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public interface LSParserFilter
LSParserFilter
s provide applications the ability to examine
nodes as they are being constructed while parsing. As each node is
examined, it may be modified or removed, or the entire parse may be
terminated early.
At the time any of the filter methods are called by the parser, the
owner Document and DOMImplementation objects exist and are accessible.
The document element is never passed to the LSParserFilter
methods, i.e. it is not possible to filter out the document element.
Document
, DocumentType
, Notation
,
Entity
, and Attr
nodes are never passed to the
acceptNode
method on the filter. The child nodes of an
EntityReference
node are passed to the filter if the
parameter "
entities" is set to false
, or if the EntityReference
node is skipped by the method LSParserFilter.acceptNode()
.
Note that, as described by the parameter "
entities", entity reference nodes to non-defined entities are never discarded and
are always passed to the filter.
All validity checking while parsing a document occurs on the source
document as it appears on the input stream, not on the DOM document as it
is built in memory. With filters, the document in memory may be a subset
of the document on the stream, and its validity may have been affected by
the filtering.
All default attributes must be present on elements when the elements
are passed to the filter methods. All other default content must be
passed to the filter methods.
DOM applications must not raise exceptions in a filter. The effect of
throwing exceptions from a filter is DOM implementation dependent.
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public static final short FILTER_ACCEPT
Accept the node.
- Field Value:
- 1
public static final short FILTER_INTERRUPT
Interrupt the normal processing of the document.
- Field Value:
- 4
public static final short FILTER_REJECT
Reject the node and its children.
- Field Value:
- 2
public static final short FILTER_SKIP
Skip this single node. The children of this node will still be considered.
- Field Value:
- 3
public short acceptNode(Node nodeArg)
This method will be called by the parser at the completion of the parsing of each node. The node and all of its descendants will exist and be complete. The parent node will also exist, although it may be incomplete, i.e. it may have additional children that have not yet been parsed. Attribute nodes are never passed to this function.
From within this method, the new node may be freely modified - children may be added or removed, text nodes modified, etc. The state of the rest of the document outside this node is not defined, and the affect of any attempt to navigate to, or to modify any other part of the document is undefined.
For validating parsers, the checks are made on the original document, before any modification by the filter. No validity checks are made on any document modifications made by the filter.
If this new node is rejected, the parser might reuse the new node and any of its descendants.
- Parameters:
nodeArg
- The newly constructed element. At the time this method is called, the element is complete - it has all of its children (and their children, recursively) and attributes, and is attached as a child to its parent.
- Returns:
FILTER_ACCEPT
if thisNode
should be included in the DOM document being built.FILTER_REJECT
if theNode
and all of its children should be rejected.FILTER_SKIP
if theNode
should be skipped and theNode
should be replaced by all the children of theNode
.FILTER_INTERRUPT
if the filter wants to stop the processing of the document. Interrupting the processing of the document does no longer guarantee that the resulting DOM tree is XML well-formed. TheNode
is accepted and will be the last completely parsed node.
public int getWhatToShow()
Tells theLSParser
what types of nodes to show to the methodLSParserFilter.acceptNode
. If a node is not shown to the filter using this attribute, it is automatically included in the DOM document being built. SeeNodeFilter
for definition of the constants. The constantsSHOW_ATTRIBUTE
,SHOW_DOCUMENT
,SHOW_DOCUMENT_TYPE
,SHOW_NOTATION
,SHOW_ENTITY
, andSHOW_DOCUMENT_FRAGMENT
are meaningless here, those nodes will never be passed toLSParserFilter.acceptNode
.
The constants used here are defined in [DOM Level 2 Traversal and Range] .
public short startElement(Element elementArg)
The parser will call this method after eachElement
start tag has been scanned, but before the remainder of theElement
is processed. The intent is to allow the element, including any children, to be efficiently skipped. Note that only element nodes are passed to thestartElement
function.
The element node passed tostartElement
for filtering will include all of the Element's attributes, but none of the children nodes. The Element may not yet be in place in the document being constructed (it may not have a parent node.)
AstartElement
filter function may access or change the attributes for the Element. Changing Namespace declarations will have no effect on namespace resolution by the parser.
For efficiency, the Element node passed to the filter may not be the same one as is actually placed in the tree if the node is accepted. And the actual node (node object identity) may be reused during the process of reading in and filtering a document.
- Parameters:
elementArg
- The newly encountered element. At the time this method is called, the element is incomplete - it will have its attributes, but no children.
- Returns:
Returning any other values will result in unspecified behavior.
FILTER_ACCEPT
if theElement
should be included in the DOM document being built.FILTER_REJECT
if theElement
and all of its children should be rejected. This return value will be ignored ifelement
is the documentElement, the documentElement cannot be rejected.FILTER_SKIP
if theElement
should be skipped. All of its children are inserted in place of the skippedElement
node. This return value will be ignored ifelement
is the documentElement, the documentElement cannot be skipped.FILTER_INTERRUPT
if the filter wants to stop the processing of the document. Interrupting the processing of the document does no longer guarantee that the resulting DOM tree is XML well-formed. TheElement
is rejected.