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DTM.javaAPI DocJava SE 5 API35750Fri Aug 26 14:56:00 BST 2005com.sun.org.apache.xml.internal.dtm

DTM

public interface DTM
DTM is an XML document model expressed as a table rather than an object tree. It attempts to provide an interface to a parse tree that has very little object creation. (DTM implementations may also support incremental construction of the model, but that's hidden from the DTM API.)

Nodes in the DTM are identified by integer "handles". A handle must be unique within a process, and carries both node identification and document identification. It must be possible to compare two handles (and thus their nodes) for identity with "==".

Namespace URLs, local-names, and expanded-names can all be represented by and tested as integer ID values. An expanded name represents (and may or may not directly contain) a combination of the URL ID, and the local-name ID. Note that the namespace URL id can be 0, which should have the meaning that the namespace is null. For consistancy, zero should not be used for a local-name index.

Text content of a node is represented by an index and length, permitting efficient storage such as a shared FastStringBuffer.

The model of the tree, as well as the general navigation model, is that of XPath 1.0, for the moment. The model will eventually be adapted to match the XPath 2.0 data model, XML Schema, and InfoSet.

DTM does _not_ directly support the W3C's Document Object Model. However, it attempts to come close enough that an implementation of DTM can be created that wraps a DOM and vice versa.

Please Note: The DTM API is still Subject To Change. This wouldn't affect most users, but might require updating some extensions.

The largest change being contemplated is a reconsideration of the Node Handle representation. We are still not entirely sure that an integer packed with two numeric subfields is really the best solution. It has been suggested that we move up to a Long, to permit more nodes per document without having to reduce the number of slots in the DTMManager. There's even been a proposal that we replace these integers with "cursor" objects containing the internal node id and a pointer to the actual DTM object; this might reduce the need to continuously consult the DTMManager to retrieve the latter, and might provide a useful "hook" back into normal Java heap management. But changing this datatype would have huge impact on Xalan's internals -- especially given Java's lack of C-style typedefs -- so we won't cut over unless we're convinced the new solution really would be an improvement!

Fields Summary
public static final int
NULL
Null node handles are represented by this value.
public static final short
ROOT_NODE
The node is a Root.
public static final short
ELEMENT_NODE
The node is an Element.
public static final short
ATTRIBUTE_NODE
The node is an Attr.
public static final short
TEXT_NODE
The node is a Text node.
public static final short
CDATA_SECTION_NODE
The node is a CDATASection.
public static final short
ENTITY_REFERENCE_NODE
The node is an EntityReference.
public static final short
ENTITY_NODE
The node is an Entity.
public static final short
PROCESSING_INSTRUCTION_NODE
The node is a ProcessingInstruction.
public static final short
COMMENT_NODE
The node is a Comment.
public static final short
DOCUMENT_NODE
The node is a Document.
public static final short
DOCUMENT_TYPE_NODE
The node is a DocumentType.
public static final short
DOCUMENT_FRAGMENT_NODE
The node is a DocumentFragment.
public static final short
NOTATION_NODE
The node is a Notation.
public static final short
NAMESPACE_NODE
The node is a namespace node. Note that this is not currently a node type defined by the DOM API.
public static final short
NTYPES
The number of valid nodetypes.
Constructors Summary
Methods Summary
public voidappendChild(int newChild, boolean clone, boolean cloneDepth)
Append a child to "the end of the document". Please note that the node is always cloned in a base DTM, since our basic behavior is immutable so nodes can't be removed from their previous location.

%REVIEW% DTM maintains an insertion cursor which performs a depth-first tree walk as nodes come in, and this operation is really equivalent to: insertionCursor.appendChild(document.importNode(newChild))) where the insert point is the last element that was appended (or the last one popped back to by an end-element operation).

param
newChild Must be a valid new node handle.
param
clone true if the child should be cloned into the document.
param
cloneDepth if the clone argument is true, specifies that the clone should include all it's children.

public voidappendTextChild(java.lang.String str)
Append a text node child that will be constructed from a string, to the end of the document. Behavior is otherwise like appendChild().

param
str Non-null reference to a string.

