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 {
}