diff --git a/gogo/command/src/main/java/org/apache/felix/gogo/command/Inspect.java b/gogo/command/src/main/java/org/apache/felix/gogo/command/Inspect.java
index 39a5822..8690d6b 100644
--- a/gogo/command/src/main/java/org/apache/felix/gogo/command/Inspect.java
+++ b/gogo/command/src/main/java/org/apache/felix/gogo/command/Inspect.java
@@ -21,8 +21,8 @@
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
-
 import java.util.Map;
+
 import org.apache.felix.service.command.Descriptor;
 import org.osgi.framework.Bundle;
 import org.osgi.framework.BundleContext;
@@ -32,9 +32,6 @@
 import org.osgi.framework.wiring.BundleRequirement;
 import org.osgi.framework.wiring.BundleWire;
 import org.osgi.framework.wiring.BundleWiring;
-import org.osgi.service.packageadmin.ExportedPackage;
-import org.osgi.service.packageadmin.PackageAdmin;
-import org.osgi.service.packageadmin.RequiredBundle;
 
 public class Inspect
 {
diff --git a/gogo/runtime/NOTICE b/gogo/runtime/NOTICE
index cb48c52..6447d3e 100644
--- a/gogo/runtime/NOTICE
+++ b/gogo/runtime/NOTICE
@@ -4,7 +4,3 @@
 This product includes software developed at
 The Apache Software Foundation (http://www.apache.org/).
 Licensed under the Apache License 2.0.
-
-This product includes software developped by
-Udo Klimaschewski (http://UdoJava.com/).
-Licensed under the MIT License.
diff --git a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Closure.java b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Closure.java
index 7dec8ec..aa63b0f 100644
--- a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Closure.java
+++ b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Closure.java
@@ -19,7 +19,11 @@
 package org.apache.felix.gogo.runtime;
 
 import java.io.EOFException;
-import java.util.*;
+import java.util.AbstractList;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
 import java.util.Map.Entry;
 
 import org.apache.felix.gogo.runtime.Tokenizer.Type;
@@ -31,7 +35,6 @@
     public static final String LOCATION = ".location";
     private static final String DEFAULT_LOCK = ".defaultLock";
 
-    private static final long serialVersionUID = 1L;
     private static final ThreadLocal<String> location = new ThreadLocal<String>();
 
     private final CommandSessionImpl session;
@@ -289,10 +292,6 @@
                 v = t.type;
                 break;
 
-            case EXPR:
-                v = expr(t.value);
-                break;
-
             default:
                 throw new SyntaxError(t.line, t.column, "unexpected token: " + t.type);
         }
@@ -534,11 +533,6 @@
         return value;
     }
 
-    private Object expr(CharSequence expr) throws Exception
-    {
-        return session.expr(expr);
-    }
-
     private Object array(Token array) throws Exception
     {
         List<Token> list = new ArrayList<Token>();
diff --git a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/CommandProcessorImpl.java b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/CommandProcessorImpl.java
index e89878d..97a1dc7 100644
--- a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/CommandProcessorImpl.java
+++ b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/CommandProcessorImpl.java
@@ -21,16 +21,11 @@
 import java.io.InputStream;
 import java.io.PrintStream;
 import java.lang.reflect.Method;
-import java.math.BigDecimal;
 import java.util.Collections;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import java.util.SortedMap;
 import java.util.TreeSet;
 import java.util.WeakHashMap;
 import java.util.concurrent.ConcurrentHashMap;
@@ -63,7 +58,8 @@
     {
         synchronized (sessions)
         {
-            if (stopped) {
+            if (stopped)
+            {
                 throw new IllegalStateException("CommandProcessor has been stopped");
             }
             CommandSessionImpl session = new CommandSessionImpl(this, in, out, err);
@@ -72,6 +68,17 @@
         }
     }
 
+    void closeSession(CommandSessionImpl session)
+    {
+        synchronized (sessions)
+        {
+            if (sessions.remove(session) != null)
+            {
+                System.out.println("CLOSED: " + session);
+            }
+        }
+    }
+
     public void stop()
     {
         synchronized (sessions)
@@ -173,8 +180,7 @@
 
     public void addCommand(String scope, Object target)
     {
-        Class<?> tc = (target instanceof Class<?>) ? (Class<?>) target
-            : target.getClass();
+        Class<?> tc = (target instanceof Class<?>) ? (Class<?>) target : target.getClass();
         addCommand(scope, target, tc);
     }
 
@@ -326,8 +332,7 @@
         }
     }
 
-    void afterExecute(CommandSession session, CharSequence commandline,
-        Exception exception)
+    void afterExecute(CommandSession session, CharSequence commandline, Exception exception)
     {
         for (CommandSessionListener l : listeners)
         {
@@ -356,8 +361,4 @@
             }
         }
     }
-
-    public Object expr(CommandSessionImpl session, CharSequence expr) {
-        return new Expression(expr.toString()).eval(session.variables);
-    }
 }
diff --git a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/CommandSessionImpl.java b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/CommandSessionImpl.java
index ee3c09b..bf75e48 100644
--- a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/CommandSessionImpl.java
+++ b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/CommandSessionImpl.java
@@ -32,9 +32,7 @@
 import java.util.Enumeration;
 import java.util.Formatter;
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
 
 import org.apache.felix.service.command.CommandSession;
 import org.apache.felix.service.command.Converter;
@@ -47,14 +45,14 @@
     public static final String VARIABLES = ".variables";
     public static final String COMMANDS = ".commands";
     private static final String COLUMN = "%-20s %s\n";
-    
+
     protected InputStream in;
     protected PrintStream out;
     PrintStream err;
-    
+
     private final CommandProcessorImpl processor;
     protected final Map<String, Object> variables = new HashMap<String, Object>();
-    private boolean closed;
+    private volatile boolean closed;
 
     protected CommandSessionImpl(CommandProcessorImpl shell, InputStream in, PrintStream out, PrintStream err)
     {
@@ -63,7 +61,7 @@
         this.out = out;
         this.err = err;
     }
-    
+
     ThreadIO threadIO()
     {
         return processor.threadIO;
@@ -71,7 +69,12 @@
 
     public void close()
     {
-        this.closed = true;
+        if (!this.closed)
+        {
+            System.out.println("CLOSING SESSION!");
+            this.processor.closeSession(this);
+            this.closed = true;
+        }
     }
 
     public Object execute(CharSequence commandline) throws Exception
@@ -119,7 +122,7 @@
         }
 
         Object val = processor.constants.get(name);
-        if( val != null )
+        if (val != null)
         {
             return val;
         }
@@ -137,13 +140,13 @@
             }
             return val;
         }
-        else if( val != null )
+        else if (val != null)
         {
             return val;
         }
 
         val = variables.get(name);
-        if( val != null )
+        if (val != null)
         {
             return val;
         }
@@ -165,8 +168,7 @@
     }
 
     @SuppressWarnings("unchecked")
-    public CharSequence format(Object target, int level, Converter escape)
-        throws Exception
+    public CharSequence format(Object target, int level, Converter escape) throws Exception
     {
         if (target == null)
         {
@@ -349,9 +351,7 @@
             try
             {
                 String name = m.getName();
-                if (m.getName().startsWith("get") && !m.getName().equals("getClass")
-                    && m.getParameterTypes().length == 0
-                    && Modifier.isPublic(m.getModifiers()))
+                if (m.getName().startsWith("get") && !m.getName().equals("getClass") && m.getParameterTypes().length == 0 && Modifier.isPublic(m.getModifiers()))
                 {
                     found = true;
                     name = name.substring(3);
@@ -396,9 +396,4 @@
         }
     }
 