public voiddispatchCharactersEvents(int nodeHandle, org.xml.sax.ContentHandler ch, boolean normalize)
Directly call the characters method on the passed ContentHandler for the string-value of the given node (see http://www.w3.org/TR/xpath#data-model for the definition of a node's string-value). Multiple calls to the ContentHandler's characters methods may well occur for a single call to this method.

param
nodeHandle The node ID.
param
ch A non-null reference to a ContentHandler.
param
normalize true if the content should be normalized according to the rules for the XPath normalize-space function.
throws
org.xml.sax.SAXException

public voiddispatchToEvents(int nodeHandle, org.xml.sax.ContentHandler ch)
Directly create SAX parser events representing the XML content of a DTM subtree. This is a "serialize" operation.

param
nodeHandle The node ID.
param
ch A non-null reference to a ContentHandler.
throws
org.xml.sax.SAXException

public voiddocumentRegistration()
As the DTM is registered with the DTMManager, this method will be called. This will give the DTM implementation a chance to initialize any subsystems that are required to build the DTM

public voiddocumentRelease()
As documents are released from the DTMManager, the DTM implementation will be notified of the event. This will allow the DTM implementation to shutdown any subsystem activity that may of been assoiated with the active DTM Implementation.

public intgetAttributeNode(int elementHandle, java.lang.String namespaceURI, java.lang.String name)
Retrieves an attribute node by local name and namespace URI %TBD% Note that we currently have no way to support the DOM's old getAttribute() call, which accesses only the qname.

param
elementHandle Handle of the node upon which to look up this attribute.
param
namespaceURI The namespace URI of the attribute to retrieve, or null.
param
name The local name of the attribute to retrieve.
return
The attribute node handle with the specified name ( nodeName) or DTM.NULL if there is no such attribute.

public com.sun.org.apache.xml.internal.dtm.DTMAxisIteratorgetAxisIterator(int axis)
This is a shortcut to the iterators that implement XPath axes. Returns a bare-bones iterator that must be initialized with a start node (using iterator.setStartNode()).

param
axis One of Axes.ANCESTORORSELF, etc.
return
A DTMAxisIterator, or null if the givin axis isn't supported.

public com.sun.org.apache.xml.internal.dtm.DTMAxisTraversergetAxisTraverser(int axis)
This returns a stateless "traverser", that can navigate over an XPath axis, though not in document order.

param
axis One of Axes.ANCESTORORSELF, etc.
return
A DTMAxisIterator, or null if the givin axis isn't supported.

public org.xml.sax.ContentHandlergetContentHandler()
Return this DTM's content handler, if it has one.

return
null if this model doesn't respond to SAX events.

public org.xml.sax.DTDHandlergetDTDHandler()
Return this DTM's DTDHandler, if it has one.

return
null if this model doesn't respond to SAX dtd events.

public org.xml.sax.ext.DeclHandlergetDeclHandler()
Return this DTM's DeclHandler, if it has one.

return
null if this model doesn't respond to SAX Decl events.

public intgetDocument()
Given a DTM which contains only a single document, find the Node Handle of the Document node. Note that if the DTM is configured so it can contain multiple documents, this call will return the Document currently under construction -- but may return null if it's between documents. Generally, you should use getOwnerDocument(nodeHandle) or getDocumentRoot(nodeHandle) instead.

return
int Node handle of document, or DTM.NULL if a shared DTM can not tell us which Document is currently active.

public booleangetDocumentAllDeclarationsProcessed()
Return an indication of whether the processor has read the complete DTD. Its value is a boolean. If it is false, then certain properties (indicated in their descriptions below) may be unknown. If it is true, those properties are never unknown.

return
true if all declarations were processed; false otherwise.

public java.lang.StringgetDocumentBaseURI()
Return the base URI of the document entity. If it is not known (because the document was parsed from a socket connection or from standard input, for example), the value of this property is unknown.

return
the document base URI String object or null if unknown.

public java.lang.StringgetDocumentEncoding(int nodeHandle)
Return the name of the character encoding scheme in which the document entity is expressed.

param
nodeHandle The node id, which can be any valid node handle.
return
the document encoding String object.

public intgetDocumentRoot(int nodeHandle)
Given a node handle, find the owning document node.

