com.saxonica.expr.flwor
Class WindowClause

java.lang.Object
  net.sf.saxon.expr.flwor.Clause
      com.saxonica.expr.flwor.WindowClause

public class WindowClause
extends Clause

Implements an XQuery 3.0 sliding or tumbling window clause within a FLWOR expression

Nested Class Summary

protected static class

WindowClause.Window Information about a window: the items making up the window, as well as the variables relating to the start and end of the window, and the status of the winoow in relation to the processing of the current input sequence.

Field Summary

static int	END_ITEM
static int	END_ITEM_POSITION
static int	END_NEXT_ITEM
static int	END_PREVIOUS_ITEM
static int	START_ITEM
static int	START_ITEM_POSITION
static int	START_NEXT_ITEM
static int	START_PREVIOUS_ITEM
static int	WINDOW_VAR

Fields inherited from class net.sf.saxon.expr.flwor.Clause

COUNT, FOR, GROUPBYCLAUSE, LET, ORDERBYCLAUSE, WHERE, WINDOW

Constructor Summary

WindowClause()

Method Summary

Clause	copy()
void	explain(ExpressionPresenter out) Diagnostic print of expression structure.
int	getClauseKey() Get a keyword identifying what kind of clause this is
Expression	getEndCondition()
TuplePull	getPullStream(TuplePull base, XPathContext context) Get a pull-mode tuple stream that implements the functionality of this clause, taking its input from another tuple stream which this clause modifies
TuplePush	getPushStream(TuplePush destination, XPathContext context) Get a push-mode tuple stream that implements the functionality of this clause, supplying its output to another tuple stream
LocalVariableBinding[]	getRangeVariables() Get the variables bound by this clause
Expression	getSequence()
Expression	getStartCondition()
LocalVariableBinding	getVariableBinding(int role)
boolean	isIncludeUnclosedWindows()
boolean	isSlidingWindow()
boolean	isTumblingWindow()
protected static ValueRepresentation	makeValue(Item item)
protected boolean	matchesEnd(WindowClause.Window window, Item previous, Item current, Item next, int position, XPathContext context) Determine whether the current item is the last item in a window
protected boolean	matchesStart(Item previous, Item current, Item next, int position, XPathContext context) Determine whether the current item is the start of a new window
void	processSubExpressions(ExpressionProcessor processor) Process the subexpressions of this clause
void	setEndCondition(Expression endCondition)
void	setIncludeUnclosedWindows(boolean include)
void	setIsSlidingWindow(boolean sliding)
void	setSequence(Expression sequence)
void	setStartCondition(Expression startCondition)
void	setVariableBinding(int role, LocalVariableBinding binding)

Methods inherited from class net.sf.saxon.expr.flwor.Clause

gatherVariableReferences, optimize, refineVariableType, typeCheck

Methods inherited from class java.lang.Object

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

Field Detail

WINDOW_VAR

public static final int WINDOW_VAR

See Also:

Constant Field Values

START_ITEM

public static final int START_ITEM

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Constant Field Values

START_ITEM_POSITION

public static final int START_ITEM_POSITION

See Also:

Constant Field Values

START_PREVIOUS_ITEM

public static final int START_PREVIOUS_ITEM

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Constant Field Values

START_NEXT_ITEM

public static final int START_NEXT_ITEM

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Constant Field Values

END_ITEM

public static final int END_ITEM

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Constant Field Values

END_ITEM_POSITION

public static final int END_ITEM_POSITION

See Also:

Constant Field Values

END_PREVIOUS_ITEM

public static final int END_PREVIOUS_ITEM

See Also:

Constant Field Values

END_NEXT_ITEM

public static final int END_NEXT_ITEM

See Also:

Constant Field Values

Constructor Detail

WindowClause

public WindowClause()

Method Detail

getClauseKey

public int getClauseKey()

Description copied from class: Clause

Get a keyword identifying what kind of clause this is

Specified by:

getClauseKey in class Clause

Returns:

the kind of clause

setIsSlidingWindow

public void setIsSlidingWindow(boolean sliding)

isSlidingWindow

public boolean isSlidingWindow()

isTumblingWindow

public boolean isTumblingWindow()

setIncludeUnclosedWindows

public void setIncludeUnclosedWindows(boolean include)

isIncludeUnclosedWindows

public boolean isIncludeUnclosedWindows()

setSequence

public void setSequence(Expression sequence)

getSequence

public Expression getSequence()

setStartCondition

public void setStartCondition(Expression startCondition)

getStartCondition

public Expression getStartCondition()

setEndCondition

public void setEndCondition(Expression endCondition)

getEndCondition

public Expression getEndCondition()

setVariableBinding

public void setVariableBinding(int role,
                               LocalVariableBinding binding)
                        throws XPathException

Throws:

XPathException

getVariableBinding

public LocalVariableBinding getVariableBinding(int role)

copy

public Clause copy()

Specified by:

copy in class Clause

getPullStream

public TuplePull getPullStream(TuplePull base,
                               XPathContext context)

Get a pull-mode tuple stream that implements the functionality of this clause, taking its input from another tuple stream which this clause modifies

Specified by:

getPullStream in class Clause

Parameters:

base - the input tuple stream

context - the dynamic evaluation context

Returns:

the output tuple stream

getPushStream

public TuplePush getPushStream(TuplePush destination,
                               XPathContext context)

Get a push-mode tuple stream that implements the functionality of this clause, supplying its output to another tuple stream

Specified by:

getPushStream in class Clause

Parameters:

destination - the output tuple stream

context - the dynamic evaluation context

Returns:

the push tuple stream that implements the functionality of this clause of the FLWOR expression

processSubExpressions

public void processSubExpressions(ExpressionProcessor processor)
                           throws XPathException

Process the subexpressions of this clause

Specified by:

processSubExpressions in class Clause

Parameters:

processor - the expression processor used to process the subexpressions

Throws:

XPathException - if any error is detected

getRangeVariables

public LocalVariableBinding[] getRangeVariables()

Get the variables bound by this clause

Overrides:

getRangeVariables in class Clause

Returns:

the variable bindings

explain

public void explain(ExpressionPresenter out)

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Specified by:

explain in class Clause

Parameters:

out - the expression presenter used to display the structure

matchesStart

protected boolean matchesStart(Item previous,
                               Item current,
                               Item next,
                               int position,
                               XPathContext context)
                        throws XPathException

Determine whether the current item is the start of a new window

Parameters:

previous - the item before the current item (null if the current item is the first)

current - the current item

next - the item after the current item (null if the current item is the last)

position - the position of the current item in the input sequence

context - the dynamic evaluation context

Returns:

true if the current item forms the start of a new window

Throws:

XPathException

matchesEnd

protected boolean matchesEnd(WindowClause.Window window,
                             Item previous,
                             Item current,
                             Item next,
                             int position,
                             XPathContext context)
                      throws XPathException

Determine whether the current item is the last item in a window

Parameters:

window - the window in question

previous - the item before the current item (null if the current item is the first)

current - the current item

next - the item after the current item (null if the current item is the last)

position - the position of the current item in the input sequence

context - the dynamic evaluation context

Returns:

true if the current item is the last item in the specified window

Throws:

XPathException

makeValue

protected static ValueRepresentation makeValue(Item item)