-    public Object expr(CharSequence expr)
-    {
-        return processor.expr(this, expr);
-    }
-
 }
diff --git a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Expression.java b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Expression.java
deleted file mode 100644
index b34c805..0000000
--- a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Expression.java
+++ /dev/null
@@ -1,1332 +0,0 @@
-/*
- * Copyright 2012 Udo Klimaschewski
- *
- * http://UdoJava.com/
- * http://about.me/udo.klimaschewski
- *
- * Permission is hereby granted, free of charge, to any person obtaining
- * a copy of this software and associated documentation files (the
- * "Software"), to deal in the Software without restriction, including
- * without limitation the rights to use, copy, modify, merge, publish,
- * distribute, sublicense, and/or sell copies of the Software, and to
- * permit persons to whom the Software is furnished to do so, subject to
- * the following conditions:
- *
- * The above copyright notice and this permission notice shall be
- * included in all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
- * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
- * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
- * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
- * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
- * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- *
- */
-package org.apache.felix.gogo.runtime;
-
-import java.math.BigDecimal;
-import java.math.BigInteger;
-import java.math.MathContext;
-import java.math.RoundingMode;
-import java.util.*;
-
-/**
- * Enhanced to provide assignment operators and variables from a map, comparison operators, string operations and more.
- */
-/**
- * <h1>EvalEx - Java Expression Evaluator</h1>
- *
- * <h2>Introduction</h2>
- * EvalEx is a handy expression evaluator for Java, that allows to evaluate simple mathematical and boolean expressions.
- * <br>
- * Key Features:
- * <ul>
- * <li>Uses BigDecimal for calculation and result</li>
- * <li>Single class implementation, very compact</li>
- * <li>No dependencies to external libraries</li>
- * <li>Precision and rounding mode can be set</li>
- * <li>Supports variables</li>
- * <li>Standard boolean and mathematical operators</li>
- * <li>Standard basic mathematical and boolean functions</li>
- * <li>Custom functions and operators can be added at runtime</li>
- * </ul>
- * <br>
- * <h2>Examples</h2>
- * <pre>
- *  BigDecimal result = null;
- *
- *  Expression expression = new Expression("1+1/3");
- *  result = expression.eval():
- *  expression.setPrecision(2);
- *  result = expression.eval():
- *
- *  result = new Expression("(3.4 + -4.1)/2").eval();
- *
- *  result = new Expression("SQRT(a^2 + b^2").with("a","2.4").and("b","9.253").eval();
- *
- *  BigDecimal a = new BigDecimal("2.4");
- *  BigDecimal b = new BigDecimal("9.235");
- *  result = new Expression("SQRT(a^2 + b^2").with("a",a).and("b",b).eval();
- *
- *  result = new Expression("2.4/PI").setPrecision(128).setRoundingMode(RoundingMode.UP).eval();
- *
- *  result = new Expression("random() > 0.5").eval();
- *
- *  result = new Expression("not(x<7 || sqrt(max(x,9)) <= 3))").with("x","22.9").eval();
- * </pre>
- * <br>
- * <h2>Supported Operators</h2>
- * <table>
- *   <tr><th>Mathematical Operators</th></tr>
- *   <tr><th>Operator</th><th>Description</th></tr>
- *   <tr><td>+</td><td>Additive operator</td></tr>
- *   <tr><td>-</td><td>Subtraction operator</td></tr>
- *   <tr><td>*</td><td>Multiplication operator</td></tr>
- *   <tr><td>/</td><td>Division operator</td></tr>
- *   <tr><td>%</td><td>Remainder operator (Modulo)</td></tr>
- *   <tr><td>^</td><td>Power operator</td></tr>
- * </table>
- * <br>
- * <table>
- *   <tr><th>Boolean Operators<sup>*</sup></th></tr>
- *   <tr><th>Operator</th><th>Description</th></tr>
- *   <tr><td>=</td><td>Equals</td></tr>
- *   <tr><td>==</td><td>Equals</td></tr>
- *   <tr><td>!=</td><td>Not equals</td></tr>
- *   <tr><td>&lt;&gt;</td><td>Not equals</td></tr>
- *   <tr><td>&lt;</td><td>Less than</td></tr>
- *   <tr><td>&lt;=</td><td>Less than or equal to</td></tr>
- *   <tr><td>&gt;</td><td>Greater than</td></tr>
- *   <tr><td>&gt;=</td><td>Greater than or equal to</td></tr>
- *   <tr><td>&amp;&amp;</td><td>Boolean and</td></tr>
- *   <tr><td>||</td><td>Boolean or</td></tr>
- * </table>
- * *Boolean operators result always in a BigDecimal value of 1 or 0 (zero). Any non-zero value is treated as a _true_ value. Boolean _not_ is implemented by a function.
- * <br>
- * <h2>Supported Functions</h2>
- * <table>
- *   <tr><th>Function<sup>*</sup></th><th>Description</th></tr>
- *   <tr><td>NOT(<i>expression</i>)</td><td>Boolean negation, 1 (means true) if the expression is not zero</td></tr>
- *   <tr><td>IF(<i>condition</i>,<i>value_if_true</i>,<i>value_if_false</i>)</td><td>Returns one value if the condition evaluates to true or the other if it evaluates to false</td></tr>
- *   <tr><td>RANDOM()</td><td>Produces a random number between 0 and 1</td></tr>
- *   <tr><td>MIN(<i>e1</i>,<i>e2</i>)</td><td>Returns the smaller of both expressions</td></tr>
- *   <tr><td>MAX(<i>e1</i>,<i>e2</i>)</td><td>Returns the bigger of both expressions</td></tr>
- *   <tr><td>ABS(<i>expression</i>)</td><td>Returns the absolute (non-negative) value of the expression</td></tr>
- *   <tr><td>ROUND(<i>expression</i>,precision)</td><td>Rounds a value to a certain number of digits, uses the current rounding mode</td></tr>
- *   <tr><td>FLOOR(<i>expression</i>)</td><td>Rounds the value down to the nearest integer</td></tr>
- *   <tr><td>CEILING(<i>expression</i>)</td><td>Rounds the value up to the nearest integer</td></tr>
- *   <tr><td>LOG(<i>expression</i>)</td><td>Returns the natural logarithm (base e) of an expression</td></tr>
- *   <tr><td>SQRT(<i>expression</i>)</td><td>Returns the square root of an expression</td></tr>
- *   <tr><td>SIN(<i>expression</i>)</td><td>Returns the trigonometric sine of an angle (in degrees)</td></tr>
- *   <tr><td>COS(<i>expression</i>)</td><td>Returns the trigonometric cosine of an angle (in degrees)</td></tr>
- *   <tr><td>TAN(<i>expression</i>)</td><td>Returns the trigonometric tangens of an angle (in degrees)</td></tr>
- *   <tr><td>SINH(<i>expression</i>)</td><td>Returns the hyperbolic sine of a value</td></tr>
- *   <tr><td>COSH(<i>expression</i>)</td><td>Returns the hyperbolic cosine of a value</td></tr>
- *   <tr><td>TANH(<i>expression</i>)</td><td>Returns the hyperbolic tangens of a value</td></tr>
- *   <tr><td>RAD(<i>expression</i>)</td><td>Converts an angle measured in degrees to an approximately equivalent angle measured in radians</td></tr>
- *   <tr><td>DEG(<i>expression</i>)</td><td>Converts an angle measured in radians to an approximately equivalent angle measured in degrees</td></tr>
- * </table>
- * *Functions names are case insensitive.
- * <br>
- * <h2>Supported Constants</h2>
- * <table>
- *   <tr><th>Constant</th><th>Description</th></tr>
- *   <tr><td>PI</td><td>The value of <i>PI</i>, exact to 100 digits</td></tr>
- *   <tr><td>TRUE</td><td>The value one</td></tr>
- *   <tr><td>FALSE</td><td>The value zero</td></tr>
- * </table>
- *
- * <h2>Add Custom Operators</h2>
- *
- * Custom operators can be added easily, simply create an instance of `Expression.Operator` and add it to the expression.
- * Parameters are the operator string, its precedence and if it is left associative. The operators `eval()` method will be called with the BigDecimal values of the operands.
- * All existing operators can also be overridden.
- * <br>
- * For example, add an operator `x >> n`, that moves the decimal point of _x_ _n_ digits to the right:
- *
- * <pre>
- * Expression e = new Expression("2.1234 >> 2");
- *
- * e.addOperator(e.new Operator(">>", 30, true) {
- *     {@literal @}Override
- *     public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
- *         return v1.movePointRight(v2.toBigInteger().intValue());
- *     }
- * });
- *
- * e.eval(); // returns 212.34
- * </pre>
- * <br>
- * <h2>Add Custom Functions</h2>
- *
- * Adding custom functions is as easy as adding custom operators. Create an instance of `Expression.Function`and add it to the expression.
- * Parameters are the function name and the count of required parameters. The functions `eval()` method will be called with a list of the BigDecimal parameters.
- * All existing functions can also be overridden.
- * <br>
- * For example, add a function `average(a,b,c)`, that will calculate the average value of a, b and c:
- * <br>
- * <pre>
- * Expression e = new Expression("2 * average(12,4,8)");
- *
- * e.addFunction(e.new Function("average", 3) {
- *     {@literal @}Override
- *     public BigDecimal eval(List<BigDecimal> parameters) {
- *         BigDecimal sum = parameters.get(0).add(parameters.get(1)).add(parameters.get(2));
- *         return sum.divide(new BigDecimal(3));
- *     }
- * });
- *
- * e.eval(); // returns 16
- * </pre>
- * The software is licensed under the MIT Open Source license (see LICENSE file).
- * <br>
- * <ul>
- * <li>The *power of* operator (^) implementation was copied from [Stack Overflow](http://stackoverflow.com/questions/3579779/how-to-do-a-fractional-power-on-bigdecimal-in-java) Thanks to Gene Marin</li>
- * <li>The SQRT() function implementation was taken from the book [The Java Programmers Guide To numerical Computing](http://www.amazon.de/Java-Number-Cruncher-Programmers-Numerical/dp/0130460419) (Ronald Mak, 2002)</li>
- * </ul>
- *
- *@author Udo Klimaschewski (http://about.me/udo.klimaschewski)
- */
-public class Expression {
-
-    /**
-     * Definition of PI as a constant, can be used in expressions as variable.
-     */
-    public static final BigDecimal PI = new BigDecimal(
-            "3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679");
-
-    /**
-     * The {@link MathContext} to use for calculations.
-     */
-    private MathContext mc = MathContext.DECIMAL32;
-
-    /**
-     * The original infix expression.
-     */
-    private String expression = null;
-
-    /**
-     * The cached RPN (Reverse Polish Notation) of the expression.
-     */
-    private List<Token> rpn = null;
-
-    /**
-     * All defined operators with name and implementation.
-     */
-    private Map<String, Operator> operators = new HashMap<String, Expression.Operator>();
-
-    /**
-     * All defined functions with name and implementation.
-     */
-    private Map<String, Function> functions = new HashMap<String, Expression.Function>();
-
-    /**
-     * All defined variables with name and value.
-     */
-    private Map<String, Object> constants = new HashMap<String, Object>();
-
-    /**
-     * What character to use for decimal separators.
-     */
-    private final char decimalSeparator = '.';
-
-    /**
-     * What character to use for minus sign (negative values).
-     */
-    private final char minusSign = '-';
-
-    /**
-     * The expression evaluators exception class.
-     */
-    public class ExpressionException extends RuntimeException {
-        private static final long serialVersionUID = 1118142866870779047L;
-
-        public ExpressionException(String message) {
-            super(message);
-        }
-    }
-
-    interface Token {
-
-    }
-
-    public class Constant implements Token {
-
-        private final Object value;
-
-        public Constant(Object value) {
-            this.value = value;
-        }
-
-        public Object getValue() {
-            return value;
-        }
-    }
-
-    public class Variable implements Token {
-
-        private final String name;
-
-        public Variable(String name) {
-            this.name = name;
-        }
-
-        public String getName() {
-            return name;
-        }
-
-        @Override
-        public String toString() {
-            return name;
-        }
-    }
-
-    public class LeftParen implements Token {
-        @Override
-        public String toString() {