param
nodeHandle the id of the node.
return
int Node handle of owning document, or the node itself if it was a Document. (Note difference from DOM, where getOwnerDocument returns null for the Document node.)
see
getOwnerDocument(int nodeHandle)

public java.lang.StringgetDocumentStandalone(int nodeHandle)
Return an indication of the standalone status of the document, either "yes" or "no". This property is derived from the optional standalone document declaration in the XML declaration at the beginning of the document entity, and has no value if there is no standalone document declaration.

param
nodeHandle The node id, which can be any valid node handle.
return
the document standalone String object, either "yes", "no", or null.

public java.lang.StringgetDocumentSystemIdentifier(int nodeHandle)
Return the system identifier of the document entity. If it is not known, the value of this property is null.

param
nodeHandle The node id, which can be any valid node handle.
return
the system identifier String object or null if unknown.

public java.lang.StringgetDocumentTypeDeclarationPublicIdentifier()
Return the public identifier of the external subset, normalized as described in 4.2.2 External Entities [XML]. If there is no external subset or if it has no public identifier, this property has no value.

param
the document type declaration handle
return
the public identifier String object, or null if there is none.

public java.lang.StringgetDocumentTypeDeclarationSystemIdentifier()
A document type declaration information item has the following properties: 1. [system identifier] The system identifier of the external subset, if it exists. Otherwise this property has no value.

return
the system identifier String object, or null if there is none.

public java.lang.StringgetDocumentVersion(int documentHandle)
Return a string representing the XML version of the document. This property is derived from the XML declaration optionally present at the beginning of the document entity, and has no value if there is no XML declaration.

param
the document handle NEEDSDOC @param documentHandle
return
the document version String object

public intgetElementById(java.lang.String elementId)
Returns the Element whose ID is given by elementId. If no such element exists, returns DTM.NULL. Behavior is not defined if more than one element has this ID. Attributes (including those with the name "ID") are not of type ID unless so defined by DTD/Schema information available to the DTM implementation. Implementations that do not know whether attributes are of type ID or not are expected to return DTM.NULL.

%REVIEW% Presumably IDs are still scoped to a single document, and this operation searches only within a single document, right? Wouldn't want collisions between DTMs in the same process.

param
elementId The unique id value for an element.
return
The handle of the matching element.

public org.xml.sax.EntityResolvergetEntityResolver()
Return this DTM's EntityResolver, if it has one.

return
null if this model doesn't respond to SAX entity ref events.

public org.xml.sax.ErrorHandlergetErrorHandler()
Return this DTM's ErrorHandler, if it has one.

return
null if this model doesn't respond to SAX error events.

public intgetExpandedTypeID(int nodeHandle)
Given a node handle, return an ID that represents the node's expanded name.

param
nodeHandle The handle to the node in question.
return
the expanded-name id of the node.

public intgetExpandedTypeID(java.lang.String namespace, java.lang.String localName, int type)
Given an expanded name, return an ID. If the expanded-name does not exist in the internal tables, the entry will be created, and the ID will be returned. Any additional nodes that are created that have this expanded name will use this ID.

param
nodeHandle The handle to the node in question. NEEDSDOC @param namespace NEEDSDOC @param localName NEEDSDOC @param type
return
the expanded-name id of the node.

public intgetFirstAttribute(int nodeHandle)
Given a node handle, get the index of the node's first attribute.

param
nodeHandle int Handle of the node.
return
Handle of first attribute, or DTM.NULL to indicate none exists.

public intgetFirstChild(int nodeHandle)
Given a node handle, get the handle of the node's first child.

param
nodeHandle int Handle of the node.
return
int DTM node-number of first child, or DTM.NULL to indicate none exists.

public intgetFirstNamespaceNode(int nodeHandle, boolean inScope)
Given a node handle, get the index of the node's first namespace node.

param
nodeHandle handle to node, which should probably be an element node, but need not be.
param
inScope true if all namespaces in scope should be returned, false if only the node's own namespace declarations should be returned.
return
handle of first namespace, or DTM.NULL to indicate none exists.

public intgetLastChild(int nodeHandle)
Given a node handle, get the handle of the node's last child.

param
nodeHandle int Handle of the node.
return
int Node-number of last child, or DTM.NULL to indicate none exists.

