Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.lucene.queries.function.valuesource; import org.apache.lucene.index.LeafReaderContext; import org.apache.lucene.queries.function.FunctionValues; import org.apache.lucene.queries.function.ValueSource; import org.apache.lucene.search.IndexSearcher; import java.io.IOException; import java.util.List; import java.util.Map; /** * Converts individual ValueSource instances to leverage the FunctionValues *Val functions that work with multiple values, * i.e. {@link org.apache.lucene.queries.function.FunctionValues#doubleVal(int, double[])} */ //Not crazy about the name, but... public class VectorValueSource extends MultiValueSource { protected final List<ValueSource> sources; public VectorValueSource(List<ValueSource> sources) { this.sources = sources; } public List<ValueSource> getSources() { return sources; } @Override public int dimension() { return sources.size(); } public String name() { return "vector"; } @Override public FunctionValues getValues(Map context, LeafReaderContext readerContext) throws IOException { int size = sources.size(); // special-case x,y and lat,lon since it's so common if (size == 2) { final FunctionValues x = sources.get(0).getValues(context, readerContext); final FunctionValues y = sources.get(1).getValues(context, readerContext); return new FunctionValues() { @Override public void byteVal(int doc, byte[] vals) throws IOException { vals[0] = x.byteVal(doc); vals[1] = y.byteVal(doc); } @Override public void shortVal(int doc, short[] vals) throws IOException { vals[0] = x.shortVal(doc); vals[1] = y.shortVal(doc); } @Override public void intVal(int doc, int[] vals) throws IOException { vals[0] = x.intVal(doc); vals[1] = y.intVal(doc); } @Override public void longVal(int doc, long[] vals) throws IOException { vals[0] = x.longVal(doc); vals[1] = y.longVal(doc); } @Override public void floatVal(int doc, float[] vals) throws IOException { vals[0] = x.floatVal(doc); vals[1] = y.floatVal(doc); } @Override public void doubleVal(int doc, double[] vals) throws IOException { vals[0] = x.doubleVal(doc); vals[1] = y.doubleVal(doc); } @Override public void strVal(int doc, String[] vals) throws IOException { vals[0] = x.strVal(doc); vals[1] = y.strVal(doc); } @Override public String toString(int doc) throws IOException { return name() + "(" + x.toString(doc) + "," + y.toString(doc) + ")"; } }; } final FunctionValues[] valsArr = new FunctionValues[size]; for (int i = 0; i < size; i++) { valsArr[i] = sources.get(i).getValues(context, readerContext); } return new FunctionValues() { @Override public void byteVal(int doc, byte[] vals) throws IOException { for (int i = 0; i < valsArr.length; i++) { vals[i] = valsArr[i].byteVal(doc); } } @Override public void shortVal(int doc, short[] vals) throws IOException { for (int i = 0; i < valsArr.length; i++) { vals[i] = valsArr[i].shortVal(doc); } } @Override public void floatVal(int doc, float[] vals) throws IOException { for (int i = 0; i < valsArr.length; i++) { vals[i] = valsArr[i].floatVal(doc); } } @Override public void intVal(int doc, int[] vals) throws IOException { for (int i = 0; i < valsArr.length; i++) { vals[i] = valsArr[i].intVal(doc); } } @Override public void longVal(int doc, long[] vals) throws IOException { for (int i = 0; i < valsArr.length; i++) { vals[i] = valsArr[i].longVal(doc); } } @Override public void doubleVal(int doc, double[] vals) throws IOException { for (int i = 0; i < valsArr.length; i++) { vals[i] = valsArr[i].doubleVal(doc); } } @Override public void strVal(int doc, String[] vals) throws IOException { for (int i = 0; i < valsArr.length; i++) { vals[i] = valsArr[i].strVal(doc); } } @Override public String toString(int doc) throws IOException { StringBuilder sb = new StringBuilder(); sb.append(name()).append('('); boolean firstTime = true; for (FunctionValues vals : valsArr) { if (firstTime) { firstTime = false; } else { sb.append(','); } sb.append(vals.toString(doc)); } sb.append(')'); return sb.toString(); } }; } @Override public void createWeight(Map context, IndexSearcher searcher) throws IOException { for (ValueSource source : sources) source.createWeight(context, searcher); } @Override public String description() { StringBuilder sb = new StringBuilder(); sb.append(name()).append('('); boolean firstTime = true; for (ValueSource source : sources) { if (firstTime) { firstTime = false; } else { sb.append(','); } sb.append(source); } sb.append(")"); return sb.toString(); } @Override public boolean equals(Object o) { if (this == o) return true; if (!(o instanceof VectorValueSource)) return false; VectorValueSource that = (VectorValueSource) o; return sources.equals(that.sources); } @Override public int hashCode() { return sources.hashCode(); } }