Add m2e support

pom.xml

@@ -134,6 +134,13 @@
       <artifactId>plexus-utils</artifactId>
       <version>3.3.0</version>
     </dependency>
+    <!-- incremental build support (http://www.eclipse.org/m2e/documentation/m2e-making-maven-plugins-compat.html) -->
+    <dependency>
+      <groupId>org.sonatype.plexus</groupId>
+      <artifactId>plexus-build-api</artifactId>
+      <version>0.0.7</version>
+      <scope>compile</scope>
+    </dependency>
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>

src/main/java/org/eclipse/sisu/mojos/IndexMojo.java

@@ -24,6 +24,7 @@
 
 import org.apache.maven.artifact.Artifact;
 import org.apache.maven.plugin.AbstractMojo;
+import org.apache.maven.plugins.annotations.Component;
 import org.apache.maven.plugins.annotations.Mojo;
 import org.apache.maven.plugins.annotations.Parameter;
 import org.apache.maven.plugins.annotations.ResolutionScope;
@@ -36,9 +37,11 @@
 import org.apache.maven.shared.artifact.filter.collection.ProjectTransitivityFilter;
 import org.apache.maven.shared.artifact.filter.collection.ScopeFilter;
 import org.apache.maven.shared.artifact.filter.collection.TypeFilter;
+import org.codehaus.plexus.util.Scanner;
 import org.codehaus.plexus.util.StringUtils;
 import org.eclipse.sisu.space.SisuIndex;
 import org.eclipse.sisu.space.URLClassSpace;
+import org.sonatype.plexus.build.incremental.BuildContext;
 
 /**
  * Generates a qualified class index for the current project and its dependencies.
@@ -47,6 +50,8 @@
 public class IndexMojo
     extends AbstractMojo
 {
+    static final String INDEX_FOLDER = "META-INF/sisu/"; // copied from AbstractSisuIndex as not public
+
     // ----------------------------------------------------------------------
     // Configurable parameters
     // ----------------------------------------------------------------------
@@ -139,6 +144,23 @@ public class IndexMojo
     @Parameter( property = "project", required = true, readonly = true )
     private MavenProject project;
 
+    /**
+     * For m2e incremental build support
+     */
+    @Component
+    protected BuildContext buildContext;
+
+    public IndexMojo()
+    {
+        super();
+    }
+
+    public IndexMojo( final BuildContext buildContext )
+    {
+        super();
+        this.buildContext = buildContext;
+    }
+
     // ----------------------------------------------------------------------
     // Public methods
     // ----------------------------------------------------------------------
@@ -183,6 +205,7 @@ protected void warn( final String message )
                     getLog().warn( message );
                 }
             }.index( new URLClassSpace( getProjectClassLoader(), getIndexPath() ) );
+            buildContext.refresh( new File( outputDirectory, INDEX_FOLDER ) );
         }
     }
 
@@ -193,11 +216,10 @@ protected void warn( final String message )
     private ClassLoader getProjectClassLoader()
     {
         final List<URL> classPath = new ArrayList<URL>();
-        appendToClassPath( classPath, outputDirectory );
-        appendToClassPath( classPath, new File( project.getBuild().getOutputDirectory() ) );
+        appendDirectoryToClassPath( classPath, outputDirectory );
         for ( final Object artifact : project.getArtifacts() )
         {
-            appendToClassPath( classPath, ( (Artifact) artifact ).getFile() );
+            appendFileToClassPath( classPath, ( (Artifact) artifact ).getFile() );
         }
         if ( getLog().isDebugEnabled() )
         {
@@ -209,8 +231,8 @@ private ClassLoader getProjectClassLoader()
     private URL[] getIndexPath()
     {
         final List<URL> indexPath = new ArrayList<URL>();
-        appendToClassPath( indexPath, outputDirectory );
-        if ( includeDependencies )
+        appendDirectoryToClassPath( indexPath, outputDirectory );
+        if ( includeDependencies && !buildContext.isIncremental() )
         {
             final FilterArtifacts filter = new FilterArtifacts();
 
@@ -227,7 +249,7 @@ private URL[] getIndexPath()
             {
                 for ( final Object artifact : filter.filter( project.getArtifacts() ) )
                 {
-                    appendToClassPath( indexPath, ( (Artifact) artifact ).getFile() );
+                    appendFileToClassPath( indexPath, ( (Artifact) artifact ).getFile() );
                 }
             }
             catch ( final ArtifactFilterException e )
@@ -251,7 +273,36 @@ private void dumpEntries( final String name, final List<URL> urls )
         }
     }
 
