Package-level Javadoc
Author: IBM

Provides support for performing structural and textual compare operations on arbitrary data and displaying the results.

## Package Specification

The class CompareUI 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.

A compare operation must be implemented as a subclass of CompareEditorInput. A CompareEditorInput 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.

The NavigationAction is used to navigate (step) through the individual differences of a CompareEditorInput.

An instance of CompareConfiguration 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 CompareEditorInput on creation.

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

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

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

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

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 path. 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 "Replace with Method Edition" for the Java language.

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

The CompareViewerPane is a convenience class which provides a label and local toolbar for a compare viewer (or any other subclass of a JFace Viewer).
Its abstract subclass CompareViewerSwitchingPane supports dynamic viewer switching, 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.

A Splitter is an extension of a SashForm that supports nesting, maximizing of panes, and propagating the visibility state of panes.

The interface IStreamMerger defines a single operation for performing a three-way merge on three input streams. The merged result is written to an output stream.
Clients must implement this interface when contributing new mergers to the `org.eclipse.compare.streamMergers` extension point. New IStreamMergers can be created for registered types with the createStreamMerger methods of CompareUI.