS.
Thanks for reporting this - I've committed a fix to trunk (r16317) and
will backport it for 1.2.9.

Cheers,
    Olly