A span is a <doc,startPosition,endPosition> tuple.
The following span query operators are implemented:
q whose end position is less than
n. This can be used to constrain matches to the first
part of the document.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);