-    private void appendToClassPath( final List<URL> urls, final File file )
+    private void appendDirectoryToClassPath( final List<URL> urls, File directory )
+    {
+        if ( directory.isDirectory() )
+        {
+            Scanner scanner = buildContext.newScanner( directory );
+            scanner.setIncludes( new String[] {"**/*.class"} );
+            scanner.scan();
+            String[] includedFiles = scanner.getIncludedFiles();
+            if ( includedFiles != null && includedFiles.length > 0 )
+            {
+                getLog().debug("Found at least one class file in " + directory );
+                appendFileToClassPath( urls, directory );
+            }
+            else
+            {
+                getLog().debug("No class files found in " + directory );
+            }
+        }
+        else
+        {
+            getLog().debug("Path " + directory + " does not exist or is no directory" );
+        }
+    }
+
+    /**
+     * 
+     * @param urls the list to which to append the URL
+     * @param file must either be a directory or a JAR file
+     */
+    private void appendFileToClassPath( final List<URL> urls, final File file )
     {
         if ( null != file )
         {

src/main/java/org/eclipse/sisu/mojos/MainIndexMojo.java

@@ -13,11 +13,13 @@
 import java.io.File;
 
 import org.apache.maven.plugin.AbstractMojo;
+import org.apache.maven.plugins.annotations.Component;
 import org.apache.maven.plugins.annotations.LifecyclePhase;
 import org.apache.maven.plugins.annotations.Mojo;
 import org.apache.maven.plugins.annotations.Parameter;
 import org.apache.maven.plugins.annotations.ResolutionScope;
 import org.apache.maven.project.MavenProject;
+import org.sonatype.plexus.build.incremental.BuildContext;
 
 /**
  * Generates a qualified class index for classes compiled by the current project.
@@ -36,13 +38,19 @@ public class MainIndexMojo
     @Parameter( property = "project", required = true, readonly = true )
     private MavenProject project;
 
+    /**
+     * For m2e incremental build support
+     */
+    @Component
+    protected BuildContext buildContext;
+
     // ----------------------------------------------------------------------
     // Public methods
     // ----------------------------------------------------------------------
 
     public void execute()
     {
-        final IndexMojo mojo = new IndexMojo();
+        final IndexMojo mojo = new IndexMojo( buildContext );
         mojo.setLog( getLog() );
         mojo.setProject( project );
         mojo.setOutputDirectory( new File( project.getBuild().getOutputDirectory() ) );

src/main/java/org/eclipse/sisu/mojos/TestIndexMojo.java

@@ -13,11 +13,13 @@
 import java.io.File;
 
 import org.apache.maven.plugin.AbstractMojo;
+import org.apache.maven.plugins.annotations.Component;
 import org.apache.maven.plugins.annotations.LifecyclePhase;
 import org.apache.maven.plugins.annotations.Mojo;
 import org.apache.maven.plugins.annotations.Parameter;
 import org.apache.maven.plugins.annotations.ResolutionScope;
 import org.apache.maven.project.MavenProject;
+import org.sonatype.plexus.build.incremental.BuildContext;
 
 /**
  * Generates a qualified class index for test classes compiled by the current project.
@@ -36,13 +38,19 @@ public class TestIndexMojo
     @Parameter( property = "project", required = true, readonly = true )
     private MavenProject project;
 
+    /**
+     * For m2e incremental build support
+     */
+    @Component
+    protected BuildContext buildContext;
+
     // ----------------------------------------------------------------------
     // Public methods
     // ----------------------------------------------------------------------
 
     public void execute()
     {
-        final IndexMojo mojo = new IndexMojo();
+        final IndexMojo mojo = new IndexMojo( buildContext );
         mojo.setLog( getLog() );
         mojo.setProject( project );
         mojo.setOutputDirectory( new File( project.getBuild().getTestOutputDirectory() ) );

src/main/resources/META-INF/m2e/lifecycle-mapping-metadata.xml

@@ -0,0 +1,25 @@
+<!--
+ All rights reserved. This program and the accompanying materials
+ are made available under the terms of the Eclipse Public License v1.0
+ which accompanies this distribution, and is available at
+ http://www.eclipse.org/legal/epl-v10.html
+  -->
+<lifecycleMappingMetadata>
+    <pluginExecutions>
+        <pluginExecution>
+            <pluginExecutionFilter>
+                <goals>
+                    <goal>index</goal>
+                    <goal>main-index</goal>
+                    <goal>test-index</goal>
+                </goals>
+            </pluginExecutionFilter>
+            <action>
+                <execute>
+                    <runOnIncremental>true</runOnIncremental>
+                    <runOnConfiguration>false</runOnConfiguration>
+                </execute>
+            </action>
+        </pluginExecution>
+    </pluginExecutions>
+</lifecycleMappingMetadata>