/*
* Copyright 2014 the original author or authors.
*
* 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 org.grails.encoder;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
public class ChainedEncoder implements Encoder, StreamingEncoder {
private final StreamingEncoder[] encoders;
private final CodecIdentifier combinedCodecIdentifier;
private final boolean safe;
// this ThreadLocal lives as long as the instance of this ChainedEncoder class, this isn't a static ThreadLocal
private final ThreadLocal<ChainedEncoderCacheItem> cacheItemThreadLocal = new ThreadLocal<ChainedEncoder.ChainedEncoderCacheItem>() {
protected ChainedEncoderCacheItem initialValue() {
return new ChainedEncoderCacheItem();
};
};
private static class ChainedEncoderCacheItem {
EncodedAppender lastAppenderForCached;
boolean lastIgnoreEncodingStateForCached;
EncodedAppender cachedChainedAppender;
void putInCache(final EncodedAppender appender, EncodedAppender target) {
lastAppenderForCached = appender;
lastIgnoreEncodingStateForCached = appender.isIgnoreEncodingState();
cachedChainedAppender = target;
}
EncodedAppender getCached(final EncodedAppender appender) {
if(lastAppenderForCached == appender && lastIgnoreEncodingStateForCached == appender.isIgnoreEncodingState()) {
return cachedChainedAppender;
}
return null;
}
}
public ChainedEncoder(List<StreamingEncoder> encoders, boolean safe) {
this(encoders.toArray(new StreamingEncoder[encoders.size()]), safe);
}
public ChainedEncoder(StreamingEncoder[] encoders, boolean safe) {
this.encoders = Arrays.copyOf(encoders, encoders.length);
this.combinedCodecIdentifier = createCodecIdentifier(encoders);
this.safe = safe;
}
public static StreamingEncoder createFor(StreamingEncoder[] encoders) {
return createFor(Arrays.asList(encoders));
}
public static StreamingEncoder createFor(List<StreamingEncoder> encoders) {
return createFor(encoders, null);
}
public static StreamingEncoder createFor(List<StreamingEncoder> encoders, Boolean safe) {
if(encoders==null) {
return null;
} else if(encoders.size()==0) {
return DefaultEncodingStateRegistry.NONE_ENCODER;
} else if(encoders.size()==1) {
return encoders.get(0);
} else {
if(safe == null) {
for(StreamingEncoder encoder : encoders) {
if(encoder.isSafe()) {
safe = true;
break;
}
}
}
return new ChainedEncoder(encoders, safe != null ? safe : false);
}
}
protected CombinedCodecIdentifier createCodecIdentifier(StreamingEncoder[] encoders) {
return new CombinedCodecIdentifier(encoders);
}
@Override
public CodecIdentifier getCodecIdentifier() {
return combinedCodecIdentifier;
}
@Override
public void encodeToStream(Encoder thisInstance, CharSequence source, int offset, int len,
EncodedAppender appender, EncodingState encodingState) throws IOException {
EncodedAppender target = chainEncodersAndCachePerThread(appender);
StreamingEncoder encoder=encoders[0];
if(appender.shouldEncode(encoder, encodingState.getPreviousEncodingState())) {
encoder.encodeToStream(encoder, source, offset, len, target, encodingState.getPreviousEncodingState());
} else {
target.appendEncoded(encoder, encodingState.getPreviousEncodingState(), source, offset, len);
}
}
protected EncodedAppender chainEncodersAndCachePerThread(final EncodedAppender appender) {
ChainedEncoderCacheItem cacheItem = cacheItemThreadLocal.get();
EncodedAppender target = cacheItem.getCached(appender);
if(target == null) {
target = doChainEncoders(appender);
cacheItem.putInCache(appender, target);
}
return target;
}
protected EncodedAppender doChainEncoders(final EncodedAppender appender) {
EncodedAppender target=appender;
for(int i=encoders.length-1;i >= 1;i--) {
StreamingEncoder encoder=encoders[i];
target=new StreamingEncoderEncodedAppender(encoder, target);
target.setIgnoreEncodingState(appender.isIgnoreEncodingState());
}
return target;
}
@Override
public Object encode(Object o) {
if(o==null) return o;
Object encoded = o;
for (StreamingEncoder encoder : encoders) {
encoded = encoder.encode(encoded);
}
return encoded;
}
@Override
public boolean isSafe() {
return safe;
}
@Override
public boolean isApplyToSafelyEncoded() {
return true;
}
@Override
public void markEncoded(CharSequence string) {
}
}