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Subject: svn commit: r689652 - in /maven/plugins/trunk/maven-help-plugin: ./
 src/main/java/org/apache/maven/plugins/help/ src/site/apt/
Date: Wed, 27 Aug 2008 23:02:17 -0000
To: commits@maven.apache.org
From: vsiveton@apache.org
Message-Id: <20080827230218.9992F23889C2@eris.apache.org>

Author: vsiveton
Date: Wed Aug 27 16:02:17 2008
New Revision: 689652

URL: http://svn.apache.org/viewvc?rev=689652&view=rev
Log:
MPH-47: Add a new goal to evaluate Maven expressions given by a user

o first implementation
o updated documentation

Added:
    maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/EvaluateMojo.java   (with props)
    maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/HelpUtil.java   (with props)
Modified:
    maven/plugins/trunk/maven-help-plugin/pom.xml
    maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/DescribeMojo.java
    maven/plugins/trunk/maven-help-plugin/src/site/apt/usage.apt

Modified: maven/plugins/trunk/maven-help-plugin/pom.xml
URL: http://svn.apache.org/viewvc/maven/plugins/trunk/maven-help-plugin/pom.xml?rev=689652&r1=689651&r2=689652&view=diff
==============================================================================
--- maven/plugins/trunk/maven-help-plugin/pom.xml (original)
+++ maven/plugins/trunk/maven-help-plugin/pom.xml Wed Aug 27 16:02:17 2008
@@ -115,6 +115,16 @@
       <artifactId>jdom</artifactId>
       <version>1.0</version>
     </dependency>
+    <dependency>
+      <groupId>com.thoughtworks.xstream</groupId>
+      <artifactId>xstream</artifactId>
+      <version>1.3</version>
+    </dependency>
+    <dependency>
+      <groupId>commons-lang</groupId>
+      <artifactId>commons-lang</artifactId>
+      <version>2.4</version>
+    </dependency>
   </dependencies>
   <reporting>
     <plugins>

Modified: maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/DescribeMojo.java
URL: http://svn.apache.org/viewvc/maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/DescribeMojo.java?rev=689652&r1=689651&r2=689652&view=diff
==============================================================================
--- maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/DescribeMojo.java (original)
+++ maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/DescribeMojo.java Wed Aug 27 16:02:17 2008
@@ -820,7 +820,7 @@
         }
 
         // goals
-        MojoDescriptor mojoDescriptor = getMojoDescriptor( cmd, session, project, cmd, true, false );
+        MojoDescriptor mojoDescriptor = HelpUtil.getMojoDescriptor( cmd, session, project, cmd, true, false );
 
         descriptionBuffer.append( "'" + cmd + "' is a plugin" ).append( ".\n" );
         plugin = mojoDescriptor.getPluginDescriptor().getId();
@@ -830,89 +830,6 @@
 
     /**
      * Invoke the following private method
-     * <code>DefaultLifecycleExecutor#getMojoDescriptor(String, MavenSession, MavenProject, String, boolean, boolean)</code>
-     *
-     * @param task not null
-     * @param session not null
-     * @param project not null
-     * @param invokedVia not null
-     * @param canUsePrefix not null
-     * @param isOptionalMojo not null
-     * @return MojoDescriptor for the task
-     * @throws MojoFailureException if any can not invoke the method
-     * @throws MojoExecutionException if no descriptor was found for <code>task</code>
-     * @see DefaultLifecycleExecutor#getMojoDescriptor(String, MavenSession, MavenProject, String, boolean, boolean)
-     */
-    private static MojoDescriptor getMojoDescriptor( String task, MavenSession session, MavenProject project,
-                                              String invokedVia, boolean canUsePrefix, boolean isOptionalMojo )
-        throws MojoFailureException, MojoExecutionException
-    {
-        try
-        {
-            DefaultLifecycleExecutor lifecycleExecutor =
-                (DefaultLifecycleExecutor) session.lookup( LifecycleExecutor.ROLE );
-
-            Method m =
-                lifecycleExecutor.getClass().getDeclaredMethod(
-                                                                "getMojoDescriptor",
-                                                                new Class[] { String.class, MavenSession.class,
-                                                                    MavenProject.class, String.class,
-                                                                    Boolean.TYPE, Boolean.TYPE } );
-            m.setAccessible( true );
-            MojoDescriptor mojoDescriptor =
-                (MojoDescriptor) m.invoke( lifecycleExecutor, new Object[] { task, session, project, invokedVia,
-                    Boolean.valueOf( canUsePrefix ), Boolean.valueOf( isOptionalMojo ) } );
-
-            if ( mojoDescriptor == null )
-            {
-                throw new MojoExecutionException( "No MOJO exists for '" + task + "'." );
-            }
-
-            return mojoDescriptor;
-        }
-        catch ( SecurityException e )
-        {
-            throw new MojoFailureException( "SecurityException: " + e.getMessage() );
-        }
-        catch ( IllegalArgumentException e )
-        {
-            throw new MojoFailureException( "IllegalArgumentException: " + e.getMessage() );
-        }
-        catch ( ComponentLookupException e )
-        {
-            throw new MojoFailureException( "ComponentLookupException: " + e.getMessage() );
-        }
-        catch ( NoSuchMethodException e )
-        {
-            throw new MojoFailureException( "NoSuchMethodException: " + e.getMessage() );
-        }
-        catch ( IllegalAccessException e )
-        {
-            throw new MojoFailureException( "IllegalAccessException: " + e.getMessage() );
-        }
-        catch ( InvocationTargetException e )
-        {
-            Throwable cause = e.getCause();
-
-            if ( cause instanceof BuildFailureException )
-            {
-                throw new MojoFailureException( "BuildFailureException: " + cause.getMessage() );
-            }
-            else if ( cause instanceof LifecycleExecutionException )
-            {
-                throw new MojoFailureException( "LifecycleExecutionException: " + cause.getMessage() );
-            }
-            else if ( cause instanceof PluginNotFoundException )
-            {
-                throw new MojoFailureException( "PluginNotFoundException: " + cause.getMessage() );
-            }
-
-            throw new MojoFailureException( "InvocationTargetException: " + e.getMessage() );
-        }
-    }
-
-    /**
-     * Invoke the following private method
      * <code>HelpMojo#toLines(String, int, int, int)</code>
      *
      * @param text The text to split into lines, must not be <code>null</code>.

