Package org.loboevolution.apache.xml.dtm

Interface DTM

All Known Implementing Classes:
DOM2DTM, DTMDefaultBase, DTMDefaultBaseIterators, DTMDefaultBaseTraversers
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

    Fields
    Modifier and Type
    Field
    Description
    static final short
    ATTRIBUTE_NODE
    The node is an Attr.
    static final short
    CDATA_SECTION_NODE
    The node is a CDATASection.
    static final short
    COMMENT_NODE
    The node is a Comment.
    static final short
    DOCUMENT_FRAGMENT_NODE
    The node is a DocumentFragment.
    static final short
    DOCUMENT_NODE
    The node is a Document.
    static final short
    DOCUMENT_TYPE_NODE
    The node is a DocumentType.
    static final short
    ELEMENT_NODE
    The node is an Element.
    static final short
    ENTITY_NODE
    The node is an Entity.
    static final short
    ENTITY_REFERENCE_NODE
    The node is an EntityReference.
    static final short
    NAMESPACE_NODE
    The node is a namespace node.
    static final short
    NOTATION_NODE
    The node is a Notation.
    static final short
    NTYPES
    The number of valid nodetypes.
    static final int
    NULL
    Null node handles are represented by this value.
    static final short
    PROCESSING_INSTRUCTION_NODE
    The node is a ProcessingInstruction.
    static final short
    TEXT_NODE
    The node is a Text node.

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    getAttributeNode(int elementHandle, String namespaceURI, String name)
    Retrieves an attribute node by local name and namespace URI
    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.
    int
    getDocument()
    Given a DTM which contains only a single document, find the Node Handle of the Document node.
    int
    getDocumentRoot(int nodeHandle)
    Given a node handle, find the owning document node.
    int
    getElementById(String elementId)
    Returns the Element whose ID is given by elementId.
    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.
    String
    getLocalName(int nodeHandle)
    Given a node handle, return its DOM-style localname.
    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.
    XString
    getStringValue(int nodeHandle)
    Get the string-value of a node as a String object (see ... for the definition of a node's string-value).
    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.

  • Field Details

    • NULL

      static final int NULL
      Null node handles are represented by this value.
      See Also:

    • ELEMENT_NODE

      static final short ELEMENT_NODE
      The node is an Element.
      See Also:

    • ATTRIBUTE_NODE

      static final short ATTRIBUTE_NODE
      The node is an Attr.
      See Also:

    • TEXT_NODE

      static final short TEXT_NODE
      The node is a Text node.
      See Also:

    • CDATA_SECTION_NODE

      static final short CDATA_SECTION_NODE
      The node is a CDATASection.
      See Also:

    • ENTITY_REFERENCE_NODE

      static final short ENTITY_REFERENCE_NODE
      The node is an EntityReference.
      See Also:

    • ENTITY_NODE

      static final short ENTITY_NODE
      The node is an Entity.
      See Also:

    • PROCESSING_INSTRUCTION_NODE

      static final short PROCESSING_INSTRUCTION_NODE
      The node is a ProcessingInstruction.
      See Also:

    • COMMENT_NODE

      static final short COMMENT_NODE
      The node is a Comment.
      See Also:

    • DOCUMENT_NODE

      static final short DOCUMENT_NODE
      The node is a Document.
      See Also:

    • DOCUMENT_TYPE_NODE

      static final short DOCUMENT_TYPE_NODE
      The node is a DocumentType.
      See Also:

    • DOCUMENT_FRAGMENT_NODE

      static final short DOCUMENT_FRAGMENT_NODE
      The node is a DocumentFragment.
      See Also:

    • NOTATION_NODE

      static final short NOTATION_NODE
      The node is a Notation.
      See Also:

    • NAMESPACE_NODE

      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.
      See Also:

    • NTYPES

      static final short NTYPES
      The number of valid nodetypes.
      See Also:

  • Method Details

    • getAxisTraverser

      DTMAxisTraverser getAxisTraverser(int axis)
      This returns a stateless "traverser", that can navigate over an XPath axis, though not in document order.
      Parameters:
      axis - One of Axes.ANCESTORORSELF, etc.
      Returns:
      A DTMAxisIterator, or null if the givin axis isn't supported.