-            return "(";
-        }
-    }
-
-    public class Comma implements Token {
-    }
-
-    /**
-     * Abstract definition of a supported expression function. A function is
-     * defined by a name, the number of parameters and the actual processing
-     * implementation.
-     */
-    public abstract class Function implements Token {
-        /**
-         * Name of this function.
-         */
-        private String name;
-        /**
-         * Number of parameters expected for this function.
-         */
-        private int numParams;
-
-        /**
-         * Creates a new function with given name and parameter count.
-         *
-         * @param name
-         *            The name of the function.
-         * @param numParams
-         *            The number of parameters for this function.
-         */
-        public Function(String name, int numParams) {
-            this.name = name.toUpperCase();
-            this.numParams = numParams;
-        }
-
-        public String getName() {
-            return name;
-        }
-
-        public int getNumParams() {
-            return numParams;
-        }
-
-        public BigDecimal eval(Map<String, Object> variables, List<Object> parameters) {
-            List<BigDecimal> numericParameters = new ArrayList<BigDecimal>(parameters.size());
-            for (Object o : parameters) {
-                numericParameters.add(toBigDecimal(variables, o));
-            }
-            return eval(numericParameters);
-        }
-
-        /**
-         * Implementation for this function.
-         *
-         * @param parameters
-         *            Parameters will be passed by the expression evaluator as a
-         *            {@link List} of {@link BigDecimal} values.
-         * @return The function must return a new {@link BigDecimal} value as a
-         *         computing result.
-         */
-        public abstract BigDecimal eval(List<BigDecimal> parameters);
-
-        @Override
-        public String toString() {
-            return name;
-        }
-    }
-
-    /**
-     * Abstract definition of a supported operator. An operator is defined by
-     * its name (pattern), precedence and if it is left- or right associative.
-     */
-    public abstract class Operator implements Token {
-        /**
-         * This operators name (pattern).
-         */
-        private String oper;
-        /**
-         * Operators precedence.
-         */
-        private int precedence;
-        /**
-         * Operator is left associative.
-         */
-        private boolean leftAssoc;
-
-        /**
-         * Creates a new operator.
-         *
-         * @param oper
-         *            The operator name (pattern).
-         * @param precedence
-         *            The operators precedence.
-         * @param leftAssoc
-         *            <code>true</code> if the operator is left associative,
-         *            else <code>false</code>.
-         */
-        public Operator(String oper, int precedence, boolean leftAssoc) {
-            this.oper = oper;
-            this.precedence = precedence;
-            this.leftAssoc = leftAssoc;
-        }
-
-        public String getOper() {
-            return oper;
-        }
-
-        public int getPrecedence() {
-            return precedence;
-        }
-
-        public boolean isLeftAssoc() {
-            return leftAssoc;
-        }
-
-        public Object eval(Map<String, Object> variables, Object v1, Object v2) {
-            if (v1 instanceof Variable) {
-                v1 = variables.get(((Variable) v1).getName());
-            }
-            if (v2 instanceof Variable) {
-                v2 = variables.get(((Variable) v2).getName());
-            }
-            boolean numeric = (v1 instanceof Number || isNumber(v1.toString()))
-                           && (v2 instanceof Number || isNumber(v2.toString()));
-            if (numeric) {
-                return eval(toBigDecimal(variables, v1), toBigDecimal(variables, v2));
-            } else {
-                return eval(v1.toString(), v2.toString());
-            }
-        }
-
-        public Object eval(String v1, String v2) {
-            return eval(toBigDecimal(v1), toBigDecimal(v2));
-        }
-
-        /**
-         * Implementation for this operator.
-         *
-         * @param v1
-         *            Operand 1.
-         * @param v2
-         *            Operand 2.
-         * @return The result of the operation.
-         */
-        public abstract BigDecimal eval(BigDecimal v1, BigDecimal v2);
-
-        @Override
-        public String toString() {
-            return oper;
-        }
-    }
-
-    public abstract class Comparator extends Operator {
-
-        public Comparator(String oper, int precedence) {
-            super(oper, precedence, false);
-        }
-
-        @Override
-        public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-            return compare(v1, v2) ? BigDecimal.ONE : BigDecimal.ZERO;
-        }
-
-        @Override
-        public Object eval(String v1, String v2) {
-            return compare(v1, v2) ? BigDecimal.ONE : BigDecimal.ZERO;
-        }
-
-        /**
-         * This method actually implements the comparison.
-         * It will be called with either 2 BigIntegers or 2 Strings.
-         *
-         * @param v1
-         *            Operand 1.
-         * @param v2
-         *            Operand 2.
-         * @return The result of the comparison.
-         */
-        public abstract boolean compare(Comparable v1, Comparable v2);
-    }
-
-    /**
-     * Marker class for assignment operators.
-     * Those operators need a variable on the left hand side.
-     */
-    public abstract class Assignment extends Operator {
-
-        public Assignment(String assign, int precedence) {
-            super(assign, precedence, true);
-        }
-
-        public Object eval(Map<String, Object> variables, Object v1, Object v2) {
-            if (!(v1 instanceof Variable))  {
-                throw new IllegalArgumentException("Left hand side of operator " + getOper() + " should be a variable but found " + v1.toString());
-            }
-            String name = ((Variable) v1).getName();
-            Object r = super.eval(variables, v1, v2);
-            if (r instanceof Number) {
-                r = toResult(toBigDecimal(r));
-            }
-            variables.put(name, r);
-            return r;
-        }
-
-    }
-
-
-    /**
-     * Expression tokenizer that allows to iterate over a {@link String}
-     * expression token by token. Blank characters will be skipped.
-     */
-    private class Tokenizer implements Iterator<String> {
-
-        /**
-         * Actual position in expression string.
-         */
-        private int pos = 0;
-
-        /**
-         * The original input expression.
-         */
-        private String input;
-        /**
-         * The previous token or <code>null</code> if none.
-         */
-        private String previousToken;
-
-        /**
-         * Creates a new tokenizer for an expression.
-         *
-         * @param input
-         *            The expression string.
-         */
-        public Tokenizer(String input) {
-            this.input = input;
-        }
-
-        public boolean hasNext() {
-            return (pos < input.length());
-        }
-
-        /**
-         * Peek at the next character, without advancing the iterator.
-         *
-         * @return The next character or character 0, if at end of string.
-         */
-        private char peekNextChar() {
-            if (pos < (input.length() - 1)) {
-                return input.charAt(pos + 1);
-            } else {
-                return 0;
-            }
-        }
-
-        public String next() {
-            StringBuilder token = new StringBuilder();
-            if (pos >= input.length()) {
-                return previousToken = null;
-            }
-            char ch = input.charAt(pos);
-            while (Character.isWhitespace(ch) && pos < input.length()) {
-                ch = input.charAt(++pos);
-            }
-            if (Character.isDigit(ch)) {
-                while ((Character.isDigit(ch) || ch == decimalSeparator)
-                        && (pos < input.length())) {
-                    token.append(input.charAt(pos++));
-                    ch = pos == input.length() ? 0 : input.charAt(pos);
-                }
-            } else if (ch == minusSign
-                    && Character.isDigit(peekNextChar())
-                    && ("(".equals(previousToken) || ",".equals(previousToken)
-                    || previousToken == null || operators
-                    .containsKey(previousToken))) {
-                token.append(minusSign);
-                pos++;
-                token.append(next());
-            } else if (Character.isLetter(ch)) {
-                while ((Character.isLetter(ch) || Character.isDigit(ch) || (ch == '_')) && (pos < input.length())) {
-                    token.append(input.charAt(pos++));
-                    ch = pos == input.length() ? 0 : input.charAt(pos);
-                }
-            } else if (ch == '"') {
-                boolean escaped = false;
-                token.append(input.charAt(pos++));
-                do {
-                    if (pos == input.length()) {
-                        throw new IllegalArgumentException("Non terminated quote");
-                    }
-                    ch = input.charAt(pos++);
-                    escaped = (!escaped && ch == '\\');
-                    token.append(ch);
-                } while (escaped || ch != '"');
-            } else if (ch == '(' || ch == ')' || ch == ',') {
-                token.append(ch);
-                pos++;
-            } else {
-                while (!Character.isLetter(ch) && !Character.isDigit(ch)
-                        && !Character.isWhitespace(ch) && ch != '('
-                        && ch != ')' && ch != ',' && (pos < input.length())) {
-                    token.append(input.charAt(pos));
-                    pos++;
-                    ch = pos == input.length() ? 0 : input.charAt(pos);
-                    if (ch == minusSign) {
-                        break;
-                    }
-                }
-                if (!operators.containsKey(token.toString())) {
-                    throw new ExpressionException("Unknown operator '" + token
-                            + "' at position " + (pos - token.length() + 1));
-                }
-            }
-            return previousToken = token.toString();
-        }
-
-        public void remove() {
-            throw new ExpressionException("remove() not supported");
-        }
-
-        /**
-         * Get the actual character position in the string.
-         *
-         * @return The actual character position.
-         */
-        public int getPos() {
-            return pos;
-        }
-
-    }
-
-    /**
-     * Creates a new expression instance from an expression string.
-     *
-     * @param expression
-     *            The expression. E.g. <code>"2.4*sin(3)/(2-4)"</code> or
-     *            <code>"sin(y)>0 & max(z, 3)>3"</code>
-     */
-    public Expression(String expression) {
-        this.expression = expression;
-
-        addOperator(new Assignment("=", 5) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return v2;
-            }
-        });
-        addOperator(new Assignment("+=", 5) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return v1.add(v2, mc);
-            }
-
-            @Override
-            public Object eval(String v1, String v2) {
-                return v1 + v2;
-            }
-        });
-        addOperator(new Assignment("-=", 5) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return v1.subtract(v2, mc);
-            }
-        });
-        addOperator(new Assignment("*=", 5) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return v1.multiply(v2, mc);