Added: maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/EvaluateMojo.java
URL: http://svn.apache.org/viewvc/maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/EvaluateMojo.java?rev=689652&view=auto
==============================================================================
--- maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/EvaluateMojo.java (added)
+++ maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/EvaluateMojo.java Wed Aug 27 16:02:17 2008
@@ -0,0 +1,792 @@
+package org.apache.maven.plugins.help;
+
+/*
+ * 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.
+ */
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.StringWriter;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Properties;
+import java.util.TreeMap;
+import java.util.jar.JarEntry;
+import java.util.jar.JarInputStream;
+
+import org.apache.commons.lang.ClassUtils;
+import org.apache.maven.artifact.Artifact;
+import org.apache.maven.artifact.ArtifactUtils;
+import org.apache.maven.artifact.factory.ArtifactFactory;
+import org.apache.maven.artifact.repository.ArtifactRepository;
+import org.apache.maven.artifact.resolver.ArtifactNotFoundException;
+import org.apache.maven.artifact.resolver.ArtifactResolutionException;
+import org.apache.maven.artifact.resolver.ArtifactResolver;
+import org.apache.maven.execution.MavenSession;
+import org.apache.maven.model.Dependency;
+import org.apache.maven.model.Model;
+import org.apache.maven.model.io.xpp3.MavenXpp3Writer;
+import org.apache.maven.plugin.AbstractMojo;
+import org.apache.maven.plugin.MojoExecution;
+import org.apache.maven.plugin.MojoExecutionException;
+import org.apache.maven.plugin.MojoFailureException;
+import org.apache.maven.plugin.PluginParameterExpressionEvaluator;
+import org.apache.maven.plugin.descriptor.MojoDescriptor;
+import org.apache.maven.project.MavenProject;
+import org.apache.maven.project.MavenProjectBuilder;
+import org.apache.maven.project.ProjectBuildingException;
+import org.apache.maven.project.path.PathTranslator;
+import org.apache.maven.settings.Settings;
+import org.apache.maven.settings.io.xpp3.SettingsXpp3Writer;
+import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluationException;
+import org.codehaus.plexus.components.interactivity.InputHandler;
+import org.codehaus.plexus.util.IOUtil;
+import org.codehaus.plexus.util.StringUtils;
+
+import com.thoughtworks.xstream.XStream;
+import com.thoughtworks.xstream.converters.MarshallingContext;
+import com.thoughtworks.xstream.converters.collections.PropertiesConverter;
+import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
+
+/**
+ * Evaluates Maven expressions from the user.
+ *
+ * @author <a href="mailto:vincent.siveton@gmail.com">Vincent Siveton</a>
+ * @version $Id$
+ * @since 2.1
+ * @goal evaluate
+ * @requiresProject false
+ */
+public class EvaluateMojo
+    extends AbstractMojo
+{
+    // ----------------------------------------------------------------------
+    // Mojo components
+    // ----------------------------------------------------------------------
+
+    /**
+     * Maven Artifact Factory component.
+     *
+     * @component
+     */
+    private ArtifactFactory artifactFactory;
+
+    /**
+     * Input handler, needed for command line handling.
+     *
+     * @component
+     */
+    private InputHandler inputHandler;
+
+    /**
+     * Maven Project Builder component.
+     *
+     * @component
+     */
+    private MavenProjectBuilder mavenProjectBuilder;
+
+    /**
+     * @component
+     */
+    private PathTranslator pathTranslator;
+
+    /**
+     * Artifact Resolver component.
+     *
+     * @component
+     */
+    private ArtifactResolver resolver;
+
+    // ----------------------------------------------------------------------
+    // Mojo parameters
+    // ----------------------------------------------------------------------
+
+    /**
+     * An artifact for evaluating Maven expressions.
+     * <br/>
+     * <b>Note</b>: Should respect the Maven format, i.e. <code>groupId:artifactId[:version][:classifier]</code>.
+     *
+     * @parameter expression="${artifact}"
+     */
+    private String artifact;
+
+    /**
+     * Local Repository.
+     *
+     * @parameter expression="${localRepository}"
+     * @required
+     * @readonly
+     */
+    private ArtifactRepository localRepository;
+
+    /**
+     * The current Maven project or the super pom.
+     *
+     * @parameter expression="${project}"
+     * @readonly
+     * @required
+     */
+    private MavenProject project;
+
+    /**
+     * Remote repositories used for the project.
+     *
+     * @parameter expression="${project.remoteArtifactRepositories}"
+     * @readonly
+     * @required
+     */
+    private List remoteRepositories;
+
+    /**
+     * The system settings for Maven.
+     *
+     * @parameter expression="${settings}"
+     * @readonly
+     * @required
+     */
+    private Settings settings;
+
+    /**
+     * The current Maven session.
+     *
+     * @parameter expression="${session}"
+     * @required
+     * @readonly
+     */
+    private MavenSession session;
+
+    // ----------------------------------------------------------------------
+    // Instance variables
+    // ----------------------------------------------------------------------
+
+    /** lazy loading evaluator variable */
