source: trunk/org.modelica.mdt.omc/src/org/modelica/mdt/omc/OMCProxy.java @ 405

/*
 * This file is part of Modelica Development Tooling.
 *
 * Copyright (c) 2005, Link�pings universitet, Department of
 * Computer and Information Science, PELAB
 *
 * All rights reserved.
 *
 * (The new BSD license, see also
 * http://www.opensource.org/licenses/bsd-license.php)
 *
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in
 *   the documentation and/or other materials provided with the
 *   distribution.
 *
 * * Neither the name of Link�pings universitet nor the names of its
 *   contributors may be used to endorse or promote products derived from
 *   this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.modelica.mdt.omc;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.Collection;
import java.util.LinkedList;
import java.util.StringTokenizer;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.runtime.Platform;
import org.modelica.mdt.core.IModelicaClass;
import org.modelica.mdt.core.IllegalTypeException;
import org.modelica.mdt.core.List;
import org.modelica.mdt.core.ListElement;
import org.modelica.mdt.core.compiler.ConnectException;
import org.modelica.mdt.core.compiler.ElementsInfo;
import org.modelica.mdt.core.compiler.IModelicaCompiler;
import org.modelica.mdt.core.compiler.InvocationError;
import org.modelica.mdt.core.compiler.ModelicaParser;
import org.modelica.mdt.core.compiler.UnexpectedReplyException;
import org.modelica.mdt.core.preferences.PreferenceManager;
import org.modelica.mdt.internal.core.ElementLocation;
import org.modelica.mdt.internal.core.ErrorManager;
import org.modelica.mdt.omc.internal.ParseResults;
import org.modelica.mdt.omc.internal.OMCParser;
import org.modelica.mdt.omc.internal.corba.OmcCommunication;
import org.modelica.mdt.omc.internal.corba.OmcCommunicationHelper;
import org.omg.CORBA.ORB;

/**
 * The OMCProxy is the glue between the OpenModelica Compiler and MDT.
 * It uses the interactive API of OMC to get information about classes
 * and to load classes into OMC.
 * 
 * @author Andreas Remar
 */
public class OMCProxy implements IModelicaCompiler
{
    /* the CORBA object */
    private static OmcCommunication omcc;
    
    
    enum osType { WINDOWS, UNIX };
    
    /* what Operating System we're running on */
    private static osType os;
    
    /* indicates if we've setup the communication with OMC */
    private boolean hasInitialized = false;
    
    /* indicates if the Modelica System Library has been loaded */
    private boolean systemLibraryLoaded = false;

    private String[] standardLibraryPackages = { "Modelica" };

    /* should we trace the calls to sendExpression? */
    private static boolean traceOMCCalls = false;
    private static boolean traceOMCStatus = false;
    static
    {
        /* load debug options and set debug flag variables accordingly */
        
        
        String value = Platform.getDebugOption  /*load trace/omcCalls flag */
            ("org.modelica.mdt.omc/trace/omcCalls");
        if (value != null && value.equalsIgnoreCase("true"))
        {
            traceOMCCalls = true;
        }
        
        value = Platform.getDebugOption
        ("org.modelica.mdt.omc/trace/omcStatus");
        if (value != null && value.equalsIgnoreCase("true"))
        {
            traceOMCStatus = true;
        }
    }
    
    public OMCProxy()
    {
        
    }

    /**
     * Reads in the OMC CORBA object reference from a file on disk.
     * @return the object reference as a <code>String</code>
     */
    private static String readObjectFromFile() throws ConnectException
    {
        File f = new File(getPathToObject());
        String stringifiedObjectReference = null;

        BufferedReader br = null;
        FileReader fr = null;
        try
        {
            fr = new FileReader(f);
        }
        catch(IOException e)
        {
            throw new ConnectException
                ("Unable to read OpenModelica Compiler CORBA object from "
                        + f.toString());
        }

        br = new BufferedReader(fr);
            
        try
        {
            stringifiedObjectReference = br.readLine();
        }
        catch(IOException e)
        {
            throw new ConnectException("Unable to read OpenModelica Compiler"
                    + " CORBA object from " + getPathToObject());
        }
        return stringifiedObjectReference;
    }
    
    /**
     * @return Returns the path to the OMC CORBA object that is stored on disk.
     */
    private static String getPathToObject()
    {
        String fileName = null;

