package test.wksp.eclipse;
/**
* A compare operation which can present its results in a special editor.
* Running the compare operation and presentating the results in a compare
* editor are combined in one class because it allows a client to keep the
* implementation all in one place while separating it from the innards of a
* specific UI implementation of compare/merge.
* <p>
* A <code>CompareEditorInput</code> defines methods for the following sequence
* steps:
* <UL>
* <LI>running a lengthy compare operation under progress monitor control,
* <LI>creating a UI for displaying the model and initializing the some widgets
* with the compare result,
* <LI>tracking the dirty state of the model in case of merge,
* <LI>saving the model.
* </UL>
* The Compare plug-in's <code>openCompareEditor</code> method takes an
* <code>ICompareEditorInput</code> and starts sequencing through the above
* steps. If the compare result is not empty a new compare editor is opened and
* takes over the sequence until eventually closed.
* <p>
* The <code>prepareInput</code> method should contain the code of the compare
* operation. It is executed under control of a progress monitor and can be
* canceled. If the result of the compare is not empty, that is if there are
* differences that needs to be presented, the <code>ICompareEditorInput</code>
* should hold onto them and return them with the <code>getCompareResult</code>
* method. If the value returned from <code>getCompareResult</code> is not
* <code>null</code> a compare editor is opened on the
* <code>ICompareEditorInput</code> with title and title image initialized by
* the corresponding methods of the <code>ICompareEditorInput</code>.
* <p>
* Creation of the editor's SWT controls is delegated to the
* <code>createContents</code> method. Here the SWT controls must be created and
* initialized with the result of the compare operation.
* <p>
* If merging is allowed, the modification state of the compared constituents
* must be tracked and the dirty state returned from method
* <code>isSaveNeeded</code>. The value <code>true</code> triggers a subsequent
* call to <code>save</code> where the modified resources can be saved.
* <p>
* The most important part of this implementation is the setup of the
* compare/merge UI. The UI uses a simple browser metaphor to present compare
* results. The top half of the layout shows the structural compare results
* (e.g. added, deleted, and changed files), the bottom half the content compare
* results (e.g. textual differences between two files). A selection in the top
* pane is fed to the bottom pane. If a content viewer is registered for the
* type of the selected object, this viewer is installed in the pane. In
* addition if a structure viewer is registered for the selection type the top
* pane is split horizontally to make room for another pane and the structure
* viewer is installed in it. When comparing Java files this second structure
* viewer would show the structural differences within a Java file, e.g. added,
* deleted or changed methods and fields.
* <p>
* Subclasses provide custom setups, e.g. for a Catchup/Release operation by
* passing a subclass of <code>CompareConfiguration</code> and by implementing
* the <code>prepareInput</code> method. If a subclass cannot use the
* <code>DiffTreeViewer</code> which is installed by default in the top left
* pane, method <code>createDiffViewer</code> can be overridden.
*
* @see CompareUI
* @see CompareEditorInput
*/
public class X08 {
}