public shortgetLevel(int nodeHandle)
Get the depth level of this node in the tree (equals 1 for a parentless node).

param
nodeHandle The node id.
return
the number of ancestors, plus one
xsl.usage
internal

public org.xml.sax.ext.LexicalHandlergetLexicalHandler()
Return this DTM's lexical handler, if it has one. %REVIEW% Should this return null if constrution already done/begun?

return
null if this model doesn't respond to lexical SAX events.

public java.lang.StringgetLocalName(int nodeHandle)
Given a node handle, return its DOM-style localname. (As defined in Namespaces, this is the portion of the name after the prefix, if present, or the whole node name if no prefix exists)

param
nodeHandle the id of the node.
return
String Local name of this node.

public java.lang.StringgetLocalNameFromExpandedNameID(int ExpandedNameID)
Given an expanded-name ID, return the local name part.

param
ExpandedNameID an ID that represents an expanded-name.
return
String Local name of this node.

public java.lang.StringgetNamespaceFromExpandedNameID(int ExpandedNameID)
Given an expanded-name ID, return the namespace URI part.

param
ExpandedNameID an ID that represents an expanded-name.
return
String URI value of this node's namespace, or null if no namespace was resolved.

public java.lang.StringgetNamespaceURI(int nodeHandle)
Given a node handle, return its DOM-style namespace URI (As defined in Namespaces, this is the declared URI which this node's prefix -- or default in lieu thereof -- was mapped to.)

param
postition int Handle of the node.
param
nodeHandle the id of the node.
return
String URI value of this node's namespace, or null if no namespace was resolved.

public intgetNextAttribute(int nodeHandle)
Given a node handle, advance to the next attribute. If an element, we advance to its first attribute; if an attr, we advance to the next attr of the same element.

param
nodeHandle int Handle of the node.
return
int DTM node-number of the resolved attr, or DTM.NULL to indicate none exists.

public intgetNextNamespaceNode(int baseHandle, int namespaceHandle, boolean inScope)
Given a namespace handle, advance to the next namespace in the same scope (local or local-plus-inherited, as selected by getFirstNamespaceNode)

param
baseHandle handle to original node from where the first child was relative to (needed to return nodes in document order).
param
namespaceHandle handle to node which must be of type NAMESPACE_NODE. NEEDSDOC @param inScope
return
handle of next namespace, or DTM.NULL to indicate none exists.

public intgetNextSibling(int nodeHandle)
Given a node handle, advance to its next sibling.

param
nodeHandle int Handle of the node.
return
int Node-number of next sibling, or DTM.NULL to indicate none exists.

public org.w3c.dom.NodegetNode(int nodeHandle)
Return an DOM node for the given node.

param
nodeHandle The node ID.
return
A node representation of the DTM node.

public java.lang.StringgetNodeName(int nodeHandle)
Given a node handle, return its DOM-style node name. This will include names such as #text or #document.

param
nodeHandle the id of the node.
return
String Name of this node, which may be an empty string. %REVIEW% Document when empty string is possible...

public java.lang.StringgetNodeNameX(int nodeHandle)
Given a node handle, return the XPath node name. This should be the name as described by the XPath data model, NOT the DOM-style name.

param
nodeHandle the id of the node.
return
String Name of this node.

public shortgetNodeType(int nodeHandle)
Given a node handle, return its DOM-style node type.

%REVIEW% Generally, returning short is false economy. Return int?

param
nodeHandle The node id.
return
int Node type, as per the DOM's Node._NODE constants.

public java.lang.StringgetNodeValue(int nodeHandle)
Given a node handle, return its node value. This is mostly as defined by the DOM, but may ignore some conveniences.

param
nodeHandle The node id.
return
String Value of this node, or null if not meaningful for this node type.

public intgetOwnerDocument(int nodeHandle)
Given a node handle, find the owning document node. This version mimics the behavior of the DOM call by the same name.

param
nodeHandle the id of the node.
return
int Node handle of owning document, or DTM.NULL if the node was a Document.
see
getDocumentRoot(int nodeHandle)

public intgetParent(int nodeHandle)
Given a node handle, find its parent node.

param
nodeHandle the id of the node.
return
int Node handle of parent, or DTM.NULL to indicate none exists.

public java.lang.StringgetPrefix(int nodeHandle)
Given a namespace handle, return the prefix that the namespace decl is mapping. Given a node handle, return the prefix used to map to the namespace. (As defined in Namespaces, this is the portion of the name before any colon character).

param
postition int Handle of the node.

