net.sf.saxon.expr
Interface XPathContext

All Known Implementing Classes:

EarlyEvaluationContext, XPathContextMajor, XPathContextMinor

public interface XPathContext

This class represents a context in which an XPath expression is evaluated.

Method Summary

void	changeOutputDestination(Properties props, Result result, boolean isFinal, int hostLanguage, int validation, SchemaType schemaType) Set a new output destination, supplying the output format details.
ValueRepresentation	evaluateLocalVariable(int slotnumber) Get the value of a local variable, identified by its slot number
XPathContext	getCaller() Get the calling XPathContext (the next one down the stack).
StringCollator	getCollation(String name) Get a named collation
Configuration	getConfiguration() Get the Configuration
Item	getContextItem() Get the context item
int	getContextPosition() Get the context position (the position of the context item)
Controller	getController() Get the Controller.
DateTimeValue	getCurrentDateTime() Get the current date and time
GroupIterator	getCurrentGroupIterator() Get the current group iterator.
SequenceIterator	getCurrentIterator() Get the current iterator.
Mode	getCurrentMode() Get the current mode.
RegexIterator	getCurrentRegexIterator() Get the current regex iterator.
Rule	getCurrentTemplateRule() Get the current template rule.
StringCollator	getDefaultCollation() Get the default collation
int	getImplicitTimezone() Get the implicit timezone
int	getLast() Get the context size (the position of the last item in the current node list)
ParameterSet	getLocalParameters() Get the local (non-tunnel) parameters that were passed to the current function or template
NamePool	getNamePool() Get the Name Pool
InstructionInfoProvider	getOrigin() Get information about the creating expression or other construct.
int	getOriginatingConstructType() Get the type of location from which this context was created.
SequenceReceiver	getReceiver() Get the Receiver to which output is currently being written.
StackFrame	getStackFrame() Get a reference to the local stack frame for variables.
ParameterSet	getTunnelParameters() Get the tunnel parameters that were passed to the current function or template.
boolean	isAtLast() Determine whether the context position is the same as the context size that is, whether position()=last().
XPathContextMajor	newCleanContext() Construct a new context without copying (used for the context in a function call)
XPathContextMajor	newContext() Construct a new context as a copy of another.
XPathContextMinor	newMinorContext() Construct a new minor context.
void	setCaller(XPathContext caller) Set the calling XPathContext
void	setCurrentIterator(SequenceIterator iter) Set a new sequence iterator.
void	setLocalVariable(int slotnumber, ValueRepresentation value) Set the value of a local variable, identified by its slot number
void	setOrigin(InstructionInfoProvider expr) Set the creating expression (for use in diagnostics).
void	setOriginatingConstructType(int loc) Set the type of creating expression (for use in diagnostics).
void	setReceiver(SequenceReceiver receiver) Change the SequenceReceiver to which output is written
void	setTemporaryReceiver(SequenceReceiver out) Set the SequenceReceiver to which output is to be written, marking it as a temporary (non-final) output destination.
boolean	useLocalParameter(StructuredQName qName, LocalParam binding, boolean isTunnel) Use local parameter.

Method Detail

newContext

XPathContextMajor newContext()

Construct a new context as a copy of another. The new context is effectively added to the top of a stack, and contains a pointer to the previous context

Returns:

a new context, created as a copy of this context

newCleanContext

XPathContextMajor newCleanContext()

Construct a new context without copying (used for the context in a function call)

Returns:

a new clean context

newMinorContext

XPathContextMinor newMinorContext()

Construct a new minor context. A minor context can only hold new values of the focus (currentIterator) and current output destination.

Returns:

a new minor context

getLocalParameters

ParameterSet getLocalParameters()

Get the local (non-tunnel) parameters that were passed to the current function or template

Returns:

a ParameterSet containing the local parameters

getTunnelParameters

ParameterSet getTunnelParameters()

Get the tunnel parameters that were passed to the current function or template. This includes all active tunnel parameters whether the current template uses them or not.

Returns:

a ParameterSet containing the tunnel parameters

setOrigin

void setOrigin(InstructionInfoProvider expr)

Set the creating expression (for use in diagnostics). The origin is generally set to "this" by the object that creates the new context. It's up to the debugger to determine whether this information is useful. Where possible, the object will be an InstructionInfoProvider, allowing information about the calling instruction to be obtained.

Parameters:

expr - the expression that created this context object

setOriginatingConstructType

void setOriginatingConstructType(int loc)

Set the type of creating expression (for use in diagnostics). When a new context is created, either this method or setOrigin(net.sf.saxon.trace.InstructionInfoProvider) should be called.

Parameters:

loc - The originating location: the argument must be one of the integer constants in class Location

getOrigin

InstructionInfoProvider getOrigin()

Get information about the creating expression or other construct.

Returns:

information about the creating expression

getOriginatingConstructType

int getOriginatingConstructType()

Get the type of location from which this context was created.

Returns:

the type of location. (The integer codes that are used are often fingerprints of instruction names, but not always. For details of the codes, see the standard trace listener which interprets them)

getController

Controller getController()

Get the Controller. May return null when running outside XSLT or XQuery

Returns:

the controller for this query or transformation

getConfiguration

Configuration getConfiguration()

Get the Configuration

Returns:

the Saxon configuration object

getNamePool

NamePool getNamePool()

Get the Name Pool

Returns:

the name pool

setCaller

void setCaller(XPathContext caller)

Set the calling XPathContext

Parameters:

caller - the XPathContext of the calling expression

getCaller

XPathContext getCaller()

Get the calling XPathContext (the next one down the stack). This will be null if unknown, or if the bottom of the stack has been reached.

