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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.rendering;
import com.yahoo.search.Result;
import com.yahoo.search.grouping.result.Group;
import com.yahoo.search.grouping.result.GroupList;
import com.yahoo.search.grouping.result.HitList;
import com.yahoo.search.query.context.QueryContext;
import com.yahoo.search.result.ErrorHit;
import com.yahoo.search.result.ErrorMessage;
import com.yahoo.search.result.Hit;
import com.yahoo.search.result.HitGroup;
import java.io.IOException;
import java.io.Writer;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
/**
* Renders each part of a result to a writer.
* The renderers are cloned just before rendering,
* and must therefore obey the following contract:
* <ol>
* <li>At construction time, only final members shall be initialized,
* and these must refer to immutable data only.
* <li>State mutated during rendering shall be initialized in the init method.
* </ol>
*
* @author Tony Vaagenes
*/
abstract public class SectionedRenderer<WRITER> extends Renderer {
/**
* Wraps the Writer instance.
* The result is given as a parameter to all the callback methods.
* Must be overridden if the generic parameter WRITER != java.io.Writer.
*/
@SuppressWarnings("unchecked")
public WRITER wrapWriter(Writer writer) {
return (WRITER)writer;
}
/**
* Called at the start of rendering.
*/
abstract public void beginResult(WRITER writer, Result result) throws IOException;
/**
* Called at the end of rendering.
*/
abstract public void endResult(WRITER writer, Result result) throws IOException;
/**
* Called if there are errors in the result.
*/
abstract public void error(WRITER writer, Collection<ErrorMessage> errorMessages) throws IOException;
/**
* Called if there are no hits in the result.
*/
abstract public void emptyResult(WRITER writer, Result result) throws IOException;
/**
* Called if there is a non-null query context for the query of the result.
*/
abstract public void queryContext(WRITER writer, QueryContext queryContext) throws IOException;
/**
* Called when a HitGroup is encountered. After all its children have been provided
* to methods of this class, endHitGroup is called.
*/
abstract public void beginHitGroup(WRITER writer, HitGroup hitGroup) throws IOException;
/**
* Called after all the children of the HitGroup have been provided to methods of this class.
* See beginHitGroup.
*/
abstract public void endHitGroup(WRITER writer, HitGroup hitGroup) throws IOException;
/**
* Called when a Hit is encountered.
*/
abstract public void hit(WRITER writer, Hit hit) throws IOException;
/**
* Called when an errorHit is encountered.
* Forwards to hit() per default.
*/
public void errorHit(WRITER writer, ErrorHit errorHit) throws IOException {
hit(writer, (Hit)errorHit);
}
/* Begin Grouping */
/**
* Same as beginHitGroup, but for Group(grouping api).
* Forwards to beginHitGroup() per default.
*/
public void beginGroup(WRITER writer, Group group) throws IOException {
beginHitGroup(writer, group);
}
/**
* Same as endHitGroup, but for Group(grouping api).
* Forwards to endHitGroup() per default.
*/
public void endGroup(WRITER writer, Group group) throws IOException {
endHitGroup(writer, group);
}
/**
* Same as beginHitGroup, but for GroupList(grouping api).
* Forwards to beginHitGroup() per default.
*/
public void beginGroupList(WRITER writer, GroupList groupList) throws IOException {
beginHitGroup(writer, groupList);
}
/**
* Same as endHitGroup, but for GroupList(grouping api).
* Forwards to endHitGroup() per default.
*/
public void endGroupList(WRITER writer, GroupList groupList) throws IOException {
endHitGroup(writer, groupList);
}
/**
* Same as beginHitGroup, but for HitList(grouping api).
* Forwards to beginHitGroup() per default.
*/
public void beginHitList(WRITER writer, HitList hitList) throws IOException {
beginHitGroup(writer, hitList);
}
/**
* Same as endHitGroup, but for HitList(grouping api).
* Forwards to endHitGroup() per default.
*/
public void endHitList(WRITER writer, HitList hitList) throws IOException {
endHitGroup(writer, hitList);
}
/* End Grouping */
/**
* Picks apart the result and feeds it to the other methods.
*/
@Override
public final void render(Writer writer, Result result) throws IOException {
WRITER wrappedWriter = wrapWriter(writer);
beginResult(wrappedWriter, result);
renderResultContent(wrappedWriter, result);
endResult(wrappedWriter, result);
}
private void renderResultContent(WRITER writer, Result result) throws IOException {
if (result.hits().getError() != null || result.hits().getQuery().errors().size() > 0) {
error(writer, asUnmodifiableSearchErrorList(result.hits().getQuery().errors(), result.hits().getError()));
}
if (result.getConcreteHitCount() == 0) {
emptyResult(writer, result);
}
if (result.getContext(false) != null) {
queryContext(writer, result.getContext(false));
}
renderHitGroup(writer, result.hits());
}
private Collection<ErrorMessage> asUnmodifiableSearchErrorList(List<com.yahoo.processing.request.ErrorMessage> queryErrors,ErrorMessage resultError) {
if (queryErrors.size() == 0)
return Collections.singletonList(resultError);
List<ErrorMessage> searchErrors = new ArrayList<>(queryErrors.size() + (resultError != null ? 1 :0) );
for (int i=0; i<queryErrors.size(); i++)
searchErrors.add(ErrorMessage.from(queryErrors.get(i)));
if (resultError != null)
searchErrors.add(resultError);
return Collections.unmodifiableCollection(searchErrors);
}
private void renderHitGroup(WRITER writer, HitGroup hitGroup) throws IOException {
if (hitGroup instanceof GroupList) {
beginGroupList(writer, (GroupList) hitGroup);
renderHitGroupContent(writer, hitGroup);
endGroupList(writer, (GroupList) hitGroup);
} else if (hitGroup instanceof HitList) {
beginHitList(writer, (HitList) hitGroup);
renderHitGroupContent(writer, hitGroup);
endHitList(writer, (HitList) hitGroup);
} else if (hitGroup instanceof Group) {
beginGroup(writer, (Group) hitGroup);
renderHitGroupContent(writer, hitGroup);
endGroup(writer, (Group) hitGroup);
} else {
beginHitGroup(writer, hitGroup);
renderHitGroupContent(writer, hitGroup);
endHitGroup(writer, hitGroup);
}
}
private void renderHitGroupContent(WRITER writer, HitGroup hitGroup) throws IOException {
for (Hit hit : hitGroup.asList()) {
renderHit(writer, hit);
}
}
private void renderHit(WRITER writer, Hit hit) throws IOException {
if (hit instanceof HitGroup) {
renderHitGroup(writer, (HitGroup) hit);
} else if (hit instanceof ErrorHit) {
errorHit(writer, (ErrorHit) hit);
} else {
hit(writer, hit);
}
}
}
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