/*
 * Copyright 2001-2004 The Apache Software Foundation
 *
 * 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 org.apache.commons.net.ftp;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import java.util.List;

/**
 * This abstract class implements both the older FTPFileListParser and
 * newer FTPFileEntryParser interfaces with default functionality.
 * All the classes in the parser subpackage inherit from this.
 *
 * @author Steve Cohen <scohen@apache.org>
 */
public abstract class FTPFileEntryParserImpl
    implements FTPFileEntryParser, FTPFileListParser
{
    /**
     * The constructor for a FTPFileEntryParserImpl object.
     */
    public FTPFileEntryParserImpl()
        {
    }


    /***
     * Parses an FTP server file listing and converts it into a usable format
     * in the form of an array of <code> FTPFile </code> instances.  If the
     * file list contains no files, <code> null </code> should be
     * returned, otherwise an array of <code> FTPFile </code> instances
     * representing the files in the directory is returned.
     * <p>
     * @param listStream The InputStream from which the file list should be
     *        read.
     * @return The list of file information contained in the given path.  null
     *     if the list could not be obtained or if there are no files in
     *     the directory.
     * @exception java.io.IOException  If an I/O error occurs reading the listStream.
     ***/
    public FTPFile[] parseFileList(InputStream listStream) throws IOException
    {
        FTPFileList ffl = FTPFileList.create(listStream, this);
        return ffl.getFiles();

    }

    /**
     * Reads the next entry using the supplied BufferedReader object up to
     * whatever delemits one entry from the next.  This default implementation
     * simply calls BufferedReader.readLine().
     *
     * @param reader The BufferedReader object from which entries are to be
     * read.
     *
     * @return A string representing the next ftp entry or null if none found.
     * @exception java.io.IOException thrown on any IO Error reading from the reader.
     */
    public String readNextEntry(BufferedReader reader) throws IOException
    {
        return reader.readLine();
    }
    /**
     * This method is a hook for those implementors (such as
     * VMSVersioningFTPEntryParser, and possibly others) which need to
     * perform some action upon the FTPFileList after it has been created
     * from the server stream, but before any clients see the list.
     *
     * This default implementation is a no-op.
     *
     * @param original Original list after it has been created from the server stream
     *
     * @return <code>original</code> unmodified.
     */
     public List preParse(List original) {
         Iterator it = original.iterator();
         while (it.hasNext()){
            String entry = (String) it.next();
            if (null == parseFTPEntry(entry)) {
                it.remove();
            } else {
                break;
            }
         }
         return original;
     }
}

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