How to check if project contains specific file for launch shortcuts

问题

Basically, I want to enable my LaunchShortcuts only when project has specific nature and contains specific file. Project's nature is not a problem. However, I can't find out how to check if project contains specific file. By far I have the following code in the plugin.xml:

<contextualLaunch>
    <enablement>
        <with variable="selection">
            <count value="1"/>
            <iterate>
                <adapt type="org.eclipse.core.resources.IResource">
                    <test property="org.eclipse.core.resources.projectNature" 
                        value="my.project.nature" />
                </adapt> 
            </iterate>
        </with>
    </enablement>
</contextualLaunch> 

Is it possible to check if a project contains a specific file ?

UPDATED:

@greg-449 gave me a great hint in the 1 comment below about using custom org.eclipse.core.expressions.propertyTesters. So, now my code looks like this:

.
. 
.
<extension point="org.eclipse.core.expressions.propertyTesters">
  <propertyTester
       id="my.tester"
       type="org.eclipse.core.resources.IResource"
       namespace="my.namespace"
       properties="myProperty"
       class="my.MyTester">
   </propertyTester>
</extension>
.
.
.
<contextualLaunch>
    <enablement>
        <with variable="selection">
            <count value="1"/>
            <iterate>
                <adapt type="org.eclipse.core.resources.IResource">
                     <and>
                        <test property="org.eclipse.core.resources.projectNature" 
                                value="my.project.nature" />
                        <test property="my.namespace.myProperty"  
                                value="true"/>
                     </and> 
                </adapt> 
            </iterate>
        </with>
    </enablement>
</contextualLaunch> 

Here is the code of MyTester:

public class MyTester extends PropertyTester {
private static final String PROPERTY_NAME = "myProperty";

@Override
public boolean test(Object receiver, String property, Object[] arg2, Object expectedValue) {
    if (property.equals(PROPERTY_NAME) && receiver instanceof IProject) {
        return FileUtil.containsSpecificFile((IProject) receiver);
    }
    return false;
}
}

But this approach doesn't seem to work. While debugging MyTester.test() is never called. Any ideas?

回答1:

The trick is coupled with using forcePluginActivation. This defines that the Plug-in defining the property tester should be activated. If it is not activated, the property test cannot be performed. So, the final version of the code should look smth. like this:

<contextualLaunch>
    <enablement>
        <with variable="selection">
            <count value="1"/>
            <iterate>
                <adapt type="org.eclipse.core.resources.IResource">
                    <and>
                       <test property="org.eclipse.core.resources.projectNature" 
                            value="my.project.nature" />
                       <test property="my.namespace.myProperty"  
                            forcePluginActivation="true"/>
                   </and> 
              </adapt> 
           </iterate>
       </with>
    </enablement>
</contextualLaunch> 

NOTE: Quoting the documentation,

forcePluginActivation - a flag indicating whether the plug-in contributing the property tester should be loaded if necessary. As such, this flag should be used judiciously, in order to avoid unnecessary plug-in activations. Most clients should avoid setting this flag to true. This flag is only honored if the evaluation context used to evaluate this expression allows plug-in activation. Otherwise the flag is ignored and no plug-in loading takes place.

来源：https://stackoverflow.com/questions/27688010/how-to-check-if-project-contains-specific-file-for-launch-shortcuts