1 files changed, 51 insertions, 0 deletions
diff --git a/plugins/infra/gmfdiag/org.eclipse.papyrus.infra.gmfdiag.common/src/org/eclipse/papyrus/infra/gmfdiag/common/spi/IGraphicalDeletionHelper.java b/plugins/infra/gmfdiag/org.eclipse.papyrus.infra.gmfdiag.common/src/org/eclipse/papyrus/infra/gmfdiag/common/spi/IGraphicalDeletionHelper.java
new file mode 100644
index 00000000000..e7b318c3139
--- /dev/null
+++ b/plugins/infra/gmfdiag/org.eclipse.papyrus.infra.gmfdiag.common/src/org/eclipse/papyrus/infra/gmfdiag/common/spi/IGraphicalDeletionHelper.java
@@ -0,0 +1,51 @@
+/*****************************************************************************
+ * Copyright (c) 2016 Christian W. Damus and others.
+ * 
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *   Christian W. Damus - Initial API and implementation
+ *   
+ *****************************************************************************/
+
+package org.eclipse.papyrus.infra.gmfdiag.common.spi;
+
+import org.eclipse.gmf.runtime.diagram.ui.editparts.IGraphicalEditPart;
+import org.eclipse.papyrus.infra.gmfdiag.common.utils.DiagramEditPartsUtil;
+
+/**
+ * Protocol of a pluggable graphical deletion helper strategy.
+ */
+public interface IGraphicalDeletionHelper {
+	/** The default instance just checks whether the edit-part is not read-only. */
+	IGraphicalDeletionHelper DEFAULT = ep -> !DiagramEditPartsUtil.isReadOnly(ep);
+
+	/**
+	 * Queries whether the specified edit-part can be deleted. If the helper
+	 * does not have a specific positive answer for the edit-part, it should
+	 * return {@code false} to let another helper answer (the ultimate fall-back
+	 * checks the standard read-only state of the edit-part).
+	 * 
+	 * @param editPart
+	 *            an edit-part that is proposed for deletion
+	 * 
+	 * @return whether it may be delete, or {@code false} if I don't know
+	 */
+	boolean canDelete(IGraphicalEditPart editPart);
+
+	/**
+	 * Composes me with an{@code other} helper in a disjuntion
+	 * on the {@link #canDelete(IGraphicalEditPart)} operation.
+	 * 
+	 * @param other
+	 *            another graphical deletion helper
+	 * 
+	 * @return the composed helper
+	 */
+	default IGraphicalDeletionHelper compose(IGraphicalDeletionHelper other) {
+		return ep -> other.canDelete(ep) || this.canDelete(ep);
+	}
+}