    • getAxisIterator

      DTMAxisIterator getAxisIterator(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()).
      Parameters:
      axis - One of Axes.ANCESTORORSELF, etc.
      Returns:
      A DTMAxisIterator, or null if the givin axis isn't supported.

    • getFirstChild

      int getFirstChild(int nodeHandle)
      Given a node handle, get the handle of the node's first child.
      Parameters:
      nodeHandle - int Handle of the node.
      Returns:
      int DTM node-number of first child, or DTM.NULL to indicate none exists.

    • getLastChild

      int getLastChild(int nodeHandle)
      Given a node handle, get the handle of the node's last child.
      Parameters:
      nodeHandle - int Handle of the node.
      Returns:
      int Node-number of last child, or DTM.NULL to indicate none exists.

    • getAttributeNode

      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.

      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.

    • getFirstAttribute

      int getFirstAttribute(int nodeHandle)
      Given a node handle, get the index of the node's first attribute.
      Parameters:
      nodeHandle - int Handle of the node.
      Returns:
      Handle of first attribute, or DTM.NULL to indicate none exists.

    • getFirstNamespaceNode

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

    • getNextSibling

      int getNextSibling(int nodeHandle)
      Given a node handle, advance to its next sibling.
      Parameters:
      nodeHandle - int Handle of the node.
      Returns:
      int Node-number of next sibling, or DTM.NULL to indicate none exists.

    • getPreviousSibling

      int getPreviousSibling(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.
      Parameters:
      nodeHandle - the id of the node.
      Returns:
      int Node-number of the previous sib, or DTM.NULL to indicate none exists.

    • getNextAttribute

      int getNextAttribute(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.
      Parameters:
      nodeHandle - int Handle of the node.
      Returns:
      int DTM node-number of the resolved attr, or DTM.NULL to indicate none exists.

    • getNextNamespaceNode

      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)
      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.

    • getParent

      int getParent(int nodeHandle)
      Given a node handle, find its parent node.
      Parameters:
      nodeHandle - the id of the node.
      Returns:
      int Node handle of parent, or DTM.NULL to indicate none exists.

    • getDocument

      int getDocument()
      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.
      Returns:
      int Node handle of document, or DTM.NULL if a shared DTM can not tell us which Document is currently active.

    • getOwnerDocument

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

    • getDocumentRoot

      int getDocumentRoot(int nodeHandle)
      Given a node handle, find the owning document node.
      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:

    • getStringValue

      XString getStringValue(int nodeHandle)
      Get the string-value of a node as a String object (see ... for the definition of a node's string-value).
      Parameters:
      nodeHandle - The node ID.
      Returns:
      A string object that represents the string-value of the given node.

    • getExpandedTypeID

      int getExpandedTypeID(int nodeHandle)
      Given a node handle, return an ID that represents the node's expanded name.
      Parameters:
      nodeHandle - The handle to the node in question.
      Returns:
      the expanded-name id of the node.

    • getExpandedTypeID

      int getExpandedTypeID(String namespace, 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.

      NEEDSDOC @param namespace NEEDSDOC @param localName NEEDSDOC @param type

      Returns:
      the expanded-name id of the node.

    • getNodeName

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

    • getNodeNameX

      String getNodeNameX(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.
      Parameters:
      nodeHandle - the id of the node.
      Returns:
      String Name of this node.

    • getLocalName

      String getLocalName(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)
      Parameters:
      nodeHandle - the id of the node.
      Returns:
      String Local name of this node.

    • getPrefix

      String getPrefix(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).

      %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.

    • getNamespaceURI

      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.)
      Parameters:
      nodeHandle - the id of the node.
      Returns:
      String URI value of this node's namespace, or null if no namespace was resolved.

    • getNodeValue

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

      Parameters:
      nodeHandle - The node id.
      Returns:
      String Value of this node, or null if not meaningful for this node type.

    • getNodeType

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

      %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.

    • getElementById

      int getElementById(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.

      Parameters:
      elementId - The unique id value for an element.
      Returns:
      The handle of the matching element.

    • isNodeAfter

      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. 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)?

      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) .

    • getNode

      Node getNode(int nodeHandle)
      Return an DOM node for the given node.
      Parameters:
      nodeHandle - The node ID.
      Returns:
      A node representation of the DTM node.