Package org.eclipse.handly.model.impl.support

Class ElementDelta

java.lang.Object
org.eclipse.handly.model.impl.support.ElementDelta
All Implemented Interfaces:
IElementDelta, IElementDeltaImpl
public class ElementDelta extends Object implements IElementDeltaImpl
A complete implementation of IElementDeltaImpl. To create a delta tree, use ElementDelta.Builder.

Note that, despite having a dependency on IResourceDelta and IMarkerDelta, this class can 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.

Clients can use this class as it stands or subclass it as circumstances warrant. Clients that subclass this class should consider registering an appropriate ElementDelta.Factory in the model context. Subclasses that introduce new fields should consider extending the copyFrom_ method.

  • Constructor Details

    • ElementDelta

      public ElementDelta(IElement element)
      Constructs an initially empty delta for the given element.
      Parameters:
      element - not null
      See Also:

  • Method Details

    • getElement_

      public final IElement getElement_()
      Description copied from interface: IElementDeltaImpl
      Returns the element that this delta describes a change to.
      Specified by:
      getElement_ in interface IElementDeltaImpl
      Returns:
      the element that this delta describes a change to (never null)

    • getKind_

      public final int getKind_()
      Description copied from interface: IElementDeltaImpl
      Returns the kind of this element delta. Normally, one of ADDED, REMOVED, or CHANGED. Returns NO_CHANGE if, and only if, the delta is empty.
      Specified by:
      getKind_ in interface IElementDeltaImpl
      Returns:
      the kind of this element delta

    • getFlags_

      public final long getFlags_()
      Description copied from interface: IElementDeltaImpl
      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 IElementDeltaImpl.getMovedToElement_() on A will return the handle for B. B will have kind ADDED, with flag F_MOVED_FROM, and IElementDeltaImpl.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.)

      Specified by:
      getFlags_ in interface IElementDeltaImpl
      Returns:
      flags that describe how an element has changed

    • findDelta_

      public final ElementDelta findDelta_(IElement element)
      Description copied from interface: IElementDeltaImpl
      Finds and returns the delta for the given element in this 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.

      Specified by:
      findDelta_ in interface IElementDeltaImpl
      Parameters:
      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 final ElementDelta[] getAffectedChildren_()
      Returns element deltas for all affected (added, removed, or changed) immediate children.

      This implementation returns an array of exactly the same runtime type as the array given in the most recent call to setAffectedChildren_.

      Specified by:
      getAffectedChildren_ in interface IElementDeltaImpl
      Returns:
      element deltas for all affected immediate children (never null). Clients must not modify the returned array.

    • getAddedChildren_

      public final ElementDelta[] getAddedChildren_()
      Returns element deltas for the immediate children that have been added.

      This implementation returns an array of exactly the same runtime type as the array given in the most recent call to setAffectedChildren_.

      Specified by:
      getAddedChildren_ in interface IElementDeltaImpl
      Returns:
      element deltas for the immediate children that have been added (never null). Clients must not modify the returned array.

    • getRemovedChildren_

      public final ElementDelta[] getRemovedChildren_()
      Returns element deltas for the immediate children that have been removed.

      This implementation returns an array of exactly the same runtime type as the array given in the most recent call to setAffectedChildren_.

      Specified by:
      getRemovedChildren_ in interface IElementDeltaImpl
      Returns:
      element deltas for the immediate children that have been removed (never null). Clients must not modify the returned array.

    • getChangedChildren_

      public final ElementDelta[] getChangedChildren_()
      Returns element deltas for the immediate children that have been changed.

      This implementation returns an array of exactly the same runtime type as the array given in the most recent call to setAffectedChildren_.

      Specified by:
      getChangedChildren_ in interface IElementDeltaImpl
      Returns:
      element deltas for the immediate children that have been changed (never null). Clients must not modify the returned array.

