Package SpecificationThe class Differencer is a differencing engine for hierarchically structured data. It takes two or three inputs and performs a two-way or three-way compare on them.
If the input elements to the differencing engine implement the IStructureComparator interface the engine recursively applies itself to the children of the input element. Leaf elements must implement the org.eclipse.compare.IStreamContentAccessor interface so that the differencer can perform a bytewise comparison on their contents.
One good example for this is org.eclipse.compare.ResourceNode which implements both interfaces (and more) for Eclipse workspace resources (org.eclipse.core.resources.IResource).
Another example is the DocumentRangeNode which can be used to compare hierarchical structures
that are superimposed on a document, that is where nodes and leafs correspond to ranges in a document
Typically DocumentRangeNodes are created while parsing a document and they represent the semantic entities of the document (e.g. a Java class, method or field). The two subclasses JavaNode (in org.eclipse.jdt.internal.ui.compare) and PropertyNode (in org.eclipse.jdt.internal.ui.compare) are good examples for this.
By default the differencing engine returns the result of the compare operation as a tree of DiffNode objects. However, this can be changed by overriding a single method of the engine.
Every DiffNode describes the changes among the two or three inputs.
A tree of DiffNodes can be displayed in a DiffTreeViewer. The DiffTreeViewer requires that inner nodes of the tree implement the IDiffContainer interface and leafs the IDiffElement interface.
The typical steps to compare hierarchically structured data and to display the differences would be to:
- map the input data into a tree of IStructureComparator and IStreamContentAccessors,
- perform the compare operation by means of the Differencer, and
- feed the differencing result into the DiffTreeViewer.
Interface Summary Interface Description ICompareInputInterface for objects used as input to a two-way or three-way compare viewer. ICompareInputChangeListenerListener that gets informed if one (or more) of the three sides of an
ICompareInputobject changes its value.
IDiffElementis used in the
DiffTreeViewerto display the kind of change detected as the result of a two-way or three-way compare.
IStructureComparatorInterface used to compare hierarchical structures. IStructureCreatorInterface used to create a hierarchical structure of
IStructureComparators for a given input object.
IStructureCreator2An extension to the
IStructureCreatorinterface that supports the use of shared documents.
Class Summary Class Description DiffContainerThe standard implementation of a diff container element. DiffElementAn abstract base implementation of the
DifferencerA generic two-way or three-way differencing engine. DiffNodeDiff node are used as the compare result of the differencing engine. DiffTreeViewerA tree viewer that works on objects implementing the
DocumentRangeNodeA document range node represents a structural element when performing a structure compare of documents. SharedDocumentAdapterWrapperAn implementation of
ISharedDocumentAdapterthat wraps another shared document adapter.
StructureCreator StructureDiffViewerA diff tree viewer that can be configured with a
IStructureCreatorto retrieve a hierarchical structure from the input object (an
ICompareInput) and perform a two-way or three-way compare on it.
StructureRootNodeA node that acts as the root of the tree returned from a