1 package org.apache.lucene.search.spans;
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20 import java.io.IOException;
23 import org.apache.lucene.index.IndexReader;
24 import org.apache.lucene.index.Term;
25 import org.apache.lucene.search.Query;
26 import org.apache.lucene.search.Weight;
27 import org.apache.lucene.search.Searcher;
28 import org.apache.lucene.search.Similarity;
29 import org.apache.lucene.util.ToStringUtils;
32 * <p>Wrapper to allow {@link SpanQuery} objects participate in composite
33 * single-field SpanQueries by 'lying' about their search field. That is,
34 * the masked SpanQuery will function as normal,
35 * but {@link SpanQuery#getField()} simply hands back the value supplied
36 * in this class's constructor.</p>
38 * <p>This can be used to support Queries like {@link SpanNearQuery} or
39 * {@link SpanOrQuery} across different fields, which is not ordinarily
42 * <p>This can be useful for denormalized relational data: for example, when
43 * indexing a document with conceptually many 'children': </p>
47 * studentfirstname: james
48 * studentsurname: jones
51 * studenfirstname: james
52 * studentsurname: smith
53 * studentfirstname: sally
54 * studentsurname: jones
57 * <p>a SpanNearQuery with a slop of 0 can be applied across two
58 * {@link SpanTermQuery} objects as follows:
60 * SpanQuery q1 = new SpanTermQuery(new Term("studentfirstname", "james"));
61 * SpanQuery q2 = new SpanTermQuery(new Term("studentsurname", "jones"));
62 * SpanQuery q2m = new FieldMaskingSpanQuery(q2, "studentfirstname");
63 * Query q = new SpanNearQuery(new SpanQuery[]{q1, q2m}, -1, false);
65 * to search for 'studentfirstname:james studentsurname:jones' and find
66 * teacherid 1 without matching teacherid 2 (which has a 'james' in position 0
67 * and 'jones' in position 1). </p>
69 * <p>Note: as {@link #getField()} returns the masked field, scoring will be
70 * done using the norms of the field name supplied. This may lead to unexpected
71 * scoring behaviour.</p>
73 public class FieldMaskingSpanQuery extends SpanQuery {
74 private SpanQuery maskedQuery;
77 public FieldMaskingSpanQuery(SpanQuery maskedQuery, String maskedField) {
78 this.maskedQuery = maskedQuery;
79 this.field = maskedField;
83 public String getField() {
87 public SpanQuery getMaskedQuery() {
91 // :NOTE: getBoost and setBoost are not proxied to the maskedQuery
92 // ...this is done to be more consistent with things like SpanFirstQuery
95 public Spans getSpans(IndexReader reader) throws IOException {
96 return maskedQuery.getSpans(reader);
100 public void extractTerms(Set<Term> terms) {
101 maskedQuery.extractTerms(terms);
105 public Weight createWeight(Searcher searcher) throws IOException {
106 return maskedQuery.createWeight(searcher);
110 public Query rewrite(IndexReader reader) throws IOException {
111 FieldMaskingSpanQuery clone = null;
113 SpanQuery rewritten = (SpanQuery) maskedQuery.rewrite(reader);
114 if (rewritten != maskedQuery) {
115 clone = (FieldMaskingSpanQuery) this.clone();
116 clone.maskedQuery = rewritten;
127 public String toString(String field) {
128 StringBuilder buffer = new StringBuilder();
129 buffer.append("mask(");
130 buffer.append(maskedQuery.toString(field));
132 buffer.append(ToStringUtils.boost(getBoost()));
133 buffer.append(" as ");
134 buffer.append(this.field);
135 return buffer.toString();
139 public boolean equals(Object o) {
140 if (!(o instanceof FieldMaskingSpanQuery))
142 FieldMaskingSpanQuery other = (FieldMaskingSpanQuery) o;
143 return (this.getField().equals(other.getField())
144 && (this.getBoost() == other.getBoost())
145 && this.getMaskedQuery().equals(other.getMaskedQuery()));
150 public int hashCode() {
151 return getMaskedQuery().hashCode()
152 ^ getField().hashCode()
153 ^ Float.floatToRawIntBits(getBoost());