Returns:

the XPathContext of the calling expression

setCurrentIterator

void setCurrentIterator(SequenceIterator iter)

Set a new sequence iterator.

Parameters:

iter - the current iterator. The context item, position, and size are determined by reference to the current iterator.

getCurrentIterator

SequenceIterator getCurrentIterator()

Get the current iterator. This encapsulates the context item, context position, and context size.

Returns:

the current iterator, or null if there is no current iterator (which means the context item, position, and size are undefined).

getContextPosition

int getContextPosition()
                       throws XPathException

Get the context position (the position of the context item)

Returns:

the context position (starting at one)

Throws:

XPathException - if the context position is undefined

getContextItem

Item getContextItem()

Get the context item

Returns:

the context item, or null if the context item is undefined

getLast

int getLast()
            throws XPathException

Get the context size (the position of the last item in the current node list)

Returns:

the context size

Throws:

XPathException - if the context position is undefined

isAtLast

boolean isAtLast()
                 throws XPathException

Determine whether the context position is the same as the context size that is, whether position()=last(). In many cases this has better performance than a direct comparison, because it does not require reading to the end of the sequence.

Returns:

true if the context position is the same as the context size.

Throws:

XPathException

getCollation

StringCollator getCollation(String name)
                            throws XPathException

Get a named collation

Parameters:

name - the name (URI) of the required collation

Returns:

a StringCollator representing the collation

Throws:

XPathException - if the collation is not recognized

getDefaultCollation

StringCollator getDefaultCollation()

Get the default collation

Returns:

a StringCollator representing the default collation

useLocalParameter

boolean useLocalParameter(StructuredQName qName,
                          LocalParam binding,
                          boolean isTunnel)
                          throws XPathException

Use local parameter. This is called when a local xsl:param element is processed. If a parameter of the relevant name was supplied, it is bound to the xsl:param element. Otherwise the method returns false, so the xsl:param default will be evaluated

Parameters:

qName - The fingerprint of the parameter name

binding - The XSLParam element to bind its value to

isTunnel - True if a tunnel parameter is required, else false

Returns:

true if a parameter of this name was supplied, false if not

Throws:

XPathException

getStackFrame

StackFrame getStackFrame()

Get a reference to the local stack frame for variables. Note that it's the caller's job to make a local copy of this. This is used for creating a Closure containing a retained copy of the variables for delayed evaluation.

Returns:

array of variables.

evaluateLocalVariable

ValueRepresentation evaluateLocalVariable(int slotnumber)

Get the value of a local variable, identified by its slot number

Parameters:

slotnumber - the slot number allocated at compile time to the variable, which identifies its position within the local stack frame

Returns:

the value of the variable.

setLocalVariable

void setLocalVariable(int slotnumber,
                      ValueRepresentation value)

Set the value of a local variable, identified by its slot number

Parameters:

slotnumber - the slot number allocated at compile time to the variable, which identifies its position within the local stack frame

value - the value of the variable

changeOutputDestination

void changeOutputDestination(Properties props,
                             Result result,
                             boolean isFinal,
                             int hostLanguage,
                             int validation,
                             SchemaType schemaType)
                             throws XPathException

Set a new output destination, supplying the output format details.
Note that it is the caller's responsibility to close the Writer after use.

Parameters:

props - properties defining the output format

result - Details of the new output destination

isFinal - true if the destination is a final result tree (either the principal output or a secondary result tree); false if not

hostLanguage - typically XSLT or XQuery

validation - validation mode: strict, lax, preserve, or strip

schemaType - type against which the output must be validated

Throws:

XPathException - if any dynamic error occurs; and specifically, if an attempt is made to switch to a final output destination while writing a temporary tree or sequence

setTemporaryReceiver

void setTemporaryReceiver(SequenceReceiver out)

Set the SequenceReceiver to which output is to be written, marking it as a temporary (non-final) output destination.

Parameters:

out - The SequenceReceiver to be used

setReceiver

void setReceiver(SequenceReceiver receiver)

Change the SequenceReceiver to which output is written

Parameters:

receiver - the SequenceReceiver to be used

getReceiver

SequenceReceiver getReceiver()

Get the Receiver to which output is currently being written.

Returns:

the current SequenceReceiver

getCurrentMode

Mode getCurrentMode()

Get the current mode.

Returns:

the current mode

getCurrentTemplateRule

Rule getCurrentTemplateRule()

Get the current template rule. This is used to support xsl:apply-imports and xsl:next-match

Returns:

the current template rule

getCurrentGroupIterator

GroupIterator getCurrentGroupIterator()

Get the current group iterator. This supports the current-group() and current-grouping-key() functions in XSLT 2.0

Returns:

the current grouped collection

getCurrentRegexIterator

RegexIterator getCurrentRegexIterator()

Get the current regex iterator. This supports the functionality of the regex-group() function in XSLT 2.0.

Returns:

the current regular expressions iterator

getCurrentDateTime

DateTimeValue getCurrentDateTime()
                                 throws NoDynamicContextException

Get the current date and time

Returns:

the current date and time. All calls within a single query or transformation will return the same value

Throws:

NoDynamicContextException

getImplicitTimezone

int getImplicitTimezone()
                        throws NoDynamicContextException

Get the implicit timezone

Returns:

the implicit timezone. This will be the timezone of the current date and time, and all calls within a single query or transformation will return the same value. The result is expressed as an offset from UTC in minutes.

Throws:

NoDynamicContextException