uk.org.retep.microkernel.shell.KernelShell Maven / Gradle / Ivy

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/*
 * Copyright (c) 1998-2010, Peter T Mount

 * All rights reserved.
 *
 * 
 *   This program 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 3 of the License, or
 *   (at your option) any later version.
 * 
 *
 * 
 *   This program 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 this program.  If not, see .
 * 
 *
 * 
 *        GNU GENERAL PUBLIC LICENSE - CLASSPATH EXCEPTION
 * 
 *
 * 
 *   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 either not derived from or based
 *   on this library, or a module who's classes extend those within this library
 *   as part of the implementation of the 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 uk.org.retep.microkernel.shell;

import groovy.lang.Binding;
import groovy.lang.GroovyShell;
import groovy.lang.Script;
import java.io.Console;
import java.io.File;
import java.io.IOException;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import javax.annotation.Nonnull;
import org.codehaus.groovy.control.CompilationFailedException;
import uk.org.retep.logging.LogSupport;
import uk.org.retep.util.services.Service;
import uk.org.retep.util.string.StringUtils;

/**
 * A Groovy shell loosely based on {@link groovy.ui.KernelShell}
 * @author peter
 */
public class KernelShell
        extends LogSupport
{

    private static final String GLOBAL_END = "\nstatic main(String[] args){}\n}";
    private static final String GLOBAL_START = "class Global {\n";
    private static final String GROOVY = ".groovy";
    private static final String LOG_EXECUTE = "execute: %s";
    private static final String LOG_RESULT = "result: %s";
    private static final String NO_CONSOLE_AVAILABLE = "No console available";
    private static final String SHELL = "shell";
    //
    private final KernelShellModule module;
    private final Console console;
    private final GroovyShell shell;
    private File scriptHome;

    /***
     * Default constructor.
     * @param module The parent module
     */
    KernelShell( @Nonnull final KernelShellModule module )
    {
        this.module = module;

        console = System.console();
        if( console == null )
        {
            throw new NullPointerException( NO_CONSOLE_AVAILABLE );
        }

        shell = new GroovyShell( new Binding() );
        // This is in the groovy example so it's here
        @SuppressWarnings( "unchecked" )
        final Map variables = shell.getContext().getVariables();
        if( variables.get( SHELL ) != null )
        {
            variables.put( SHELL, shell );
        }

        // Provide access to this class to scripts
        GlobalAdapter.getInstance().setShell( this );

        generateGlobal();
    }

    final GroovyShell getShell()
    {
        return shell;
    }

    final KernelShellModule getModule()
    {
        return module;
    }

    final Console getConsole()
    {
        return console;
    }

    private void generateGlobal()
    {
        // Preload any imports etc from a services file
        final Collection globalClass = Service.providerClassNames(
                KernelShell.class.getName(),
                Thread.currentThread().getContextClassLoader() );
        final Iterator it = globalClass.iterator();
        while( it.hasNext() )
        {
            final String imp = it.next();
            // Remove blank or lines beginning with #
            if( StringUtils.isStringEmpty( imp ) || imp.charAt( 0 ) == '#' )
            {
                it.remove();
            }
        }

        // Evaluate to generate the Global class
        evaluate( 
                GLOBAL_START + StringUtils.join( '\n', globalClass ) + GLOBAL_END );
    }

    public Object call( @Nonnull final String script )
            throws CompilationFailedException,
                   IOException
    {
        final String scriptName = script.endsWith( GROOVY ) ? script : (script + GROOVY);

        // locate the script in the current directory (or if it's absolute)
        File scriptFile = new File( scriptName );

        // Don't hunt if the supplied script name is absolute
        if( !scriptFile.exists() && !scriptFile.isAbsolute() )
        {
            // Look in script directory
            if( !scriptFile.exists() )
            {
                scriptFile = new File( module.getScriptDir(), scriptName );
            }

            // If we have a previous script file reference, look in that directory
            if( !scriptFile.exists() && scriptHome != null )
            {
                scriptFile = new File( scriptHome, scriptName );
            }
        }

        if( scriptFile.exists() )
        {
            return evaluate( scriptFile );
        }
        else
        {
            throw new ScriptNotFoundException( script );
        }
    }

    public Object evaluate( @Nonnull final String command )
    {
        getLog().debug( LOG_EXECUTE, command );

        return evaluate( shell.parse( command ) );
    }

    public Object evaluate( @Nonnull final File file )
            throws CompilationFailedException,
                   IOException
    {
        getLog().debug( LOG_EXECUTE, file.getAbsolutePath() );

        if( !file.exists() )
        {
            throw new ScriptNotFoundException( file );
        }

        // set scriptHome so we can call scripts in the same directory
        if( scriptHome == null )
        {
            scriptHome = file.getParentFile();
        }

        return evaluate( shell.parse( file ) );
    }

    public Object evaluate( @Nonnull final Script script )
    {
        script.setBinding( shell.getContext() );

        final Object result = script.run();

        if( getLog().isDebugEnabled() )
        {
            getLog().debug( LOG_RESULT, result );
        }

        return result;
    }

    public void setVariable( final String name, final Object value )
    {
        shell.setVariable( name, value );
    }

    public Object getVariable( final String name )
    {
        return shell.getVariable( name );
    }
}