+    private PluginParameterExpressionEvaluator evaluator;
+
+    /** lazy loading xstream variable */
+    private XStream xstream;
+
+    // ----------------------------------------------------------------------
+    // Public methods
+    // ----------------------------------------------------------------------
+
+    /** {@inheritDoc} */
+    public void execute()
+        throws MojoExecutionException, MojoFailureException
+    {
+        if ( !settings.isInteractiveMode() )
+        {
+            StringBuffer msg = new StringBuffer();
+            msg.append( "Maven is configured to NOT interact with the user for input. " );
+            msg.append( "This Mojo requires that 'interactiveMode' in your settings file is flag to 'true'." );
+
+            getLog().error( msg.toString() );
+            return;
+        }
+
+        validateParameters();
+
+        if ( StringUtils.isNotEmpty( artifact ) )
+        {
+            Artifact artifactObj = getArtifact( artifact );
+
+            try
+            {
+                project = getMavenProject( artifactObj );
+            }
+            catch ( ProjectBuildingException e )
+            {
+                throw new MojoExecutionException( "Unable to get the POM for the artifact '" + artifact
+                    + "'. Verify the artifact parameter." );
+            }
+        }
+
+        while ( true )
+        {
+            getLog().info( "Enter the Maven expression i.e. ${project.groupId} or 0 to exit?:" );
+
+            try
+            {
+                String userExpression = inputHandler.readLine();
+                if ( userExpression == null || userExpression.toLowerCase( Locale.ENGLISH ).equals( "0" ) )
+                {
+                    break;
+                }
+
+                handleResponse( userExpression );
+            }
+            catch ( IOException e )
+            {
+                throw new MojoExecutionException( "Unable to read from standard input.", e );
+            }
+        }
+    }
+
+    // ----------------------------------------------------------------------
+    // Private methods
+    // ----------------------------------------------------------------------
+
+    /**
+     * Validate Mojo parameters.
+     */
+    private void validateParameters()
+    {
+        if ( artifact == null )
+        {
+            // using project if found or super-pom
+            getLog().info( "No artifact parameter specified, using '" + project.getId() + "' as project." );
+        }
+    }
+
+    /**
+     * @param artifactString should respect the format <code>groupId:artifactId[:version][:classifier]</code>
+     * @return the <code>Artifact</code> object for the <code>artifactString</code> parameter.
+     * @throws MojoExecutionException if the <code>artifactString</code> doesn't respect the format.
+     */
+    private Artifact getArtifact( String artifactString )
+        throws MojoExecutionException
+    {
+        if ( StringUtils.isEmpty( artifactString ) )
+        {
+            throw new IllegalArgumentException( "artifact parameter could not be empty" );
+        }
+
+        String groupId = null; // required
+        String artifactId = null; // required
+        String version = null; // optional
+        String classifier = null; // optional
+
+        String[] artifactParts = artifactString.split( ":" );
+
+        switch ( artifactParts.length )
+        {
+            case ( 2 ):
+                groupId = artifactParts[0];
+                artifactId = artifactParts[1];
+                version = Artifact.LATEST_VERSION;
+                break;
+            case ( 3 ):
+                groupId = artifactParts[0];
+                artifactId = artifactParts[1];
+                version = artifactParts[2];
+                break;
+            case ( 4 ):
+                groupId = artifactParts[0];
+                artifactId = artifactParts[1];
+                version = artifactParts[2];
+                classifier = artifactParts[3];
+                break;
+            default:
+                throw new MojoExecutionException( "The artifact parameter '" + artifactString
+                    + "' should be conform to: " + "'groupId:artifactId[:version][:classifier]'." );
+        }
+
+        if ( StringUtils.isNotEmpty( classifier ) )
+        {
+            return artifactFactory.createArtifactWithClassifier( groupId, artifactId, version, "jar", classifier );
+        }
+
+        return artifactFactory.createArtifact( groupId, artifactId, version, Artifact.SCOPE_COMPILE, "jar" );
+    }
+
+    /**
+     * @param artifactObj not null
+     * @return the POM for the given artifact.
+     * @throws MojoExecutionException if the artifact has a system scope.
+     * @throws ProjectBuildingException when building pom.
+     */
+    private MavenProject getMavenProject( Artifact artifactObj )
+        throws MojoExecutionException, ProjectBuildingException
+    {
+        if ( Artifact.SCOPE_SYSTEM.equals( artifactObj.getScope() ) )
+        {
+            throw new MojoExecutionException( "System artifact is not be handled." );
+        }
+
+        Artifact copyArtifact = ArtifactUtils.copyArtifact( artifactObj );
+        if ( !"pom".equals( copyArtifact.getType() ) )
+        {
+            copyArtifact =
