Package org.eclipse.core.expressions

Class PropertyTester

java.lang.Object
org.eclipse.core.expressions.PropertyTester
All Implemented Interfaces:
IPropertyTester
Direct Known Subclasses:
OpenPerspectivePropertyTester
public abstract class PropertyTester extends Object implements IPropertyTester
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

  • Constructor Summary

    Constructors
    Constructor
    Description
    PropertyTester()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    final boolean
    handles(String namespace, String property)
    Returns whether the property tester can handle the given property or not.
    final IPropertyTester
    instantiate()
    Loads the implementation class for this property tester and returns an instance of this class.
    final org.eclipse.core.internal.expressions.PropertyTesterDescriptor
    internalCreateDescriptor()
    Note: this method is for internal use only.
    final void
    internalInitialize(org.eclipse.core.internal.expressions.PropertyTesterDescriptor descriptor)
    Initialize the property tester with the given name space and property.
    boolean
    isDeclaringPluginActive()
    Returns true if the implementation class of this property tester can be loaded.
    final boolean
    isInstantiated()
    Returns whether the implementation class for this property tester is loaded or not.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    Methods inherited from interface org.eclipse.core.expressions.IPropertyTester

    test

  • Constructor Details

    • PropertyTester

      public PropertyTester()

  • Method Details

    • internalInitialize

      public final void internalInitialize(org.eclipse.core.internal.expressions.PropertyTesterDescriptor descriptor)
      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.

      Parameters:
      descriptor - the descriptor object for this tester
      Restriction:
      This method is not intended to be referenced by clients.

    • internalCreateDescriptor

      public final org.eclipse.core.internal.expressions.PropertyTesterDescriptor internalCreateDescriptor()
      Note: this method is for internal use only. Clients must not call this method.
      Returns:
      the property tester descriptor
      Restriction:
      This method is not intended to be referenced by clients.

    • handles

      public final boolean handles(String namespace, String property)
      Description copied from interface: IPropertyTester
      Returns whether the property tester can handle the given property or not.
      Specified by:
      handles in interface IPropertyTester
      Parameters:
      namespace - the name space to be considered
      property - the property to test
      Returns:
      true if the tester provides an implementation for the given property; otherwise false is returned

    • isInstantiated

      public final boolean isInstantiated()
      Description copied from interface: IPropertyTester
      Returns whether the implementation class for this property tester is loaded or not.
      Specified by:
      isInstantiated in interface IPropertyTester
      Returns:
      trueif the implementation class is loaded; false otherwise

    • isDeclaringPluginActive

      public boolean isDeclaringPluginActive()
      Description copied from interface: IPropertyTester
      Returns true if the implementation class of this property tester can be loaded. This is the case if the plug-in providing the implementation class is active. Returns false otherwise.
      Specified by:
      isDeclaringPluginActive in interface IPropertyTester
      Returns:
      whether the implementation class can be loaded or not

    • instantiate

      public final IPropertyTester instantiate()
      Description copied from interface: IPropertyTester
      Loads the implementation class for this property tester and returns an instance of this class.
      Specified by:
      instantiate in interface IPropertyTester
      Returns:
      an instance of the implementation class for this property tester