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Eclipse Platform
Release 3.0

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org.eclipse.jface.text
Class DefaultPositionUpdater

java.lang.Object
  org.eclipse.jface.text.DefaultPositionUpdater

All Implemented Interfaces:

IPositionUpdater

Direct Known Subclasses:

MultiPassContentFormatter.NonDeletingPositionUpdater

public class DefaultPositionUpdater

extends Object

implements IPositionUpdater

Default implementation of IPositionUpdater.

A default position updater must be configured with the position category whose positions it will update. Other position categories are not affected by this updater.

This implementation follows the following specification:

• Inserting or deleting text before the position shifts the position accordingly.
• Inserting text at the position offset shifts the position accordingly.
• Inserting or deleting text completely surrounded by the position shrinks or stretches the position.
• Inserting or deleting text after a position does not affect the position.
• Deleting text which completely contains the position deletes the position.
• Replacing text overlapping with the position considered as a sequence of first deleting the replaced text and afterwards inserting the new text. Thus, a position might first be shifted and shrink and then be stretched.

This class can be used as is or be adapted by subclasses. Fields are protected to allow subclasses direct access. Because of the frequency with which position updaters are used this is a performance decision.

Field Summary

protected IDocument	fDocument Catches the document
protected int	fLength Caches the length of the replaced text
protected int	fOffset Caches the offset of the replaced text
protected Position	fOriginalPosition Remembers the original state of the investigated position
protected Position	fPosition Caches the currently investigated position
protected int	fReplaceLength Caches the length of the newly inserted text

Constructor Summary

DefaultPositionUpdater(String category)
Creates a new default position updater for the given category.

Method Summary

protected void	adaptToInsert() Adapts the currently investigated position to an insertion.
protected void	adaptToRemove() Adapts the currently investigated position to a deletion.
protected void	adaptToReplace() Adapts the currently investigated position to the replace operation.
protected String	getCategory() Returns the category this updater is responsible for.
protected boolean	isAffectingReplace() Returns whether the current event describes a well formed replace by which the current position is directly affected.
protected boolean	notDeleted() Determines whether the currently investigated position has been deleted by the replace operation specified in the current event.
void	update(DocumentEvent event) Adapts positions to the change specified by the document event.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

fPosition

protected Position fPosition

Caches the currently investigated position

fOriginalPosition

protected Position fOriginalPosition

Remembers the original state of the investigated position

Since:

2.1

fOffset

protected int fOffset

Caches the offset of the replaced text

fLength

protected int fLength

Caches the length of the replaced text

fReplaceLength

protected int fReplaceLength

Caches the length of the newly inserted text

fDocument

protected IDocument fDocument

Catches the document

Constructor Detail

DefaultPositionUpdater

public DefaultPositionUpdater(String category)

Creates a new default position updater for the given category.

Parameters:

category - the category the updater is responsible for

Method Detail

getCategory

protected String getCategory()

Returns the category this updater is responsible for.

Returns:

the category this updater is responsible for

isAffectingReplace

protected boolean isAffectingReplace()

Returns whether the current event describes a well formed replace by which the current position is directly affected.

Returns:

true the current position is directly affected

Since:

3.0

adaptToInsert

protected void adaptToInsert()

Adapts the currently investigated position to an insertion.

adaptToRemove

protected void adaptToRemove()

Adapts the currently investigated position to a deletion.

adaptToReplace

protected void adaptToReplace()

Adapts the currently investigated position to the replace operation. First it checks whether the change replaces the whole range of the position. If not, it performs first the deletion of the previous text and afterwards the insertion of the new text.

notDeleted

protected boolean notDeleted()

Determines whether the currently investigated position has been deleted by the replace operation specified in the current event. If so, it deletes the position and removes it from the document's position category.

Returns:

true if position has been deleted

update

public void update(DocumentEvent event)

Description copied from interface: IPositionUpdater

Adapts positions to the change specified by the document event. It is ensured that the document's partitioning has been adapted to this document change and that all the position updaters which have a smaller index in the document's position updater list have been called.

Specified by:

update in interface IPositionUpdater

Parameters:

event - the document event describing the document change