-            }
-        });
-        addOperator(new Assignment("/=", 5) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return v1.divide(v2, mc);
-            }
-        });
-        addOperator(new Assignment("%=", 5) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return v1.remainder(v2, mc);
-            }
-        });
-        addOperator(new Assignment("|=", 5) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return new BigDecimal(v1.toBigInteger().or(v2.toBigInteger()), mc);
-            }
-        });
-        addOperator(new Assignment("&=", 5) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return new BigDecimal(v1.toBigInteger().and(v2.toBigInteger()), mc);
-            }
-        });
-        addOperator(new Assignment("^=", 5) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return new BigDecimal(v1.toBigInteger().xor(v2.toBigInteger()), mc);
-            }
-        });
-        addOperator(new Assignment("<<=", 5) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return new BigDecimal(v1.toBigInteger().shiftLeft(v2.intValue()), mc);
-            }
-        });
-        addOperator(new Assignment(">>=", 5) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return new BigDecimal(v1.toBigInteger().shiftRight(v2.intValue()), mc);
-            }
-        });
-
-        addOperator(new Operator("<<", 10, true) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return new BigDecimal(v1.toBigInteger().shiftLeft(v2.intValue()), mc);
-            }
-        });
-        addOperator(new Operator(">>", 10, true) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return new BigDecimal(v1.toBigInteger().shiftRight(v2.intValue()), mc);
-            }
-        });
-        addOperator(new Operator("|", 15, true) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return new BigDecimal(v1.toBigInteger().or(v2.toBigInteger()), mc);
-            }
-        });
-        addOperator(new Operator("&", 15, true) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return new BigDecimal(v1.toBigInteger().and(v2.toBigInteger()), mc);
-            }
-        });
-        addOperator(new Operator("^", 15, true) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return new BigDecimal(v1.toBigInteger().xor(v2.toBigInteger()), mc);
-            }
-        });
-        addOperator(new Operator("+", 20, true) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return v1.add(v2, mc);
-            }
-            @Override
-            public Object eval(String v1, String v2) {
-                return v1 + v2;
-            }
-        });
-        addOperator(new Operator("-", 20, true) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return v1.subtract(v2, mc);
-            }
-        });
-        addOperator(new Operator("*", 30, true) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return v1.multiply(v2, mc);
-            }
-        });
-        addOperator(new Operator("/", 30, true) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return v1.divide(v2, mc);
-            }
-        });
-        addOperator(new Operator("%", 30, true) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                return v1.remainder(v2, mc);
-            }
-        });
-        addOperator(new Operator("**", 40, false) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-				/*-
-				 * Thanks to Gene Marin:
-				 * http://stackoverflow.com/questions/3579779/how-to-do-a-fractional-power-on-bigdecimal-in-java
-				 */
-                int signOf2 = v2.signum();
-                double dn1 = v1.doubleValue();
-                v2 = v2.multiply(new BigDecimal(signOf2)); // n2 is now positive
-                BigDecimal remainderOf2 = v2.remainder(BigDecimal.ONE);
-                BigDecimal n2IntPart = v2.subtract(remainderOf2);
-                BigDecimal intPow = v1.pow(n2IntPart.intValueExact(), mc);
-                BigDecimal doublePow = new BigDecimal(Math.pow(dn1,
-                        remainderOf2.doubleValue()));
-
-                BigDecimal result = intPow.multiply(doublePow, mc);
-                if (signOf2 == -1) {
-                    result = BigDecimal.ONE.divide(result, mc.getPrecision(),
-                            RoundingMode.HALF_UP);
-                }
-                return result;
-            }
-        });
-        addOperator(new Operator("&&", 4, false) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                boolean b1 = !v1.equals(BigDecimal.ZERO);
-                boolean b2 = !v2.equals(BigDecimal.ZERO);
-                return b1 && b2 ? BigDecimal.ONE : BigDecimal.ZERO;
-            }
-        });
-
-        addOperator(new Operator("||", 2, false) {
-            @Override
-            public BigDecimal eval(BigDecimal v1, BigDecimal v2) {
-                boolean b1 = !v1.equals(BigDecimal.ZERO);
-                boolean b2 = !v2.equals(BigDecimal.ZERO);
-                return b1 || b2 ? BigDecimal.ONE : BigDecimal.ZERO;
-            }
-        });
-
-        addOperator(new Comparator(">", 10) {
-            @Override @SuppressWarnings("unchecked")
-            public boolean compare(Comparable v1, Comparable v2) {
-                return v1.compareTo(v2) > 0;
-            }
-        });
-
-        addOperator(new Comparator(">=", 10) {
-            @Override @SuppressWarnings("unchecked")
-            public boolean compare(Comparable v1, Comparable v2) {
-                return v1.compareTo(v2) >= 0;
-            }
-        });
-
-        addOperator(new Comparator("<", 10) {
-            @Override @SuppressWarnings("unchecked")
-            public boolean compare(Comparable v1, Comparable v2) {
-                return v1.compareTo(v2) < 0;
-            }
-        });
-
-        addOperator(new Comparator("<=", 10) {
-            @Override @SuppressWarnings("unchecked")
-            public boolean compare(Comparable v1, Comparable v2) {
-                return v1.compareTo(v2) <= 0;
-            }
-        });
-
-        addOperator(new Comparator("==", 7) {
-            @Override @SuppressWarnings("unchecked")
-            public boolean compare(Comparable v1, Comparable v2) {
-                return v1.compareTo(v2) == 0;
-            }
-        });
-
-        addOperator(new Comparator("!=", 7) {
-            @Override @SuppressWarnings("unchecked")
-            public boolean compare(Comparable v1, Comparable v2) {
-                return v1.compareTo(v2) != 0;
-            }
-        });
-
-        addFunction(new Function("NOT", 1) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                boolean zero = parameters.get(0).compareTo(BigDecimal.ZERO) == 0;
-                return zero ? BigDecimal.ONE : BigDecimal.ZERO;
-            }
-        });
-
-        addFunction(new Function("IF", 3) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                boolean isTrue = !parameters.get(0).equals(BigDecimal.ZERO);
-                return isTrue ? parameters.get(1) : parameters.get(2);
-            }
-        });
-
-        addFunction(new Function("RANDOM", 0) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                double d = Math.random();
-                return new BigDecimal(d, mc);
-            }
-        });
-        addFunction(new Function("SIN", 1) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                double d = Math.sin(Math.toRadians(parameters.get(0)
-                        .doubleValue()));
-                return new BigDecimal(d, mc);
-            }
-        });
-        addFunction(new Function("COS", 1) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                double d = Math.cos(Math.toRadians(parameters.get(0)
-                        .doubleValue()));
-                return new BigDecimal(d, mc);
-            }
-        });
-        addFunction(new Function("TAN", 1) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                double d = Math.tan(Math.toRadians(parameters.get(0)
-                        .doubleValue()));
-                return new BigDecimal(d, mc);
-            }
-        });
-        addFunction(new Function("SINH", 1) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                double d = Math.sinh(parameters.get(0).doubleValue());
-                return new BigDecimal(d, mc);
-            }
-        });
-        addFunction(new Function("COSH", 1) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                double d = Math.cosh(parameters.get(0).doubleValue());
-                return new BigDecimal(d, mc);
-            }
-        });
-        addFunction(new Function("TANH", 1) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                double d = Math.tanh(parameters.get(0).doubleValue());
-                return new BigDecimal(d, mc);
-            }
-        });
-        addFunction(new Function("RAD", 1) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                double d = Math.toRadians(parameters.get(0).doubleValue());
-                return new BigDecimal(d, mc);
-            }
-        });
-        addFunction(new Function("DEG", 1) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                double d = Math.toDegrees(parameters.get(0).doubleValue());
-                return new BigDecimal(d, mc);
-            }
-        });
-        addFunction(new Function("MAX", 2) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                BigDecimal v1 = parameters.get(0);
-                BigDecimal v2 = parameters.get(1);
-                return v1.compareTo(v2) > 0 ? v1 : v2;
-            }
-        });
-        addFunction(new Function("MIN", 2) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                BigDecimal v1 = parameters.get(0);
-                BigDecimal v2 = parameters.get(1);
-                return v1.compareTo(v2) < 0 ? v1 : v2;
-            }
-        });
-        addFunction(new Function("ABS", 1) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                return parameters.get(0).abs(mc);
-            }
-        });
-        addFunction(new Function("LOG", 1) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                double d = Math.log(parameters.get(0).doubleValue());
-                return new BigDecimal(d, mc);
-            }
-        });
-        addFunction(new Function("ROUND", 2) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                BigDecimal toRound = parameters.get(0);
-                int precision = parameters.get(1).intValue();
-                return toRound.setScale(precision, mc.getRoundingMode());
-            }
-        });
-        addFunction(new Function("FLOOR", 1) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                BigDecimal toRound = parameters.get(0);
-                return toRound.setScale(0, RoundingMode.FLOOR);
-            }
-        });
-        addFunction(new Function("CEILING", 1) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-                BigDecimal toRound = parameters.get(0);
-                return toRound.setScale(0, RoundingMode.CEILING);
-            }
-        });
-        addFunction(new Function("SQRT", 1) {
-            @Override
-            public BigDecimal eval(List<BigDecimal> parameters) {
-				/*
-				 * From The Java Programmers Guide To numerical Computing
-				 * (Ronald Mak, 2003)
-				 */
-                BigDecimal x = parameters.get(0);
-                if (x.compareTo(BigDecimal.ZERO) == 0) {
-                    return new BigDecimal(0);
-                }
-                if (x.signum() < 0) {
-                    throw new ExpressionException(
-                            "Argument to SQRT() function must not be negative");
-                }
-                BigInteger n = x.movePointRight(mc.getPrecision() << 1)
-                        .toBigInteger();
-
-                int bits = (n.bitLength() + 1) >> 1;
-                BigInteger ix = n.shiftRight(bits);
-                BigInteger ixPrev;
-
-                do {
