UnsetProperty.java

package org.ant4eclipse.ant.platform;

import java.lang.reflect.Field;
import java.util.Hashtable;

import org.ant4eclipse.ant.core.ThreadDispatchingPropertyHelper;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Task;

public class UnsetProperty extends Task {

  private String name = null;

  /**
   * Set the name of the property. Required unless 'file' is used.
   * 
   * @param name
   *          the name of the property.
   */
  public void setName(String name) {
    this.name = name;
  }

  /**
   * Execute this task.
   * 
   * @exception BuildException
   *              Description of the Exception
   */
  @Override
  public void execute() throws BuildException {

    // assert
    if (this.name == null || this.name.equals("")) {
      throw new BuildException("The 'name' attribute is required with 'unset'.");
    }

    // the done variable
    boolean done = false;

    //
    if (ThreadDispatchingPropertyHelper.hasInstance(getProject())) {
      done = ThreadDispatchingPropertyHelper.getInstance(getProject()).removeProperty(this.name);
    }

    //
    if (!done) {

      // remove property
      removeProperty(this.name);
    }
    //
    return;
  }

  /**
   * Remove a property from the project's property table and the userProperty table. Note that Ant 1.6 uses a helper for
   * this.
   */
  private void removeProperty(String name) {

    Hashtable properties = null;

    // Ant 1.5 stores properties in Project
    try {
      properties = (Hashtable) getValue(getProject(), "properties");
      if (properties != null) {
        properties.remove(name);
      }
    } catch (Exception e) {
      // ignore, could be Ant 1.6
    }
    try {
      properties = (Hashtable) getValue(getProject(), "userProperties");
      if (properties != null) {
        properties.remove(name);
      }
    } catch (Exception e) {
      // ignore, could be Ant 1.6
    }

    // Ant 1.6 uses a PropertyHelper, can check for it by checking for a
    // reference to "ant.PropertyHelper"
    try {
      Object property_helper = getProject().getReference("ant.PropertyHelper");
      if (property_helper != null) {
        try {
          properties = (Hashtable) getValue(property_helper, "properties");
          if (properties != null) {
            properties.remove(name);
          }
        } catch (Exception e) {
          // ignore
        }
        try {
          properties = (Hashtable) getValue(property_helper, "userProperties");
          if (properties != null) {
            properties.remove(name);
          }
        } catch (Exception e) {
          // ignore
        }
      }
    } catch (Exception e) {
      // ignore, could be Ant 1.5
    }
  }

  /**
   * Object rape: fondle the private parts of an object without it's permission.
   * 
   * @param thisClass
   *          The class to rape.
   * @param fieldName
   *          The field to fondle
   * @return The field value
   * @exception NoSuchFieldException
   *              Darn, nothing to fondle.
   */
  private Field getField(Class thisClass, String fieldName) throws NoSuchFieldException {
    if (thisClass == null) {
      throw new NoSuchFieldException("Invalid field : " + fieldName);
    }
    try {
      return thisClass.getDeclaredField(fieldName);
    } catch (NoSuchFieldException e) {
      return getField(thisClass.getSuperclass(), fieldName);
    }
  }

  /**
   * Object rape: fondle the private parts of an object without it's permission.
   * 
   * @param instance
   *          the object instance
   * @param fieldName
   *          the name of the field
   * @return an object representing the value of the field
   * @exception IllegalAccessException
   *              foiled by the security manager
   * @exception NoSuchFieldException
   *              Darn, nothing to fondle
   */
  private Object getValue(Object instance, String fieldName) throws IllegalAccessException, NoSuchFieldException {
    Field field = getField(instance.getClass(), fieldName);
    field.setAccessible(true);
    return field.get(instance);
  }
}