        /* This mirrors the way OMC creates the object file. */     
        switch (os)
        {
        case UNIX:
            String username = System.getenv("USER");
            if(username == null)
            {
                username = "nobody";
            }
            fileName = "/tmp/openmodelica." + username + ".objid";
            break;
        case WINDOWS:
            String temp = System.getenv("TMP");         
            fileName = temp + "\\openmodelica.objid";
            break;
        default:
            ErrorManager.logBug("org.modelica.mdt.omc",
                    "os variable set to unexpected os-type");
        }
        
        logOMCStatus("Will look for OMC object reference in '" 
                + fileName + "'.");
        
        return fileName;
    }
    
    /**
     * With the help of voodoo magic determines the path to the
     * omc binary that user (probably) wants to use and the working
     * direcoty of where that binary (most likely) should be started in
     * 
     * This will returns for example 'c:\openmodelica132\omc.exe'
     * or '/usr/local/share/openmodelica/omc' depending on
     * such factors as: OS type, environment variables settings,
     * plugin user preferences, where the first matching
     * binary found and the weather outside. 
     * 
     * @return full path to the omc binary  
     * @throws ConnectException if the path could not be determined
     */
    private static File[] getOmcBinaryPaths() throws ConnectException
    {
        String binaryName = "omc";
        
        if (os == osType.WINDOWS)
        {
            binaryName += ".exe";
        }
        
        File omcBinary = null;
        File omcWorkingDirectory = null;
        if (PreferenceManager.getUseStandardOmcPath())
        {
            /*
             * user specified that standard path to omc should be used,
             * try to determine the omc path via the OPENMODELICAHOME and
             * by checking in it's varius subdirectory for the omc binary file
             */
            logOMCStatus("Using OPENMODELICAHOME environment variable to find omc-binary");
            
            /* 
             * Standard path to omc (or omc.exe) binary is encoded in OPENMODELICAHOME
             * variable. 
             */
            String openModelicaHome = System.getenv("OPENMODELICAHOME");
            if(openModelicaHome == null)
            {
                final String m = "Environment variable OPENMODELICAHOME not set";
                logOMCStatus("Environment variable OPENMODELICAHOME not set,"+
                        " don't know how to start OMC from standard path.");
                throw new ConnectException(m);
            }
            
            omcWorkingDirectory = new File(openModelicaHome);
            
            /* the subdirectories where omc binary may be located, hurray for standards! */
            String[] subdirs = { "", "bin", "Compiler" };
            
            for (String subdir : subdirs)
            {
            
                String path = omcWorkingDirectory.getAbsolutePath() + File.separator;
                path += subdir.equals("") ? binaryName :  subdir + File.separator + binaryName;

                File file = new File(path); 

                if (file.exists())
                {
                    omcBinary = file;
                    logOMCStatus("Using omc-binary at '" + omcBinary.getAbsolutePath() + "'");
                    break;
                }
                else
                {
                    logOMCStatus("No omc binary at: [" + path + "]");
                }
            }
            
            if (omcBinary == null)
            {
                logOMCStatus("Could not fine omc-binary on the OPENMODELICAHOME path");
                throw new ConnectException("Unable to start the OpenModelica Compiler, binary not found");
            }
        }
        else
        {
            omcBinary = new File(PreferenceManager.getCustomOmcPath());
            
            logOMCStatus("Using userspecified omc-binary at '" +
                    omcBinary.getAbsolutePath() + "'");
            
            if (!omcBinary.exists())
            {
                logOMCStatus("file '" + omcBinary.getAbsolutePath() + "' does not exist");
                throw new ConnectException("Specified omc-binary '" + omcBinary.getAbsolutePath() +
                    "' does not exist");
            }
            
            /*
             * take an educated guess at where the user wants the binary to be
             * started. The guessing heuristics are as follows:
             * 
             * If binary is inside the 'bin' or 'compiler' directory, use the
             * above directory as working directory.
             * 
             * Otherwise use the directory where binary is located as working 
             * directory.
             * 
             * e.g. binary path /foo/bar/bin/omc      => working directory /foo/bar
             *      binary path /foo/bar/compiler/omc => working directory /foo/bar
             *      binary path /foo/bar/omc          => working directory /foo/bar
             */
            File parent = omcBinary.getParentFile();
            
            if (parent.getName().equalsIgnoreCase("bin") || 
                parent.getName().equalsIgnoreCase("compiler"))
            {
                omcWorkingDirectory = parent.getParentFile();
            }
            else
            {
                omcWorkingDirectory = parent;
            }
            
        }

        return new File[] {omcBinary, omcWorkingDirectory};
    }
    
    /**
     * Start a new OMC server.
     */
    private static void startServer() throws ConnectException
    {
        File tmp[] = getOmcBinaryPaths();

        File omcBinary = tmp[0];
        File workingDirectory = tmp[1];

        
        /* 
         * Delete old object reference file. We need to do this because we're
         * checking if the file exists to determine if the server has started
         * or not (further down). 
         */
        File f = new File(getPathToObject());
        if(f.exists())
        {
            logOMCStatus("Removing old OMC object reference file.");
            f.delete();
        }
        
        String command[] = { omcBinary.getAbsolutePath(), "+d=interactiveCorba" };
        try
        {
            logOMCStatus("Running command " + command[0] + " " + command[1]);
            logOMCStatus("Setting working directory to " + workingDirectory.getAbsolutePath());
            Runtime.getRuntime().exec(command, null, workingDirectory);
            logOMCStatus("Command run successfully.");
        }
        catch(IOException e)
        {
            logOMCStatus("Error running command " + e.getMessage());
            logOMCStatus("Unable to start OMC, giving up."); 
            throw new ConnectException
                ("Unable to start the OpenModelica Compiler. ");
        }           

        logOMCStatus("Waiting for OMC CORBA object reference to appear on disk.");
        
        /*
         * Wait until the object exists on disk, but if it takes longer than
         * 5 seconds, abort. (Very arbitrary 5 seconds..)
         */
        int ticks = 0;
        while(!f.exists())
        {
            try
            {
                Thread.sleep(100);
            }
            catch(InterruptedException e)
            {
                /* ignore */
            }
            ticks++;
            
            /* If we've waited for around 5 seconds, abort the wait for OMC */
            if(ticks > 50)
            {
                logOMCStatus("No OMC object reference file created after " + 
                        "approximately 5 seconds.");
                logOMCStatus("It seems OMC does not want to come up, giving " +
                        "up.");
                throw new ConnectException
                    ("Unable to start the Open Modelica Compiler. Waited for 5"
                            +" seconds, but it didn't respond.");
            }
        }
        logOMCStatus("OMC object reference found.");
    }
    
    /**
     * Initializes an ORB, converts the stringified OMC object to a real
     * CORBA object, and then narrows that object to an OmcCommunication
     * object. 
     */
    private static void setupOmcc(String stringifiedObjectReference)
    {
        /* Can't remember why this is needed. But it is. */
        String args[] = {null};
        
        ORB orb;
        orb = ORB.init(args, null);
        
        /* Convert string to object. */
        org.omg.CORBA.Object obj
            = orb.string_to_object(stringifiedObjectReference);
        
        /* Convert object to OmcCommunication object. */
        omcc = OmcCommunicationHelper.narrow(obj);
    }
    
    /**
     * @return the name of the operating system. If an unknown os is found,
     * the default is Unix. 
     */
    private static osType getOs()
    {
        String osName = System.getProperty("os.name");
        if(osName.contains("Linux"))
        {
            return osType.UNIX;
        }
        else if(osName.contains("Windows"))
        {
            return osType.WINDOWS;
        }
        else
        {
            ErrorManager.logWarning("'" + osName + "' not officialy supported OS");
            /* If the OS is not GNU/Linux or Windows, default to Unix */
            return osType.UNIX;
        }
    }

    /**
     * Initialize the communication with OMC
     * @throws ConnectException if we're unable to start communicating with
     * the server
     */
    private void init() throws ConnectException
    {
        /* 
         * Get type of operating system, used for finding object
         * reference and starting OMC if the reference is faulty 
         */
        os = getOs();
        
        /* See if an OMC server is already running */
        File f = new File(getPathToObject());
        String stringifiedObjectReference = null;
        if(!f.exists())
        {
            /* If a server isn't running, start it */
            logOMCStatus("No OMC object reference found, starting server.");
            startServer();
        }
        else
        {
            logOMCStatus("Old OMC CORBA object reference present," +
                    " assuming OMC is running.");
        }
        