-                    ixPrev = ix;
-                    ix = ix.add(n.divide(ix)).shiftRight(1);
-                    // Give other threads a chance to work;
-                    Thread.yield();
-                } while (ix.compareTo(ixPrev) != 0);
-
-                return new BigDecimal(ix, mc.getPrecision());
-            }
-        });
-
-        constants.put("PI", PI);
-        constants.put("TRUE", Boolean.TRUE);
-        constants.put("FALSE", Boolean.FALSE);
-
-    }
-
-    /**
-     * Is the string a number?
-     *
-     * @param st
-     *            The string.
-     * @return <code>true</code>, if the input string is a number.
-     */
-    private boolean isNumber(String st) {
-        if (st.charAt(0) == minusSign && st.length() == 1)
-            return false;
-        for (char ch : st.toCharArray()) {
-            if (!Character.isDigit(ch) && ch != minusSign
-                    && ch != decimalSeparator)
-                return false;
-        }
-        return true;
-    }
-
-    /**
-     * Implementation of the <i>Shunting Yard</i> algorithm to transform an
-     * infix expression to a RPN expression.
-     *
-     * @param expression
-     *            The input expression in infx.
-     * @return A RPN representation of the expression, with each token as a list
-     *         member.
-     */
-    private List<Token> shuntingYard(String expression) {
-        List<Token> outputQueue = new ArrayList<Token>();
-        Stack<Token> stack = new Stack<Token>();
-
-        Tokenizer tokenizer = new Tokenizer(expression);
-
-        String previousToken = null;
-        while (tokenizer.hasNext()) {
-            String token = tokenizer.next();
-            if (token.charAt(0) == '"') {
-                StringBuilder sb = new StringBuilder();
-                boolean escaped = false;
-                for (int i = 1; i < token.length() - 1; i++) {
-                    char ch = token.charAt(i);
-                    if (escaped || ch != '\\') {
-                        sb.append(ch);
-                    } else {
-                        escaped = true;
-                    }
-                }
-                outputQueue.add(new Constant(sb.toString()));
-            } else if (isNumber(token)) {
-                outputQueue.add(new Constant(toBigDecimal(token)));
-            } else if (constants.containsKey(token)) {
-                outputQueue.add(new Constant(constants.get(token)));
-            } else if (functions.containsKey(token.toUpperCase())) {
-                stack.push(functions.get(token.toUpperCase()));
-            } else if (Character.isLetter(token.charAt(0))) {
-                outputQueue.add(new Variable(token));
-            } else if (",".equals(token)) {
-                while (!stack.isEmpty() && !(stack.peek() instanceof LeftParen)) {
-                    outputQueue.add(stack.pop());
-                }
-                if (stack.isEmpty()) {
-                    outputQueue.add(new Comma());
-                }
-            } else if (operators.containsKey(token)) {
-                Operator o1 = operators.get(token);
-                Token token2 = stack.isEmpty() ? null : stack.peek();
-                while (token2 instanceof Operator
-                        && ((o1.isLeftAssoc() && o1.getPrecedence() <= ((Operator) token2).getPrecedence())
-                          || (o1.getPrecedence() < ((Operator) token2).getPrecedence()))) {
-                    outputQueue.add(stack.pop());
-                    token2 = stack.isEmpty() ? null : stack.peek();
-                }
-                stack.push(o1);
-            } else if ("(".equals(token)) {
-                if (previousToken != null) {
-                    if (isNumber(previousToken)) {
-                        throw new ExpressionException("Missing operator at character position " + tokenizer.getPos());
-                    }
-                }
-                stack.push(new LeftParen());
-            } else if (")".equals(token)) {
-                while (!stack.isEmpty() && !(stack.peek() instanceof LeftParen)) {
-                    outputQueue.add(stack.pop());
-                }
-                if (stack.isEmpty()) {
-                    throw new RuntimeException("Mismatched parentheses");
-                }
-                stack.pop();
-                if (!stack.isEmpty() && stack.peek() instanceof Function) {
-                    outputQueue.add(stack.pop());
-                }
-            }
-            previousToken = token;
-        }
-        while (!stack.isEmpty()) {
-            Token element = stack.pop();
-            if (element instanceof LeftParen) {
-                throw new RuntimeException("Mismatched parentheses");
-            }
-            if (!(element instanceof Operator)) {
-                throw new RuntimeException("Unknown operator or function: " + element);
-            }
-            outputQueue.add(element);
-        }
-        return outputQueue;
-    }
-
-    /**
-     * Evaluates the expression.
-     *
-     * @return The result of the expression.
-     */
-    public Object eval() {
-        return eval(new HashMap<String, Object>());
-    }
-
-    /**
-     * Evaluates the expression.
-     *
-     * @return The result of the expression.
-     */
-    public Object eval(Map<String, Object> variables) {
-
-        Stack<Object> stack = new Stack<Object>();
-
-        for (Token token : getRPN()) {
-            if (token instanceof Operator) {
-                Object v1 = stack.pop();
-                Object v2 = stack.pop();
-                Object oResult = ((Operator) token).eval(variables, v2, v1);
-                stack.push(oResult);
-            } else if (token instanceof Constant) {
-                stack.push(((Constant) token).getValue());
-            } else if (token instanceof Function) {
-                Function f = (Function) token;
-                List<Object> p = new ArrayList<Object>(f.getNumParams());
-                for (int i = 0; i < f.numParams; i++) {
-                    p.add(0, stack.pop());
-                }
-                Object fResult = f.eval(variables, p);
-                stack.push(fResult);
-            } else if (token instanceof Comma) {
-                stack.pop();
-            } else {
-                stack.push(token);
-            }
-        }
-        if (stack.size() > 1) {
-            throw new IllegalArgumentException("Missing operator");
-        }
-        Object result = stack.pop();
-        if (result instanceof Variable) {
-            result = variables.get(((Variable) result).getName());
-        }
-        if (result instanceof BigDecimal) {
-            result = toResult((BigDecimal) result);
-        }
-        return result;
-    }
-
-    private Number toResult(BigDecimal r) {
-        long l = r.longValue();
-        if (new BigDecimal(l).compareTo(r) == 0) {
-            return l;
-        }
-        double d = r.doubleValue();
-        if (new BigDecimal(d).compareTo(r) == 0) {
-            return d;
-        } else {
-            return r.stripTrailingZeros();
-        }
-    }
-
-    private BigDecimal toBigDecimal(Map<String, Object> variables, Object o) {
-        if (o instanceof Variable) {
-            o = variables.get(((Variable) o).getName());
-        }
-        if (o instanceof String) {
-            if (isNumber((String) o)) {
-                return new BigDecimal((String) o, mc);
-            } else if (Character.isLetter(((String) o).charAt(0))) {
-                o = variables.get(o);
-            }
-        }
-        return toBigDecimal(o);
-    }
-
-    private BigDecimal toBigDecimal(Object o) {
-        if (o == null) {
-            return BigDecimal.ZERO;
-        } else if (o instanceof Boolean) {
-            return ((Boolean) o) ? BigDecimal.ONE : BigDecimal.ZERO;
-        } else if (o instanceof BigDecimal) {
-            return ((BigDecimal) o).round(mc);
-        } else if (o instanceof BigInteger) {
-            return new BigDecimal((BigInteger) o, mc);
-        } else if (o instanceof Number) {
-            return new BigDecimal(((Number) o).doubleValue(), mc);
-        } else {
-            try {
-                return new BigDecimal(o.toString(), mc);
-            } catch (NumberFormatException e) {
-                return new BigDecimal(Double.NaN);
-            }
-        }
-    }
-
-    /**
-     * Sets the precision for expression evaluation.
-     *
-     * @param precision
-     *            The new precision.
-     *
-     * @return The expression, allows to chain methods.
-     */
-    public Expression setPrecision(int precision) {
-        this.mc = new MathContext(precision);
-        return this;
-    }
-
-    /**
-     * Sets the rounding mode for expression evaluation.
-     *
-     * @param roundingMode
-     *            The new rounding mode.
-     * @return The expression, allows to chain methods.
-     */
-    public Expression setRoundingMode(RoundingMode roundingMode) {
-        this.mc = new MathContext(mc.getPrecision(), roundingMode);
-        return this;
-    }
-
-    /**
-     * Adds an operator to the list of supported operators.
-     *
-     * @param operator
-     *            The operator to add.
-     * @return The previous operator with that name, or <code>null</code> if
-     *         there was none.
-     */
-    public Operator addOperator(Operator operator) {
-        return operators.put(operator.getOper(), operator);
-    }
-
-    /**
-     * Adds a function to the list of supported functions
-     *
-     * @param function
-     *            The function to add.
-     * @return The previous operator with that name, or <code>null</code> if
-     *         there was none.
-     */
-    public Function addFunction(Function function) {
-        return functions.put(function.getName(), function);
-    }
-
-    /**
-     * Sets a constant value.
-     *
-     * @param name
-     *            The constant name.
-     * @param value
-     *            The constant value.
-     * @return The expression, allows to chain methods.
-     */
-    public Expression addConstant(String name, Object value) {
-        constants.put(name, value);
-        return this;
-    }
-
-    /**
-     * Get an iterator for this expression, allows iterating over an expression
-     * token by token.
-     *
-     * @return A new iterator instance for this expression.
-     */
-    public Iterator<String> getExpressionTokenizer() {
-        return new Tokenizer(this.expression);
-    }
-
-    /**
-     * Cached access to the RPN notation of this expression, ensures only one
-     * calculation of the RPN per expression instance. If no cached instance
-     * exists, a new one will be created and put to the cache.
-     *
-     * @return The cached RPN instance.
-     */
-    private List<Token> getRPN() {
-        if (rpn == null) {
-            rpn = shuntingYard(this.expression);
-        }
-        return rpn;
-    }
-
-    /**
-     * Get a string representation of the RPN (Reverse Polish Notation) for this
-     * expression.
-     *
-     * @return A string with the RPN representation for this expression.
-     */
-    public String toRPN() {
-        StringBuilder result = new StringBuilder();
-        for (Token st : getRPN()) {
-            if (result.length() > 0) {
-                result.append(" ");
-            }
-            result.append(st);
-        }
-        return result.toString();
-    }
-
-}
\ No newline at end of file
diff --git a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Parser.java b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Parser.java
index 23c2f65..271bb8a 100644
--- a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Parser.java
+++ b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Parser.java
@@ -97,7 +97,6 @@
                 case EXECUTION:
                 case ARRAY:
                 case ASSIGN:
-                case EXPR:
                     break;
                     
