An abstract base implementation for the Document interface.
This class provides some common functionality for all Elements,
most notably it implements a locking mechanism to make document modification
thread-safe.
Creates and returns a branch element with the specified
parent and attributes. Note that the new
Element is linked to the parent Element
through Element.getParentElement(), but it is not yet added
to the parent Element as child.
Parameters:
parent - the parent Element for the new branch element
attributes - the text attributes to be installed in the new element
Creates and returns a leaf element with the specified
parent and attributes. Note that the new
Element is linked to the parent Element
through Element.getParentElement(), but it is not yet added
to the parent Element as child.
Parameters:
parent - the parent Element for the new branch element
attributes - the text attributes to be installed in the new element
Returns the thread that currently modifies this Document
if there is one, otherwise null. This can be used to
distinguish between a method call that is part of an ongoing modification
or if it is a separate modification for which a new lock must be aquired.
Returns:
the thread that currently modifies this Document
if there is one, otherwise null
Returns the default root Element of this Document.
Usual Documents only have one root element and return this.
However, there may be Document implementations that
support multiple root elements, they have to return a default root element
here.
Returns all root elements of this Document. By default
this just returns the single root element returned by
getDefaultRootElement(). Document implementations
that support multiple roots must override this method and return all roots
here.
Called to indicate that text has been inserted into this
Document. The default implementation does nothing.
This method is executed within a write lock.
Parameters:
chng - the DefaultDocumentEvent describing the change
If a DocumentFilter is installed in this document, the
corresponding method of the filter object is called. The
DocumentFilter is called even if length
is zero. This is different from replace(int,int,String,AttributeSet).
Note: When length is zero or below the call is not
forwarded to the underlying AbstractDocument.Content instance
of this document and no exception is thrown.
Called before some content gets removed from this Document.
The default implementation does nothing but may be overridden by
subclasses to modify the Document structure in response
to a remove request. The method is executed within a write lock.
Parameters:
chng - the DefaultDocumentEvent describing the change
Called to render this Document visually. It obtains a read
lock, ensuring that no changes will be made to the document
during the rendering process. It then calls the Runnable.run()
method on runnable. This method must not attempt
to modifiy the Document, since a deadlock will occur if it
tries to obtain a write lock. When the Runnable.run() method
completes (either naturally or by throwing an exception), the read lock
is released. Note that there is nothing in this method related to
the actual rendering. It could be used to execute arbitrary code within
a read lock.