org.apache.lucene.expressions.XSimpleBindings Maven / Gradle / Ivy
package org.apache.lucene.expressions;
/*
* 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.
*/
import java.util.HashMap;
import java.util.Map;
import org.apache.lucene.queries.function.ValueSource;
import org.apache.lucene.queries.function.valuesource.DoubleFieldSource;
import org.apache.lucene.queries.function.valuesource.FloatFieldSource;
import org.apache.lucene.queries.function.valuesource.IntFieldSource;
import org.apache.lucene.queries.function.valuesource.LongFieldSource;
import org.apache.lucene.search.SortField;
/**
* Simple class that binds expression variable names to {@link SortField}s
* or other {@link Expression}s.
*
* Example usage:
*
* XSimpleBindings bindings = new XSimpleBindings();
* // document's text relevance score
* bindings.add(new SortField("_score", SortField.Type.SCORE));
* // integer NumericDocValues field (or from FieldCache)
* bindings.add(new SortField("popularity", SortField.Type.INT));
* // another expression
* bindings.add("recency", myRecencyExpression);
*
* // create a sort field in reverse order
* Sort sort = new Sort(expr.getSortField(bindings, true));
*
*
* @lucene.experimental
*/
public final class XSimpleBindings extends Bindings {
static {
assert org.elasticsearch.Version.CURRENT.luceneVersion == org.apache.lucene.util.Version.LUCENE_4_9: "Remove this code once we upgrade to Lucene 4.10 (LUCENE-5806)";
}
final Map map = new HashMap<>();
/** Creates a new empty Bindings */
public XSimpleBindings() {}
/**
* Adds a SortField to the bindings.
*
* This can be used to reference a DocValuesField, a field from
* FieldCache, the document's score, etc.
*/
public void add(SortField sortField) {
map.put(sortField.getField(), sortField);
}
/**
* Bind a {@link ValueSource} directly to the given name.
*/
public void add(String name, ValueSource source) { map.put(name, source); }
/**
* Adds an Expression to the bindings.
*
* This can be used to reference expressions from other expressions.
*/
public void add(String name, Expression expression) {
map.put(name, expression);
}
@Override
public ValueSource getValueSource(String name) {
Object o = map.get(name);
if (o == null) {
throw new IllegalArgumentException("Invalid reference '" + name + "'");
} else if (o instanceof Expression) {
return ((Expression)o).getValueSource(this);
} else if (o instanceof ValueSource) {
return ((ValueSource)o);
}
SortField field = (SortField) o;
switch(field.getType()) {
case INT:
return new IntFieldSource(field.getField());
case LONG:
return new LongFieldSource(field.getField());
case FLOAT:
return new FloatFieldSource(field.getField());
case DOUBLE:
return new DoubleFieldSource(field.getField());
case SCORE:
return getScoreValueSource();
default:
throw new UnsupportedOperationException();
}
}
/**
* Traverses the graph of bindings, checking there are no cycles or missing references
* @throws IllegalArgumentException if the bindings is inconsistent
*/
public void validate() {
for (Object o : map.values()) {
if (o instanceof Expression) {
Expression expr = (Expression) o;
try {
expr.getValueSource(this);
} catch (StackOverflowError e) {
throw new IllegalArgumentException("Recursion Error: Cycle detected originating in (" + expr.sourceText + ")");
}
}
}
}
}