+                artifactFactory.createProjectArtifact( copyArtifact.getGroupId(), copyArtifact.getArtifactId(),
+                                                       copyArtifact.getVersion(), copyArtifact.getScope() );
+        }
+
+        return mavenProjectBuilder.buildFromRepository( copyArtifact, remoteRepositories, localRepository );
+    }
+
+    /**
+     * @return a lazy loading evaluator object.
+     * @throws MojoExecutionException if any
+     * @throws MojoFailureException if any reflection exceptions occur or missing components.
+     * @see #getMojoDescriptor(String, MavenSession, MavenProject, String, boolean, boolean)
+     */
+    private PluginParameterExpressionEvaluator getEvaluator()
+        throws MojoExecutionException, MojoFailureException
+    {
+        if ( evaluator == null )
+        {
+            MojoDescriptor mojoDescriptor =
+                HelpUtil.getMojoDescriptor( "help:evaluate", session, project, "help:evaluate", true, false );
+            MojoExecution mojoExecution = new MojoExecution( mojoDescriptor );
+            evaluator =
+                new PluginParameterExpressionEvaluator( session, mojoExecution, pathTranslator,
+                                                        session.getContainer().getLogger(), project,
+                                                        session.getExecutionProperties() );
+        }
+
+        return evaluator;
+    }
+
+    /**
+     * @param expression the user expression asked.
+     * @throws MojoExecutionException if any
+     * @throws MojoFailureException if any reflection exceptions occur or missing components.
+     */
+    private void handleResponse( String expression )
+        throws MojoExecutionException, MojoFailureException
+    {
+        StringBuffer response = new StringBuffer();
+
+        Object obj;
+        try
+        {
+            obj = getEvaluator().evaluate( expression );
+        }
+        catch ( ExpressionEvaluationException e )
+        {
+            throw new MojoExecutionException( "Error when evaluating the Maven expression", e );
+        }
+
+        if ( obj != null && expression.equals( obj.toString() ) )
+        {
+            getLog().warn( "The Maven expression was invalid. Please use a valid expression." );
+            return;
+        }
+
+        // handle null
+        if ( obj == null )
+        {
+            response.append( "null object or invalid expression" );
+        }
+        // handle primitives objects
+        else if ( obj instanceof String )
+        {
+            response.append( obj.toString() );
+        }
+        else if ( obj instanceof Boolean )
+        {
+            response.append( obj.toString() );
+        }
+        else if ( obj instanceof Byte )
+        {
+            response.append( obj.toString() );
+        }
+        else if ( obj instanceof Character )
+        {
+            response.append( obj.toString() );
+        }
+        else if ( obj instanceof Double )
+        {
+            response.append( obj.toString() );
+        }
+        else if ( obj instanceof Float )
+        {
+            response.append( obj.toString() );
+        }
+        else if ( obj instanceof Integer )
+        {
+            response.append( obj.toString() );
+        }
+        else if ( obj instanceof Long )
+        {
+            response.append( obj.toString() );
+        }
+        else if ( obj instanceof Short )
+        {
+            response.append( obj.toString() );
+        }
+        // handle specific objects
+        else if ( obj instanceof File )
+        {
+            File f = (File) obj;
+            response.append( f.getAbsolutePath() );
+        }
+        // handle Maven pom object
+        else if ( obj instanceof MavenProject )
+        {
+            MavenProject projectAsked = (MavenProject) obj;
+            StringWriter sWriter = new StringWriter();
+            MavenXpp3Writer pomWriter = new MavenXpp3Writer();
+            try
+            {
+                pomWriter.write( sWriter, projectAsked.getModel() );
+            }
+            catch ( IOException e )
+            {
+                throw new MojoExecutionException( "Error when writing pom", e );
+            }
+
+            response.append( sWriter.toString() );
+        }
+        // handle Maven Settings object
+        else if ( obj instanceof Settings )
+        {
+            Settings settingsAsked = (Settings) obj;
+            StringWriter sWriter = new StringWriter();
+            SettingsXpp3Writer settingsWriter = new SettingsXpp3Writer();
+            try
+            {
+                settingsWriter.write( sWriter, settingsAsked );
+            }
+            catch ( IOException e )
+            {
+                throw new MojoExecutionException( "Error when writing settings", e );
+            }
+
+            response.append( sWriter.toString() );
+        }
+        else
+        {
+            // others Maven objects
+            response.append( toXML( expression, obj ) );
+        }
+
+        getLog().info( "\n" + response.toString() );
+    }
+
+    private String toXML( String question, Object obj )
+    {
+        XStream currentXStream = getXStream();
+
+        // beautify list
+        if ( obj instanceof List )
+        {
+            List list = (List) obj;
+            if ( list.size() > 0 )
+            {
