Package net.sf.saxon.event

package net.sf.saxon.event

This package provides support for push pipeline processing based on the Receiver interface and its implementation classes. The classes are mainly for internal use, but are available for use in advanced applications. The classes provided feed SAX-like events from one tree to another. Some of these classes are associated with serializing the output of a stylesheet, but there are also classes for building a tree from a stream of events, for stripping whitespace, and so on.

The Receiver interface defines a class that accepts a stream of events, with one method defined for each kind of event. The events are modelled on the design of SAX, but adapted to the XPath data model and to the use of Saxon's NamePool. Attributes and namespaces are notified individually after the start of the relevant element. Many of the classes in this package are implementations of the Receiver interface.

The immediate output of node constructors in a query or stylesheet goes to a Outputter. When constructing the content of an element, a ComplexContentOutputter is used; when constructing the content of a node such as a text node or attribute, a SequenceOutputter is used instead.

The final destination of the push pipeline is sometimes a serializer, and sometimes a tree builder. The final serialization classes are subclasses of Emitter, but some of the serialization work (such as indentation or application of character maps) is done by other classes on the pipeline. These are generally constructed by extending the ProxyReceiver class.

The Emitter is an abstract implementation of the Receiver interface. As well as supporting the Receiver interface, it provides methods for controlling the destination of serialized output (a Writer or OutputStream) and for setting serialization properties (in a Properties object). In practice nearly all the implementations of Receiver are currently subclasses of Emitter, but this may change in the future.

The package includes emitters for the standard output methods xml, html, and text, and proxy emitters to allow a sequence of filters to be applied to the output.

The class ContentHandlerProxy allows events to be converted into standard SAX events and sent to a SAX2 ContentHandler. Similarly, the class ProxyReceiver acts as a ContentHandler, accepting SAX2 events and feeding them into a Receiver pipeline.

The class Builder is a Receiver that constructs a tree representation of the document in memory. There are two subclasses for Saxon's two native tree models. Other classes such as a Stripper and a NamespaceReducer are used to modify the document by adding filters to the pipeline.

Saxon's schema validator and serializer are both implemented using this push pipeline model. The classes that perform schema validation are part of package: com.saxonica.ee.validate, while the serialization classes are in net.sf.saxon.serialize.

Related Packages

Package	Description
net.sf.saxon	This is the top-level package containing the code used to build Saxon-HE.

