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Command Core Expressions

Core expressions are declarative or programmatic expressions based on the org.eclipse.core.expressions plugin.

Expressions and the Command Framework

The Platform Command Framework uses core expressions for enabledWhen and activeWhen for handlers, programmatic activation of contexts, and for visibleWhen for menu contributions. The command framework provides the IEvaluationContext that command core expressions are evaluate against.

The IEvaluationContext provides a default variable for evaluations, and a number of named variables. In the command framework, we provide the global selection as a java.util.Collection as the default variable. It can either be empty, have one entry (if the ISelection was something like an ITextSelection), or have the contents of an IStructuredSelection.

The <with/> element can be used to change which variable the child expression elements are evaluating against.

Variables and the Command Framework

The variables used for command framework evaluation are listed in ISources.java

Some of the variables may not be set, depending on the current application context when they are evaluated.

<td>3.2</td> <tr> <td>activeActionSets</td> <td>An IActionSetDescriptor[]</td> <td> Note: This is currently not used as points to an internal class and the type might change in any released. </td> <td>3.2</td> </tr> <tr> <td>activeShell</td> <td>org.eclipse.swt.widgets.Shell</td> <td> The currently active shell. It can be a dialog or workbench window shell. </td> <td>3.2</td> </tr> <tr> <td>activeWorkbenchWindowShell</td> <td>org.eclipse.swt.widgets.Shell</td> <td> The active workbench window shell. </td> <td>3.2</td> </tr> <tr> <td>activeWorkbenchWindow</td> <td>org.eclipse.ui.IWorkbenchWindow</td> <td> The active workbench window. </td> <td>3.2</td> </tr> <tr> <td>activeWorkbenchWindow.isCoolbarVisible</td> <td>java.lang.Boolean</td> <td> Reports coolbar visibility for the currently active workbench window. </td> <td>3.3</td> </tr> <tr> <td>activeWorkbenchWindow.isPerspectiveBarVisible</td> <td>java.lang.Boolean</td> <td> Reports perspective bar visibility for the currently active workbench window. </td> <td>3.3</td> </tr> <tr> <td>activeEditor</td> <td>org.eclipse.ui.IEditorPart</td> <td> The currently active editor. This is remembered even if the editor is not the currently active part. </td> <td>3.2</td> </tr> <tr> <td>activeEditorId</td> <td>java.lang.String</td> <td> The ID of the currently active editor. This can be used for expressions on the editor type. </td> <td>3.2</td> </tr> <tr> <td>activePart</td> <td>org.eclipse.ui.IWorkbenchPart</td> <td> The active part, which can be the same as the active editor. </td> <td>3.2</td> </tr> <tr> <td>activePartId</td> <td>java.lang.String</td> <td> The ID of the currently active part. </td> <td>3.2</td> </tr> <tr> <td>activeSite</td> <td>org.eclipse.ui.IWorkbenchPartSite</td> <td> The site of the currently active part. </td> <td>3.2</td> </tr> <tr> <td>selection</td> <td>org.eclipse.jface.viewers.ISelection</td> <td> The current global selection. It can be used in <test/> elements with org.eclipse.core.expressions.PropertyTester, in programmatic core expressions, and in 3.3 with <iterate/> and <count/< elements. </td> <td>3.2</td> </tr> <tr> <td>activeMenu</td> <td>A java.util.Collection of java.lang.String</td> <td> This is the list of IDs of the showing context menu. Examples are like #TextEditorRuler or a part ID. Most commonly used with <iterate> and <count>, and can also be used with <test> and a org.eclipse.common.expressions.PropertyTester. </td> <td>3.2</td> </tr> <tr> <td>activeMenuSelection</td> <td>org.eclipse.jface.viewers.ISelection</td> <td> This is a selection that is available while a context menu is showing. It is the selection from the selection provider used to register the context menu, usually from getSite().registerContextMenu(*). It is usually the same as the selectionvariable, but not always. This is more for legacy compatibility. </td> <td>3.3</td> </tr> <tr> <td>activeMenuEditorInput</td> <td>org.eclipse.jface.viewers.ISelection</td> <td> This is a selection that is available while a context menu is showing. It is the selection from the editor input, usually if includeEditorInput was set to true during getEditorSite().registerContextMenu(*). This is more for legacy compatibility. </td> <td>3.3</td> </tr> <tr> <td>activeFocusControl</td> <td>org.eclipse.swt.widgets.Control</td> <td> </td> <td>3.3</td> </tr> <tr> <td>activeFocusControlId</td> <td>java.lang.String</td> <td> </td> <td>3.3</td> </tr> </table>

Expression examples

Here are some examples. I'll pretend all of the examples are deciding when a handler is active.

Basic IStructuredSelection

A view provides a structured selection through its selection provider. An example would be the InfoView in org.eclipse.ui.examples.contributions. You can browse the plugin.xml and InfoView.java files. The InfoView provides an IStructuredSelection with 0 or more org.eclipse.ui.examples.contributions.model.Person.

When using the default variable, you must treat it as an java.util.Collection. That means using <count> or <iterate>


<activeWhen>
   <iterate>
      <instanceof value="org.eclipse.ui.examples.contributions.model.Person"/>
   </iterate>
</activeWhen>

Package Explorer IStructuredSelection

The Package Explorer is a mixture of org.eclipse.core.resources.IResource and

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Name Type Description Since
activeContexts A java.util.Collection of java.lang.String

This is a collection of the active context IDs as strings. Most commonly used with <iterate> and <count>, and can also be used with <test> and a org.eclipse.common.expressions.PropertyTester.</code>.