1 files changed, 138 insertions, 0 deletions
diff --git a/sandbox/ant/sca/trunk/modules/workspace/src/main/java/org/apache/tuscany/sca/workspace/builder/DefaultContributionBuilderExtensionPoint.java b/sandbox/ant/sca/trunk/modules/workspace/src/main/java/org/apache/tuscany/sca/workspace/builder/DefaultContributionBuilderExtensionPoint.java
new file mode 100644
index 0000000000..8ce6f53f20
--- /dev/null
+++ b/sandbox/ant/sca/trunk/modules/workspace/src/main/java/org/apache/tuscany/sca/workspace/builder/DefaultContributionBuilderExtensionPoint.java
@@ -0,0 +1,138 @@
+/*
+ * 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.tuscany.sca.workspace.builder;
+
+import java.lang.reflect.Constructor;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+
+import org.apache.tuscany.sca.contribution.Contribution;
+import org.apache.tuscany.sca.core.ExtensionPointRegistry;
+import org.apache.tuscany.sca.core.FactoryExtensionPoint;
+import org.apache.tuscany.sca.extensibility.ServiceDeclaration;
+import org.apache.tuscany.sca.extensibility.ServiceDiscovery;
+import org.apache.tuscany.sca.monitor.Monitor;
+import org.apache.tuscany.sca.workspace.Workspace;
+
+/**
+ * Default implementation of a provider factory extension point.
+ *
+ * @version $Rev$ $Date$
+ */
+public class DefaultContributionBuilderExtensionPoint implements ContributionBuilderExtensionPoint {
+
+    private ExtensionPointRegistry registry;
+    private final Map<String, ContributionBuilder> builders = new HashMap<String, ContributionBuilder>();
+    private boolean loaded;
+
+    public DefaultContributionBuilderExtensionPoint(ExtensionPointRegistry registry) {
+        this.registry = registry;
+    }
+
+    public void addContributionBuilder(ContributionBuilder builder) {
+        builders.put(builder.getID(), builder);
+    }
+
+    public void removeContributionBuilder(ContributionBuilder builder) {
+        builders.remove(builder.getID());
+    }
+
+    public ContributionBuilder getContributionBuilder(String id) {
+        loadBuilders();
+        return builders.get(id);
+    }
+
+    /**
+     * Load builders declared under META-INF/services.
+     */
+    private synchronized void loadBuilders() {
+        if (loaded)
+            return;
+        
+        FactoryExtensionPoint factories = registry.getExtensionPoint(FactoryExtensionPoint.class);
+        
+        // Get the provider factory service declarations
+        Set<ServiceDeclaration> builderDeclarations;
+        ServiceDiscovery serviceDiscovery = ServiceDiscovery.getInstance();
+        try {
+            builderDeclarations = serviceDiscovery.getServiceDeclarations(ContributionBuilder.class.getName());
+        } catch (Exception e) {
+            throw new IllegalStateException(e);
+        }
+
+        for (ServiceDeclaration builderDeclaration : builderDeclarations) {
+        Map<String, String> attributes = builderDeclaration.getAttributes();
+            String id = attributes.get("id");
+
+            ContributionBuilder builder = new LazyContributionBuilder(id, builderDeclaration, this, factories);
+            builders.put(id, builder);
+        }
+    }
+
+    /**
+     * A wrapper around a contribution builder allowing lazy
+     * loading and initialization of implementation providers.
+     */
+    private static class LazyContributionBuilder implements ContributionBuilder {
+
+        private FactoryExtensionPoint factories;
+        private String id;
+        private ServiceDeclaration builderDeclaration;
+        private ContributionBuilder builder;
+        private ContributionBuilderExtensionPoint builders;
+
+        private LazyContributionBuilder(String id, ServiceDeclaration factoryDeclaration,
+                                     ContributionBuilderExtensionPoint builders, FactoryExtensionPoint factories) {
+            this.id = id;
+            this.builderDeclaration = factoryDeclaration;
+            this.builders = builders;
+            this.factories = factories;
+        }
+        
+        public String getID() {
+            return id;
+        }
+        
+        public void build(Contribution contribution, Workspace workspace, Monitor monitor) throws ContributionBuilderException {
+            getBuilder().build(contribution, workspace, monitor);
+        }
+
+        private ContributionBuilder getBuilder() {
+            if (builder == null) {
+                try {
+                    Class<ContributionBuilder> builderClass = (Class<ContributionBuilder>)builderDeclaration.loadClass();
+                    try {
+                        Constructor<ContributionBuilder> constructor = builderClass.getConstructor(FactoryExtensionPoint.class);
+                        builder = constructor.newInstance(factories);
+                    } catch (NoSuchMethodException e) {
+                        Constructor<ContributionBuilder> constructor = builderClass.getConstructor(ContributionBuilderExtensionPoint.class, FactoryExtensionPoint.class);
+                        builder = constructor.newInstance(builders, factories);
+                    }
+                } catch (Exception e) {
+                    throw new IllegalStateException(e);
+                }
+            }
+            return builder;
+        }
+
+    }
+
+}