/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.tsfile.external.commons.io.input;

import org.apache.tsfile.external.commons.io.IOUtils;

import java.io.InputStream;

import static org.apache.tsfile.external.commons.io.IOUtils.EOF;

/**
 * Always returns {@link IOUtils#EOF} to all attempts to read something from the stream.
 *
 * <p>Typically uses of this class include testing for corner cases in methods that accept input
 * streams and acting as a sentinel value instead of a {@code null} input stream.
 *
 * @since 1.4
 */
public class ClosedInputStream extends InputStream {

  /**
   * The singleton instance.
   *
   * @since 2.12.0
   */
  public static final ClosedInputStream INSTANCE = new ClosedInputStream();

  /**
   * The singleton instance.
   *
   * @deprecated Use {@link #INSTANCE}.
   */
  @Deprecated public static final ClosedInputStream CLOSED_INPUT_STREAM = INSTANCE;

  /**
   * Returns -1 to indicate that the stream is closed.
   *
   * @return always -1
   */
  @Override
  public int read() {
    return EOF;
  }
}
