net.sf.saxon.event

Class RegularSequenceChecker

java.lang.Object

net.sf.saxon.event.SequenceReceiver

net.sf.saxon.event.ProxyReceiver

net.sf.saxon.event.RegularSequenceChecker

All Implemented Interfaces:

javax.xml.transform.Result, Receiver

public class RegularSequenceChecker
extends ProxyReceiver

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. Many (though not all) implementations of Outputter require the sequence of events to be regular according to this definition.

A sequence of Receiver events is regular if the following conditions are satisfied:

1. Calls to Outputter.startElement(NodeName, SchemaType, Location, int), endElement(), Outputter.startDocument(int), and endDocument() are properly paired and nested.
2. Events must only occur in a state where they are permitted; the states and transitions between states are defined by the table below. The initial state is initial, and the final state must be final.

Permitted state transitions

State	Events	Next State
initial	open()	open
open	open()	open
open	Outputter.append(Item, Location, int), SequenceReceiver.append(Item), Outputter.characters(CharSequence, Location, int), Outputter.comment(CharSequence, Location, int), Outputter.processingInstruction(String, CharSequence, Location, int)	open
open	Outputter.startDocument(int)	content
open	Outputter.startElement(NodeName, SchemaType, Location, int)	content
content	Outputter.characters(CharSequence, Location, int), Outputter.comment(CharSequence, Location, int), Outputter.processingInstruction(String, CharSequence, Location, int)	content
content	Outputter.startElement(NodeName, SchemaType, Location, int)	startTag
content	endDocument(), endElement()	if the stack is empty, then content, otherwise open
(any)	close	final
final	close	final

This class is not normally used in production within Saxon, but is available for diagnostics when needed.

Some implementations of Receiver accept sequences of events that are not regular; indeed, some implementations are explicitly designed to produce a regular sequence from an irregular sequence. Examples of such irregularities are append or startDocument events appearing within element content, or attribute events being followed by text events with no intervening startContent.

The rules for a regular sequence imply that the top level events (any events not surrounded by startElement-endElement or startDocument-endDocument) can represent any sequence of items, including for example multiple document nodes, free-standing attribute and namespace nodes, maps, arrays, and functions; but within a startElement-endElement or startDocument-endDocument pair, the events represent content that has been normalized and validated according to the XSLT rules for constructing complex content, or the XQuery equivalent: for example, attributes and namespaces must appear before child nodes, adjacent text nodes should have been merged, zero-length text nodes should have been eliminated, all namespaces should be explicitly declared, document nodes should be replaced by their children.

Element nodes in "composed form" (that is, existing as a tree in memory) may be passed through the SequenceReceiver.append(Item) method at the top level, but within a startElement-endElement or startDocument-endDocument pair, elements must be represented in "decomposed form" as a sequence of events.

A call to close() is permitted in any state, but it should only be called in Open state except on an error path; on error paths calling close() is recommended to ensure that resources are released.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	RegularSequenceChecker.State

Field Summary

Fields inherited from class net.sf.saxon.event.ProxyReceiver

nextReceiver

Fields inherited from class net.sf.saxon.event.SequenceReceiver

pipelineConfiguration, previousAtomic, systemId

Fields inherited from interface javax.xml.transform.Result

PI_DISABLE_OUTPUT_ESCAPING, PI_ENABLE_OUTPUT_ESCAPING

Constructor Summary

Constructors

Constructor and Description
RegularSequenceChecker(Receiver nextReceiver, boolean fullChecking) Create a RegularSequenceChecker and allocate a unique Id.

Method Summary

Modifier and Type	Method and Description
void	append(Item item, Location locationId, int copyNamespaces) Append an arbitrary item (node or atomic value) to the output.
void	characters(java.lang.CharSequence chars, Location locationId, int properties) Character data (corresponding to a text node).
void	close() End of sequence
void	comment(java.lang.CharSequence chars, Location locationId, int properties) Output a comment
void	endDocument() Notify the end of a document node
void	endElement() End of element
void	open() Start of event stream
void	processingInstruction(java.lang.String target, java.lang.CharSequence data, Location locationId, int properties) Processing Instruction
void	startDocument(int properties) Start of a document node.
void	startElement(NodeName elemName, SchemaType type, AttributeMap attributes, NamespaceMap namespaces, Location location, int properties) Notify the start of an element.

Methods inherited from class net.sf.saxon.event.ProxyReceiver

getNamePool, getNextReceiver, setPipelineConfiguration, setSystemId, setUnderlyingReceiver, setUnparsedEntity, usesTypeAnnotations

Methods inherited from class net.sf.saxon.event.SequenceReceiver

append, decompose, flatten, getConfiguration, getErrorCodeForDecomposingFunctionItems, getPipelineConfiguration, getSystemId, handlesAppend

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RegularSequenceChecker

public RegularSequenceChecker(Receiver nextReceiver,
                              boolean fullChecking)

Create a RegularSequenceChecker and allocate a unique Id.

Parameters:

nextReceiver - the underlying receiver to which the events will be sent (without change)

fullChecking - requests full validation of the content passed across the interface. If false, the only checking is that the sequence of events is correct. If true, more thorough validation is carried out (though this does not necessarily mean that every violation is detected).

Method Detail

append

public void append(Item item,
                   Location locationId,
                   int copyNamespaces)
            throws XPathException

Append an arbitrary item (node or atomic value) to the output. In a regular sequence, append events occur only at the top level, that is, when the document / element stack is empty.

Specified by:

append in interface Receiver

Overrides:

append in class ProxyReceiver

Parameters:

item - the item to be appended

locationId - the location of the calling instruction, for diagnostics

copyNamespaces - if the item is an element node, this indicates whether its namespaces need to be copied. Values are ReceiverOption.ALL_NAMESPACES; the default (0) means

Throws:

XPathException - if an error occurs

characters

public void characters(java.lang.CharSequence chars,
                       Location locationId,
                       int properties)
                throws XPathException

Character data (corresponding to a text node). For character data within content (that is, events occurring when the startDocument / startElement stack is non-empty), character data events will never be consecutive and will never be zero-length.

Specified by:

characters in interface Receiver

Overrides:

characters in class ProxyReceiver

Parameters:

chars - The characters

locationId - provides information such as line number and system ID.

properties - Bit significant value. The following bits are defined:

DISABLE_ESCAPING

Disable escaping for this text node

USE_CDATA

Output as a CDATA section

Throws:

XPathException - if an error occurs

close

public void close()
           throws XPathException

End of sequence

Specified by:

close in interface Receiver

Overrides:

close in class ProxyReceiver

Throws:

XPathException - if an error occurs

comment

public void comment(java.lang.CharSequence chars,
                    Location locationId,
                    int properties)
             throws XPathException

Output a comment

Specified by:

comment in interface Receiver

Overrides:

comment in class ProxyReceiver

Parameters:

chars - The content of the comment

locationId - provides information such as line number and system ID.

properties - Additional information about the comment.

Throws:

XPathException - if an error occurs

endDocument

public void endDocument()
                 throws XPathException

Notify the end of a document node

Specified by:

endDocument in interface Receiver

Overrides:

endDocument in class ProxyReceiver

Throws:

XPathException - if an error occurs

endElement

public void endElement()
                throws XPathException

End of element

Specified by:

endElement in interface Receiver

Overrides:

endElement in class ProxyReceiver

Throws:

XPathException - if an error occurs

open

public void open()
          throws XPathException

Start of event stream

Specified by:

open in interface Receiver

Overrides:

open in class ProxyReceiver

Throws:

XPathException - if an error occurs

processingInstruction

public void processingInstruction(java.lang.String target,
                                  java.lang.CharSequence data,
                                  Location locationId,
                                  int properties)
                           throws XPathException

Processing Instruction

Specified by:

processingInstruction in interface Receiver

Overrides:

processingInstruction in class ProxyReceiver

Parameters:

target - The PI name. This must be a legal name (it will not be checked).

data - The data portion of the processing instruction

locationId - provides information such as line number and system ID.

properties - Additional information about the PI.

Throws:

XPathException - if an error occurs

startDocument

public void startDocument(int properties)
                   throws XPathException

Start of a document node.

Specified by:

startDocument in interface Receiver

Overrides:

startDocument in class ProxyReceiver

Parameters:

properties - properties of the document node.

Throws:

XPathException - if an error occurs

startElement

public void startElement(NodeName elemName,
                         SchemaType type,
                         AttributeMap attributes,
                         NamespaceMap namespaces,
                         Location location,
                         int properties)
                  throws XPathException

Notify the start of an element.

All attributes must satisfy the following constraints:

1. The namespace prefix and URI must either both be present (non-zero-length) or both absent
2. The prefix "xml" and the URI "http://www.w3.org/XML/1998/namespace" are allowed only in combination.
3. The namespace URI "http://www.w3.org/2000/xmlns/" is not allowed.
4. The namespace prefix "xmlns" is not allowed.
5. The local name "xmlns" is not allowed in the absence of a namespace prefix and URI.

The following additional constraints apply to the set of attributes as a whole:

1. No two attributes may have the same (local-name, namespace URI) combination.
2. No namespace prefix may be used in conjunction with more than one namespace URI.
3. Every (namespace prefix, namespace URI) combination must correspond to an in-scope namespace: that is, unless the (prefix, URI) pair is ("", "") or ("xml", "http://www.w3.org/XML/1998/namespace"), it must be present in the in-scope namespaces.

These constraints are not all enforced by this class.

Specified by:

startElement in interface Receiver

Overrides:

startElement in class ProxyReceiver

Parameters:

elemName - the name of the element. If the name is in a namespace (non-empty namespace URI) then the Outputter.namespace(String, String, int) event must include a binding for the relevant prefix (or absence of a prefix) to the relevant URI.

type - the type annotation of the element.

attributes - the attributes of the element

namespaces - the in-scope namespaces of the element

location - provides information such as line number and system ID.

properties - properties of the element node

Throws:

XPathException - if an error occurs