net.sf.saxon.expr

Interface XPathContext

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 Details

changeOutputDestination

public 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

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)
            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

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()
            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

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()
            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

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

getDefaultCollation

public StringCollator getDefaultCollation()
Get the default collation
Returns:
a StringCollator representing the default collation

getImplicitTimezone

public 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.

getLast

public 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

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 InstructionInfoProvider 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()
            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.

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(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

public void setOriginatingConstructType(int loc)
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 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