Package org.eclipse.handly.model

Class ElementDeltas

java.lang.Object
org.eclipse.handly.model.ElementDeltas
public class ElementDeltas extends Object
Provides static methods for generic access to IElementDeltas. Given a delta, clients can access the element that has changed, and any children that have changed.

Note that, despite having a dependency on IResourceDelta and IMarkerDelta, this class can safely be used even when org.eclipse.core.resources bundle is not available. This is based on the "outward impression" of late resolution of symbolic references a JVM must provide according to the JVMS.

  • Field Details

    • EMPTY_ARRAY

      public static final IElementDelta[] EMPTY_ARRAY
      A zero-length array of the runtime type IElementDelta[].

  • Method Details

    • getElement

      public static IElement getElement(IElementDelta delta)
      Returns the element that the delta describes a change to.
      Parameters:
      delta - not null
      Returns:
      the element that the delta describes a change to (never null)

    • isEmpty

      public static boolean isEmpty(IElementDelta delta)
      Returns whether the element delta is empty, i.e., represents an unchanged element.
      Parameters:
      delta - not null
      Returns:
      true if the element delta is empty, and false otherwise

    • isNullOrEmpty

      public static boolean isNullOrEmpty(IElementDelta delta)
      Returns whether the element delta is null or empty. Convenience method.
      Parameters:
      delta - may be null
      Returns:
      true if the element delta is null or empty, and false otherwise

    • getKind

      public static int getKind(IElementDelta delta)
      Returns the kind of the element delta. Normally, one of ADDED, REMOVED, or CHANGED. Returns NO_CHANGE if, and only if, the delta is empty.
      Parameters:
      delta - not null
      Returns:
      the kind of the element delta

    • getFlags

      public static long getFlags(IElementDelta delta)
      Returns flags which describe in more detail how an element has changed. Such flags should be tested using the & operator. For example: 
          if ((flags & F_CONTENT) != 0) // a content change

      Some change flags make sense for most models and are predefined in IElementDeltaConstants, while others are model-specific and are defined by the model implementor. The range for model-specific change flags starts from 1L << 32 and includes the upper 32 bits of the long value. The lower 32 bits are reserved for predefined generic change flags.

      Move operations are indicated by special change flags. If an element is moved from A to B (with no other changes to A or B), then A will have kind REMOVED, with flag F_MOVED_TO, and getMovedToElement on A will return the handle for B. B will have kind ADDED, with flag F_MOVED_FROM, and getMovedFromElement on B will return the handle for A. (Note that the handle for A in this case represents an element that no longer exists.)

      Parameters:
      delta - not null
      Returns:
      flags that describe how an element has changed

    • isStructuralChange

      public static boolean isStructuralChange(IElementDelta delta)
      Returns whether the element delta designates a structural change, i.e., a change that affects or might affect the element tree as opposed to only the element itself.
      Parameters:
      delta - may be null
      Returns:
      true if the element delta designates a structural change, and false otherwise

    • findDelta

      public static IElementDelta findDelta(IElementDelta delta, IElement element)
      Finds and returns the delta for the given element in a delta subtree (subtree root included), or null if no such delta can be found.

      This is a convenience method to avoid manual traversal of the delta tree in cases where the listener is only interested in changes to particular elements. Calling this method will generally be faster than manually traversing the delta to a particular descendant.

      Parameters:
      delta - the delta at which to start the search (not null)
      element - the element of the desired delta (may be null, in which case null will be returned)
      Returns:
      the delta for the given element, or null if no such delta can be found

    • getAffectedChildren

      public static IElementDelta[] getAffectedChildren(IElementDelta delta)
      Returns element deltas for all affected (added, removed, or changed) immediate children.
      Parameters:
      delta - not null
      Returns:
      element deltas for all affected immediate children (never null). Clients must not modify the returned array.

    • getAddedChildren

      public static IElementDelta[] getAddedChildren(IElementDelta delta)
      Returns element deltas for the immediate children that have been added.
      Parameters:
      delta - not null
      Returns:
      element deltas for the immediate children that have been added (never null). Clients must not modify the returned array.

    • getRemovedChildren

      public static IElementDelta[] getRemovedChildren(IElementDelta delta)
      Returns element deltas for the immediate children that have been removed.
      Parameters:
      delta - not null
      Returns:
      element deltas for the immediate children that have been removed (never null). Clients must not modify the returned array.

    • getChangedChildren

      public static IElementDelta[] getChangedChildren(IElementDelta delta)
      Returns element deltas for the immediate children that have been changed.
      Parameters:
      delta - not null
      Returns:
      element deltas for the immediate children that have been changed (never null). Clients must not modify the returned array.

    • getMovedFromElement

      public static IElement getMovedFromElement(IElementDelta delta)
      Returns an element describing the delta's element before it was moved to its current location, or null if the F_MOVED_FROM change flag is not set.
      Parameters:
      delta - not null
      Returns:
      an element describing the delta's element before it was moved to its current location, or null if the F_MOVED_FROM change flag is not set
      See Also:

    • getMovedToElement

      public static IElement getMovedToElement(IElementDelta delta)
      Returns an element describing the delta's element in its new location, or null if the F_MOVED_TO change flag is not set.
      Parameters:
      delta - not null
      Returns:
      an element describing the delta's element in its new location, or null if the F_MOVED_TO change flag is not set
      See Also:

    • getMarkerDeltas

      public static org.eclipse.core.resources.IMarkerDelta[] getMarkerDeltas(IElementDelta delta)
      Returns the changes to markers on the corresponding resource of the delta's element.

      Returns null if no markers changed. Note that this is an exception to the general convention of returning an empty array rather than null. This makes the method safe to call even when org.eclipse.core.resources bundle is not available.

      Note that marker deltas, like element deltas, are generally only valid for the dynamic scope of change notification. Clients must not hang on to these objects.

      Parameters:
      delta - not null
      Returns:
      the marker deltas, or null if none. Clients must not modify the returned array.

    • getResourceDeltas

      public static org.eclipse.core.resources.IResourceDelta[] getResourceDeltas(IElementDelta delta)
      Returns the changes to children of the delta element's corresponding resource that cannot be described in terms of element deltas.

      Returns null if there were no such changes. Note that this is an exception to the general convention of returning an empty array rather than null. This makes the method safe to call even when org.eclipse.core.resources bundle is not available.

      Note that resource deltas, like element deltas, are generally only valid for the dynamic scope of change notification. Clients must not hang on to these objects.

      Parameters:
      delta - not null
      Returns:
      the resource deltas, or null if none. Clients must not modify the returned array.

    • toString

      public static String toString(IElementDelta delta, IContext context)
      Returns a string representation of the element delta in a form suitable for debugging purposes. Clients can influence the result with format options specified in the given context; unrecognized options are ignored and an empty context is permitted.

      Model implementations are encouraged to support common options defined in ToStringOptions and interpret the FORMAT_STYLE as follows:

      • FULL - A full representation that lists affected children.
      • LONG - May be an alias for FULL.
      • MEDIUM - May be an alias for SHORT.
      • SHORT - A minimal representation that does not list affected children.
      Parameters:
      delta - not null
      context - not null
      Returns:
      a string representation of the element delta (never null)