                 default:
diff --git a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Tokenizer.java b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Tokenizer.java
index 8b5d91f..b1c529e 100644
--- a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Tokenizer.java
+++ b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Tokenizer.java
@@ -46,7 +46,7 @@
 {
     public enum Type
     {
-        ASSIGN('='), PIPE('|'), SEMICOLON(';'), NEWLINE, ARRAY, CLOSURE, EXPR, EXECUTION, WORD, EOT;
+        ASSIGN('='), PIPE('|'), SEMICOLON(';'), NEWLINE, ARRAY, CLOSURE, EXECUTION, WORD, EOT;
 
         private char c;
 
@@ -265,43 +265,25 @@
     private CharSequence group()
     {
         final char push = ch;
-        final char push2;
         final char pop;
-        final char pop2;
 
         switch (ch)
         {
             case '{':
                 type = Type.CLOSURE;
-                push2 = 0;
                 pop = '}';
-                pop2 = 0;
                 break;
             case '(':
-                if (peek() == '(') {
-                    getch();
-                    push2 = '(';
-                    type = Type.EXPR;
-                    pop = ')';
-                    pop2 = ')';
-                } else {
-                    type = Type.EXECUTION;
-                    push2 = 0;
-                    pop = ')';
-                    pop2 = 0;
-                }
+                type = Type.EXECUTION;
+                pop = ')';
                 break;
             case '[':
                 type = Type.ARRAY;
-                push2 = 0;
                 pop = ']';
-                pop2 = 0;
                 break;
             default:
                 assert false;
-                push2 = 0;
                 pop = 0;
-                pop2 = 0;
         }
 
         short sLine = line;
@@ -345,17 +327,10 @@
                     break;
 
                 default:
-                    if (push == ch) {
+                    if (push == ch)
                         depth++;
-                    }
-                    else if (pop == ch && --depth == 0) {
-                        if (pop2 == 0)
-                            return text.subSequence(start, index - 1);
-                        else if (pop2 == peek()) {
-                            getch();
-                            return text.subSequence(start, index - 2);
-                        }
-                    }
+                    else if (pop == ch && --depth == 0)
+                        return text.subSequence(start, index - 1);
             }
         }
 
@@ -614,20 +589,11 @@
         if (getch() != '{')
         {
             if ('(' == ch)
-            {
+            { // support $(...) FELIX-2433
                 short sLine = line;
                 short sCol = column;
-                if ('(' == peek())
-                {
-                    val = evaluate.eval(new Token(Type.EXPR, group(), sLine, sCol));
-                    getch();
-                }
-                else
-                {
-                    // support $(...) FELIX-2433
-                    val = evaluate.eval(new Token(Type.EXECUTION, group(), sLine, sCol));
-                    getch();
-                }
+                val = evaluate.eval(new Token(Type.EXECUTION, group(), sLine, sCol));
+                getch();
             }
             else
             {
diff --git a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/activator/Activator.java b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/activator/Activator.java
index 37a26a8..fbd8aed 100644
--- a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/activator/Activator.java
+++ b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/activator/Activator.java
@@ -25,10 +25,13 @@
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 
+import org.apache.felix.gogo.api.CommandSessionListener;
 import org.apache.felix.gogo.runtime.CommandProcessorImpl;
 import org.apache.felix.gogo.runtime.CommandProxy;
-import org.apache.felix.gogo.api.CommandSessionListener;
 import org.apache.felix.gogo.runtime.threadio.ThreadIOImpl;
+import org.apache.felix.service.command.CommandProcessor;
+import org.apache.felix.service.command.Converter;
+import org.apache.felix.service.threadio.ThreadIO;
 import org.osgi.framework.BundleActivator;
 import org.osgi.framework.BundleContext;
 import org.osgi.framework.Constants;
@@ -36,10 +39,6 @@
 import org.osgi.framework.InvalidSyntaxException;
 import org.osgi.framework.ServiceReference;
 import org.osgi.framework.ServiceRegistration;
-import org.apache.felix.service.command.CommandProcessor;
-import org.apache.felix.service.command.Converter;
-import org.apache.felix.service.command.Function;
-import org.apache.felix.service.threadio.ThreadIO;
 import org.osgi.util.tracker.ServiceTracker;
 
