On Nov 10, 2004, at 9:51 PM, Satoshi Hasegawa wrote:
Our program accepts input in the form of Lucene query syntax from the user,
but we wish to perform additional tasks such as thesaurus expansion. So I
want to manipulate the Query object that results from parsing.
You may want to consider using an Analyzer to expand queries rather than manipulating the query object itself.
My question is, is the result of the Query#rewrite method guaranteed to be
either a TermQuery, a PhraseQuery, or a BooleanQuery, and if it is a
BooleanQuery, do all the constituent clauses also reduce to one of the above
three classes?
No. For example, look at the SpanQuery family. These do no explicit rewriting and thus are left as themselves.
If not, what if the original Query object was the one that
was obtained from QueryParser#parse method? Can I assume the above in this
restricted case?
I experimented with the current version, and the above seems to be positive
in this version; I'm asking if this could change in the future. Thank you.
I think we'll see QueryParser, or at least more sophisticated versions of it, emerge that support SpanQuery's. In fact, in our book, I created a subclas of QueryParser that overrides getFieldQuery and returns a SpanNearQuery in order to achieve ordered phrase searching.
Erik
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