com.yelp.nrtsearch.server.highlights.Highlighter Maven / Gradle / Ivy
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/*
* Copyright 2023 Yelp Inc.
*
* Licensed 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 com.yelp.nrtsearch.server.highlights;
import com.yelp.nrtsearch.server.field.TextBaseFieldDef;
import com.yelp.nrtsearch.server.search.SearchContext;
import java.io.IOException;
import org.apache.lucene.index.LeafReaderContext;
/**
* This is the highlighter interface to provide the new highlighters with different implementations.
* Highlighters are supposed to be initiated once at the startup time and registered in the {@link
* HighlighterService}. Therefore, a single instance of the highlighter will be responsible for
* handling all the corresponding highlighting fetch tasks.
*/
public interface Highlighter {
/**
* The name is used as the identifier of this highlighter. It must be unique. The highlight_type
* in the search request will be used to match this name during the highlighter selection.
*
* @return the unique name/identifier of this highlighter
*/
String getName();
/**
* Get highlighted segments for the given leafDocId and field.
*
* The indexReader gives the full readabity access to the highlighter. And using the leafDocId
* and the fieldName derived from the textBasedFieldDef, the target field can be retrieved.
*
* @param hitLeaf the hitLeaf context has the random access to the segment
* @param settings the highlight settings derived from the search request for this field
* @param textBaseFieldDef the target's field information
* @param leafDocId the target's identifier to retrieve the highlighting document from the
* leafReaderContext base (luceneId - hitLeaf.docBase)
* @param searchContext the searchContext to keep the contexts for this search request
* @return an array of Strings containing all highlighted fragments
* @throws IOException will be thrown when fail during the document reading
*/
String[] getHighlights(
LeafReaderContext hitLeaf,
HighlightSettings settings,
TextBaseFieldDef textBaseFieldDef,
int leafDocId,
SearchContext searchContext)
throws IOException;
/**
* This will be invoked once per highlighted field before execution of the search request. All
* highlighter implementations' additional highlight-ability checks should be done here.
*
*
If failed, an {@link IllegalArgumentException} with detailed explanation must be thrown.
* Otherwise, do nothing.
*
* @param fieldDef a {@link TextBaseFieldDef} object of the field that is intended to be
* highlighted
*/
default void verifyFieldIsSupported(TextBaseFieldDef fieldDef) {}
}