QueryScorer and SpanRegexQuery are incompatible.
------------------------------------------------
Key: LUCENE-2013
URL: https://issues.apache.org/jira/browse/LUCENE-2013
Project: Lucene - Java
Issue Type: Bug
Components: contrib/highlighter
Affects Versions: 2.9
Environment: Lucene-Java 2.9
Reporter: Benjamin Keil
Since the resolution of #LUCENE-1685, users are not supposed to rewrite their
queries before submitting them to QueryScorer:
bq.{{------------------------------------------------------------------------
r800796 | markrmiller | 2009-08-04 06:56:11 -0700 (Tue, 04 Aug 2009) | 1 line
LUCENE-1685: The position aware SpanScorer has become the default scorer for
Highlighting. The SpanScorer implementation has replaced QueryScorer and the
old term highlighting QueryScorer has been renamed to QueryTermScorer.
Multi-term queries are also now expanded by default. If you were previously
rewritting the query for multi-term query highlighting, you should no longer do
that (unless you switch to using QueryTermScorer). The SpanScorer API (now
QueryScorer) has also been improved to more closely match the API of the
previous QueryScorer implementation.
------------------------------------------------------------------------}}
This is a great convenience for the most part, but it's causing me difficulties
with {{SpanRegexQuery}}s, as the {{WeightedSpanTermExtractor}} uses
{{Query.extractTerms()}} to collect the fields used in the query, but
{{SpanRegexQuery}} does not implement this method, so highlighting any query
with a {{SpanRegexQuery}} throws an UnsupportedOpertationException. If this
issue is circumvented, there is still the issue of {{SpanRegexQuery}} throwing
an exception when someone calls its {{getSpans()}} method.
I can provide the patch that I am currently using, but I'm not sure that my
solution is optimal. It adds two methods to {{SpanQuery}}:
{{extractFields(Set<String> fields)}} which is {{fields.add(getField())}} for
everything except {{MaskedFieldQuery}}, and {{mustBeRewrittenToGetSpans()}}
which returns {{true}} for {{SpanQuery}}, {{false}} for {{SpanTermQuery}}, and
is overridden in each composite {{SpanQuery}} to return a value depending on
its components. In this way {{SpanRegexQuery}} (and any other custom
{{SpanQuery}}s) do not need to be adjusted.
Currently the collection of fields and non-weighted terms are done in a single
step. In the proposed patch the {{WeightedSpanTerm}} extraction from a
{{SpanQuery}} proceeds in two steps. First, if the {{QueryScorer}}'s field is
{{null}}, then the fields are collected from the {{SpanQuery}} using the
{{extractFields()}} method. Second the terms are collected using
{{extractTerms()}}, rewriting the query for each field if
{{mustBeRewrittenToGetSpans()}} returns {{true}}.
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