feat(search-engine): Support for boosting queries

Author: aholstenson

silo-search-api/src/main/java/se/l4/silo/index/search/internal/BoostQueryImpl.java

@@ -0,0 +1,60 @@
+package se.l4.silo.index.search.internal;
+
+import java.util.Objects;
+
+import se.l4.silo.index.search.QueryClause;
+import se.l4.silo.index.search.query.BoostQuery;
+
+/**
+ * Implementation of {@link BoostQuery}.
+ */
+public class BoostQueryImpl
+	implements BoostQuery
+{
+	private final QueryClause clause;
+	private final float boost;
+
+	public BoostQueryImpl(
+		QueryClause clause,
+		float boost
+	)
+	{
+		this.clause = clause;
+		this.boost = boost;
+	}
+
+	@Override
+	public QueryClause getClause()
+	{
+		return clause;
+	}
+
+	@Override
+	public float getBoost()
+	{
+		return boost;
+	}
+
+	@Override
+	public int hashCode()
+	{
+		return Objects.hash(boost, clause);
+	}
+
+	@Override
+	public boolean equals(Object obj)
+	{
+		if(this == obj) return true;
+		if(obj == null) return false;
+		if(getClass() != obj.getClass()) return false;
+		BoostQueryImpl other = (BoostQueryImpl) obj;
+		return Float.floatToIntBits(boost) == Float.floatToIntBits(other.boost)
+			&& Objects.equals(clause, other.clause);
+	}
+
+	@Override
+	public String toString()
+	{
+		return "BoostQuery{boost=" + boost + ", clause=" + clause + "}";
+	}
+}

silo-search-api/src/main/java/se/l4/silo/index/search/query/BoostQuery.java

@@ -0,0 +1,42 @@
+package se.l4.silo.index.search.query;
+
+import se.l4.silo.index.search.QueryClause;
+import se.l4.silo.index.search.internal.BoostQueryImpl;
+
+/**
+ * {@link QueryClause} to increase or lower the important of another clause.
+ */
+public interface BoostQuery
+	extends QueryClause
+{
+	/**
+	 * The clause to apply a boost to.
+	 *
+	 * @return
+	 */
+	QueryClause getClause();
+
+	/**
+	 * Boost to apply. Less than one will reduce the importance of the clause,
+	 * more than one will increase the important of the clause.
+	 *
+	 * @return
+	 */
+	float getBoost();
+
+	/**
+	 * Create an instance that will boost the given clause.
+	 *
+	 * @param clause
+	 *   clause that will be boosted
+	 * @param boost
+	 *   boost to apply. Less than one will reduce the importance of the clause,
+	 *   more than one will increase the important of the clause.
+	 * @return
+	 */
+	static BoostQuery create(QueryClause clause, float boost)
+	{
+		return new BoostQueryImpl(clause, boost);
+	}
+}
+

silo-search-engine/src/main/java/se/l4/silo/engine/index/search/internal/query/BoostQueryBuilder.java

@@ -0,0 +1,27 @@
+package se.l4.silo.engine.index.search.internal.query;
+
+import java.io.IOException;
+
+import org.apache.lucene.search.Query;
+
+import se.l4.silo.engine.index.search.query.QueryBuilder;
+import se.l4.silo.engine.index.search.query.QueryEncounter;
+import se.l4.silo.index.search.query.BoostQuery;
+
+/**
+ * Builder that handles {@link BoostQuery}.
+ */
+public class BoostQueryBuilder
+	implements QueryBuilder<BoostQuery>
+{
+	@Override
+	public Query parse(QueryEncounter<BoostQuery> encounter)
+		throws IOException
+	{
+		BoostQuery instance = encounter.clause();
+		return new org.apache.lucene.search.BoostQuery(
+			encounter.parse(instance.getClause()),
+			instance.getBoost()
+		);
+	}
+}

silo-search-engine/src/main/java/se/l4/silo/engine/index/search/internal/query/QueryBuildersImpl.java

@@ -22,6 +22,7 @@ public class QueryBuildersImpl
 		.add(new OrQueryBuilder())
 		.add(new FieldQueryBuilder())
 		.add(new NegateQueryBuilder())
+		.add(new BoostQueryBuilder())
 		.add(new UserQueryBuilder());
 
 	public static final QueryBuilders DEFAULT = DEFAULT_BUILDER.build();