+                Object elt = list.iterator().next();
+
+                String name = StringUtils.lowercaseFirstLetter( ClassUtils.getShortClassName( elt.getClass() ) );
+                currentXStream.alias( pluralize( name ), List.class );
+            }
+            else
+            {
+                // try to detect the alias from question
+                if ( question.indexOf( "." ) != -1 )
+                {
+                    String name = question.substring( question.indexOf( "." ) + 1, question.indexOf( "}" ) );
+                    currentXStream.alias( name, List.class );
+                }
+            }
+        }
+
+        return currentXStream.toXML( obj );
+    }
+
+    /**
+     * @return lazy loading xstream object.
+     */
+    private XStream getXStream()
+    {
+        if ( xstream == null )
+        {
+            xstream = new XStream();
+            addAlias( xstream );
+
+            // handle Properties a la Maven
+            xstream.registerConverter( new PropertiesConverter()
+            {
+                /** {@inheritDoc} */
+                public boolean canConvert( Class type )
+                {
+                    return Properties.class == type;
+                }
+
+                /** {@inheritDoc} */
+                public void marshal( Object source, HierarchicalStreamWriter writer, MarshallingContext context )
+                {
+                    Properties properties = (Properties) source;
+                    Map map = new TreeMap( properties ); // sort
+                    for ( Iterator iterator = map.entrySet().iterator(); iterator.hasNext(); )
+                    {
+                        Map.Entry entry = (Map.Entry) iterator.next();
+
+                        writer.startNode( entry.getKey().toString() );
+                        writer.setValue( entry.getValue().toString() );
+                        writer.endNode();
+                    }
+                }
+            } );
+        }
+
+        return xstream;
+    }
+
+    /**
+     * @param xstreamObject not null
+     */
+    private void addAlias( XStream xstreamObject )
+    {
+        try
+        {
+            addAlias( xstreamObject, getMavenModelJarFile(), "org.apache.maven.model" );
+            addAlias( xstreamObject, getMavenSettingsJarFile(), "org.apache.maven.settings" );
+        }
+        catch ( MojoExecutionException e )
+        {
+            if ( getLog().isDebugEnabled() )
+            {
+                getLog().debug( "MojoExecutionException: " + e.getMessage(), e );
+            }
+        }
+        catch ( ArtifactResolutionException e )
+        {
+            if ( getLog().isDebugEnabled() )
+            {
+                getLog().debug( "ArtifactResolutionException: " + e.getMessage(), e );
+            }
+        }
+        catch ( ArtifactNotFoundException e )
+        {
+            if ( getLog().isDebugEnabled() )
+            {
+                getLog().debug( "ArtifactNotFoundException: " + e.getMessage(), e );
+            }
+        }
+        catch ( ProjectBuildingException e )
+        {
+            if ( getLog().isDebugEnabled() )
+            {
+                getLog().debug( "ProjectBuildingException: " + e.getMessage(), e );
+            }
+        }
+
+        // TODO need to handle specific Maven objects like DefaultArtifact?
+    }
+
+    /**
+     * @param xstreamObject not null
+     * @param jarFile not null
+     * @param packageFilter a package name to filter.
+     */
+    private void addAlias( XStream xstreamObject, File jarFile, String packageFilter )
+    {
+        JarInputStream jarStream = null;
+        try
+        {
+            jarStream = new JarInputStream( new FileInputStream( jarFile ) );
+            JarEntry jarEntry = jarStream.getNextJarEntry();
+            while ( jarEntry != null )
+            {
+                if ( jarEntry == null )
+                {
+                    break;
+                }
+
+                if ( jarEntry.getName().toLowerCase( Locale.ENGLISH ).endsWith( ".class" ) )
+                {
+                    String name = jarEntry.getName().substring( 0, jarEntry.getName().indexOf( "." ) );
+                    name = name.replaceAll( "/", "\\." );
+
+                    if ( name.indexOf( packageFilter ) != -1 )
+                    {
+                        try
+                        {
+                            Class clazz = ClassUtils.getClass( name );
+                            xstreamObject.alias(
+                                                 StringUtils.lowercaseFirstLetter( ClassUtils.getShortClassName( clazz ) ),
+                                                 clazz );
+                            if ( !clazz.equals( Model.class ) )
+                            {
+                                xstreamObject.omitField( clazz, "modelEncoding" ); // unnecessary field
+                            }
+                        }
+                        catch ( ClassNotFoundException e )
+                        {
+                            e.printStackTrace();
+                        }
+                    }
+                }
+
+                jarStream.closeEntry();
+                jarEntry = jarStream.getNextJarEntry();
+            }
+        }
+        catch ( IOException e )
+        {
+            if ( getLog().isDebugEnabled() )