Class	Description
Builder	The abstract Builder class is responsible for taking a stream of SAX events and constructing a Document tree.
BuilderMonitor	A BuilderMonitor can be inserted into a pipeline immediately in front of a Builder.
CheckSumFilter	A filter to go on a Receiver pipeline and calculate a checksum of the data passing through the pipeline.
CloseNotifier	A receiver that performs specified actions when closed
CommentStripper	The CommentStripper class is a filter that removes all comments and processing instructions.
ComplexContentOutputter	This class is used for generating complex content, that is, the content of an element or document node.
ContentHandlerProxy	A ContentHandlerProxy is a Receiver that converts events into the form expected by an underlying SAX2 ContentHandler.
ContentHandlerProxy.ContentHandlerProxyTraceListener	Create a TraceListener that will collect information about the current location in the source document.
ContentHandlerProxyLocator	Implementation of the SAX Locator interface, used to supply location information to the ContentHandler.
CopyInformee	A CopyInformee is an agent that receives extra information while a tree is being copied.
CopyNamespaceSensitiveException	Exception indicating that an attempt was made to copy namespace-sensitive content without copying its associated namespaces
DocumentValidator	DocumentValidator checks that a document is well-formed: specifically, that it contains a single element node child and no text node children.
Event	An event is an object representing one of the events that can be passed to a receiver: for example, a startElement, endElement, characters, or comment event.
Event.Append	Event representing an arbitrary item being sent to the event stream in composed form.
Event.Comment	Event representing a comment node
Event.EndDocument	Event representing end of document
Event.EndElement	Event representing the end of an element
Event.ProcessingInstruction	Event representing a processing instruction node
Event.StartDocument	Event representing start of document
Event.StartElement	Event representing the start of an element (including attributes or namespaces)
Event.Text	Event representing a text node
EventBuffer	An EventBuffer is a receiver of events that records the events in memory for subsequent replay.
EventMonitor	An EventMonitor is a filter that passes all events down the pipeline unchanged, keeping a note of whether any data has passed through the filter.
EventSource	An implementation of the JAXP Source class that supplies a document in the form of a stream of push events sent to a Receiver
FilterFactory	Factory class to create a ProxyReceiver which filters events on a push pipeline
IDFilter	IDFilter is a ProxyReceiver that extracts the subtree of a document rooted at the element with a given ID value.
IgnorableWhitespaceStripper	The IgnorableWhitespaceStripper removes whitespace text nodes belonging to elements whose schema-defined type defines element-only content
LocationCopier	A Receiver that can be inserted into an event pipeline to copy location information.
NamePoolConverter	This class is a filter that passes all Receiver events through unchanged, except that it changes namecodes to allow for the source and the destination using different NamePools.
NamespaceDifferencer	NamespaceDifferencer is a ProxyReceiver responsible for removing duplicate namespace declarations.
NamespaceReducer	NamespaceReducer is a ProxyReceiver responsible for removing duplicate namespace declarations.
NoOpenStartTagException	Exception indicating that an attribute or namespace node has been written when there is no open element to write it to
Outputter	Outputter: This interface represents a recipient of XML tree-walking (push) events.
OutputterEvent	An outputter event is an object representing one of the events that can be passed to an Outputter : for example, a startElement, attribute, namespace endElement, characters, or comment event.
OutputterEvent.Append	Event representing an arbitrary item being sent to the event stream in composed form.
OutputterEvent.Attribute	Event representing an attribute node
OutputterEvent.Comment	Event representing a comment node
OutputterEvent.EndDocument	Event representing end of document
OutputterEvent.EndElement	Event representing the end of an element
OutputterEvent.Namespace	Event representing a namespace node
OutputterEvent.ProcessingInstruction	Event representing a processing instruction node
OutputterEvent.StartContent	Event representing the start of element content
OutputterEvent.StartDocument	Event representing start of document
OutputterEvent.StartElement	Event representing the start of an element (including attributes or namespaces)
OutputterEvent.Text	Event representing a text node
OutputterEventBuffer	An EventBuffer is a receiver of events that records the events in memory for subsequent replay.
PathMaintainer	This class sits in a receiver (push) pipeline and maintains the current path.
PIGrabber	The PIGrabber class is a ProxyReceiver that looks for xml-stylesheet processing instructions and tests whether they match specified criteria; for those that do, it creates a Source object referring to the relevant stylesheet
PipelineConfiguration	A PipelineConfiguration sets options that apply to all the operations in a pipeline.
ProxyOutputter
ProxyReceiver	A ProxyReceiver is an Receiver that filters data before passing it to another underlying Receiver.
PushToReceiver
Receiver	Receiver: This interface represents a recipient of XML tree-walking (push) events.
ReceiverOption	ReceiverOption defines a set of constants representing boolean flags, which can be used in calls to methods on the Receiver interface.
ReceiverWithOutputProperties	Marker interface attached to a Outputter that retains serialization properties (typically, a Receiver that forms part of the serialization pipeline).
ReceivingContentHandler	ReceivingContentHandler is a glue class that provides a standard SAX ContentHandler interface to a Saxon Receiver.
ReceivingContentHandler.LocalLocator	An implementation of the Saxon Location interface that wraps the SAX Locator information.
RegularSequenceChecker	A RegularSequenceChecker is a filter that can be inserted into a Receiver pipeline to check that the sequence of events passed in is a regular event sequence.
RegularSequenceChecker.State
RepairingContentHandler	A RepairingContentHandler is a SAX filter that can be placed on the input pipeline in front of a ReceivingContentHandler for use in cases where the events supplied by the XML parser are not guaranteed to satisfy all the consistency constraints.
Sender	Sender is a helper class that sends events to a Receiver from any kind of Source object
SequenceCollector	This receiver is used when writing a sequence of atomic values and nodes, that is, when xsl:variable is used with content and an "as" attribute.
SequenceCopier	Copies a sequence, supplied as a SequenceIterator, to a push pipeline, represented by a SequenceReceiver
SequenceNormalizer	Implement the "sequence normalization" logic as defined in the XSLT 3.0/XQuery 3.0 serialization spec.
SequenceNormalizerWithItemSeparator	Implement the "sequence normalization" logic as defined in the XSLT 3.0/XQuery 3.0 serialization spec.
SequenceNormalizerWithSpaceSeparator	Implement the "sequence normalization" logic as defined in the XSLT 3.0/XQuery 3.0 serialization spec, for the case where there is no item-separator.
SequenceReceiver	SequenceReceiver: this extension of the Receiver interface is used when processing a sequence constructor.
SequenceWriter	The SequenceWriter is used when writing a sequence of items, for example, when xsl:variable is used with content and an "as" attribute.
SignificantItemDetector	This receiver is inserted into the output pipeline whenever on-empty or on-non-empty is used (XSLT 3.0).
Sink	A Sink is a Receiver that discards all information passed to it
SinkOutputter	An Outputter that swallows (discards) all input supplied to it
StreamWriterToReceiver	This class implements the XmlStreamWriter interface, translating the events into Saxon Receiver events.
Stripper	The Stripper class performs whitespace stripping according to the rules of the xsl:strip-space and xsl:preserve-space instructions.
Stripper.StripRuleTarget
TeeOutputter	TeeOutputter: a SequenceReceiver that duplicates received events to two different destinations
TransformerReceiver	TransformerReceiver is similar in concept to the JAXP TransformerHandler, except that it implements Saxon's Receiver interface rather than the standard SAX2 interface.
TreeReceiver	A TreeReceiver acts as a bridge between a SequenceReceiver, which can receive events for constructing any kind of sequence, and an ordinary Receiver, which only handles events relating to the building of trees.
TypeCheckingFilter	A filter on the push pipeline that performs type checking, both of the item type and the cardinality.
Valve	A Valve is a general-purpose component for use in a pipeline of receivers.
WherePopulatedOutputter	This class acts as a filter on a push pipeline, allowing through only those items that are deemed non-empty according to the rules of the xsl:where-populated instruction.