JETEmitterTask.java

/**
 * Copyright (c) 2004-2007 IBM Corporation and others.
 * 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
 * 
 * Contributors: 
 *   IBM - Initial API and implementation
 */
package org.eclipse.emf.ant.taskdefs.codegen;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.tools.ant.BuildException;

import org.eclipse.emf.ant.util.Util;
import org.eclipse.emf.codegen.jet.JETEmitter;
import org.eclipse.emf.codegen.jet.JETException;


/**
 * <p>
 * Exposes some functionalities available on the 
 * {@link org.eclipse.emf.codegen.jet.JETEmitter JETEmitter} class. 
 * </p>
 * <p>
 * This task is supposed to be executed by a Eclipse driver with the 
 * <b>org.eclipse.emf.ant</b> plugin.  It is neither necessary to use Ant's task
 * <tt>TaskDef</tt> to declare this task in a script nor to change the Ant's runtime 
 * classpath.
 * </p>
 * <p>
 * The following command line will start a headless Eclipse instance and run the specified Ant script.
 * </p>
 * <p>
 * <i>eclipseDir</i>/eclipse
 *      -noSplash
 *      -data <i>worspaceDir</i>
 *      -application org.eclipse.ant.core.antRunner
 *      -buildfile <i>antScript</i>
 * </p>
 * <p>In Windows you should execute <i>eclipsec</i> instead of <i>eclipse</i> in order to have
 * access to the Ant build script console output.</p>
 * <p>You can also use the Eclipse UI to execute an Ant script containing this task by right-clicking the script and selecting 
 * <i>Run As > Ant Build... > JRE > "Run in the same JRE as the workspace"</i>.</p>
 * 
 * <p>
 
 * <p>
 * Usage examples:
 * </p>
 * <pre>
 * <emf.JETEmitter templateURI="http://www.example.com/jetTemplate.txtjet"
 *                 newFile="c:\output.txt"/>
 * </pre>
 * <pre>
 * <emf.JETEmitter templateFile="jetTemplate.txtjet"
 *                 newFile="c:\output.txt"/>
 * </pre>
 * <pre>
 * <emf.JETEmitter templateURI="d:\templates\jetTemplate.txtjet"
 *                 newFile="c:\output.txt">
 *     <variable name="MY_VAR" pluginID="com.myplugin;/>
 *     <variable name="JUNIT_HOME" pluginID="org.eclipse.jdt.junit;/>
 * </emf.JETEmitter>
 * </pre>
 * 
 * @since 2.1.0
 */
public class JETEmitterTask extends JETTask
{
  public static class Variable
  {
    private String name;
    private String pluginID;

    public String getName()
    {
      return name;
    }

    public void setName(String name)
    {
      this.name = name;
    }

    public String getPluginID()
    {
      return pluginID;
    }

    public void setPluginID(String pluginID)
    {
      this.pluginID = pluginID;
    }
  }

  private String project;
  private List<Variable> variables;
  private Object argument;
  private Class<?> argumentClass;

  public void setProject(String project)
  {
    this.project = project;
  }

  public Variable createVariable()
  {
    Variable variable = new Variable();
    if (variables == null)
    {
      variables = new ArrayList<Variable>();
    }
    variables.add(variable);
    return variable;
  }

  public void setArgument(Object argument)
  {
    this.argument = argument;
  }

  public void setArgumentClass(Class<?> argumentClass)
  {
    this.argumentClass = argumentClass;
  }
  
  @Override
  protected void checkAttributes() throws BuildException
  {
    assertTrue("The 'newFile' attribute must be specified.", newFile != null);
  }  

  @Override
  protected void doExecute() throws Exception
  {
    invokeEmitter(createJETEmitter());
  }

  protected JETEmitter createJETEmitter() throws JETException
  {
    JETEmitter emitter = new JETEmitter(getTemplateURIAsString());
    
    if (project != null)
    {
      emitter.setProjectName(project);
    }

    if (variables != null)
    {
      for (Variable variable : variables)
      {
        emitter.addVariable(variable.getName(), variable.getPluginID());
      }
    }

    return emitter;
  }

  protected void invokeEmitter(JETEmitter emitter) throws JETException, IOException, InstantiationException, IllegalAccessException
  {
    Object[] arguments = null;
    if (argument != null)
    {
      arguments = argument instanceof Object[] ? (Object[])argument : new Object []{ argument };
    }
    else if (argumentClass != null)
    {
      arguments = new Object []{ argumentClass.newInstance() };
    }
    else
    {
      arguments = new Object [1];
    }

    String result = emitter.generate(getProgressMonitor(), arguments);
    Util.writeFile(newFile, result);
  }
}