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Provides support for performing structural and textual
compare operations on arbitrary data and displaying the results.
<h2>
Package Specification</h2>

The class <b>CompareUI</b> defines the entry point to initiate a configurable
compare operation on arbitrary resources. The result of the compare is
opened into a compare editor where the details can be browsed and edited
in dynamically selected structure and content viewers.
<p>

A compare operation must be implemented as a subclass of <b>CompareEditorInput</b>.
A <b>CompareEditorInput</b> runs a (potentially lengthy) compare operation
under progress monitor control, creates a UI for drilling-down into the
compare results, tracks the dirty state of the result in case of merge,
and saves any changes that occured during a merge.
<p>

The <b>NavigationAction</b> is used to navigate (step) through the individual
differences of a <b>CompareEditorInput</b>.
<p>

An instance of <b>CompareConfiguration</b> configures various UI aspects
of compare/merge viewers like title labels and images, or whether a side
of a merge viewer is editable. It is passed to the <b>CompareEditorInput</b>
on creation.
<p>

When implementing a hierarchical compare operation as a subclass of
<b>CompareEditorInput</b> clients have to provide a tree of objects where each
node implements the interface
<b>org.eclipse.compare.structuremergeviewer.IStructureComparator</b>.
This interface is used by the hierarchical differencing engine
(<b>org.eclipse.compare.structuremergeviewer.Differencer</b>) to walk the tree.
<br>
In addition every leaf of the tree must implement the <b>IStreamContentAccessor</b>
interface in order to give the differencing engine access to its stream content.
<p>

The abstract class <b>BufferedContent</b> provides a default implementation
for the <b>IStreamContentAccessor</b> and <b>IContentChangeNotifier</b> interfaces.
Its subclass <b>ResourceNode</b> adds an implementation for the
<b>IStructureComparator</b> and <b>ITypedElement</b> interfaces
based on Eclipse workbench resources (org.eclipse.core.resources.IResource). 
It can be used without modification as the input to the differencing engine.
<p>

The <b>ZipFileStructureCreator</b> is an implementation of the
<b>org.eclipse.compare.structuremergeviewer.IStructureCreator</b> interface
and makes the contents of a zip archive available as a
hierarchical structure of <b>IStructureComparator</b>s which can be easily compared
by the differencing engine (<b>org.eclipse.compare.structuremergeviewer.Differencer</b>).
It is a good example for how to make structured files available to the hierarchical 
compare functionality of the Compare plugin.
<p>

The <b>EditionSelectionDialog</b> is a simple selection dialog where
one input element can be compared against a list of historic variants (<i>editions</i>)
of the same input element. The dialog can be used to implement functions
like <i>"Replace with Version"</i> or <i>"Replace with Edition"</i> on workbench resources.
<p>

In addition it is possible to specify a subsection of the input element
(e.g. a method in a Java source file) by means of a <i>path</i>. In this
case the dialog compares only the subsection (as specified by the path)
with the corresponding subsection in the list of editions. This functionality
can be used to implement <i>"Replace with Method Edition"</i> for the Java
language.
<p>

The <b>EditionSelectionDialog</b> requires that the editions implement
the <b>IStreamContentAccessor</b> and <b>IModificationDate</b> interfaces.
The <b>HistoryItem</b> is a convenience class that implements these interfaces
for <b>IFileState</b> objects.
<p>


The <b>CompareViewerPane</b> is a convenience class which provides
a label and local toolbar for a compare viewer (or any other subclass of a 
JFace <b>Viewer</b>).
<br>
Its abstract subclass <b>CompareViewerSwitchingPane</b> supports <i>dynamic
viewer switching</i>, that is the viewer installed in the pane is dynamically 
determined by the pane's input object.
Both classes are useful if you want to use compare viewers outside the context of
a compare editor, for example in a dialog or wizard.


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