net.sf.saxon.expr

Interface XPathContext

public interface XPathContext

This class represents a context in which an XPath expression is evaluated.
Method Summary
voidchangeOutputDestination(Receiver receiver, boolean isFinal, int validation, SchemaType schemaType)
Set a new output destination, supplying the output format details.
ValueRepresentationevaluateLocalVariable(int slotnumber)
Get the value of a local variable, identified by its slot number
XPathContextgetCaller()
Get the calling XPathContext (the next one down the stack).
StringCollatorgetCollation(String name)
Get a named collation.
ConfigurationgetConfiguration()
Get the Configuration
ItemgetContextItem()
Get the context item
intgetContextPosition()
Get the context position (the position of the context item)
ControllergetController()
Get the Controller.
DateTimeValuegetCurrentDateTime()
Get the current date and time
XPathExceptiongetCurrentException()
Get the current exception (in saxon:catch)
GroupIteratorgetCurrentGroupIterator()
Get the current group iterator.
SequenceIteratorgetCurrentIterator()
Get the current iterator.
ModegetCurrentMode()
Get the current mode.
RegexIteratorgetCurrentRegexIterator()
Get the current regex iterator.
RulegetCurrentTemplateRule()
Get the current template rule.
intgetImplicitTimezone()
Get the implicit timezone
intgetLast()
Get the context size (the position of the last item in the current node list)
ParameterSetgetLocalParameters()
Get the local (non-tunnel) parameters that were passed to the current function or template
NamePoolgetNamePool()
Get the Name Pool
InstructionInfogetOrigin()
Get information about the creating expression or other construct.
intgetOriginatingConstructType()
Get the type of location from which this context was created.
SequenceReceivergetReceiver()
Get the Receiver to which output is currently being written.
StackFramegetStackFrame()
Get a reference to the local stack frame for variables.
ParameterSetgetTunnelParameters()
Get the tunnel parameters that were passed to the current function or template.
booleanisAtLast()
Determine whether the context position is the same as the context size that is, whether position()=last().
IteratoriterateStackFrames()
Get the context stack.
XPathContextMajornewCleanContext()
Construct a new context without copying (used for the context in a function call)
XPathContextMajornewContext()
Construct a new context as a copy of another.
XPathContextMinornewMinorContext()
Construct a new minor context.
voidsetCaller(XPathContext caller)
Set the calling XPathContext
voidsetCurrentIterator(SequenceIterator iter)
Set a new sequence iterator.
voidsetLocalVariable(int slotnumber, ValueRepresentation value)
Set the value of a local variable, identified by its slot number
voidsetOrigin(InstructionInfo expr)
Set the creating expression (for use in diagnostics).
voidsetOriginatingConstructType(int loc)
Set the type of creating expression (for use in diagnostics).
voidsetReceiver(SequenceReceiver receiver)
Change the SequenceReceiver to which output is written
voidsetTemporaryReceiver(SequenceReceiver out)
Set the SequenceReceiver to which output is to be written, marking it as a temporary (non-final) output destination.
intuseLocalParameter(StructuredQName qName, LocalParam binding, boolean isTunnel)
Use local parameter.

Method Detail

changeOutputDestination

public void changeOutputDestination(Receiver receiver, boolean isFinal, int validation, SchemaType schemaType)
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: 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 @param isFinal true if the destination is a final result tree (either the principal output or a secondary result tree); false if not

evaluateLocalVariable

public 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.

getCaller

public 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

getCollation

public StringCollator getCollation(String name)
Get a named collation.

Note: although collations are defined in the specification as being part of the static context, Saxon assumes that all available collations have global scope for a transformation or query, so that a collation URI can be translated into an actual collation without knowing where in the source code the collation URI was used. The default collation, however, can vary in different parts of a query or stylesheet, and expressions using the default collation must therefore get it from the static context.

Parameters: name the name (URI) of the required collation

Returns: a StringCollator representing the collation

Throws: XPathException if the collation is not recognized

getConfiguration

public Configuration getConfiguration()
Get the Configuration

Returns: the Saxon configuration object

getContextItem

public Item getContextItem()
Get the context item

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

getContextPosition

public int getContextPosition()
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

getController

public Controller getController()
Get the Controller. May return null when running outside XSLT or XQuery

Returns: the controller for this query or transformation

getCurrentDateTime

public DateTimeValue getCurrentDateTime()
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

getCurrentException

public XPathException getCurrentException()
Get the current exception (in saxon:catch)

Returns: the current exception, or null if there is none defined

getCurrentGroupIterator

public 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

getCurrentIterator

public 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).

getCurrentMode

public Mode getCurrentMode()
Get the current mode.

Returns: the current mode

getCurrentRegexIterator

public 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

getCurrentTemplateRule

public Rule getCurrentTemplateRule()
Get the current template rule. This is used to support xsl:apply-imports and xsl:next-match

Returns: the current template rule

getImplicitTimezone

public int getImplicitTimezone()
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.

getLast

public int getLast()
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

getLocalParameters

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

Returns: a ParameterSet containing the local parameters

getNamePool

public NamePool getNamePool()
Get the Name Pool

Returns: the name pool

getOrigin

public InstructionInfo getOrigin()
Get information about the creating expression or other construct.

Returns: information about the creating expression

getOriginatingConstructType

public 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)

getReceiver

public SequenceReceiver getReceiver()
Get the Receiver to which output is currently being written.

Returns: the current SequenceReceiver

getStackFrame

public 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.

getTunnelParameters

public 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

isAtLast

public boolean isAtLast()
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.

iterateStackFrames

public Iterator iterateStackFrames()
Get the context stack. This method returns an iterator whose items are instances of ContextStackFrame, starting with the top-most stackframe and ending at the point the query or transformation was invoked by a calling application.

Returns: an iterator over a copy of the run-time call stack

newCleanContext

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

Returns: a new clean context

newContext

public 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

newMinorContext

public 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

setCaller

public void setCaller(XPathContext caller)
Set the calling XPathContext

Parameters: caller the XPathContext of the calling expression

setCurrentIterator

public 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.

setLocalVariable

public 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

setOrigin

public void setOrigin(InstructionInfo 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 Expression, allowing information about the calling instruction to be obtained.

Parameters: expr the expression that created this context object

setOriginatingConstructType

public void setOriginatingConstructType(int loc)
Set the type of creating expression (for use in diagnostics). When a new context is created, either this method or XPathContext should be called.

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

setReceiver

public void setReceiver(SequenceReceiver receiver)
Change the SequenceReceiver to which output is written

Parameters: receiver the SequenceReceiver to be used

setTemporaryReceiver

public 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

useLocalParameter

public int useLocalParameter(StructuredQName qName, LocalParam binding, boolean isTunnel)
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: ParameterSet.NOT_SUPPLIED, ParameterSet.SUPPLIED, or ParameterSet.SUPPLIED_AND_CHECKED