Package org.apache.lucene.search.spans

The calculus of spans.

See: Description

Interface Summary

Interface	Description
Spans	Expert: an enumeration of span matches.

Class Summary

Class	Description
EmptySpans	Expert: An empty list of spans, suitable for ORing with other lists.
FieldSpans	Keeps a record of the matching spans and search terms for each field.
NearSpans	Calculates spans that match several queries "near" each other.
OrNearSpans	Calculates spans that match several queries "near" each other.
Span	Data holder to keep track of a single matching span.
SpanFirstQuery	Matches spans near the beginning of a field.
SpanNearQuery	Matches spans which are near one another.
SpanNotNearQuery	Removes matches which from one SpanQuery which are too close to spans from another SpanQuery.
SpanNotQuery	Removes matches which overlap with another SpanQuery.
SpanOrNearQuery	Matches spans which are near one another.
SpanOrQuery	Matches the union of its clauses.
SpanPosComparator	Comparator on Spans that orders them by ascending start position, then end position.
SpanQuery	Base class for span-based queries.
SpanRangeQuery	Matches spans containing terms within a specified range.
SpanRecordingScorer	Runs a span query and scores the resulting spans, passing them to a SpanHitCollector if specified.
SpanScorer
SpanTermQuery	Matches spans containing a term.
SpanWeight
SpanWildcardQuery	Matches spans containing a wildcard term.

Package org.apache.lucene.search.spans Description

The calculus of spans.

A span is a <doc,startPosition,endPosition> tuple.

The following span query operators are implemented:

• A SpanTermQuery matches all spans containing a particular Term.
• A SpanNearQuery matches spans which occur near one another, and can be used to implement things like phrase search (when constructed from SpanTermQueries and inter-phrase proximity (when constructed from other SpanNearQueries.
• A SpanOrQuery merges spans from a number of other SpanQueries.
• A SpanNotQuery removes spans matching one SpanQuery which overlap another. This can be used, e.g., to implement within-paragraph search.
• A SpanFirstQuery matches spans matching q whose end position is less than n. This can be used to constrain matches to the first part of the document.
• A SpanRangeQuery matches spans containing terms within a specified range (e.g. "1999" to "2004")
• A SpanWildcardQuery matches spans containing terms that match a wildcard specification (e.g. "man*" matches "man", "manor", "maniac", etc.)

In all cases, output spans are minimally inclusive. In other words, a span formed by matching a span in x and y starts at the lesser of the two starts and ends at the greater of the two ends.

For example, a span query which matches "John Kerry" within ten words of "George Bush" within the first 100 words of the document could be constructed with:

SpanQuery john   = new SpanTermQuery(new Term("content", "john"));
SpanQuery kerry  = new SpanTermQuery(new Term("content", "kerry"));
SpanQuery george = new SpanTermQuery(new Term("content", "george"));
SpanQuery bush   = new SpanTermQuery(new Term("content", "bush"));

SpanQuery johnKerry =
   new SpanNearQuery(new SpanQuery[] {john, kerry}, 0, true);

SpanQuery georgeBush =
   new SpanNearQuery(new SpanQuery[] {george, bush}, 0, true);

SpanQuery johnKerryNearGeorgeBush =
   new SpanNearQuery(new SpanQuery[] {johnKerry, georgeBush}, 10, false);

SpanQuery johnKerryNearGeorgeBushAtStart =
   new SpanFirstQuery(johnKerryNearGeorgeBush, 100);

Span queries may be freely intermixed with other Lucene queries. So, for example, the above query can be restricted to documents which also use the word "iraq" with:

Query query = new BooleanQuery();
query.add(johnKerryNearGeorgeBushAtStart, true, false);
query.add(new TermQuery("content", "iraq"), true, false);