Eclipse Enablement Expressions for Files with Specific Extension

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While developing a UI plugin for Eclipse, I wanted to activate a specific context menu entry only for files with a specific extension. Because it took some time to figure the solution out, I decided to share it for others who want to implement this.

This example demonstrates the enablement for a launch shortcut, but of course this can be adapted to other extensions with enablement support, too.

One or More Files with Specific Extension

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<extension point="org.eclipse.debug.ui.launchShortcuts">
  <shortcut class="tld.domain.plugin.ui.MyLaunchShortcut"
            icon="icons/icon.png"
            id="tld.domain.plugin.ui.launchShortcut"
            label="My Launch Shortcut"
            modes="run">
    <contextualLaunch>
      <enablement>
        <with variable="selection">
          <count value="+"/>
          <iterate operator="and">
            <adapt type="org.eclipse.core.resources.IFile">
              <test property="org.eclipse.core.resources.extension"
                    value="ext">
              </test>
            </adapt>
          </iterate>
        </with>
      </enablement>
    </contextualLaunch>
  </shortcut>
</extension>

The enablement is based on the selection, which should contain at least one element (count=+). Then the resources are iterated and adapted to IFile if applicable. Then the file extension is checked (in my example the extension ext, i.e. all files with the file name pattern *.ext are permitted). Note that the test properties must be given with a namespace (e.g. extension is wrong, whereas org.eclipse.core.resources.extension is correct).

One or More Files with Multiple Valid File Extensions

Another use case is to allow multiple file extensions. In this case, an additional <or> element is required as child of the <adapt> instruction as shown below:

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<enablement>
  <with variable="selection">
    <count value="+"/>
    <iterate operator="and">
      <adapt type="org.eclipse.core.resources.IFile">
        <or>
          <test property="org.eclipse.core.resources.extension" value="xml"/>
          <test property="org.eclipse.core.resources.extension" value="xsd"/>
        </or>
      </adapt>
    </iterate>
  </with>
</enablement>

Added June 18, 2019:

Multiple Files with Multiple Valid Extensions

The following enablement tree will show the element if more than one file .xml or .xsd file is selected simultaneously. Note the corresponding count expression (1-, which means 1 to unbounded, where 1 is excluded.

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<enablement>
  <with variable="selection">
    <count value="(1-">
    </count>
    <iterate operator="and">
      <adapt type="org.eclipse.core.resources.IResource">
        <or>
          <test
                property="org.eclipse.core.resources.extension"
                value="xml">
          </test>
          <test 
                property="org.eclipse.core.resources.extension"
                value="xsd">
          </test>
        </or>
      </adapt>
    </iterate>
  </with>
</enablement>

Single File with Specific Extension or Container (Project / Folder)

This will enable the UI element if a file with a specific extension, a project or a folder is selected:

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<enablement>
  <with variable="selection">
    <count value="1">
    </count>
    <iterate ifEmpty="false" operator="or">
      <or>
        <adapt type="org.eclipse.core.resources.IFile">
          <test
                property="org.eclipse.core.resources.extension"
                value="mcl">
          </test>
        </adapt>
        <instanceof
                    value="org.eclipse.core.resources.IContainer">
        </instanceof>
      </or>
    </iterate>
  </with>
</enablement>

Also see the Eclipse Documentation for a full list of available properties and the Platform Expression Framework documentation.

2 thoughts on “Eclipse Enablement Expressions for Files with Specific Extension”

  2. I tried but it does not work for me (still shows the launch button on every file). Do you know the solution?

    Reply ↓

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