RRFRetrieverComponent added:

Author: mridula-s109

x-pack/plugin/rank-rrf/src/main/java/org/elasticsearch/xpack/rank/rrf/RRFRetrieverComponent.java

@@ -0,0 +1,66 @@
+package org.elasticsearch.xpack.rank.rrf;
+
+import org.elasticsearch.search.retriever.RetrieverBuilder;
+import org.elasticsearch.search.retriever.RetrieverParserContext;
+import org.elasticsearch.xcontent.ConstructingObjectParser;
+import org.elasticsearch.xcontent.ParseField;
+import org.elasticsearch.xcontent.ToXContentObject;
+import org.elasticsearch.xcontent.XContentBuilder;
+import org.elasticsearch.xcontent.XContentParser;
+
+import java.io.IOException;
+
+import static org.elasticsearch.xcontent.ConstructingObjectParser.constructorArg;
+import static org.elasticsearch.xcontent.ConstructingObjectParser.optionalConstructorArg;
+
+public class RRFRetrieverComponent implements ToXContentObject {
+    
+    public static final ParseField RETRIEVER_FIELD = new ParseField("retriever");
+    public static final ParseField WEIGHT_FIELD = new ParseField("weight");
+
+    static final float DEFAULT_WEIGHT = 1f;
+
+    RetrieverBuilder retriever;
+    float weight;
+    
+    public RRFRetrieverComponent(RetrieverBuilder retrieverBuilder, Float weight) {
+        assert retrieverBuilder != null;
+        this.retriever = retrieverBuilder;
+        this.weight = weight == null ? DEFAULT_WEIGHT : weight;
+        if (this.weight < 0) {
+            throw new IllegalArgumentException("[weight] must be non-negative");
+        }
+    }
+
+    @Override
+    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
+        builder.field(RETRIEVER_FIELD.getPreferredName(), retriever);
+        builder.field(WEIGHT_FIELD.getPreferredName(), weight);
+        return builder;
+    }
+
+
+    @SuppressWarnings("unchecked")
+    static final ConstructingObjectParser<RRFRetrieverComponent, RetrieverParserContext> PARSER = new ConstructingObjectParser<>(
+        "rrf_component",
+        false,
+        args -> {
+            RetrieverBuilder retrieverBuilder = (RetrieverBuilder) args[0];
+            Float weight = (Float) args[1];
+            return new RRFRetrieverComponent(retrieverBuilder, weight);
+        }
+    );
+
+    static {
+        PARSER.declareNamedObject(constructorArg(), (p, c, n) -> {
+            RetrieverBuilder innerRetriever = p.namedObject(RetrieverBuilder.class, n, c);
+            c.trackRetrieverUsage(innerRetriever.getName());
+            return innerRetriever;
+        }, RETRIEVER_FIELD);
+        PARSER.declareFloat(optionalConstructorArg(), WEIGHT_FIELD);
+    }
+
+    public static RRFRetrieverComponent fromXContent(XContentParser parser, RetrieverParserContext context) throws IOException {
+        return PARSER.apply(parser, context);
+    }
+}