 public class Activator implements BundleActivator
diff --git a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/activator/EventAdminListener.java b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/activator/EventAdminListener.java
index 2368ce1..19ca3b5 100644
--- a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/activator/EventAdminListener.java
+++ b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/activator/EventAdminListener.java
@@ -29,13 +29,10 @@
 
 public class EventAdminListener implements CommandSessionListener
 {
-
-    private BundleContext bundleContext;
     private ServiceTracker tracker;
 
     public EventAdminListener(BundleContext bundleContext)
     {
-        this.bundleContext = bundleContext;
         tracker = new ServiceTracker(bundleContext, EventAdmin.class.getName(), null);
         tracker.open();
     }
diff --git a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/threadio/ThreadPrintStream.java b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/threadio/ThreadPrintStream.java
index 6cd14bc..1cfaf61 100644
--- a/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/threadio/ThreadPrintStream.java
+++ b/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/threadio/ThreadPrintStream.java
@@ -20,7 +20,6 @@
 
 import java.io.IOException;
 import java.io.PrintStream;
-import java.io.InputStream;
 import java.util.Locale;
 
 public class ThreadPrintStream extends PrintStream
diff --git a/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/Context.java b/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/Context.java
index b96a313..adbb66f 100644
--- a/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/Context.java
+++ b/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/Context.java
@@ -68,9 +68,4 @@
         session.put(name, value);
     }
 
-    public Object get(String name)
-    {
-        return session.get(name);
-    }
-
 }
diff --git a/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/TestParser.java b/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/TestParser.java
index 937ef80..13c52f1 100644
--- a/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/TestParser.java
+++ b/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/TestParser.java
@@ -46,7 +46,7 @@
 
         assertEquals("a", c.execute("echo a | capture"));
         assertEquals("a", c.execute("(echo a) | capture"));
-        assertEquals("a", c.execute("( (echo a) ) | capture"));
+        assertEquals("a", c.execute("((echo a)) | capture"));
     }
 
     public void testUnknownCommand() throws Exception
diff --git a/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/TestParser3.java b/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/TestParser3.java
deleted file mode 100644
index 7e65c09..0000000
--- a/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/TestParser3.java
+++ /dev/null
@@ -1,61 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-package org.apache.felix.gogo.runtime;
-
-import junit.framework.TestCase;
-
-import java.io.EOFException;
-
-/*
- * Test features of the new parser/tokenizer, many of which are not supported
- * by the original parser.
- */
-public class TestParser3 extends TestCase
-{
-    public void testArithmetic() throws Exception
-    {
-        Context c = new Context();
-        c.addCommand("echo", this);
-
-        assertEquals("10", c.execute("echo $((2*(3+2)))"));
-        assertEquals(3l, c.execute("((1+2))"));
-
-        c.set("a", 2l);
-        assertEquals(3l, c.execute("((a+=1))"));
-        assertEquals(3l, c.get("a"));
-    }
-
-    public CharSequence echo(Object args[])
-    {
-        if (args == null)
-        {
-            return "null args!";
-        }
-
-        StringBuilder sb = new StringBuilder();
-        for (Object arg : args)
-        {
-            if (sb.length() > 0)
-                sb.append(' ');
-            sb.append(String.valueOf(arg));
-        }
-        return sb.toString();
-    }
-
-}
diff --git a/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/TestTokenizer.java b/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/TestTokenizer.java
index ae9f18c..da1f959 100644
--- a/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/TestTokenizer.java
+++ b/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/TestTokenizer.java
@@ -18,20 +18,24 @@
  */
 package org.apache.felix.gogo.runtime;
 
+import static org.mockito.Matchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import java.io.ByteArrayInputStream;
 import java.io.File;
 import java.net.URI;
 import java.util.HashMap;
 import java.util.Map;
 
-import org.apache.felix.gogo.runtime.Evaluate;
-import org.apache.felix.gogo.runtime.Parser;
-import org.apache.felix.gogo.runtime.SyntaxError;
-import org.apache.felix.gogo.runtime.Token;
-import org.apache.felix.gogo.runtime.Tokenizer;
-import org.apache.felix.gogo.runtime.Tokenizer.Type;
-
 import junit.framework.TestCase;
 
+import org.apache.felix.gogo.runtime.Tokenizer.Type;
+import org.apache.felix.gogo.runtime.threadio.ThreadIOImpl;
+import org.junit.Test;
+import org.osgi.framework.Bundle;
+import org.osgi.framework.BundleContext;
+
 public class TestTokenizer extends TestCase
 {
     private final Map<String, Object> vars = new HashMap<String, Object>();
@@ -58,6 +62,7 @@
         };
     }
 
+    @Test
     public void testHello() throws Exception
     {
         testHello("hello world\n");
@@ -98,7 +103,8 @@
         assertEquals(Type.NEWLINE, t.next());
         assertEquals(Type.EOT, t.next());
     }
-
+    
+    @Test
     public void testString() throws Exception
     {
         testString("'single $quote' \"double $quote\"\n");
@@ -116,6 +122,7 @@
         assertEquals(Type.EOT, t.next());
     }
 
+    @Test
     public void testClosure() throws Exception
     {
         testClosure2("x = { echo '}' $args //comment's\n}\n");
@@ -127,6 +134,7 @@
     /*
      * x = {echo $args};
      */
+    @Test
     private void testClosure2(CharSequence text) throws Exception
     {
         Tokenizer t = new Tokenizer(text);
@@ -147,6 +155,7 @@
         return type;
     }
 
+    @Test
     public void testExpand() throws Exception
     {
         final URI home = new URI("/home/derek");
@@ -269,6 +278,7 @@
         return Tokenizer.expand(word, evaluate);
     }
 
+    @Test
     public void testParser() throws Exception
     {
         new Parser("// comment\n" + "a=\"who's there?\"; ps -ef;\n" + "ls | \n grep y\n").program();
@@ -277,4 +287,43 @@
         new Parser(new Token(Type.ARRAY, p1, (short) 0, (short) 0)).program();
     }
 
+    /**
+     * FELIX-4679 / FELIX-4671. 
+     */
+    @Test
+    public void testScriptFelix4679() throws Exception
+    {
+        String script = "addcommand system (((${.context} bundles) 0) loadclass java.lang.System)";
+
+        ThreadIOImpl tio = new ThreadIOImpl();
+        tio.start();
+
+        try
+        {
+            BundleContext bc = createMockContext();
+
+            CommandProcessorImpl processor = new CommandProcessorImpl(tio);
+            processor.addCommand("gogo", processor, "addcommand");
+            processor.addConstant(".context", bc);
+
+            CommandSessionImpl session = new CommandSessionImpl(processor, new ByteArrayInputStream(script.getBytes()), System.out, System.err);
+
+            Closure c = new Closure(session, null, script);
+            assertNull(c.execute(session, null));
+        }
+        finally
+        {
+            tio.stop();
+        }
+    }
+
+    private BundleContext createMockContext() throws ClassNotFoundException
+    {
+        Bundle systemBundle = mock(Bundle.class);
+        when(systemBundle.loadClass(eq("java.lang.System"))).thenReturn(System.class);
+
+        BundleContext bc = mock(BundleContext.class);
+        when(bc.getBundles()).thenReturn(new Bundle[] { systemBundle });
+        return bc;
+    }
 }
diff --git a/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/expr/ExpressionTest.java b/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/expr/ExpressionTest.java
deleted file mode 100644
index bb16cd9..0000000
--- a/gogo/runtime/src/test/java/org/apache/felix/gogo/runtime/expr/ExpressionTest.java
+++ /dev/null
@@ -1,58 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-package org.apache.felix.gogo.runtime.expr;
-
-import junit.framework.TestCase;
-import org.apache.felix.gogo.runtime.Expression;
-
-import java.util.HashMap;
-import java.util.Map;
-
-public class ExpressionTest extends TestCase {
-
-    public void testExpr() {
-
-        Map<String, Object> variables = new HashMap<String, Object>();
-        variables.put("a", 2d);
-        variables.put("b", 5l);
-        variables.put("c", 1l);
-        variables.put("d", 2l);
-        variables.put("s", " foo ");
-        variables.put("t", "bar");
-
-        assertEquals(4l, new Expression("c+=1, d+=2").eval(variables));
-
-        assertEquals(" foo ", new Expression("\" foo \"").eval());
-        assertEquals(" foo bar", new Expression("s + t").eval(variables));
-        assertEquals(1l, new Expression("s < t").eval(variables));
-        assertEquals(1l, new Expression("s > t || t == \"bar\"").eval(variables));
-
-        assertEquals(3l, new Expression("a += 1").eval(variables));
-        assertEquals(3l, variables.get("a"));
-
-        assertEquals(30l, new Expression("10 + 20 | 30").eval());
-
-        assertEquals(8l, new Expression("a + b").eval(variables));
-        assertEquals(3l, new Expression("if(a < b, a, b)").eval(variables));
-
-        assertEquals(16l, new Expression("2 + 2 << 2").eval());
-        assertEquals(8l, new Expression("2 | 2 << 2").eval());
-    }
-
-}
diff --git a/gogo/shell/src/main/java/org/apache/felix/gogo/shell/Activator.java b/gogo/shell/src/main/java/org/apache/felix/gogo/shell/Activator.java
index ec9b62e..dcf4ebb 100644
--- a/gogo/shell/src/main/java/org/apache/felix/gogo/shell/Activator.java
+++ b/gogo/shell/src/main/java/org/apache/felix/gogo/shell/Activator.java
@@ -23,6 +23,11 @@
 import java.util.Hashtable;
 import java.util.Iterator;
 import java.util.Set;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.TimeUnit;
+
 import org.apache.felix.service.command.CommandProcessor;
 import org.apache.felix.service.command.CommandSession;
 import org.apache.felix.service.command.Converter;
@@ -32,30 +37,28 @@
 import org.osgi.framework.ServiceRegistration;
 import org.osgi.util.tracker.ServiceTracker;
 
