Package com.cedarsoft.couchdb.io

Source Code of com.cedarsoft.couchdb.io.CouchSerializerWrapper

/**
* Copyright (C) cedarsoft GmbH.
*
* Licensed under the GNU General Public License version 3 (the "License")
* with Classpath Exception; you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
*         http://www.cedarsoft.org/gpl3ce
*         (GPL 3 with Classpath Exception)
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 3 only, as
* published by the Free Software Foundation. cedarsoft GmbH designates this
* particular file as subject to the "Classpath" exception as provided
* by cedarsoft GmbH in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
* version 3 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 3 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact cedarsoft GmbH, 72810 Gomaringen, Germany,
* or visit www.cedarsoft.com if you need additional information or
* have any questions.
*/
package com.cedarsoft.couchdb.io;

import com.cedarsoft.couchdb.core.DocId;
import com.cedarsoft.couchdb.core.Revision;
import com.cedarsoft.couchdb.core.UniqueId;
import com.cedarsoft.serialization.jackson.AbstractJacksonSerializer;
import com.cedarsoft.serialization.jackson.filter.Filter;
import com.cedarsoft.serialization.jackson.filter.FilteringJsonParser;
import com.cedarsoft.version.Version;
import com.cedarsoft.version.VersionException;
import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.JsonParser;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.WillNotClose;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
* This wrapper skips couchdb specific entries ("_id" and "_rev").
* <p/>
* Wraps a default serializer.
* <p/>
* ATTENTION: Serializing is only supported for test cases and requires additional informations. Use
* {@link #serialize(Object, OutputStream, DocId, Revision)} for those cases!
*
* @param <T> the type
* @author Johannes Schneider (<a href="mailto:js@cedarsoft.com">js@cedarsoft.com</a>)
*/
public class CouchSerializerWrapper<T> extends AbstractJacksonSerializer<T> {
  public static final String ID = "_id";
  public static final String REV = "_rev";

  @Nonnull
  private final AbstractJacksonSerializer<T> delegate;

  public CouchSerializerWrapper( @Nonnull AbstractJacksonSerializer<T> delegate ) {
    super( delegate.getType(), delegate.getFormatVersionRange() );
    if ( !delegate.isObjectType() ) {
      throw new IllegalStateException( "Not supported for object type serializer: " + delegate.getClass().getName() );
    }

    this.delegate = delegate;
  }

  /**
   * Serialization is only supported for test cases. This method just delegates everything
   *
   * @param serializeTo   serialize to
   * @param object        the object
   * @param formatVersion the format version
   * @throws IOException
   * @throws VersionException
   */
  @Override
  public void serialize( @Nonnull JsonGenerator serializeTo, @Nonnull T object, @Nonnull Version formatVersion ) throws IOException, VersionException {
    delegate.serialize( serializeTo, object, formatVersion );
  }

  @Override
  protected void beforeTypeAndVersion( @Nonnull T object, @Nonnull JsonGenerator serializeTo ) throws IOException {
    UniqueId uniqueId = getUniqueId();

    serializeTo.writeStringField( ID, uniqueId.getId().asString() );
    serializeTo.writeStringField( REV, uniqueId.getRevision().asString() );
    super.beforeTypeAndVersion( object, serializeTo );
  }

  /**
   * @noinspection RefusedBequest
   */
  @Deprecated
  @Override
  public void serialize( @Nonnull T object, @WillNotClose @Nonnull OutputStream out ) throws IOException {
    throw new UnsupportedOperationException( "Use #serialize(Object, OutputStream, DocId, Revision) instead" );
  }

  /**
   * @param object   the object to serialize
   * @param out      the output stream
   * @param id       the document id
   * @param revision the revision
   */
  @Deprecated
  public void serialize( @Nonnull T object, @WillNotClose @Nonnull OutputStream out, @Nonnull DocId id, @Nonnull Revision revision ) throws IOException {
    storeUniqueId( new UniqueId( id, revision ) );
    super.serialize( object, out );
  }

  /**
   * Only necessary for serialization in tests!
   */
  @Nonnull
  @Deprecated
  private static final ThreadLocal<UniqueId> uniqueIdThreadLocal = new ThreadLocal<>();

  @Deprecated
  private static void storeUniqueId( @Nonnull UniqueId uniqueId ) {
    uniqueIdThreadLocal.set( uniqueId );
  }

  @Deprecated
  @Nonnull
  private static UniqueId getUniqueId() {
    @Nullable UniqueId resolved = uniqueIdThreadLocal.get();
    if ( resolved == null ) {
      throw new IllegalStateException( "No unique id found" );
    }

    uniqueIdThreadLocal.remove();
    return resolved;
  }

  @Nonnull
  @Override
  protected JsonParser createJsonParser( @Nonnull JsonFactory jsonFactory, @Nonnull InputStream in ) throws IOException {
    JsonParser parser = super.createJsonParser( jsonFactory, in );
    return new FilteringJsonParser( parser, new Filter() {
      @Override
      public boolean shallFilterOut( @Nonnull JsonParser parser ) throws IOException, JsonParseException {
        @Nullable String currentName = parser.getCurrentName();
        return currentName.startsWith( "_" );
      }
    } );
  }

  @Nonnull
  @Override
  public T deserialize( @Nonnull JsonParser deserializeFrom, @Nonnull Version formatVersion ) throws IOException, VersionException {
    return delegate.deserialize( deserializeFrom, formatVersion );
  }
}
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