net.sf.saxon.expr
Class EarlyEvaluationContext

java.lang.Object
  net.sf.saxon.expr.EarlyEvaluationContext

All Implemented Interfaces:

Serializable, XPathContext

public class EarlyEvaluationContext
extends Object
implements XPathContext, Serializable

This class is an implementation of XPathContext used when evaluating constant sub-expressions at compile time.

See Also:

Serialized Form

Constructor Summary

EarlyEvaluationContext(Configuration config, CollationMap map)
Create an early evaluation context, used for evaluating constant expressions at compile time

Method Summary

void	changeOutputDestination(Receiver receiver, boolean isFinal, 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.
XPathException	getCurrentException() Get the current exception (in saxon:catch)
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.
int	getImplicitTimezone() Get the implicit timezone, as a positive or negative offset from UTC in minutes.
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
InstructionInfo	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()
Iterator	iterateStackFrames() Get the context stack.
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(InstructionInfo 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 Receiver to which output is written
void	setTemporaryReceiver(SequenceReceiver out) Set the receiver to which output is to be written, marking it as a temporary (non-final) output destination.
int	useLocalParameter(StructuredQName qName, LocalParam binding, boolean isTunnel) Use local parameter.

Methods inherited from class java.lang.Object

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

Constructor Detail

EarlyEvaluationContext

public EarlyEvaluationContext(Configuration config,
                              CollationMap map)

Create an early evaluation context, used for evaluating constant expressions at compile time

Parameters:

config - the Saxon configuration

map - the available collations

Method Detail

changeOutputDestination

public void changeOutputDestination(Receiver receiver,
                                    boolean isFinal,
                                    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.

Specified by:

changeOutputDestination in interface XPathContext

Parameters:

isFinal - true if the destination is a final result tree (either the principal output or a secondary result tree); false if it is a temporary tree, xsl:attribute, etc.

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

Specified by:

evaluateLocalVariable in interface XPathContext

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.

Specified by:

getCaller in interface XPathContext

Returns:

the XPathContext of the calling expression

getCollation

public StringCollator getCollation(String name)
                            throws XPathException

Get a named collation

Specified by:

getCollation in interface XPathContext

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

Specified by:

getConfiguration in interface XPathContext

Returns:

the Saxon configuration object

getContextItem

public Item getContextItem()

Get the context item

Specified by:

getContextItem in interface XPathContext

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)

Specified by:

getContextPosition in interface XPathContext

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

Specified by:

getController in interface XPathContext

Returns:

the controller for this query or transformation

getCurrentGroupIterator

public GroupIterator getCurrentGroupIterator()

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

Specified by:

getCurrentGroupIterator in interface XPathContext

Returns:

the current grouped collection

getCurrentIterator

public SequenceIterator getCurrentIterator()

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

Specified by:

getCurrentIterator in interface XPathContext

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.

Specified by:

getCurrentMode in interface XPathContext

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.

Specified by:

getCurrentRegexIterator in interface XPathContext

Returns:

the current regular expressions iterator

getCurrentTemplateRule

public Rule getCurrentTemplateRule()

Get the current template. This is used to support xsl:apply-imports

Specified by:

getCurrentTemplateRule in interface XPathContext

Returns:

the current template

getLast

public int getLast()
            throws XPathException

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

Specified by:

getLast in interface XPathContext

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

Specified by:

getLocalParameters in interface XPathContext

Returns:

a ParameterSet containing the local parameters

getNamePool

public NamePool getNamePool()

Get the Name Pool

Specified by:

getNamePool in interface XPathContext

Returns:

the name pool

getOrigin

public InstructionInfo getOrigin()

Get information about the creating expression or other construct.

Specified by:

getOrigin in interface XPathContext

Returns:

information about the creating expression

getOriginatingConstructType

public int getOriginatingConstructType()

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

Specified by:

getOriginatingConstructType in interface XPathContext

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.

Specified by:

getReceiver in interface XPathContext

Returns:

the current Receiver

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.

Specified by:

getStackFrame in interface XPathContext

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.

Specified by:

getTunnelParameters in interface XPathContext

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()

Specified by:

isAtLast in interface XPathContext

Returns:

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

Throws:

XPathException

newCleanContext

public XPathContextMajor newCleanContext()

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

Specified by:

newCleanContext in interface XPathContext

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

Specified by:

newContext in interface XPathContext

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.

Specified by:

newMinorContext in interface XPathContext

Returns:

a new minor context

setCaller

public void setCaller(XPathContext caller)

Set the calling XPathContext

Specified by:

setCaller in interface XPathContext

Parameters:

caller - the XPathContext of the calling expression

setCurrentIterator

public void setCurrentIterator(SequenceIterator iter)

Set a new sequence iterator.

Specified by:

setCurrentIterator in interface XPathContext

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

Specified by:

setLocalVariable in interface XPathContext

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.

Specified by:

setOrigin in interface XPathContext

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.setOrigin(net.sf.saxon.trace.InstructionInfo) should be called.

Specified by:

setOriginatingConstructType in interface XPathContext

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 Receiver to which output is written

Specified by:

setReceiver in interface XPathContext

Parameters:

receiver - the SequenceReceiver to be used

setTemporaryReceiver

public void setTemporaryReceiver(SequenceReceiver out)

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

Specified by:

setTemporaryReceiver in interface XPathContext

Parameters:

out - The SequenceOutputter to be used

useLocalParameter

public int 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

Specified by:

useLocalParameter in interface XPathContext

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

getCurrentDateTime

public DateTimeValue getCurrentDateTime()
                                 throws NoDynamicContextException

Get the current date and time. This implementation always throws a NoDynamicContextException.

Specified by:

getCurrentDateTime in interface XPathContext

Returns:

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

Throws:

NoDynamicContextException

getImplicitTimezone

public int getImplicitTimezone()
                        throws NoDynamicContextException

Get the implicit timezone, as a positive or negative offset from UTC in minutes. The range is -14hours to +14hours. This implementation always throws a NoDynamicContextException.

Specified by:

getImplicitTimezone in interface XPathContext

Returns:

the implicit timezone, as an offset from UTC in minutes

Throws:

NoDynamicContextException

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.

Specified by:

iterateStackFrames in interface XPathContext

Returns:

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

getCurrentException

public XPathException getCurrentException()

Get the current exception (in saxon:catch)

Specified by:

getCurrentException in interface XPathContext

Returns:

the current exception, or null if there is none defined