%REVIEW% Are you sure you want "" for no prefix?

param
nodeHandle the id of the node.
return
String prefix of this node's name, or "" if no explicit namespace prefix was given.

public intgetPreviousSibling(int nodeHandle)
Given a node handle, find its preceeding sibling. WARNING: DTM implementations may be asymmetric; in some, this operation has been resolved by search, and is relatively expensive.

param
nodeHandle the id of the node.
return
int Node-number of the previous sib, or DTM.NULL to indicate none exists.

public javax.xml.transform.SourceLocatorgetSourceLocatorFor(int node)
Get the location of a node in the source document.

param
node an int value
return
a SourceLocator value or null if no location is available

public com.sun.org.apache.xml.internal.utils.XMLStringgetStringValue(int nodeHandle)
Get the string-value of a node as a String object (see http://www.w3.org/TR/xpath#data-model for the definition of a node's string-value).

param
nodeHandle The node ID.
return
A string object that represents the string-value of the given node.

public char[]getStringValueChunk(int nodeHandle, int chunkIndex, int[] startAndLen)
Get a character array chunk in the string-value of a node. (see http://www.w3.org/TR/xpath#data-model for the definition of a node's string-value). Note that a single text node may have multiple text chunks.

param
nodeHandle The node ID.
param
chunkIndex Which chunk to get.
param
startAndLen A two-integer array which, upon return, WILL BE FILLED with values representing the chunk's start position within the returned character buffer and the length of the chunk.
return
The character array buffer within which the chunk occurs, setting startAndLen's contents as a side-effect.

public intgetStringValueChunkCount(int nodeHandle)
Get number of character array chunks in the string-value of a node. (see http://www.w3.org/TR/xpath#data-model for the definition of a node's string-value). Note that a single text node may have multiple text chunks.

param
nodeHandle The node ID.
return
number of character array chunks in the string-value of a node.

public com.sun.org.apache.xml.internal.dtm.DTMAxisIteratorgetTypedAxisIterator(int axis, int type)
Get an iterator that can navigate over an XPath Axis, predicated by the extended type ID.

param
axis
param
type An extended type ID.
return
A DTMAxisIterator, or null if the givin axis isn't supported.

public java.lang.StringgetUnparsedEntityURI(java.lang.String name)
The getUnparsedEntityURI function returns the URI of the unparsed entity with the specified name in the same document as the context node (see [3.3 Unparsed Entities]). It returns the empty string if there is no such entity.

XML processors may choose to use the System Identifier (if one is provided) to resolve the entity, rather than the URI in the Public Identifier. The details are dependent on the processor, and we would have to support some form of plug-in resolver to handle this properly. Currently, we simply return the System Identifier if present, and hope that it a usable URI or that our caller can map it to one. %REVIEW% Resolve Public Identifiers... or consider changing function name.

If we find a relative URI reference, XML expects it to be resolved in terms of the base URI of the document. The DOM doesn't do that for us, and it isn't entirely clear whether that should be done here; currently that's pushed up to a higher level of our application. (Note that DOM Level 1 didn't store the document's base URI.) %REVIEW% Consider resolving Relative URIs.

(The DOM's statement that "An XML processor may choose to completely expand entities before the structure model is passed to the DOM" refers only to parsed entities, not unparsed, and hence doesn't affect this function.)

param
name A string containing the Entity Name of the unparsed entity.
return
String containing the URI of the Unparsed Entity, or an empty string if no such entity exists.

public booleanhasChildNodes(int nodeHandle)
Given a node handle, test if it has child nodes.