    • getMovedFromElement_

      public final IElement getMovedFromElement_()
      Description copied from interface: IElementDeltaImpl
      Returns an element describing this delta's element before it was moved to its current location, or null if the F_MOVED_FROM change flag is not set.
      Specified by:
      getMovedFromElement_ in interface IElementDeltaImpl
      Returns:
      an element describing this 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 final IElement getMovedToElement_()
      Description copied from interface: IElementDeltaImpl
      Returns an element describing this delta's element in its new location, or null if the F_MOVED_TO change flag is not set.
      Specified by:
      getMovedToElement_ in interface IElementDeltaImpl
      Returns:
      an element describing this delta's element in its new location, or null if the F_MOVED_TO change flag is not set
      See Also:

    • getMarkerDeltas_

      public final org.eclipse.core.resources.IMarkerDelta[] getMarkerDeltas_()
      Description copied from interface: IElementDeltaImpl
      Returns the changes to markers on the corresponding resource of this 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.

      Specified by:
      getMarkerDeltas_ in interface IElementDeltaImpl
      Returns:
      the marker deltas, or null if none. Clients must not modify the returned array.

    • getResourceDeltas_

      public final org.eclipse.core.resources.IResourceDelta[] getResourceDeltas_()
      Description copied from interface: IElementDeltaImpl
      Returns the changes to children of the 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.

      Specified by:
      getResourceDeltas_ in interface IElementDeltaImpl
      Returns:
      the resource deltas, or null if none. Clients must not modify the returned array.

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • toString_

      public String toString_(IContext context)
      Description copied from interface: IElementDeltaImpl
      Returns a string representation of this 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.

      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.
      Specified by:
      toString_ in interface IElementDeltaImpl
      Parameters:
      context - not null
      Returns:
      a string representation of this element delta (never null)

    • toStringChildren_

      protected void toStringChildren_(StringBuilder builder, IContext context)

    • toStringResourceDeltas_

      protected void toStringResourceDeltas_(StringBuilder builder, IContext context)

    • toStringKind_

      protected void toStringKind_(StringBuilder builder, IContext context)

    • toStringFlags_

      protected boolean toStringFlags_(StringBuilder builder, IContext context)
      Appends a string representation for this delta's flags to the given string builder.
      Parameters:
      builder - a string builder to append the delta flags to
      context - not null
      Returns:
      true if a flag was appended to the builder, and false if the builder was not modified by this method
      See Also:

    • newDelta_

      protected ElementDelta newDelta_(IElement element)
      Returns a new, initially empty delta for the given element.

      This implementation uses ElementDelta.Factory registered in the element's model context. If no delta factory is registered in the model context, a new instance of this class (i.e., ElementDelta) is returned.

      Parameters:
      element - not null
      Returns:
      a new, initially empty delta for the given element (never null)

    • needsChildIndex_

      protected boolean needsChildIndex_()
      Returns whether an index needs to be used for child lookup.
      Returns:
      true if the child index needs to be used, and false otherwise

    • setKind_

      protected void setKind_(int kind)
      Sets the kind of this delta.

      This is a low-level mutator method. In particular, it is the caller's responsibility to ensure validity of the given value.

      Parameters:
      kind - the delta kind
      See Also:

    • setFlags_

      protected void setFlags_(long flags)
      Sets the flags for this delta.

      This is a low-level mutator method. In particular, it is the caller's responsibility to ensure validity of the given value.

      Parameters:
      flags - the delta flags
      See Also:

    • setMovedFromElement_

      protected void setMovedFromElement_(IElement movedFromElement)
      Sets an element describing this delta's element before it was moved to its current location.

      This is a low-level mutator method. In particular, it is the caller's responsibility to set appropriate kind and flags for this delta.

      Parameters:
      movedFromElement - an element describing this delta's element before it was moved to its current location
      See Also:

    • setMovedToElement_

      protected void setMovedToElement_(IElement movedToElement)
      Sets an element describing this delta's element in its new location.

      This is a low-level mutator method. In particular, it is the caller's responsibility to set appropriate kind and flags for this delta.

      Parameters:
      movedToElement - an element describing this delta's element in its new location
      See Also:

    • setMarkerDeltas_

      protected void setMarkerDeltas_(org.eclipse.core.resources.IMarkerDelta[] markerDeltas)
      Sets the marker deltas for this delta. Clients must not modify the given array afterwards.