+            {
+                getLog().debug( "IOException: " + e.getMessage(), e );
+            }
+        }
+        finally
+        {
+            IOUtil.close( jarStream );
+        }
+    }
+
+    /**
+     * @return the <code>org.apache.maven:maven-model</code> artifact jar file in the local repository.
+     * @throws MojoExecutionException if any
+     * @throws ProjectBuildingException if any
+     * @throws ArtifactResolutionException if any
+     * @throws ArtifactNotFoundException if any
+     */
+    private File getMavenModelJarFile()
+        throws MojoExecutionException, ProjectBuildingException, ArtifactResolutionException,
+        ArtifactNotFoundException
+    {
+        return getArtifactFile( true );
+    }
+
+    /**
+     * @return the <code>org.apache.maven:maven-settings</code> artifact jar file in the local repository.
+     * @throws MojoExecutionException if any
+     * @throws ProjectBuildingException if any
+     * @throws ArtifactResolutionException if any
+     * @throws ArtifactNotFoundException if any
+     */
+    private File getMavenSettingsJarFile()
+        throws MojoExecutionException, ProjectBuildingException, ArtifactResolutionException,
+        ArtifactNotFoundException
+    {
+        return getArtifactFile( false );
+    }
+
+    /**
+     *
+     * @param isPom <code>true</code> to lookup the <code>maven-model</code> artifact jar, <code>false</code> to
+     * lookup the <code>maven-settings</code> artifact jar.
+     * @return the <code>org.apache.maven:maven-model|maven-settings</code> artifact jar file for this current
+     * HelpPlugin pom.
+     * @throws MojoExecutionException if any
+     * @throws ProjectBuildingException if any
+     * @throws ArtifactResolutionException if any
+     * @throws ArtifactNotFoundException if any
+     */
+    private File getArtifactFile( boolean isPom )
+        throws MojoExecutionException, ProjectBuildingException, ArtifactResolutionException,
+        ArtifactNotFoundException
+    {
+        for ( Iterator it = getHelpPluginPom().getDependencies().iterator(); it.hasNext(); )
+        {
+            Dependency depependency = (Dependency) it.next();
+
+            if ( !( depependency.getGroupId().equals( "org.apache.maven" ) ) )
+            {
+                continue;
+            }
+
+            if ( isPom )
+            {
+                if ( !( depependency.getArtifactId().equals( "maven-model" ) ) )
+                {
+                    continue;
+                }
+            }
+            else
+            {
+                if ( !( depependency.getArtifactId().equals( "maven-settings" ) ) )
+                {
+                    continue;
+                }
+            }
+
+            Artifact mavenArtifact =
+                getArtifact( depependency.getGroupId() + ":" + depependency.getArtifactId() + ":"
+                    + depependency.getVersion() );
+            resolver.resolveAlways( mavenArtifact, remoteRepositories, localRepository );
+
+            return mavenArtifact.getFile();
+        }
+
+        throw new MojoExecutionException( "Unable to find the 'org.apache.maven:"
+            + ( isPom ? "maven-model" : "maven-settings" ) + "' artifact" );
+    }
+
+    /**
+     * @return the Maven POM for the current help plugin
+     * @throws MojoExecutionException if any
+     * @throws ProjectBuildingException if any
+     */
+    private MavenProject getHelpPluginPom()
+        throws MojoExecutionException, ProjectBuildingException
+    {
+        String resource = "META-INF/maven/org.apache.maven.plugins/maven-help-plugin/pom.properties";
+
+        InputStream resourceAsStream = EvaluateMojo.class.getClassLoader().getResourceAsStream( resource );
+        Artifact helpPluginArtifact = null;
+        if ( resourceAsStream != null )
+        {
+            Properties properties = new Properties();
+            try
+            {
+                properties.load( resourceAsStream );
+            }
+            catch ( IOException e )
+            {
+                if ( getLog().isDebugEnabled() )
+                {
+                    getLog().debug( "IOException: " + e.getMessage(), e );
+                }
+            }
+
+            String artifactString =
+                properties.getProperty( "groupId", "unknown" ) + ":"
+                    + properties.getProperty( "artifactId", "unknown" ) + ":"
+                    + properties.getProperty( "version", "unknown" );
+
+            helpPluginArtifact = getArtifact( artifactString );
+        }
+
+        if ( helpPluginArtifact == null )
+        {
+            throw new MojoExecutionException( "The help plugin artifact was not found." );
+        }
+
+        return getMavenProject( helpPluginArtifact );
+    }
+
+    /**
+     * @param name not null
+     * @return the plural of the name
+     */
+    private static String pluralize( String name )
+    {
+        if ( StringUtils.isEmpty( name ) )
+        {
+            throw new IllegalArgumentException( "name is required" );
+        }
+
+        if ( name.endsWith( "y" ) )
+        {
+            return name.substring( 0, name.length() - 1 ) + "ies";
+        }
+        else if ( name.endsWith( "s" ) )
+        {
+            return name;
+        }
+        else
+        {
+            return name + "s";
+        }
+    }
+}

Propchange: maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/EvaluateMojo.java
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Propchange: maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/EvaluateMojo.java
------------------------------------------------------------------------------
    svn:keywords = Author Date Id Revision

Added: maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/HelpUtil.java
URL: http://svn.apache.org/viewvc/maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/HelpUtil.java?rev=689652&view=auto
==============================================================================
--- maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/HelpUtil.java (added)
+++ maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/HelpUtil.java Wed Aug 27 16:02:17 2008
@@ -0,0 +1,133 @@
+package org.apache.maven.plugins.help;
+
+/*
+ * 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.
+ */
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+
+import org.apache.maven.BuildFailureException;
+import org.apache.maven.execution.MavenSession;
+import org.apache.maven.lifecycle.DefaultLifecycleExecutor;
+import org.apache.maven.lifecycle.LifecycleExecutionException;
+import org.apache.maven.lifecycle.LifecycleExecutor;
+import org.apache.maven.plugin.MojoExecutionException;
+import org.apache.maven.plugin.MojoFailureException;
+import org.apache.maven.plugin.PluginNotFoundException;
+import org.apache.maven.plugin.descriptor.MojoDescriptor;
+import org.apache.maven.project.MavenProject;
+import org.codehaus.plexus.component.repository.exception.ComponentLookupException;
+
+/**
+ * Utility methods to play with Help Mojos.
+ *
+ * @author <a href="mailto:vincent.siveton@gmail.com">Vincent Siveton</a>
+ * @version $Id$
+ */
+public class HelpUtil
+{
+    /**
+     * Invoke the following private method
+     * <code>DefaultLifecycleExecutor#getMojoDescriptor(String, MavenSession, MavenProject, String, boolean, boolean)</code>
+     *
+     * @param task not null
+     * @param session not null
+     * @param project not null
+     * @param invokedVia not null
+     * @param canUsePrefix not null
+     * @param isOptionalMojo not null
+     * @return MojoDescriptor for the task
+     * @throws MojoFailureException if can not invoke the method.
+     * @throws MojoExecutionException if no descriptor was found for <code>task</code>.
+     * @see DefaultLifecycleExecutor#getMojoDescriptor(String, MavenSession, MavenProject, String, boolean, boolean)
+     */
+    protected static MojoDescriptor getMojoDescriptor( String task, MavenSession session, MavenProject project,
+                                              String invokedVia, boolean canUsePrefix, boolean isOptionalMojo )
+        throws MojoFailureException, MojoExecutionException
+    {
+        try
+        {
+            DefaultLifecycleExecutor lifecycleExecutor =
+                (DefaultLifecycleExecutor) session.lookup( LifecycleExecutor.ROLE );
+
+            Method m =
+                lifecycleExecutor.getClass().getDeclaredMethod(
+                                                                "getMojoDescriptor",
+                                                                new Class[] { String.class, MavenSession.class,
+                                                                    MavenProject.class, String.class,
+                                                                    Boolean.TYPE, Boolean.TYPE } );
+            m.setAccessible( true );
+            MojoDescriptor mojoDescriptor =
+                (MojoDescriptor) m.invoke( lifecycleExecutor, new Object[] { task, session, project, invokedVia,
+                    Boolean.valueOf( canUsePrefix ), Boolean.valueOf( isOptionalMojo ) } );
+
+            if ( mojoDescriptor == null )
+            {
+                throw new MojoExecutionException( "No MOJO exists for '" + task + "'." );
+            }
+
+            return mojoDescriptor;
+        }
+        catch ( SecurityException e )
+        {
+            throw new MojoFailureException( "SecurityException: " + e.getMessage() );
+        }
+        catch ( IllegalArgumentException e )
+        {
+            throw new MojoFailureException( "IllegalArgumentException: " + e.getMessage() );
+        }
+        catch ( ComponentLookupException e )
+        {
+            throw new MojoFailureException( "ComponentLookupException: " + e.getMessage() );
+        }
+        catch ( NoSuchMethodException e )
+        {
+            throw new MojoFailureException( "NoSuchMethodException: " + e.getMessage() );
+        }
+        catch ( IllegalAccessException e )
+        {
+            throw new MojoFailureException( "IllegalAccessException: " + e.getMessage() );
+        }
+        catch ( InvocationTargetException e )
+        {
+            Throwable cause = e.getCause();
+
+            if ( cause instanceof BuildFailureException )
+            {
+                throw new MojoFailureException( "BuildFailureException: " + cause.getMessage() );
+            }
+            else if ( cause instanceof LifecycleExecutionException )
+            {
+                throw new MojoFailureException( "LifecycleExecutionException: " + cause.getMessage() );
+            }
+            else if ( cause instanceof PluginNotFoundException )
+            {
+                throw new MojoFailureException( "PluginNotFoundException: " + cause.getMessage() );
+            }
+
+            StringWriter s = new StringWriter();
+            PrintWriter writer = new PrintWriter( s );
+            e.printStackTrace( writer );
+
+            throw new MojoFailureException( "InvocationTargetException: " + e.getMessage() + "\n" + s.toString() );
+        }
+    }
+}

Propchange: maven/plugins/trunk/maven-help-plugin/src/main/java/org/apache/maven/plugins/help/HelpUtil.java
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    svn:keywords = Author Date Id Revision

Modified: maven/plugins/trunk/maven-help-plugin/src/site/apt/usage.apt
URL: http://svn.apache.org/viewvc/maven/plugins/trunk/maven-help-plugin/src/site/apt/usage.apt?rev=689652&r1=689651&r2=689652&view=diff
==============================================================================
--- maven/plugins/trunk/maven-help-plugin/src/site/apt/usage.apt (original)
+++ maven/plugins/trunk/maven-help-plugin/src/site/apt/usage.apt Wed Aug 27 16:02:17 2008
@@ -4,7 +4,7 @@
  John Casey
  Maria Odea Ching
  ------
- 2008-08-04
+ 2008-08-27
  ------
 
  ~~ Licensed to the Apache Software Foundation (ASF) under one
@@ -213,3 +213,20 @@
 +-----+
 # mvn help:all-profiles
 +-----+
+
+* Evaluate some Maven expressions
+
++-----+
+# mvn help:evaluate -Dartifact=org.apache.maven.plugins:maven-help-plugin
+...
+[INFO] [help:evaluate]
+[INFO] Enter the Maven expression i.e. ${project.groupId} or 0 to exit?:
+${project.artifactId}
+[INFO]
+maven-help-plugin
+[INFO] Enter the Maven expression i.e. ${project.groupId} or 0 to exit?:
+${project.none}
+[INFO]
+null object or invalid expression
+...
++-----+