%REVIEW% This is obviously useful at the DOM layer, where it would permit testing this without having to create a proxy node. It's less useful in the DTM API, where (dtm.getFirstChild(nodeHandle)!=DTM.NULL) is just as fast and almost as self-evident. But it's a convenience, and eases porting of DOM code to DTM.

param
nodeHandle int Handle of the node.
return
int true if the given node has child nodes.

public booleanisAttributeSpecified(int attributeHandle)
5. [specified] A flag indicating whether this attribute was actually specified in the start-tag of its element, or was defaulted from the DTD (or schema).

param
the attribute handle NEEDSDOC @param attributeHandle
return
true if the attribute was specified; false if it was defaulted or the handle doesn't refer to an attribute node.

public booleanisCharacterElementContentWhitespace(int nodeHandle)
2. [element content whitespace] A boolean indicating whether a text node represents white space appearing within element content (see [XML], 2.10 "White Space Handling"). Note that validating XML processors are required by XML 1.0 to provide this information... but that DOM Level 2 did not support it, since it depends on knowledge of the DTD which DOM2 could not guarantee would be available.

If there is no declaration for the containing element, an XML processor must assume that the whitespace could be meaningful and return false. If no declaration has been read, but the [all declarations processed] property of the document information item is false (so there may be an unread declaration), then the value of this property is indeterminate for white space characters and should probably be reported as false. It is always false for text nodes that contain anything other than (or in addition to) white space.

Note too that it always returns false for non-Text nodes.

%REVIEW% Joe wants to rename this isWhitespaceInElementContent() for clarity

param
nodeHandle the node ID.
return
true if the node definitely represents whitespace in element content; false otherwise.

public booleanisDocumentAllDeclarationsProcessed(int documentHandle)
10. [all declarations processed] This property is not strictly speaking part of the infoset of the document. Rather it is an indication of whether the processor has read the complete DTD. Its value is a boolean. If it is false, then certain properties (indicated in their descriptions below) may be unknown. If it is true, those properties are never unknown.

param
the document handle
param
documentHandle A node handle that must identify a document.
return
true if all declarations were processed; false otherwise.

public booleanisNodeAfter(int firstNodeHandle, int secondNodeHandle)
Figure out whether nodeHandle2 should be considered as being later in the document than nodeHandle1, in Document Order as defined by the XPath model. This may not agree with the ordering defined by other XML applications.

There are some cases where ordering isn't defined, and neither are the results of this function -- though we'll generally return true.

%REVIEW% Make sure this does the right thing with attribute nodes!!!

%REVIEW% Consider renaming for clarity. Perhaps isDocumentOrder(a,b)?

param
firstNodeHandle DOM Node to perform position comparison on.
param
secondNodeHandle DOM Node to perform position comparison on.
return
false if secondNode comes before firstNode, otherwise return true. You can think of this as (firstNode.documentOrderPosition <= secondNode.documentOrderPosition).

public booleanisSupported(java.lang.String feature, java.lang.String version)
Tests whether DTM DOM implementation implements a specific feature and that feature is supported by this node.

param
feature The name of the feature to test.
param
version This is the version number of the feature to test. If the version is not specified, supporting any version of the feature will cause the method to return true.
return
Returns true if the specified feature is supported on this node, false otherwise.

public voidmigrateTo(com.sun.org.apache.xml.internal.dtm.DTMManager manager)
Migrate a DTM built with an old DTMManager to a new DTMManager. After the migration, the new DTMManager will treat the DTM as one that is built by itself. This is used to support DTM sharing between multiple transformations.

param
manager the DTMManager

public booleanneedsTwoThreads()

return
true iff we're building this model incrementally (eg we're partnered with a CoroutineParser) and thus require that the transformation and the parse run simultaneously. Guidance to the DTMManager.

public voidsetDocumentBaseURI(java.lang.String baseURI)
Set the base URI of the document entity.

param
baseURI the document base URI String object or null if unknown.

public voidsetFeature(java.lang.String featureId, boolean state)
Set an implementation dependent feature.

%REVIEW% Do we really expect to set features on DTMs?

param
featureId A feature URL.
param
state true if this feature should be on, false otherwise.

public voidsetProperty(java.lang.String property, java.lang.Object value)
Set a run time property for this DTM instance.

param
property a String value
param
value an Object value

public booleansupportsPreStripping()
Return true if the xsl:strip-space or xsl:preserve-space was processed during construction of the document contained in this DTM. NEEDSDOC ($objectName$) @return