Copyright (c) 2000, 2012 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2012 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.core.expressions;

import org.osgi.framework.Bundle;

import org.eclipse.core.internal.expressions.PropertyTesterDescriptor;

import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.Platform;

Abstract superclass of all property testers. Implementation classes of
the extension point org.eclipse.core.expresssions.propertyTesters
 must extend PropertyTester.

A property tester implements the property tests enumerated in the property
tester extension point. For the following property test extension

  <propertyTester
    	 namespace="org.eclipse.jdt.core"
      id="org.eclipse.jdt.core.IPackageFragmentTester"
      properties="isDefaultPackage"
      type="org.eclipse.jdt.core.IPackageFragment"
      class="org.eclipse.demo.MyPackageFragmentTester">
    </propertyTester>

the corresponding implementation class looks like:
  public class MyPackageFragmentTester extends PropertyTester {
      public boolean test(Object receiver, String property, Object[] args, Object expectedValue) {
          IPackageFragment fragment= (IPackageFragment)receiver;
         if ("isDefaultPackage".equals(property)) {
              return expectedValue == null
              	? fragment.isDefaultPackage()
              	: fragment.isDefaultPackage() == ((Boolean)expectedValue).booleanValue();
          }
          Assert.isTrue(false);
          return false;
      }
  }

The property can then be used in a test expression as follows:
  <instanceof value="org.eclipse.core.IPackageFragment"/>
  <test property="org.eclipse.jdt.core.isDefaultPackage"/>


There is no guarantee that the same instance of a property tester is used
to handle <test property="..."/> requests. So property testers
should always be implemented in a stateless fashion.

Since:
3.0/**
 * Abstract superclass of all property testers. Implementation classes of
 * the extension point <code>org.eclipse.core.expresssions.propertyTesters
 * </code> must extend <code>PropertyTester</code>.
 * <p>
 * A property tester implements the property tests enumerated in the property
 * tester extension point. For the following property test extension
 * </p>
 * <pre>
 *   &lt;propertyTester
 *     	 namespace="org.eclipse.jdt.core"
 *       id="org.eclipse.jdt.core.IPackageFragmentTester"
 *       properties="isDefaultPackage"
 *       type="org.eclipse.jdt.core.IPackageFragment"
 *       class="org.eclipse.demo.MyPackageFragmentTester"&gt;
 *     &lt;/propertyTester&gt;
 * </pre>
 * the corresponding implementation class looks like:
 * <pre>
 *   public class MyPackageFragmentTester extends PropertyTester {
 *       public boolean test(Object receiver, String property, Object[] args, Object expectedValue) {
 *           IPackageFragment fragment= (IPackageFragment)receiver;
 *	         if ("isDefaultPackage".equals(property)) {
 *               return expectedValue == null
 *               	? fragment.isDefaultPackage()
 *               	: fragment.isDefaultPackage() == ((Boolean)expectedValue).booleanValue();
 *           }
 *           Assert.isTrue(false);
 *           return false;
 *       }
 *   }
 * </pre>
 * The property can then be used in a test expression as follows:
 * <pre>
 *   &lt;instanceof value="org.eclipse.core.IPackageFragment"/&gt;
 *   &lt;test property="org.eclipse.jdt.core.isDefaultPackage"/&gt;
 * </pre>
 * <p>
 * There is no guarantee that the same instance of a property tester is used
 * to handle &lt;test property="..."/&gt; requests. So property testers
 * should always be implemented in a stateless fashion.
 * </p>
 * @since 3.0
 */
public abstract class PropertyTester implements IPropertyTester {

	private IConfigurationElement fConfigElement;
	private String fNamespace;
	private String fProperties;

	
Initialize the property tester with the given name space and property.

Note: this method is for internal use only. Clients must not call
this method.

Params:
descriptor – the descriptor object for this tester
@noreference
This method is not intended to be referenced by clients./**
	 * Initialize the property tester with the given name space and property.
	 * <p>
	 * Note: this method is for internal use only. Clients must not call
	 * this method.
	 * </p>
	 * @param descriptor the descriptor object for this tester
	 *
	 * @noreference This method is not intended to be referenced by clients.
	 */
	public final void internalInitialize(PropertyTesterDescriptor descriptor) {
		fProperties= descriptor.getProperties();
		fNamespace= descriptor.getNamespace();
		fConfigElement= descriptor.getConfigurationElement();
	}

	
Note: this method is for internal use only. Clients must not call
this method.
Returns:
the property tester descriptor
@noreference
This method is not intended to be referenced by clients./**
	 * Note: this method is for internal use only. Clients must not call
	 * this method.
	 *
	 * @return the property tester descriptor
	 *
	 * @noreference This method is not intended to be referenced by clients.
	 */
	public final PropertyTesterDescriptor internalCreateDescriptor() {
		return new PropertyTesterDescriptor(fConfigElement, fNamespace, fProperties);
	}

	@Override
	public final boolean handles(String namespace, String property) {
		return fNamespace.equals(namespace) && fProperties.contains("," + property + ",");  //$NON-NLS-1$//$NON-NLS-2$
	}

	@Override
	public final boolean isInstantiated() {
		return true;
	}

	@Override
	public boolean isDeclaringPluginActive() {
		Bundle bundle= Platform.getBundle(fConfigElement.getContributor().getName());
		return bundle.getState() == Bundle.ACTIVE;
	}

	@Override
	public final IPropertyTester instantiate() {
		return this;
	}
}