#21 Preference Page

Sep 23, 2013 | 12 minutes | Eclipse

In this episode I build a simple preference page customizing an Xtext generator.

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In the episode demonstrated method separating preferences and preferences UI was originally published by Kathir:

http://random-eclipse-tips.blogspot.de/2009/02/eclipse-keeping-preferences-and.html

Non-UI plugin

For the preferences we use the non-UI plugin preference store. This allows us to use Xtext generator without the UI part. In the org.xtext.example.mydsl.preferences package we define preference store preference accessor and initializer classes:

              MyDslPreferences.java
                    
        public class MyDslPreferences {
  public static final String P_GREETING_TEXT = "greetingText";
  
  public static String getGreetingText() {
    return getPreferenceStore().get(P_GREETING_TEXT, "");
  }
  public static IEclipsePreferences getPreferenceStore() {
    return InstanceScope.INSTANCE.getNode("org.xtext.example.mydsl");
  }
}
        
        
        
        
        
        
        
        
        
      
public class MyDslPreferences {
  public static final String P_GREETING_TEXT = "greetingText";
  
  public static String getGreetingText() {
    return getPreferenceStore().get(P_GREETING_TEXT, "");
  }
  public static IEclipsePreferences getPreferenceStore() {
    return InstanceScope.INSTANCE.getNode("org.xtext.example.mydsl");
  }
}

              PreferenceInitializer.java
                    
        public class PreferenceInitializer extends AbstractPreferenceInitializer {
  public void initializeDefaultPreferences() {
    getPreferenceStore().put(MyDslPreferences.P_GREETING_TEXT, "Hello");
  }
  
  public static IEclipsePreferences getPreferenceStore() {
    return DefaultScope.INSTANCE.getNode("org.xtext.example.mydsl");
  }
}
        
public class PreferenceInitializer extends AbstractPreferenceInitializer {
  public void initializeDefaultPreferences() {
    getPreferenceStore().put(MyDslPreferences.P_GREETING_TEXT, "Hello");
  }
  
  public static IEclipsePreferences getPreferenceStore() {
    return DefaultScope.INSTANCE.getNode("org.xtext.example.mydsl");
  }
}

The initializer has to be bound in the plugin.xml

              plugin.xml
                    
        <extension point="org.eclipse.core.runtime.preferences">
  <initializer class="org.xtext.example.mydsl.preferences.PreferenceInitializer">
  </initializer>
</extension>
        
<extension point="org.eclipse.core.runtime.preferences">
  <initializer class="org.xtext.example.mydsl.preferences.PreferenceInitializer">
  </initializer>
</extension>

Now we can use the customizable value in the generator:

              MyDslGenerator.xtend
                    
        class MyDslGenerator implements IGenerator {
  override void doGenerate(Resource resource, IFileSystemAccess fsa) {
    fsa.generateFile('greetings.txt', resource.allContents.filter(typeof(Greeting)).map [
      '''
        «MyDslPreferences.greetingText» «name»
      '''
    ].join)
  }
}
        
        
        
        
        
        
        
        
        
      
class MyDslGenerator implements IGenerator {
  override void doGenerate(Resource resource, IFileSystemAccess fsa) {
    fsa.generateFile('greetings.txt', resource.allContents.filter(typeof(Greeting)).map [
      '''
        «MyDslPreferences.greetingText» «name»
      '''
    ].join)
  }
}

Note: In the video the name attribute was converted to the Name class during "Organize Imports". I fixed that mistake off screen later on.

Addons plugin

In the org.xtext.example.mydsl.ui.addons plugin we define preference page based on the non-UI plugin preference store.

In the plugin.xml we define our preference page and preference initializer (preference initializer referenced from the non-UI plugin org.xtext.example.mydsl)

              plugin.xml
                    
        <?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.4"?>
<plugin>
  <extension point="org.eclipse.ui.preferencePages">
    <page category="org.xtext.example.mydsl.MyDsl"
      class="org.xtext.example.mydsl.ui.addons.preferences.TextPreferencePage"
      id="org.xtext.example.mydsl.ui.addons.preferences.TextPreferencePage"
      name="Text">
    </page>
  </extension>
  <extension point="org.eclipse.core.runtime.preferences">
    <initializer class="org.xtext.example.mydsl.preferences.PreferenceInitializer">
    </initializer>
  </extension>
</plugin>
        
        
        
        
        
        
        
        
        
      
<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.4"?>
<plugin>
  <extension point="org.eclipse.ui.preferencePages">
    <page category="org.xtext.example.mydsl.MyDsl"
      class="org.xtext.example.mydsl.ui.addons.preferences.TextPreferencePage"
      id="org.xtext.example.mydsl.ui.addons.preferences.TextPreferencePage"
      name="Text">
    </page>
  </extension>
  <extension point="org.eclipse.core.runtime.preferences">
    <initializer class="org.xtext.example.mydsl.preferences.PreferenceInitializer">
    </initializer>
  </extension>
</plugin>

The TextPreferencePage.java defines preference page with a single text field.

              TextPreferencePage.java
                    
        public class TextPreferencePage extends FieldEditorPreferencePage implements IWorkbenchPreferencePage {

  public TextPreferencePage() {
    super(GRID);
    IPreferenceStore store = new ScopedPreferenceStore(InstanceScope.INSTANCE, "org.xtext.example.mydsl");
    setPreferenceStore(store);
    setDescription("A demonstration of a preference page implementation");
  }
  
  public void createFieldEditors() {
    addField(new StringFieldEditor(MyDslPreferences.P_GREETING_TEXT, "Greeting text:", getFieldEditorParent()));
  }

  public void init(IWorkbench workbench) {}
}
        
        
        
        
        
        
        
        
        
      
public class TextPreferencePage extends FieldEditorPreferencePage implements IWorkbenchPreferencePage {

  public TextPreferencePage() {
    super(GRID);
    IPreferenceStore store = new ScopedPreferenceStore(InstanceScope.INSTANCE, "org.xtext.example.mydsl");
    setPreferenceStore(store);
    setDescription("A demonstration of a preference page implementation");
  }
  
  public void createFieldEditors() {
    addField(new StringFieldEditor(MyDslPreferences.P_GREETING_TEXT, "Greeting text:", getFieldEditorParent()));
  }

  public void init(IWorkbench workbench) {}
}

Version information

Eclipse: 4.3 (Kepler)
Xtext: 2.4.2