/*******************************************************************************
* Copyright (c) 2005, 2008 IBM Corporation 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:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.core.commands.operations;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
/**
* <p>
* IUndoableOperation defines an operation that can be executed, undone, and
* redone. Operations typically have fully defined parameters. That is, they are
* usually created after the user has been queried for any input needed to
* define the operation.
* </p>
* <p>
* Operations determine their ability to execute, undo, or redo according to the
* current state of the application. They do not make decisions about their
* validity based on where they occur in the operation history. That is left to
* the particular operation history.
* </p>
*
* @since 3.1
*/
public interface IUndoableOperation {
/**
* <p>
* Add the specified context to the operation. If a context equal to the
* specified context is already present, do not add it again. Note that
* determining whether a context is already present is based on equality,
* not whether the context matches ({@link IUndoContext#matches(IUndoContext)})
* another context.
* </p>
*
* @param context
* the context to be added
*/
void addContext(IUndoContext context);
/**
* <p>
* Returns whether the operation can be executed in its current state.
* </p>
*
* <p>
* Note: The computation for this method must be fast, as it is called
* frequently. If necessary, this method can be optimistic in its
* computation (returning true) and later perform more time-consuming
* computations during the actual execution of the operation, returning the
* appropriate status if the operation cannot actually execute at that time.
* </p>
*
* @return <code>true</code> if the operation can be executed;
* <code>false</code> otherwise.
*/
boolean canExecute();
/**
* <p>
* Returns whether the operation can be redone in its current state.
* </p>
*
* <p>
* Note: The computation for this method must be fast, as it is called
* frequently. If necessary, this method can be optimistic in its
* computation (returning true) and later perform more time-consuming
* computations during the actual redo of the operation, returning the
* appropriate status if the operation cannot actually be redone at that
* time.
* </p>
*
* @return <code>true</code> if the operation can be redone;
* <code>false</code> otherwise.
*/
boolean canRedo();
/**
* <p>
* Returns whether the operation can be undone in its current state.
* </p>
*
* <p>
* Note: The computation for this method must be fast, as it is called
* frequently. If necessary, this method can be optimistic in its
* computation (returning true) and later perform more time-consuming
* computations during the actual undo of the operation, returning the
* appropriate status if the operation cannot actually be undone at that
* time.
* </p>
*
* @return <code>true</code> if the operation can be undone;
* <code>false</code> otherwise.
*/
boolean canUndo();
/**
* Dispose of the operation. This method is used when the operation is no
* longer kept in the history. Implementers of this method typically
* unregister any listeners.
*
*/
void dispose();
/**
* Execute the operation. This method should only be called the first time
* that an operation is executed.
*
* @param monitor
* the progress monitor (or <code>null</code>) to use for
* reporting progress to the user.
* @param info
* the IAdaptable (or <code>null</code>) provided by the
* caller in order to supply UI information for prompting the
* user if necessary. When this parameter is not
* <code>null</code>, it should minimally contain an adapter
* for the org.eclipse.swt.widgets.Shell.class.
*
* @return the IStatus of the execution. The status severity should be set
* to <code>OK</code> if the operation was successful, and
* <code>ERROR</code> if it was not. Any other status is assumed
* to represent an incompletion of the execution.
* @throws ExecutionException
* if an exception occurred during execution.
*/
IStatus execute(IProgressMonitor monitor, IAdaptable info)
throws ExecutionException;
/**
* <p>
* Returns the array of contexts that have been assigned to the operation.
* </p>
* <p>
* This method may be called by the operation history from inside a
* synchronized block. To avoid deadlock conditions, implementers of this
* method must avoid dispatching and waiting on threads that modify the
* operation history during this method.
* </p>
*
* @return the array of contexts
*/
IUndoContext[] getContexts();
/**
* Return the label that should be used to show the name of the operation to
* the user. This label is typically combined with the command strings shown
* to the user in "Undo" and "Redo" user interfaces.
*
* @return the String label. Should never be <code>null</code>.
*/
String getLabel();
/**
* <p>
* Returns whether the operation has a matching context for the specified
* context.
* </p>
* <p>
* This method may be called by the operation history from inside a
* synchronized block. To avoid deadlock conditions, implementers of this
* method must avoid dispatching and waiting on threads that modify the
* operation history during this method.
* </p>
*
* @see IUndoContext#matches(IUndoContext)
*
* @param context
* the context in question
* @return <code>true</code> if the context is present, <code>false</code>
* if it is not.
*/
boolean hasContext(IUndoContext context);
/**
* Redo the operation. This method should only be called after an operation
* has been undone.
*
* @param monitor
* the progress monitor (or <code>null</code>) to use for
* reporting progress to the user.
* @param info
* the IAdaptable (or <code>null</code>) provided by the
* caller in order to supply UI information for prompting the
* user if necessary. When this parameter is not
* <code>null</code>, it should minimally contain an adapter
* for the org.eclipse.swt.widgets.Shell.class.
* @return the IStatus of the redo. The status severity should be set to
* <code>OK</code> if the redo was successful, and
* <code>ERROR</code> if it was not. Any other status is assumed
* to represent an incompletion of the redo.
* @throws ExecutionException
* if an exception occurred during redo.
*/
IStatus redo(IProgressMonitor monitor, IAdaptable info)
throws ExecutionException;
/**
* Remove the specified context from the operation. This method has no
* effect if the context is not equal to another context in the context
* list. Note that determining whether a context is present when removing it
* is based on equality, not whether the context matches ({@link
* IUndoContext#matches(IUndoContext)}) another context.
*
* @param context
* the context to be removed
*/
void removeContext(IUndoContext context);
/**
* Undo the operation. This method should only be called after an operation
* has been executed.
*
* @param monitor
* the progress monitor (or <code>null</code>) to use for
* reporting progress to the user.
* @param info
* the IAdaptable (or <code>null</code>) provided by the
* caller in order to supply UI information for prompting the
* user if necessary. When this parameter is not
* <code>null</code>, it should minimally contain an adapter
* for the org.eclipse.swt.widgets.Shell.class.
* @return the IStatus of the undo. The status severity should be set to
* <code>OK</code> if the redo was successful, and
* <code>ERROR</code> if it was not. Any other status is assumed
* to represent an incompletion of the undo.
* @throws ExecutionException
* if an exception occurred during undo.
*/
IStatus undo(IProgressMonitor monitor, IAdaptable info)
throws ExecutionException;
}
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