Add a try-catch taks to emulate javas try-catch constructs

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@271236 13f79535-47bb-0310-9956-ffa450edef68

proposal/myrmidon/src/java/org/apache/antlib/core/Resources.properties

@@ -25,4 +25,12 @@ enum.missing.getNames.error=Enum class "{0}" is missing a public static method n
 invalid.enum.error=Invalid value "{0}" for enum, expected one of {1}.
 
 if.ifelse-duplicate.error=Can only set one of if/else for If task type.
-if.no-condition.error=No condition was specified for If task.
+if.no-condition.error=No condition was specified for If task.
+
+trycatch.multiple-trys.error=Multiple <try/> elements can not be placed inside <try-catch/> task.
+trycatch.missing-try-before-catch.error=There needs to be a <try/> element before <catch/> element.
+trycatch.multiple-catches.error=Multiple <catch/> elements can not be placed inside <try-catch/> task.
+trycatch.missing-try-before-finally.error=There needs to be a <try/> element before <finally/> element.
+trycatch.multiple-finallys.error=Multiple <finally/> elements can not be placed inside <try-catch/> task.
+trycatch.no-try.error=Missing <try/> element from <try-catch/> task.
+trycatch.missing-second.error=Missing <catch/> or <finally/> elements from <try-catch/> task.

proposal/myrmidon/src/java/org/apache/antlib/core/TaskList.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) The Apache Software Foundation. All rights reserved.
+ *
+ * This software is published under the terms of the Apache Software License
+ * version 1.1, a copy of which has been included  with this distribution in
+ * the LICENSE.txt file.
+ */
+package org.apache.antlib.core;
+
+import java.util.ArrayList;
+import org.apache.avalon.framework.configuration.Configuration;
+
+/**
+ * This object contains an ordered list of tasks.
+ *
+ * @author <a href="mailto:peter@apache.org">Peter Donald</a>
+ * @version $Revision$ $Date$
+ */
+public class TaskList
+{
+    private ArrayList m_tasks = new ArrayList();
+
+    public void add( final Configuration task )
+    {
+        m_tasks.add( task );
+    }
+
+    public Configuration[] getTasks()
+    {
+        return (Configuration[])m_tasks.toArray( new Configuration[ m_tasks.size() ] );
+    }
+}

proposal/myrmidon/src/java/org/apache/antlib/core/TryCatchTask.java

@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) The Apache Software Foundation. All rights reserved.
+ *
+ * This software is published under the terms of the Apache Software License
+ * version 1.1, a copy of which has been included  with this distribution in
+ * the LICENSE.txt file.
+ */
+package org.apache.antlib.core;
+
+import org.apache.avalon.excalibur.i18n.ResourceManager;
+import org.apache.avalon.excalibur.i18n.Resources;
+import org.apache.avalon.framework.configuration.Configuration;
+import org.apache.myrmidon.api.TaskException;
+import org.apache.myrmidon.framework.AbstractContainerTask;
+import org.apache.myrmidon.interfaces.executor.ExecutionFrame;
+import org.apache.myrmidon.interfaces.executor.Executor;
+
+/**
+ * A task that emulates the try-catch-finally construct in a number
+ * of languages.
+ *
+ * @author <a href="mailto:peter@apache.org">Peter Donald</a>
+ * @version $Revision$ $Date$
+ * @ant:task name="try-catch"
+ */
+public final class TryCatchTask
+    extends AbstractContainerTask
+{
+    private final static Resources REZ =
+        ResourceManager.getPackageResources( TryCatchTask.class );
+
+    private TaskList m_try;
+    private TaskList m_catch;
+    private TaskList m_finally;
+
+    public void addTry( final TaskList taskList )
+        throws TaskException
+    {
+        if( null != m_try )
+        {
+            final String message = REZ.getString( "trycatch.multiple-trys.error" );
+            throw new TaskException( message );
+        }
+        m_try = taskList;
+    }
+
+    public void addCatch( final TaskList taskList )
+        throws TaskException
+    {
+        if( null == m_try )
+        {
+            final String message = REZ.getString( "trycatch.missing-try-before-catch.error" );
+            throw new TaskException( message );
+        }
+        else if( null != m_catch )
+        {
+            final String message = REZ.getString( "trycatch.multiple-catches.error" );
+            throw new TaskException( message );
+        }
+        m_catch = taskList;
+    }
+
+    public void addFinally( final TaskList taskList )
+        throws TaskException
+    {
+        if( null == m_try )
+        {
+            final String message = REZ.getString( "trycatch.missing-try-before-finally.error" );
+            throw new TaskException( message );
+        }
+        else if( null != m_finally )
+        {
+            final String message = REZ.getString( "trycatch.multiple-finallys.error" );
+            throw new TaskException( message );
+        }
+        m_finally = taskList;
+    }
+
+    public void execute()
+        throws TaskException
+    {
+        validate();
+
+        final ExecutionFrame frame = (ExecutionFrame)getService( ExecutionFrame.class );
+        final Executor executor = (Executor)getService( Executor.class );
+
+        try
+        {
+            final Configuration[] tasks = m_try.getTasks();
+            executeTasks( executor, frame, tasks );
+        }
+        catch( final TaskException te )
+        {
+            if( null != m_catch )
+            {
+                final Configuration[] tasks = m_catch.getTasks();
+                executeTasks( executor, frame, tasks );
+            }
+            else
+            {
+                throw te;
+            }
+        }
+        finally
+        {
+            if( null != m_finally )
+            {
+                final Configuration[] tasks = m_finally.getTasks();
+                executeTasks( executor, frame, tasks );
+            }
+        }
+    }
+
+    private void validate()
+        throws TaskException
+    {
+        if( null == m_try )
+        {
+            final String message = REZ.getString( "trycatch.no-try.error" );
+            throw new TaskException( message );
+        }
+        else if( null == m_catch && null == m_finally )
+        {
+            final String message = REZ.getString( "trycatch.missing-second.error" );
+            throw new TaskException( message );
+        }
+    }
+
+    /**
+     * Utility method to execute the tasks in an appropriate environment.
+     */
+    private void executeTasks( final Executor executor,
+                               final ExecutionFrame frame,
+                               final Configuration[] tasks )
+        throws TaskException
+    {
+        for( int i = 0; i < tasks.length; i++ )
+        {
+            final Configuration task = tasks[ i ];
+            executor.execute( task, frame );
+        }
+    }
+
+    public String toString()
+    {
+        return "Try-Catch-Finally";
+    }
+}