Scala example source code file (TerminalSupport.java)

This example Scala source code file (TerminalSupport.java) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

abstractmethoderror, default_height, default_width, exception, failed, inputstream, ioexception, restorehook, string, thread

The TerminalSupport.java Scala example source code

/*
 * Copyright (c) 2002-2007, Marc Prud'hommeaux. All rights reserved.
 *
 * This software is distributable under the BSD license. See the terms of the
 * BSD license in the documentation provided with this software.
 */

package scala.tools.jline;

import scala.tools.jline.internal.Log;
import scala.tools.jline.internal.Configuration;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * Provides support for {@link Terminal} instances.
 *
 * @author <a href="mailto:jason@planet57.com">Jason Dillon</a>
 * @since 2.0
 */
public abstract class TerminalSupport
    implements Terminal
{
    public static String DEFAULT_KEYBINDINGS_PROPERTIES = "keybindings.properties";

    public static final String JLINE_SHUTDOWNHOOK = "jline.shutdownhook";

    public static final int DEFAULT_WIDTH = 80;

    public static final int DEFAULT_HEIGHT = 24;

    private Thread shutdownHook;

    private boolean shutdownHookEnabled;

    private boolean supported;

    private boolean echoEnabled;

    private boolean ansiSupported;

    protected TerminalSupport(final boolean supported) {
        this.supported = supported;
        this.shutdownHookEnabled = Configuration.getBoolean(JLINE_SHUTDOWNHOOK, false);
    }

    public void init() throws Exception {
        installShutdownHook(new RestoreHook());
    }

    public void restore() throws Exception {
        TerminalFactory.resetIf(this);
        removeShutdownHook();
    }

    public void reset() throws Exception {
        restore();
        init();
    }

    // Shutdown hooks causes classloader leakage in sbt,
    // so they are only installed if -Djline.shutdownhook is true.
    protected void installShutdownHook(final Thread hook) {
        if (!shutdownHookEnabled) {
            Log.debug("Not install shutdown hook " + hook + " because they are disabled.");
            return;
        }

        assert hook != null;

        if (shutdownHook != null) {
            throw new IllegalStateException("Shutdown hook already installed");
        }

        try {
            Runtime.getRuntime().addShutdownHook(hook);
            shutdownHook = hook;
        }
        catch (AbstractMethodError e) {
            // JDK 1.3+ only method. Bummer.
            Log.trace("Failed to register shutdown hook: ", e);
        }
    }

    protected void removeShutdownHook() {
        if (!shutdownHookEnabled)
            return;

        if (shutdownHook != null) {
            try {
                Runtime.getRuntime().removeShutdownHook(shutdownHook);
            }
            catch (AbstractMethodError e) {
                // JDK 1.3+ only method. Bummer.
                Log.trace("Failed to remove shutdown hook: ", e);
            }
            catch (IllegalStateException e) {
                // The VM is shutting down, not a big deal; ignore
            }
            shutdownHook = null;
        }
    }

    public final boolean isSupported() {
        return supported;
    }

    public synchronized boolean isAnsiSupported() {
        return ansiSupported;
    }

    protected synchronized void setAnsiSupported(final boolean supported) {
        this.ansiSupported = supported;
        Log.debug("Ansi supported: ", supported);
    }

    /**
     * Subclass to change behavior if needed.
     * @return the passed out
     */
    public OutputStream wrapOutIfNeeded(OutputStream out) {
        return out;
    }

    /**
     * Defaults to true which was the behaviour before this method was added.
     */
    public boolean hasWeirdWrap() {
        return true;
    }

    public int getWidth() {
        return DEFAULT_WIDTH;
    }

    public int getHeight() {
        return DEFAULT_HEIGHT;
    }

    public synchronized boolean isEchoEnabled() {
        return echoEnabled;
    }

    public synchronized void setEchoEnabled(final boolean enabled) {
        this.echoEnabled = enabled;
        Log.debug("Echo enabled: ", enabled);
    }

    public int readCharacter(final InputStream in) throws IOException {
        return in.read();
    }

    public int readVirtualKey(final InputStream in) throws IOException {
        return readCharacter(in);
    }

    public InputStream getDefaultBindings() {
        return TerminalSupport.class.getResourceAsStream(DEFAULT_KEYBINDINGS_PROPERTIES);
    }

    //
    // RestoreHook
    //

    protected class RestoreHook
        extends Thread
    {
        public void start() {
            try {
                restore();
            }
            catch (Exception e) {
                Log.trace("Failed to restore: ", e);
            }
        }
    }
}