Class TreeWalker

  • All Implemented Interfaces:
    javax.xml.transform.SourceLocator, PullProvider, UnfailingPullProvider, Location, org.xml.sax.Locator

    public class TreeWalker
    extends java.lang.Object
    implements UnfailingPullProvider, Location
    This implementation of the Saxon pull interface starts from any NodeInfo, and returns the events corresponding to that node and its descendants (including their attributes and namespaces). This works with any tree model: alternative implementations may be available that take advantage of particular implementations of the tree model.
    • Method Detail

      • makeTreeWalker

        public static UnfailingPullProvider makeTreeWalker​(NodeInfo startNode)
        Factory method to get a tree walker starting an a given node
        Parameters:
        startNode - the start node
        Returns:
        a PullProvider that delivers events associated with the subtree starting at the given node
      • setPipelineConfiguration

        public void setPipelineConfiguration​(PipelineConfiguration pipe)
        Set configuration information. This must only be called before any events have been read.
        Specified by:
        setPipelineConfiguration in interface PullProvider
        Parameters:
        pipe - the pipeline configuration
      • current

        public PullProvider.Event current()
        Get the event most recently returned by next(), or by other calls that change the position, for example getStringValue() and skipToMatchingEnd(). This method does not change the position of the PullProvider.
        Specified by:
        current in interface PullProvider
        Specified by:
        current in interface UnfailingPullProvider
        Returns:
        the current event
      • getAttributes

        public AttributeMap getAttributes()
        Get the attributes associated with the current element. This method must be called only after a START_ELEMENT event has been notified. The contents of the returned AttributeMap are immutable.

        Attributes may be read before or after reading the namespaces of an element, but must not be read after the first child node has been read, or after calling one of the methods skipToEnd(), getStringValue(), or getTypedValue().

        Specified by:
        getAttributes in interface PullProvider
        Specified by:
        getAttributes in interface UnfailingPullProvider
        Returns:
        an AttributeMap representing the attributes of the element that has just been notified.
      • getNamespaceDeclarations

        public NamespaceBinding[] getNamespaceDeclarations()
        Get the namespace declarations associated with the current element. This method must be called only after a START_ELEMENT event has been notified. In the case of a top-level START_ELEMENT event (that is, an element that either has no parent node, or whose parent is not included in the sequence being read), the NamespaceDeclarations object returned will contain a namespace declaration for each namespace that is in-scope for this element node. In the case of a non-top-level element, the NamespaceDeclarations will contain a set of namespace declarations and undeclarations, representing the differences between this element and its parent.

        It is permissible for this method to return namespace declarations that are redundant.

        The NamespaceDeclarations object is guaranteed to remain unchanged until the next START_ELEMENT event, but may then be overwritten. The object should not be modified by the client.

        Namespaces may be read before or after reading the attributes of an element, but must not be read after the first child node has been read, or after calling one of the methods skipToEnd(), getStringValue(), or getTypedValue().

        Specified by:
        getNamespaceDeclarations in interface PullProvider
        Specified by:
        getNamespaceDeclarations in interface UnfailingPullProvider
        Returns:
        the namespace declarations associated with the current START_ELEMENT event.
      • skipToMatchingEnd

        public PullProvider.Event skipToMatchingEnd()
        Skip the current subtree. This method may be called only immediately after a START_DOCUMENT or START_ELEMENT event. This call returns the matching END_DOCUMENT or END_ELEMENT event; the next call on next() will return the event following the END_DOCUMENT or END_ELEMENT.
        Specified by:
        skipToMatchingEnd in interface PullProvider
        Specified by:
        skipToMatchingEnd in interface UnfailingPullProvider
        Returns:
        the matching END_DOCUMENT or END_ELEMENT event
      • close

        public void close()
        Close the event reader. This indicates that no further events are required. It is not necessary to close an event reader after PullProvider.Event.END_OF_INPUT has been reported, but it is recommended to close it if reading terminates prematurely. Once an event reader has been closed, the effect of further calls on next() is undefined.
        Specified by:
        close in interface PullProvider
        Specified by:
        close in interface UnfailingPullProvider
      • getNamePool