        /* Read in the CORBA OMC object from a file on disk */
        stringifiedObjectReference = readObjectFromFile();

        /*
         * Setup up OMC object reference by initializing ORB and then
         * converting the string object to a real CORBA object.
         */
        setupOmcc(stringifiedObjectReference);

        try
        {
            /*
             * Test the server by trying to send an expression to it. 
             * This might fail if the object reference found on disk didn't
             * have a corresponding server running. If a server is missing,
             * catch an exception and try starting a server.
             */
            logOMCStatus("Trying to send expression to OMC.");
            omcc.sendExpression("1+1");
            logOMCStatus("Expression sent successfully.");
        }
        catch(org.omg.CORBA.COMM_FAILURE e)
        {
            /* Start server and set up omcc */
            logOMCStatus("Failed sending expression, will try to start OMC.");
            startServer();
            stringifiedObjectReference = readObjectFromFile();
            setupOmcc(stringifiedObjectReference);

            try
            {
                /* Once again try to send an expression to OMC. If it fails this
                 * time it's time to send back an exception to the caller of
                 * this function. */
                logOMCStatus("Trying to send expression to OMC.");
                omcc.sendExpression("1+1");
                logOMCStatus("Expression sent successfully.");
            }
            catch(org.omg.CORBA.COMM_FAILURE x)
            {
                logOMCStatus("Failed sending expression, giving up.");
                throw new ConnectException("Unable to start the OpenModelica"
                        +" Compiler.");
            }
        }

        hasInitialized = true;
    }
    
    /**
     * Send expression to OMC. If communication is not initialized, it
     * is initialized here.
     * @param exp the expression to send to OMC 
     * @throws ConnectException if we're unable to start communicating with
     * the server
     */
    // TODO add synchronization so that two threads don't fudge up each others
    // communication with OMC
    // old synchronization aka 'private synchronized String sendExpression(String exp)'
    // doesnt work when there is possibility of multiple instances of OMCProxy objects
    private String sendExpression(String exp)
        throws ConnectException
    {
        String retval = null;
        
        if(hasInitialized == false)
        {
            init();
        }
        
        try
        {
            logOMCCall(exp);
            retval = omcc.sendExpression(exp);
            logOMCReply(retval);
        }
        catch(org.omg.CORBA.COMM_FAILURE x)
        {
            logOMCCallError("Error while sending expression " + exp + " ["+x+"]");
            /* lost connection to OMC or something */
            throw new ConnectException("Couldn't send expression to the "+
                    "OpenModelica Compiler. Tried sending: " + exp);
        }
        
        return retval;
    }
    
    /**
     * Logs the expression sent to OMC if the
     * tracing flag (traceOMCCalls) is set
     * 
     * @param expression the expression that is about to be sent to OMC
     */
    private static void logOMCCall(String expression)
    {
        if (!traceOMCCalls)
        {
            return;
        }
        System.out.println(">> " + expression);
    }
    
    /**
     * outputs the message about a call error that occured
     * when communicating with omc
     * @param message the message to log
     */
    private static void logOMCCallError(String message)
    {
        if(!traceOMCCalls)
        {
            return;
        }
        System.out.println(message);
    }
    
    /**
     * loggs the message conserning OMC status if the
     * tracing flag traceOMCStatus is set
     * @param message the message to log
     */
    private static void logOMCStatus(String message)
    {
        if (!traceOMCStatus)
        {
            return;
        }
        System.out.println("OMCSTATUS: " + message);
    }

    /**
     * Logs the reply received from OMC if
     * the tracing flag (traceOMCCalls) is set
     * 
     * @param reply the reply recieved from the OMC
     */
    private static void logOMCReply(String reply)
    {
        if (!traceOMCCalls)
        {
            return;
        }

        StringTokenizer tokenizer = new StringTokenizer(reply, "\n");
        
        while (tokenizer.hasMoreTokens())
        {
            System.out.println("<< " + tokenizer.nextToken());
        }
    }
    