      This is a low-level mutator method. In particular, it is the caller's responsibility to set appropriate kind and flags for this delta.

      Parameters:
      markerDeltas - the marker deltas
      See Also:

    • setResourceDeltas_

      protected void setResourceDeltas_(org.eclipse.core.resources.IResourceDelta[] resourceDeltas)
      Sets the resource deltas for this delta. Clients must not modify the given array afterwards.

      This is a low-level mutator method. In particular, it is the caller's responsibility to set appropriate kind and flags for this delta.

      Parameters:
      resourceDeltas - the resource deltas
      See Also:

    • addResourceDelta_

      protected void addResourceDelta_(org.eclipse.core.resources.IResourceDelta resourceDelta)
      Adds the given resource delta to the collection of resource deltas of this delta if permitted by the current state of this delta. Note that in contrast to setResourceDeltas_, this method can change this delta's kind and flags as appropriate.

      If the kind of this delta is ADDED or REMOVED, this implementation returns without adding the given resource delta; otherwise, it sets the kind of this delta to CHANGED and adds the F_CONTENT change flag.

      Parameters:
      resourceDelta - the resource delta to add (not null)
      See Also:

    • insertSubTree_

      protected void insertSubTree_(ElementDelta delta)
      Based on the given delta, creates a delta tree that can be directly parented by this delta and adds the created tree as an affected child of this delta.

      Note that after calling insertSubTree_(delta) there is no guarantee that 

          findDelta_(d.getElement_()) == d

      or even that 

          findDelta_(d.getElement_()) != null

      for any delta d in the subtree delta (subtree root included). For example, if this delta tree already contains a delta for d.getElement_(), that delta will be merged with d, which may even result in a logically empty delta, i.e., no delta for the element.

      Parameters:
      delta - the delta to insert (not null)
      Throws:
      IllegalArgumentException - if the given delta cannot be rooted in this delta

    • addAffectedChild_

      protected void addAffectedChild_(ElementDelta child)
      Adds the given delta as an affected child of this delta if permitted by the current state of this delta. If this delta already contains a child delta for the same element as the given delta, merges the existing child delta with the given delta. Note that in contrast to setAffectedChildren_, this method can change this delta's kind and flags as appropriate.

      It is the caller's responsibility to ensure that the given delta can be directly parented by this delta.

      Note that after calling addAffectedChild_(delta) there is no guarantee that 

          findDelta_(d.getElement_()) == d

      or even that 

          findDelta_(d.getElement_()) != null

      for any delta d in the subtree delta (subtree root included).

      If the kind of this delta is ADDED or REMOVED, this implementation returns without adding the given delta; otherwise, it sets the kind of this delta to CHANGED and adds the F_CHILDREN change flag and, if this delta's element is an ISourceElement, the F_FINE_GRAINED change flag.

      Parameters:
      child - the delta to add as an affected child (not null)
      See Also:

    • mergeWith_

      protected void mergeWith_(ElementDelta delta)
      Merges this delta with the given delta; the given delta is not modified in any way.

      It is the caller's responsibility to ensure that the given delta pertains to the same element as this delta.

      This implementation implements merge semantics in terms of calls to copyFrom_.

      Parameters:
      delta - the delta to merge with (not null)

    • copyFrom_

      protected void copyFrom_(ElementDelta delta, boolean init)
      Copies data from the given delta to this delta; the given delta is not modified in any way.

      It is the caller's responsibility to ensure that the given delta pertains to the same element as this delta.

      Subclasses that introduce new fields should consider extending this method.

      Parameters:
      delta - the delta to copy data from (not null)
      init - true if this delta needs to be completely (re-)initialized with data from the given delta; false if this delta needs to be augmented with data from the given delta

    • setAffectedChildren_

      protected void setAffectedChildren_(ElementDelta[] children)
      Sets the affected children for this delta. Clients must not modify the given array afterwards.

      This is a low-level mutator method. In particular, it is the caller's responsibility to set appropriate kind and flags for this delta.

      Parameters:
      children - the affected children (not null)
      See Also: