/home/leaf/crossfire/jxclient/trunk/gui/src/main/java/com/realtime/crossfire/jxclient/settings/CommandHistory.java

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/*
 * This file is part of JXClient, the Fullscreen Java Crossfire Client.
 *
 * JXClient 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 of the License, or
 * (at your option) any later version.
 *
 * JXClient 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 JXClient; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Copyright (C) 2005-2008 Yann Chachkoff.
 * Copyright (C) 2006-2011 Andreas Kirschbaum.
 */

package com.realtime.crossfire.jxclient.settings;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

public class CommandHistory {

    private static final int HISTORY_SIZE = 100;

    @NotNull
    private final List<String> commands = new ArrayList<String>(HISTORY_SIZE);

    private int commandIndex = 0;

    public CommandHistory(@NotNull final String ident) {
    }

    public void addCommand(@NotNull final String command) {
        final String trimmedCommand = command.trim();
        if (trimmedCommand.length() <= 0) {
            return;
        }
        removeCommand(trimmedCommand);
        commands.add(trimmedCommand);
        commandIndex = commands.size();
        trimToMaxSize();
    }

    private void trimToMaxSize() {
        while (commands.size() > HISTORY_SIZE) {
            commands.remove(0);
            if (commandIndex > 0) {
                commandIndex--;
            }
        }
    }

    private void removeCommand(@NotNull final String command) {
        final Iterator<String> it = commands.iterator();
        while (it.hasNext()) {
            final String oldCommand = it.next();
            if (oldCommand.equals(command)) {
                it.remove();
                break;
            }
        }
    }

    @Nullable
    public String up() {
        return 1 <= commandIndex && commandIndex <= commands.size() ? commands.get(--commandIndex) : null;
    }

    @Nullable
    public String down() {
        if (commandIndex < commands.size()) {
            commandIndex++;
        }
        return commandIndex < commands.size() ? commands.get(commandIndex) : null;
    }

}

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