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/* NodeReader - Reads and imports preferences nodes from files

   Copyright (C) 2001 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2, or (at your option)

any later version.

GNU Classpath is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

General Public License for more details.

You should have received a copy of the GNU General Public License

along with GNU Classpath; see the file COPYING.  If not, write to the

Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301 USA.

Linking this library statically or dynamically with other modules is

making a combined work based on this library.  Thus, the terms and

conditions of the GNU General Public License cover the whole

combination.

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

modules, and to copy and distribute the resulting executable under

terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

module.  An independent module is a module which is not derived from

or based on this library.  If you modify this library, you may extend

this exception to your version of the library, but you are not

obligated to do so.  If you do not wish to do so, delete this

exception statement from your version. */

package gnu.java.util.prefs;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.Reader;

import java.util.prefs.InvalidPreferencesFormatException;

import java.util.prefs.Preferences;

import java.util.prefs.PreferencesFactory;

/**

 * Reads and imports preferences nodes from files.

 *

 * @author Mark Wielaard (mark@klomp.org)

 */

public class NodeReader {

    private final BufferedReader br;

    private String line = "";

    private final PreferencesFactory factory;

    public NodeReader(Reader r, PreferencesFactory factory) {

        if(r instanceof BufferedReader) {

            br = (BufferedReader) r;

        } else {

            br = new BufferedReader(r);

        }

        this.factory = factory;

    }

    public NodeReader(InputStream is, PreferencesFactory factory) {

        this(new InputStreamReader(is), factory);

    }

    public void importPreferences()

                    throws InvalidPreferencesFormatException, IOException

    {

        readPreferences();

    }

    private void readPreferences()

                    throws InvalidPreferencesFormatException, IOException

    {

        // Begin starting tag

        skipTill("<preferences");

        readRoot();

        // Ending tag

        skipTill("</preferences>");

    }

    private void readRoot()

                    throws InvalidPreferencesFormatException, IOException

    {

        // Begin starting tag

        skipTill("<root");

        // type attribute

        skipTill("type=\"");

        String type = readTill("\"");

        Preferences root;

        if ("user".equals(type)) {

            root = factory.userRoot();

        } else if ("system".equals(type)) {

            root = factory.systemRoot();

        } else {

            throw new InvalidPreferencesFormatException("Unknown type: "

                                                        + type);

        }

        // Read root map and subnodes

        readMap(root);

        readNodes(root);

        // Ending tag

        skipTill("</root>");

    }

    private void readNodes(Preferences node)

                    throws InvalidPreferencesFormatException, IOException

    {

        while ("node".equals(nextTag())) {

            skipTill("<node");

            skipTill("name=\"");

            String name = readTill("\"");

            Preferences subnode = node.node(name);

            readMap(subnode);

            readNodes(subnode);

            skipTill("</node>");

        }

    }

    private void readMap(Preferences node)

                    throws InvalidPreferencesFormatException, IOException

    {

        // Begin map tag

        skipTill("<map");

        // Empty map?

        if (line.startsWith("/>")) {

            line = line.substring(2);

            return;

        }

        // Map entries

        readEntries(node);

        // Ending tag

        skipTill("</map>");

    }

    private void readEntries(Preferences node)

                    throws InvalidPreferencesFormatException, IOException

    {

        while ("entry".equals(nextTag())) {

            skipTill("<entry");

            skipTill("key=\"");

            String key = readTill("\"");

            skipTill("value=\"");

            String value = readTill("\"");

            node.put(key, value);

        }

    }

    private void skipTill(String s)

                    throws InvalidPreferencesFormatException, IOException

    {

        while(true) {

            if (line == null)

                throw new InvalidPreferencesFormatException(s + " not found");

            int index = line.indexOf(s);

            if (index == -1)  {

                line = br.readLine();

            } else {

                line = line.substring(index+s.length());

                return;

            }

        }

    }

    private String readTill(String s)

                    throws InvalidPreferencesFormatException

    {

        int index = line.indexOf(s);

        if (index == -1)

                throw new InvalidPreferencesFormatException(s + " not found");

        String read = line.substring(0, index);

        line = line.substring(index+s.length());

        return read;

    }

    private String nextTag()

                    throws InvalidPreferencesFormatException, IOException

    {

        while(true) {

            if (line == null)

                throw new InvalidPreferencesFormatException("unexpected EOF");

            int start = line.indexOf("<");

            if (start == -1)  {

                line = br.readLine();

            } else {

                // Find end of tag

                int end = start+1;

                while (end != line.length()

                       && " \t\r\n".indexOf(line.charAt(end)) == -1) {

                    end++;

                }

                // Line now starts at the found tag

                String tag = line.substring(start+1,end);

                line = line.substring(start);

                return tag;

            }

        }

    }

}