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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.index.query.functionscore;
import org.elasticsearch.common.ParseField;
import org.elasticsearch.common.bytes.BytesReference;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentFactory;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.common.ParsingException;
import org.elasticsearch.index.query.QueryParseContext;
import org.elasticsearch.index.query.functionscore.gauss.GaussDecayFunctionBuilder;
import org.elasticsearch.index.query.functionscore.gauss.GaussDecayFunctionParser;
import org.elasticsearch.search.MultiValueMode;
import java.io.IOException;
/**
* This class provides the basic functionality needed for adding a decay
* function.
*
* This parser parses this kind of input
*
* <pre>
* <code>
* {
* "fieldname1" : {
* "origin" = "someValue",
* "scale" = "someValue"
* },
* "multi_value_mode" : "min"
* }
* </code>
* </pre>
*
* "origin" here refers to the reference point and "scale" to the level of
* uncertainty you have in your origin.
* <p>
*
* For example, you might want to retrieve an event that took place around the
* 20 May 2010 somewhere near Berlin. You are mainly interested in events that
* are close to the 20 May 2010 but you are unsure about your guess, maybe it
* was a week before or after that. Your "origin" for the date field would be
* "20 May 2010" and your "scale" would be "7d".
*
* This class parses the input and creates a scoring function from the
* parameters origin and scale.
* <p>
* To write a new scoring function, create a new class that inherits from this
* one and implements {@link #getBuilderPrototype()} and {@link #getNames()}.
* Also create its corresponding {@link DecayFunctionBuilder}. The latter needs to
* implement {@link DecayFunctionBuilder#doReadFrom(StreamInput)} and
* {@link DecayFunctionBuilder#doWriteTo(StreamOutput)} for serialization purposes,
* {@link DecayFunctionBuilder#doEquals(DecayFunctionBuilder)} and
* {@link DecayFunctionBuilder#doHashCode()} for equality checks,
* {@link DecayFunctionBuilder#getName()} that returns the name of the function and
* {@link DecayFunctionBuilder#getDecayFunction()} which returns the corresponding lucene function.
* <p>
* See {@link GaussDecayFunctionBuilder} and {@link GaussDecayFunctionParser}
* for an example. The parser furthermore needs to be registered in the
* {@link org.elasticsearch.search.SearchModule SearchModule}.
*
*/
public abstract class DecayFunctionParser<DFB extends DecayFunctionBuilder<DFB>> implements ScoreFunctionParser<DFB> {
public static final ParseField MULTI_VALUE_MODE = new ParseField("multi_value_mode");
/**
* Parses bodies of the kind
*
* <pre>
* <code>
* {
* "fieldname1" : {
* "origin" : "someValue",
* "scale" : "someValue"
* },
* "multi_value_mode" : "min"
* }
* </code>
* </pre>
*/
@Override
public DFB fromXContent(QueryParseContext context, XContentParser parser) throws IOException, ParsingException {
String currentFieldName;
XContentParser.Token token;
MultiValueMode multiValueMode = DecayFunctionBuilder.DEFAULT_MULTI_VALUE_MODE;
String fieldName = null;
BytesReference functionBytes = null;
while ((token = parser.nextToken()) == XContentParser.Token.FIELD_NAME) {
currentFieldName = parser.currentName();
token = parser.nextToken();
if (token == XContentParser.Token.START_OBJECT) {
fieldName = currentFieldName;
XContentBuilder builder = XContentFactory.jsonBuilder();
builder.copyCurrentStructure(parser);
functionBytes = builder.bytes();
} else if (context.parseFieldMatcher().match(currentFieldName, MULTI_VALUE_MODE)) {
multiValueMode = MultiValueMode.fromString(parser.text());
} else {
throw new ParsingException(parser.getTokenLocation(), "malformed score function score parameters.");
}
}
if (fieldName == null || functionBytes == null) {
throw new ParsingException(parser.getTokenLocation(), "malformed score function score parameters.");
}
DFB functionBuilder = getBuilderPrototype().createFunctionBuilder(fieldName, functionBytes);
functionBuilder.setMultiValueMode(multiValueMode);
return functionBuilder;
}
}
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