/*
 *  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.codehaus.groovy.control.io;

import java.io.IOException;
import java.io.Reader;
import java.net.URI;

import org.codehaus.groovy.control.HasCleanup;
import org.codehaus.groovy.control.Janitor;

/**
 *  An interface for things that can supply (and potentially resupply) a Reader
 *  on a source stream.
 *
 *  @author <a href="mailto:cpoirier@dreaming.org">Chris Poirier</a>
 */
public interface ReaderSource extends HasCleanup {
   /**
    *  Returns a new Reader on the underlying source object.  Returns
    *  null if the source can't be reopened.
    * @throws java.io.IOException if there was an error opening for stream
    * @return the reader to the resource
    */
    Reader getReader() throws IOException;
    
   /**
    *  Returns true if the source can be restarted (ie. if getReader()
    *  will return non-null on subsequent calls.
    * @return true if the resource can be reopened for reading
    */
    boolean canReopenSource();
    
   /**
    *  Returns a line from the source, or null, if unavailable.  If
    *  you supply a Janitor, resources will be cached.
    * @param lineNumber the number of the line of interest
    * @param janitor helper to clean up afterwards
    * @return the line of interest
    */
    String getLine( int lineNumber, Janitor janitor );
    
   /**
    *  Cleans up any cached resources used by getLine().
    */
    void cleanup();

    /**
     * Returns a URI for this source.
     *
     * @since 2.3.0
     */
    URI getURI();
}