/*

* Copyright 2013 Netflix, 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 feign.codec;

import org.xml.sax.ContentHandler;

import org.xml.sax.InputSource;

import org.xml.sax.SAXException;

import org.xml.sax.XMLReader;

import org.xml.sax.helpers.XMLReaderFactory;

import javax.inject.Provider;

import java.io.IOException;

import java.io.Reader;

import java.lang.reflect.Type;

import static feign.Util.checkNotNull;

import static feign.Util.checkState;

public class SAXDecoder<T> implements Decoder.TextStream<T> {

/* Implementations are not intended to be shared across requests. */

public interface ContentHandlerWithResult<T> extends ContentHandler {

/*

* expected to be set following a call to {@link

* XMLReader#parse(InputSource)}

*/

T result();

}

private final Provider<? extends ContentHandlerWithResult<T>> handlers;

/**

* You must subclass this, in order to prevent type erasure on {@code T}. In

* addition to making a concrete type, you can also use the following form.

* <p/>

* <br>

* <p/>

* <pre>

* new SaxDecoder&lt;Foo&gt;(fooHandlers) {

* }; // note the curly braces ensures no type erasure!

* </pre>

*/

protected SAXDecoder(Provider<? extends ContentHandlerWithResult<T>> handlers) {

this.handlers = checkNotNull(handlers, "handlers");

}

@Override

public T decode(Reader reader, Type type) throws IOException, DecodeException {

ContentHandlerWithResult<T> handler = handlers.get();

checkState(handler != null, "%s returned null for type %s", this, type);

try {

XMLReader xmlReader = XMLReaderFactory.createXMLReader();

xmlReader.setFeature("http://xml.org/sax/features/namespaces", false);

xmlReader.setFeature("http://xml.org/sax/features/validation", false);

xmlReader.setContentHandler(handler);

xmlReader.parse(new InputSource(reader));

return handler.result();

} catch (SAXException e) {

throw new DecodeException(e.getMessage(), e);

}

}

}