org.apache.xml.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!
Field Summary | |
---|---|
static short | ATTRIBUTE_NODE
The node is an Attr . |
static short | CDATA_SECTION_NODE
The node is a CDATASection . |
static short | COMMENT_NODE
The node is a Comment . |
static short | DOCUMENT_FRAGMENT_NODE
The node is a DocumentFragment . |
static short | DOCUMENT_NODE
The node is a Document . |
static short | DOCUMENT_TYPE_NODE
The node is a DocumentType . |
static short | ELEMENT_NODE
The node is an Element . |
static short | ENTITY_NODE
The node is an Entity . |
static short | ENTITY_REFERENCE_NODE
The node is an EntityReference . |
static short | NAMESPACE_NODE
The node is a namespace node . |
static short | NOTATION_NODE
The node is a Notation . |
static short | NTYPES
The number of valid nodetypes. |
static int | NULL
Null node handles are represented by this value. |
static short | PROCESSING_INSTRUCTION_NODE
The node is a ProcessingInstruction . |
static short | ROOT_NODE
The node is a Root . |
static short | TEXT_NODE
The node is a Text node. |
Method Summary | |
---|---|
void | appendChild(int newChild, boolean clone, boolean cloneDepth)
Append a child to "the end of the document". |
void | appendTextChild(String str)
Append a text node child that will be constructed from a string,
to the end of the document. |
void | dispatchCharactersEvents(int nodeHandle, 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). |
void | dispatchToEvents(int nodeHandle, ContentHandler ch)
Directly create SAX parser events representing the XML content of
a DTM subtree. |
void | documentRegistration()
As the DTM is registered with the DTMManager, this method
will be called. |
void | documentRelease()
As documents are released from the DTMManager, the DTM implementation
will be notified of the event. |
int | getAttributeNode(int elementHandle, String namespaceURI, 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.
|
DTMAxisIterator | getAxisIterator(int axis)
This is a shortcut to the iterators that implement
XPath axes.
|
DTMAxisTraverser | getAxisTraverser(int axis)
This returns a stateless "traverser", that can navigate over an
XPath axis, though not in document order.
|
ContentHandler | getContentHandler()
Return this DTM's content handler, if it has one.
|
DeclHandler | getDeclHandler()
Return this DTM's DeclHandler, if it has one.
|
int | getDocument()
Given a DTM which contains only a single document,
find the Node Handle of the Document node. |
boolean | getDocumentAllDeclarationsProcessed()
Return an indication of
whether the processor has read the complete DTD. |
String | getDocumentBaseURI()
Return the base URI of the document entity. |
String | getDocumentEncoding(int nodeHandle)
Return the name of the character encoding scheme
in which the document entity is expressed.
|
int | getDocumentRoot(int nodeHandle)
Given a node handle, find the owning document node.
|
String | getDocumentStandalone(int nodeHandle)
Return an indication of the standalone status of the document,
either "yes" or "no". |
String | getDocumentSystemIdentifier(int nodeHandle)
Return the system identifier of the document entity. |
String | getDocumentTypeDeclarationPublicIdentifier()
Return the public identifier of the external subset,
normalized as described in 4.2.2 External Entities [XML]. |
String | getDocumentTypeDeclarationSystemIdentifier()
A document type declaration information item has the following properties:
1. [system identifier] The system identifier of the external subset, if
it exists. |
String | getDocumentVersion(int documentHandle)
Return a string representing the XML version of the document. |
DTDHandler | getDTDHandler()
Return this DTM's DTDHandler, if it has one.
|
int | getElementById(String elementId)
Returns the Element whose ID is given by
elementId . |
EntityResolver | getEntityResolver()
Return this DTM's EntityResolver, if it has one.
|
ErrorHandler | getErrorHandler()
Return this DTM's ErrorHandler, if it has one.
|
int | getExpandedTypeID(int nodeHandle)
Given a node handle, return an ID that represents the node's expanded name.
|
int | getExpandedTypeID(String namespace, String localName, int type)
Given an expanded name, return an ID. |
int | getFirstAttribute(int nodeHandle)
Given a node handle, get the index of the node's first attribute.
|
int | getFirstChild(int nodeHandle)
Given a node handle, get the handle of the node's first child.
|
int | getFirstNamespaceNode(int nodeHandle, boolean inScope)
Given a node handle, get the index of the node's first namespace node.
|
int | getLastChild(int nodeHandle)
Given a node handle, get the handle of the node's last child.
|
short | getLevel(int nodeHandle)
Get the depth level of this node in the tree (equals 1 for
a parentless node).
|
LexicalHandler | getLexicalHandler()
Return this DTM's lexical handler, if it has one.
|
String | getLocalName(int nodeHandle)
Given a node handle, return its DOM-style localname.
|
String | getLocalNameFromExpandedNameID(int ExpandedNameID)
Given an expanded-name ID, return the local name part.
|
String | getNamespaceFromExpandedNameID(int ExpandedNameID)
Given an expanded-name ID, return the namespace URI part.
|
String | getNamespaceURI(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.) |
int | getNextAttribute(int nodeHandle)
Given a node handle, advance to the next attribute. |
int | getNextNamespaceNode(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)
|
int | getNextSibling(int nodeHandle)
Given a node handle, advance to its next sibling. |
Node | getNode(int nodeHandle)
Return an DOM node for the given node.
|
String | getNodeName(int nodeHandle)
Given a node handle, return its DOM-style node name. |
String | getNodeNameX(int nodeHandle)
Given a node handle, return the XPath node name. |
short | getNodeType(int nodeHandle)
Given a node handle, return its DOM-style node type.
|
String | getNodeValue(int nodeHandle)
Given a node handle, return its node value. |
int | getOwnerDocument(int nodeHandle)
Given a node handle, find the owning document node. |
int | getParent(int nodeHandle)
Given a node handle, find its parent node.
|
String | getPrefix(int nodeHandle)
Given a namespace handle, return the prefix that the namespace decl is
mapping.
|
int | getPreviousSibling(int nodeHandle)
Given a node handle, find its preceeding sibling.
|
SourceLocator | getSourceLocatorFor(int node)
Get the location of a node in the source document.
|
XMLString | getStringValue(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).
|
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).
|
int | getStringValueChunkCount(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).
|
DTMAxisIterator | getTypedAxisIterator(int axis, int type)
Get an iterator that can navigate over an XPath Axis, predicated by
the extended type ID.
|
String | getUnparsedEntityURI(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]). |
boolean | hasChildNodes(int nodeHandle)
Given a node handle, test if it has child nodes.
|
boolean | isAttributeSpecified(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).
|
boolean | isCharacterElementContentWhitespace(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"). |
boolean | isDocumentAllDeclarationsProcessed(int documentHandle)
10. [all declarations processed] This property is not strictly speaking
part of the infoset of the document. |
boolean | isNodeAfter(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. |
boolean | isSupported(String feature, String version)
Tests whether DTM DOM implementation implements a specific feature and
that feature is supported by this node. |
void | migrateTo(DTMManager manager)
Migrate a DTM built with an old DTMManager to a new DTMManager.
|
boolean | needsTwoThreads() |
void | setDocumentBaseURI(String baseURI)
Set the base URI of the document entity.
|
void | setFeature(String featureId, boolean state)
Set an implementation dependent feature.
|
void | setProperty(String property, Object value)
Set a run time property for this DTM instance.
|
boolean | supportsPreStripping()
Return true if the xsl:strip-space or xsl:preserve-space was processed
during construction of the document contained in this DTM.
|
Attr
.CDATASection
.Comment
.DocumentFragment
.Document
.DocumentType
.Element
.Entity
.EntityReference
.namespace node
. Note that this is not
currently a node type defined by the DOM API.Notation
.ProcessingInstruction
.Root
.Text
node.%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).
Parameters: newChild Must be a valid new node handle. clone true if the child should be cloned into the document. cloneDepth if the clone argument is true, specifies that the clone should include all it's children.
Parameters: str Non-null reference to a string.
Parameters: nodeHandle The node ID. ch A non-null reference to a ContentHandler. normalize true if the content should be normalized according to the rules for the XPath normalize-space function.
Throws: org.xml.sax.SAXException
Parameters: nodeHandle The node ID. ch A non-null reference to a ContentHandler.
Throws: org.xml.sax.SAXException
Parameters: elementHandle Handle of the node upon which to look up this attribute. namespaceURI The namespace URI of the attribute to retrieve, or null. name The local name of the attribute to retrieve.
Returns: The attribute node handle with the specified name (
nodeName
) or DTM.NULL
if there is no such
attribute.
Parameters: axis One of Axes.ANCESTORORSELF, etc.
Returns: A DTMAxisIterator, or null if the givin axis isn't supported.
Parameters: axis One of Axes.ANCESTORORSELF, etc.
Returns: A DTMAxisIterator, or null if the givin axis isn't supported.
Returns: null if this model doesn't respond to SAX events.
Returns: null if this model doesn't respond to SAX Decl events.
Returns: int Node handle of document, or DTM.NULL if a shared DTM can not tell us which Document is currently active.
Returns: true
if all declarations were processed;
false
otherwise.
Returns: the document base URI String object or null if unknown.
Parameters: nodeHandle The node id, which can be any valid node handle.
Returns: the document encoding String object.
Parameters: nodeHandle the id of the node.
Returns: 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 Also: DTM
Parameters: nodeHandle The node id, which can be any valid node handle.
Returns: the document standalone String object, either "yes", "no", or null.
Parameters: nodeHandle The node id, which can be any valid node handle.
Returns: the system identifier String object or null if unknown.
Returns: the public identifier String object, or null if there is none.
Returns: the system identifier String object, or null if there is none.
Parameters: documentHandle the document handle
Returns: the document version String object
Returns: null if this model doesn't respond to SAX dtd events.
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.
Parameters: elementId The unique id
value for an element.
Returns: The handle of the matching element.
Returns: null if this model doesn't respond to SAX entity ref events.
Returns: null if this model doesn't respond to SAX error events.
Parameters: nodeHandle The handle to the node in question.
Returns: the expanded-name id of the node.
Returns: the expanded-name id of the node.
Parameters: nodeHandle int Handle of the node.
Returns: Handle of first attribute, or DTM.NULL to indicate none exists.
Parameters: nodeHandle int Handle of the node.
Returns: int DTM node-number of first child, or DTM.NULL to indicate none exists.
Parameters: nodeHandle handle to node, which should probably be an element node, but need not be. inScope true if all namespaces in scope should be returned, false if only the node's own namespace declarations should be returned.
Returns: handle of first namespace, or DTM.NULL to indicate none exists.
Parameters: nodeHandle int Handle of the node.
Returns: int Node-number of last child, or DTM.NULL to indicate none exists.
Parameters: nodeHandle The node id.
Returns: the number of ancestors, plus one
UNKNOWN: internal
Returns: null if this model doesn't respond to lexical SAX events.
Parameters: nodeHandle the id of the node.
Returns: String Local name of this node.
Parameters: ExpandedNameID an ID that represents an expanded-name.
Returns: String Local name of this node.
Parameters: ExpandedNameID an ID that represents an expanded-name.
Returns: String URI value of this node's namespace, or null if no namespace was resolved.
Parameters: nodeHandle the id of the node.
Returns: String URI value of this node's namespace, or null if no namespace was resolved.
Parameters: nodeHandle int Handle of the node.
Returns: int DTM node-number of the resolved attr, or DTM.NULL to indicate none exists.
Parameters: baseHandle handle to original node from where the first child was relative to (needed to return nodes in document order). namespaceHandle handle to node which must be of type NAMESPACE_NODE. NEEDSDOC @param inScope
Returns: handle of next namespace, or DTM.NULL to indicate none exists.
Parameters: nodeHandle int Handle of the node.
Returns: int Node-number of next sibling, or DTM.NULL to indicate none exists.
Parameters: nodeHandle The node ID.
Returns: A node representation of the DTM node.
Parameters: nodeHandle the id of the node.
Returns: String Name of this node, which may be an empty string. %REVIEW% Document when empty string is possible...
Parameters: nodeHandle the id of the node.
Returns: String Name of this node.
%REVIEW% Generally, returning short is false economy. Return int?
Parameters: nodeHandle The node id.
Returns: int Node type, as per the DOM's Node._NODE constants.
Parameters: nodeHandle The node id.
Returns: String Value of this node, or null if not meaningful for this node type.
Parameters: nodeHandle the id of the node.
Returns: int Node handle of owning document, or DTM.NULL if the node was a Document.
See Also: DTM
Parameters: nodeHandle the id of the node.
Returns: int Node handle of parent, or DTM.NULL to indicate none exists.
%REVIEW% Are you sure you want "" for no prefix?
Parameters: nodeHandle the id of the node.
Returns: String prefix of this node's name, or "" if no explicit namespace prefix was given.
Parameters: nodeHandle the id of the node.
Returns: int Node-number of the previous sib, or DTM.NULL to indicate none exists.
Parameters: node an int
value
Returns: a SourceLocator
value or null if no location
is available
Parameters: nodeHandle The node ID.
Returns: A string object that represents the string-value of the given node.
Parameters: nodeHandle The node ID. chunkIndex Which chunk to get. 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.
Returns: The character array buffer within which the chunk occurs, setting startAndLen's contents as a side-effect.
Parameters: nodeHandle The node ID.
Returns: number of character array chunks in the string-value of a node.
Parameters: axis type An extended type ID.
Returns: A DTMAxisIterator, or null if the givin axis isn't supported.
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.)
Parameters: name A string containing the Entity Name of the unparsed entity.
Returns: String containing the URI of the Unparsed Entity, or an empty string if no such entity exists.
%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.
Parameters: nodeHandle int Handle of the node.
Returns: int true if the given node has child nodes.
Parameters: attributeHandle The attribute handle
Returns: true
if the attribute was specified;
false
if it was defaulted or the handle doesn't
refer to an attribute node.
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
Parameters: nodeHandle the node ID.
Returns: true
if the node definitely represents whitespace in
element content; false
otherwise.
Parameters: documentHandle A node handle that must identify a document.
Returns: true
if all declarations were processed;
false
otherwise.
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)?
Parameters: firstNodeHandle DOM Node to perform position comparison on. secondNodeHandle DOM Node to perform position comparison on.
Returns: false if secondNode comes before firstNode, otherwise return true.
You can think of this as
(firstNode.documentOrderPosition <= secondNode.documentOrderPosition)
.
Parameters: feature The name of the feature to test. 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
.
Returns: Returns true
if the specified feature is
supported on this node, false
otherwise.
Parameters: manager the DTMManager
Returns: 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.
Parameters: baseURI the document base URI String object or null if unknown.
%REVIEW% Do we really expect to set features on DTMs?
Parameters: featureId A feature URL. state true if this feature should be on, false otherwise.
Parameters: property a String
value value an Object
value