content: /*
   * 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.calcite.util;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.Reader;
  import java.net.URL;
  import java.util.Optional;
  
  /**
   * Source of data.
   */
  public interface Source {
    URL url();
    File file();
    Optional<File> fileOpt();
    String path();
    Reader reader() throws IOException;
    InputStream openStream() throws IOException;
    String protocol();
  
    /** Looks for a suffix on a path and returns
     * either the path with the suffix removed
     * or the original path. */
    Source trim(String suffix);
  
    /** Looks for a suffix on a path and returns
     * either the path with the suffix removed
     * or null. */
    @Nullable Source trimOrNull(String suffix);
  
    /** Returns a source whose path concatenates this with a child.
     *
     * <p>For example,
     * <ul>
     *   <li>source("/foo").append(source("bar"))
     *   returns source("/foo/bar")
     *   <li>source("/foo").append(source("/bar"))
     *   returns source("/bar")
     *   because "/bar" was already absolute
     * </ul>
     */
    Source append(Source child);
  
    /** Returns a relative source, if this source is a child of a given base.
     *
     * <p>For example,
     * <ul>
     *   <li>source("/foo/bar").relative(source("/foo"))
     *   returns source("bar")
     *   <li>source("/baz/bar").relative(source("/foo"))
     *   returns source("/baz/bar")
     * </ul>
     */
    Source relative(Source source);
  }
  