-public class Activator implements BundleActivator, Runnable
+public class Activator implements BundleActivator
 {
     private BundleContext context;
     private ServiceTracker commandProcessorTracker;
-    private Set<ServiceRegistration> regs = new HashSet<ServiceRegistration>();
-    private CommandSession session;
-    private Shell shell;
-    private Thread thread;
+    private Set<ServiceRegistration> regs;
 
-    public void start(final BundleContext ctxt) throws Exception
+    private ExecutorService executor;
+
+    public Activator()
     {
-        context = ctxt;
-        commandProcessorTracker = processorTracker();
+        regs = new HashSet<ServiceRegistration>();
+    }
+
+    public void start(BundleContext context) throws Exception
+    {
+        this.context = context;
+        this.commandProcessorTracker = createCommandProcessorTracker();
+        this.commandProcessorTracker.open();
     }
 
     public void stop(BundleContext context) throws Exception
     {
-        if (thread != null)
-        {
-            thread.interrupt();
-        }
-
-        commandProcessorTracker.close();
-        
         Iterator<ServiceRegistration> iterator = regs.iterator();
         while (iterator.hasNext())
         {
@@ -63,74 +66,15 @@
             reg.unregister();
             iterator.remove();
         }
+
+        stopShell();
+
+        this.commandProcessorTracker.close();
     }
 
-    public void run()
+    private ServiceTracker createCommandProcessorTracker()
     {
-        try
-        {
-            // wait for gosh command to be registered
-            for (int i = 0; (i < 100) && session.get("gogo:gosh") == null; ++i) {
-	            Thread.sleep(10);
-            }
-            
-            String args = context.getProperty("gosh.args");
-            args = (args == null) ? "" : args;
-            session.execute("gosh --login " + args);
-        }
-        catch (Exception e)
-        {
-            Object loc = session.get(".location");
-            if (null == loc || !loc.toString().contains(":"))
-            {
-                loc = "gogo";
-            }
-
-            System.err.println(loc + ": " + e.getClass().getSimpleName() + ": " + e.getMessage());
-            e.printStackTrace();
-        }
-        finally
-        {
-            session.close();
-        }
-    }
-
-    private void startShell(BundleContext context, CommandProcessor processor)
-    {
-        Dictionary<String, Object> dict = new Hashtable<String, Object>();
-        dict.put(CommandProcessor.COMMAND_SCOPE, "gogo");
-
-        // register converters
-        regs.add(context.registerService(Converter.class.getName(), new Converters(context), null));
-        
-        // register commands
-        
-        dict.put(CommandProcessor.COMMAND_FUNCTION, Builtin.functions);
-        regs.add(context.registerService(Builtin.class.getName(), new Builtin(), dict));
-
-        dict.put(CommandProcessor.COMMAND_FUNCTION, Procedural.functions);
-        regs.add(context.registerService(Procedural.class.getName(), new Procedural(), dict));
-
-        dict.put(CommandProcessor.COMMAND_FUNCTION, Posix.functions);
-        regs.add(context.registerService(Posix.class.getName(), new Posix(), dict));
-
-        dict.put(CommandProcessor.COMMAND_FUNCTION, Telnet.functions);
-        regs.add(context.registerService(Telnet.class.getName(), new Telnet(processor), dict));
-        
-        shell = new Shell(context, processor);
-        dict.put(CommandProcessor.COMMAND_FUNCTION, Shell.functions);
-        regs.add(context.registerService(Shell.class.getName(), shell, dict));
-        
-        // start shell
-        session = processor.createSession(System.in, System.out, System.err);
-        thread = new Thread(this, "Gogo shell");
-        thread.start();
-    }
-
-    private ServiceTracker processorTracker()
-    {
-        ServiceTracker t = new ServiceTracker(context, CommandProcessor.class.getName(),
-            null)
+        return new ServiceTracker(context, CommandProcessor.class.getName(), null)
         {
             @Override
             public Object addingService(ServiceReference reference)
@@ -143,15 +87,112 @@
             @Override
             public void removedService(ServiceReference reference, Object service)
             {
-                if (thread != null)
-                {
-                    thread.interrupt();
-                }
+                stopShell();
                 super.removedService(reference, service);
             }
         };
+    }
 
-        t.open();
-        return t;
+    private void startShell(BundleContext context, CommandProcessor processor)
+    {
+        Dictionary<String, Object> dict = new Hashtable<String, Object>();
+        dict.put(CommandProcessor.COMMAND_SCOPE, "gogo");
+
+        // register converters
+        regs.add(context.registerService(Converter.class.getName(), new Converters(context), null));
+
+        // register commands
+
+        dict.put(CommandProcessor.COMMAND_FUNCTION, Builtin.functions);
+        regs.add(context.registerService(Builtin.class.getName(), new Builtin(), dict));
+
+        dict.put(CommandProcessor.COMMAND_FUNCTION, Procedural.functions);
+        regs.add(context.registerService(Procedural.class.getName(), new Procedural(), dict));
+
+        dict.put(CommandProcessor.COMMAND_FUNCTION, Posix.functions);
+        regs.add(context.registerService(Posix.class.getName(), new Posix(), dict));
+
+        dict.put(CommandProcessor.COMMAND_FUNCTION, Telnet.functions);
+        regs.add(context.registerService(Telnet.class.getName(), new Telnet(processor), dict));
+
+        Shell shell = new Shell(context, processor);
+        dict.put(CommandProcessor.COMMAND_FUNCTION, Shell.functions);
+        regs.add(context.registerService(Shell.class.getName(), shell, dict));
+
+        // start shell on a separate thread...
+        executor = Executors.newSingleThreadExecutor(new ThreadFactory()
+        {
+            public Thread newThread(Runnable runnable)
+            {
+                return new Thread(runnable, "Gogo shell");
+            }
+        });
+        executor.submit(new StartShellJob(context, processor));
+    }
+
+    private void stopShell()
+    {
+        if (executor != null && !(executor.isShutdown() || executor.isTerminated()))
+        {
+            executor.shutdownNow();
+
+            try
+            {
+                if (!executor.awaitTermination(5, TimeUnit.SECONDS))
+                {
+                    System.err.println("!!! FAILED TO STOP EXECUTOR !!!");
+                }
+            }
+            catch (InterruptedException e)
+            {
+                // Restore administration...
+                Thread.currentThread().interrupt();
+            }
+            executor = null;
+        }
+    }
+
+    private static class StartShellJob implements Runnable
+    {
+        private final BundleContext context;
+        private final CommandProcessor processor;
+
+        public StartShellJob(BundleContext context, CommandProcessor processor)
+        {
+            this.context = context;
+            this.processor = processor;
+        }
+
+        public void run()
+        {
+            CommandSession session = processor.createSession(System.in, System.out, System.err);
+            try
+            {
+                // wait for gosh command to be registered
+                for (int i = 0; (i < 100) && session.get("gogo:gosh") == null; ++i)
+                {
+                    TimeUnit.MILLISECONDS.sleep(10);
+                }
+
+                String args = context.getProperty("gosh.args");
+                args = (args == null) ? "" : args;
+                session.execute("gosh --login " + args);
+            }
+            catch (Exception e)
+            {
+                Object loc = session.get(".location");
+                if (null == loc || !loc.toString().contains(":"))
+                {
+                    loc = "gogo";
+                }
+
+                System.err.println(loc + ": " + e.getClass().getSimpleName() + ": " + e.getMessage());
+                e.printStackTrace();
+            }
+            finally
+            {
+                session.close();
+            }
+        }
     }
 }
\ No newline at end of file