        public NamePool getNamePool()
        Get the namePool used to lookup all name codes and namespace codes
        Returns:
        the namePool
      • getSchemaType

        public SchemaType getSchemaType()
        Get the type annotation of the current attribute or element node, or atomic value. The result of this method is undefined unless the most recent event was START_ELEMENT, START_CONTENT, ATTRIBUTE, or ATOMIC_VALUE.
        Specified by:
        getSchemaType in interface PullProvider
        Specified by:
        getSchemaType in interface UnfailingPullProvider
        Returns:
        the type code.
      • getAtomicValue

        public AtomicValue getAtomicValue()
        Get an atomic value. This call may be used only when the last event reported was ATOMIC_VALUE. This indicates that the PullProvider is reading a sequence that contains a free-standing atomic value; it is never used when reading the content of a node.
        Specified by:
        getAtomicValue in interface PullProvider
        Specified by:
        getAtomicValue in interface UnfailingPullProvider
        Returns:
        the atomic value
      • getSourceLocator

        public Location getSourceLocator()
        Get the location of the current event. For an event stream representing a real document, the location information should identify the location in the lexical XML source. For a constructed document, it should identify the location in the query or stylesheet that caused the node to be created. A value of null can be returned if no location information is available.
        Specified by:
        getSourceLocator in interface PullProvider
        Specified by:
        getSourceLocator in interface UnfailingPullProvider
        Returns:
        the SourceLocator giving the location of the current event, or null if no location information is available
      • getPublicId

        public java.lang.String getPublicId()
        Return the public identifier for the current document event.

        The return value is the public identifier of the document entity or of the external parsed entity in which the markup that triggered the event appears.

        Specified by:
        getPublicId in interface Location
        Specified by:
        getPublicId in interface org.xml.sax.Locator
        Specified by:
        getPublicId in interface javax.xml.transform.SourceLocator
        Returns:
        A string containing the public identifier, or null if none is available.
        See Also:
        getSystemId()
      • getSystemId

        public java.lang.String getSystemId()
        Return the system identifier for the current document event.

        The return value is the system identifier of the document entity or of the external parsed entity in which the markup that triggered the event appears.

        If the system identifier is a URL, the parser must resolve it fully before passing it to the application.

        Specified by:
        getSystemId in interface Location
        Specified by:
        getSystemId in interface org.xml.sax.Locator
        Specified by:
        getSystemId in interface javax.xml.transform.SourceLocator
        Returns:
        A string containing the system identifier, or null if none is available.
        See Also:
        getPublicId()
      • getLineNumber

        public int getLineNumber()
        Return the line number where the current document event ends.

        Warning: The return value from the method is intended only as an approximation for the sake of error reporting; it is not intended to provide sufficient information to edit the character content of the original XML document.

        The return value is an approximation of the line number in the document entity or external parsed entity where the markup that triggered the event appears.

        Specified by:
        getLineNumber in interface Location
        Specified by:
        getLineNumber in interface org.xml.sax.Locator
        Specified by:
        getLineNumber in interface javax.xml.transform.SourceLocator
        Returns:
        The line number, or -1 if none is available.
        See Also:
        getColumnNumber()
      • getColumnNumber

        public int getColumnNumber()
        Return the character position where the current document event ends.

        Warning: The return value from the method is intended only as an approximation for the sake of error reporting; it is not intended to provide sufficient information to edit the character content of the original XML document.

        The return value is an approximation of the column number in the document entity or external parsed entity where the markup that triggered the event appears.

        Specified by:
        getColumnNumber in interface Location
        Specified by:
        getColumnNumber in interface org.xml.sax.Locator
        Specified by:
        getColumnNumber in interface javax.xml.transform.SourceLocator
        Returns:
        The column number, or -1 if none is available.
        See Also:
        getLineNumber()
      • saveLocation

        public Location saveLocation()
        Get an immutable copy of this Location object. By default Location objects may be mutable, so they should not be saved for later use. The result of this operation holds the same location information, but in an immutable form.
        Specified by:
        saveLocation in interface Location
        Returns:
        an immutable copy (which may be the original object, if it is already immutable)