    /**
     * Get the classes contained in a class (a package is a class..)
     *
     * 
     * @param className full class name where to look for packages
     * @return a <code>List</code> of subclasses defined (and loaded into OMC)
     * inside the class named className.
     * 
     * @throws ConnectException 
     * @throws UnexpectedReplyException 
     * @throws InitializationException
     */ 
    public List getClassNames(String className)
        throws ConnectException, UnexpectedReplyException
    {
        String retval = sendExpression("getClassNames("+className+")");
        
        /* fetch error string but ignore it */
        getErrorString();
        
        return ModelicaParser.parseList(retval);
    }

    /**
     * Gets the restriction type of a class.
     * 
     * @param className fully qualified class name
     * @return the restriction type of the class or Type.CLASS if 
     *         type can't be determined
     * @throws ConnectException
     * @throws UnexpectedReplyException
     */
    public IModelicaClass.Type getRestrictionType(String className)
        throws ConnectException, UnexpectedReplyException
    {
        String reply = 
            sendExpression("getClassRestriction(" + className + ")");

        /* remove " around the reply */
        reply = reply.trim();
        
        if(reply.equals(""))
        {
            throw new UnexpectedReplyException("getClassRestriction("+className
                    +") returned an empty result");
        }
        
        reply = reply.substring(1, reply.length()-1);
        
        /* fetch error string but ignore it */
        getErrorString();
        
        IModelicaClass.Type type = null;
        try
        {
            type = IModelicaClass.Type.parse(reply);
        }
        catch(IllegalTypeException e)
        {
            throw new UnexpectedReplyException("Illegal type: "
                    + e.getMessage());
        }
        
        return type;
    }
    
    /**
     * Fetches the error string from OMC. This should be called after an "Error"
     * is received. (Or whenever the queue of errors should be emptied.)
     * @return the <code>String</code> of errors
     * @throws ConnectException
     */
    private String getErrorString()
        throws ConnectException
    {
        String res = sendExpression("getErrorString()");
        
        /* Make sure the error string isn't empty */
        if(res != null && res.length() > 2)
        {
            res = res.trim();
            return res.substring(1, res.length() - 1);
        }
        else
            return "";
    }
    

    /**
     * Tries to load file into OMC which causes it to be parsed and the syntax
     * checked.
     * @param file the file we want to load
     * @return a <code>ParseResult</code> containing the classes found in the
     * file and the error messages from OMC 
     * @throws ConnectException 
     * @throws UnexpectedReplyException 
     * @throws InitializationException
     */
    public ParseResults loadSourceFile(IFile file)
        throws ConnectException, UnexpectedReplyException
    {
        ParseResults res = new ParseResults();

        String fullName = file.getLocation().toString();
        String retval = 
            sendExpression("loadFileInteractiveQualified(\"" + fullName + "\")");
        
        /* Always keep your stuff nice and tidy! */
        retval = retval.trim();
        
        String errorString = getErrorString();

        /*
         * See if there were parse errors, an empty list {} also denotes error
         */
        if(retval.toLowerCase().contains("error") || retval.equals("{}"))
        {           
            res.setClassNames(new List());
            if(errorString.equals("") == false)
            {
                res.setCompileErrors(OMCParser.parseErrorString(errorString));
            }
        }
        /*
         * File loaded and parsed successfully
         */
        else
        {
            res.setClassNames(ModelicaParser.parseList(retval));

            /*
             * If there were errors, but the compilation went through,
             * collect the error messages. (Test if errorString != "") 
             */
            if(errorString.equals("") == false)
            {
                res.setCompileErrors(OMCParser.parseErrorString(errorString));              
            }
        }

        return res;
    }

    /**
     * Gets the location (file, starting and ending line number and column
     * number) of a Modelica element. 
     * @param className the element we want to get location of
     * @return an <code>ElementLocation</code> containing the file, starting and
     * ending line number and column number of the given class 
     * @throws ConnectException
     * @throws UnexpectedReplyException
     * @throws InvocationError
     */
    public ElementLocation getClassLocation(String className)
        throws ConnectException, UnexpectedReplyException, InvocationError 
    {
        String retval = sendExpression("getCrefInfo(" + className + ")");
        
        /* fetch error string but ignore it */
        getErrorString();
        
        if(retval.contains("Error") || retval.contains("error"))
        {
            throw new 
                InvocationError("Fetching file position of " + className,
                        "getCrefInfo(" + className + ")");
        }
        
