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ProGuardCORE is a free library to read, analyze, modify, and write Java class files.
There is a newer version: 9.1.6
/*
 * ProGuardCORE -- library to process Java bytecode.
 *
 * Copyright (c) 2002-2020 Guardsquare NV
 *
 * 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 proguard.io;

import java.io.*;

/**
 * This {@link DataEntryWriter} delegates to a given {@link DataEntryWriter}, or failing that, to
 * another given {@link DataEntryWriter}.
 *
 * @author Eric Lafortune
 */
public class CascadingDataEntryWriter implements DataEntryWriter {
  private DataEntryWriter dataEntryWriter1;
  private DataEntryWriter dataEntryWriter2;

  /**
   * Creates a new CascadingDataEntryWriter.
   *
   * @param dataEntryWriter1 the DataEntryWriter to which the writing will be delegated first.
   * @param dataEntryWriter2 the DataEntryWriter to which the writing will be delegated, if the
   *     first one can't provide an output stream.
   */
  public CascadingDataEntryWriter(
      DataEntryWriter dataEntryWriter1, DataEntryWriter dataEntryWriter2) {
    this.dataEntryWriter1 = dataEntryWriter1;
    this.dataEntryWriter2 = dataEntryWriter2;
  }

  // Implementations for DataEntryWriter.

  @Override
  public boolean createDirectory(DataEntry dataEntry) throws IOException {
    // Try to create a directory with the first data entry writer, or
    // otherwise with the second data entry writer.
    return dataEntryWriter1.createDirectory(dataEntry)
        || dataEntryWriter2.createDirectory(dataEntry);
  }

  @Override
  public boolean sameOutputStream(DataEntry dataEntry1, DataEntry dataEntry2) throws IOException {
    return dataEntryWriter1.sameOutputStream(dataEntry1, dataEntry2)
        || dataEntryWriter2.sameOutputStream(dataEntry1, dataEntry2);
  }

  @Override
  public OutputStream createOutputStream(DataEntry dataEntry) throws IOException {
    // Try to get an output stream from the first data entry writer.
    OutputStream outputStream = dataEntryWriter1.createOutputStream(dataEntry);

    // Return it, if it's not null. Otherwise try to get an output stream
    // from the second data entry writer.
    return outputStream != null ? outputStream : dataEntryWriter2.createOutputStream(dataEntry);
  }

  @Override
  public void close() throws IOException {
    if (dataEntryWriter1 != null) {
      dataEntryWriter1.close();
      dataEntryWriter1 = null;
    }

    if (dataEntryWriter2 != null) {
      dataEntryWriter2.close();
      dataEntryWriter2 = null;
    }
  }

  @Override
  public void println(PrintWriter pw, String prefix) {
    pw.println(prefix + "CascadingDataEntryWriter");
    dataEntryWriter1.println(pw, prefix + "  ");
    dataEntryWriter2.println(pw, prefix + "  ");
  }
}