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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.pagetemplates.engine;
import com.yahoo.component.AbstractComponent;
import com.yahoo.component.ComponentId;
import com.yahoo.search.Query;
import com.yahoo.search.Result;
import com.yahoo.search.pagetemplates.PageTemplate;
import com.yahoo.search.pagetemplates.model.Choice;
import com.yahoo.search.pagetemplates.model.MapChoice;
import com.yahoo.search.pagetemplates.model.PageTemplateVisitor;
/**
* Superclass of page template choice resolvers.
* <p>
* Subclasses overrides one of the two resolve methods to either resolve each choices individually
* or look at all choices at once.
* <p>
* All subclasses of this must be multithread safe. I.e multiple calls may be made
* to resolve at the same time from different threads.
*
* @author bratseth
*/
public abstract class Resolver extends AbstractComponent {
public Resolver(String id) {
super(new ComponentId(id));
}
public Resolver(ComponentId id) {
super(id);
}
protected Resolver() {}
/**
* Override this to resolve choices. Before retuning this method <i>must</i> resolve the given choice
* between a set of page templates <i>and</i> all choices found recursively within the <i>chosen</i>
* page template. It is permissible but not required to add solutions also to choices present within those
* templates which are not chosen.
* <p>
* This default implementation creates a Resolution and calls
* <code>resolve(choice/mapChoice,query,result,resolution)</code> first on the given page template choice, then
* on each choice found in that temnplate. This provides a simple API to resolvers which make each choice
* independently.
*
* @param pageTemplate the choice of page templates to resolve - a choice containing singleton lists of PageTemplate elements
* @param query the query, from which information useful for correct resolution can be found
* @param result the result, from which further information useful for correct resolution can be found
* @return the resolution of the choices contained in the given page template
*/
public Resolution resolve(Choice pageTemplate, Query query, Result result) {
Resolution resolution=new Resolution();
resolve(pageTemplate,query,result,resolution);
PageTemplate chosenPageTemplate=(PageTemplate)pageTemplate.get(resolution.getResolution(pageTemplate)).get(0);
ChoiceResolverVisitor choiceResolverVisitor=new ChoiceResolverVisitor(query,result,resolution);
chosenPageTemplate.accept(choiceResolverVisitor);
return choiceResolverVisitor.getResolution();
}
/**
* Override this to resolve <i>each</i> choice independently.
* This default implementation does nothing.
*
* @param choice the choice to resolve
* @param query the query for which this should be resolved, typically used to extract features
* @param result the result for which this should be resolved, typically used to extract features
* @param resolution the set of resolutions made so far, to which this should be added:
* <code>resolution.addChoiceResolution(choice,chosenAlternativeIndex)</code>
*/
public void resolve(Choice choice,Query query,Result result,Resolution resolution) {
}
/**
* Override this to resolve <i>each</i> map choice independently.
* This default implementation does nothing.
*
* @param choice the choice to resolve
* @param query the query for which this should be resolved, typically used to extract features
* @param result the result for which this should be resolved, typically used to extract features
* @param resolution the set of resolutions made so far, to which this should be added:
* <code>resolution.addMapChoiceResolution(choice,chosenMapping)</code>
*/
public void resolve(MapChoice choice,Query query,Result result,Resolution resolution) {
}
private class ChoiceResolverVisitor extends PageTemplateVisitor {
private Resolution resolution;
private Query query;
private Result result;
public ChoiceResolverVisitor(Query query,Result result,Resolution resolution) {
this.query=query;
this.result=result;
this.resolution=resolution;
}
@Override
public void visit(Choice choice) {
if (choice.alternatives().size()<2) return; // No choice...
resolve(choice,query,result,resolution);
}
@Override
public void visit(MapChoice choice) {
resolve(choice,query,result,resolution);
}
public Resolution getResolution() { return resolution; }
}
}
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