        
        /*
         * The getCrefInfo reply has the following format:
         * 
         * <file path>,<something>,<start line>,<start column>,<end line>,<end column>
         * 
         * for example:
         * /foo/Modelica/package.mo,writable,1,1,1029,13
         */

        /* For some reason, the list returned doesn't contain curly braces. */
        retval = retval.trim();
        retval = "{" + retval + "}"; 

        List tokens = ModelicaParser.parseList(retval);
        
        String filePath = tokens.elementAt(0).toString();
        int startLine;
        int startColumn;
        int endLine;
        int endColumn;

        try
        {
            startLine = Integer.parseInt(tokens.elementAt(2).toString());
            startColumn = Integer.parseInt(tokens.elementAt(3).toString());
            endLine = Integer.parseInt(tokens.elementAt(4).toString());
            endColumn = Integer.parseInt(tokens.elementAt(5).toString());
        }
        catch (NumberFormatException e)
        {
            throw new 
                UnexpectedReplyException("Can't parse getCrefInfo() reply, "+
                                         "unexpected format");
        }
        
        return new ElementLocation(filePath, 
                    startLine, startColumn, endLine, endColumn);
    }
    
    /**
     * Queries the compiler if a particular modelica class/package is a package.
     * 
     * @param className fully qualified name of the class/package
     * @return true if className is a package, false otherwise
     * @throws ConnectException 
     */
    public boolean isPackage(String className)
        throws ConnectException 
    {
        String retval = sendExpression("isPackage(" + className + ")");

        /* fetch error string but ignore it */
        getErrorString();
        
        return retval.contains("true");
    }
    
    /**
     * Uses the OMC API call getElementsInfo to fetch lots of information
     * about a class definition. See interactive_api.txt in the OMC
     * source tree.
     * @param className the fully qualified name of a class
     * @return a <code>Collection</code> (of <code>ElementsInfo</code>)
     * containing the information about className
     */
    public Collection<ElementsInfo> getElementsInfo(String className)
        throws ConnectException, InvocationError, UnexpectedReplyException
    {
        String retval = sendExpression("getElementsInfo("+ className +")");
        
        /* fetch error string but ignore it */
        getErrorString();
        
        /*
         * we need a efficient way to check if the result is
         * humongosly huge list or 'Error' or maybe 'error' 
         */
        for (int i = 0; i < retval.length(); i++)
        {
            if (retval.charAt(i) == '{')
            {
                /* 
                 * we found the begining of the list, send it to parser and 
                 * hope for the best 
                 */
                List parsedList = ModelicaParser.parseList(retval);
                
                /* convert the parsedList to a collection of ElementsInfo:s */
                LinkedList<ElementsInfo> elementsInfo = 
                    new LinkedList<ElementsInfo>();

                for (ListElement element : parsedList)
                {
                    elementsInfo.add(new ElementsInfo((List)element));
                }
                
                return elementsInfo;
            }
            else if (retval.charAt(i) == 'E' || retval.charAt(i) == 'e')
            {
                /*
                 * this is the unreadable way to check if the retval 
                 * equals 'Error' or 'error'
                 */
                if (retval.substring(i+1,i+5).equals("rror"))
                {
                    throw new 
                        InvocationError("fetching contents of " + className,
                                "getElementsInfo("+ className +")");
                }
                else
                {
                    /* OMC returned someting wierd, panic mode ! */
                    break;
                }
            }
        }
        /* we have no idea what OMC returned */
        throw new UnexpectedReplyException("getElementsInfo("+ className +")" + 
                        "replies:'" + retval + "'");
    }

    /**
     * @return the name of the compiler that this plugin tries to communicate
     * with (at least it tries...)
     */
    public String getCompilerName()
    {
        return "OpenModelica Compiler";
    }

    /**
     * Loads in the Modelica System Library and returns names of the top-level
     * packages.
     *  
     * @throws ConnectException if we're unable to start communicating with
     * the server
     */ 
    public String[] getStandardLibrary() throws ConnectException
    {
        if (!systemLibraryLoaded)
        {
            sendExpression("loadModel(Modelica)");
            
            /* fetch error string but ignore it */
            getErrorString();
            
            systemLibraryLoaded = true;
        }

        return standardLibraryPackages;
    }
}