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// Copyright 2017 Yahoo Holdings. 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.Query;
import com.yahoo.search.Result;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.SettableFuture;
import com.yahoo.io.ByteWriter;
import com.yahoo.processing.Request;
import com.yahoo.processing.execution.Execution;
import java.io.IOException;
import java.io.OutputStream;
import java.io.Writer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
/**
* Renders a search result to a writer synchronously - the result is completely rendered when the render method returns..
* 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>
* <li>State mutated during rendering shall be initialized in the init method.</li>
* </ol>
*
* @author Tony Vaagenes
*/
abstract public class Renderer extends com.yahoo.processing.rendering.Renderer<Result> {
/**
* Renders synchronously and returns when rendering is complete.
*
* @return a future which is always completed to true
*/
@Override
public final ListenableFuture<Boolean> render(OutputStream stream, Result response, Execution execution, Request request) {
Writer writer = null;
try {
writer = createWriter(stream,response);
render(writer, response);
}
catch (IOException e) {
throw new RuntimeException(e);
}
finally {
if (writer !=null)
try { writer.close(); } catch (IOException e2) {};
}
SettableFuture<Boolean> completed=SettableFuture.create();
completed.set(true);
return completed;
}
/**
* Renders the result to the writer.
*/
protected abstract void render(Writer writer, Result result) throws IOException;
private Writer createWriter(OutputStream stream,Result result) {
Charset cs = Charset.forName(getCharacterEncoding(result));
CharsetEncoder encoder = cs.newEncoder();
return new ByteWriter(stream, encoder);
}
public String getCharacterEncoding(Result result) {
String encoding = result.getQuery().getModel().getEncoding();
return (encoding != null) ? encoding : getEncoding();
}
/**
* @return The summary class to fill the hits with if no summary class was
* specified in the query presentation.
*/
public String getDefaultSummaryClass() {
return null;
}
/** Returns the encoding of the query, or the encoding given by the template if none is set */
public final String getRequestedEncoding(Query query) {
String encoding = query.getModel().getEncoding();
if (encoding != null) return encoding;
return getEncoding();
}
/**
* Used to create a separate instance for each result to render.
*/
@Override
public Renderer clone() {
return (Renderer) super.clone();
}
}
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