ch.ethz.mxquery.model
Class Window

java.lang.Object
  ch.ethz.mxquery.model.Iterator
      ch.ethz.mxquery.model.Window

All Implemented Interfaces:

IndexIterator, XDMIterator, Traversable

Direct Known Subclasses:

LLStoreIterator, WindowIterator

public abstract class Window
extends Iterator
implements IndexIterator

A window iterator works always on a store, which materializes the tokens. A window can either be a window with a start and end edge or (also the name states something else) selected items form the store.

Field Summary

static int	END_OF_STREAM_NODE
static int	END_OF_STREAM_POSITION

Fields inherited from interface ch.ethz.mxquery.model.XDMIterator

EXPR_CATEGORY_SEQUENTIAL, EXPR_CATEGORY_SIMPLE, EXPR_CATEGORY_UPDATING, EXPR_CATEGORY_VACUOUS, EXPR_PARAM_CHEAPEVAL, EXPR_PARAM_VARIABLE, EXPR_PARAM_WINDOW, EXPR_PARAM_XDMGEN

Constructor Summary

Window()

Method Summary

abstract void	destroyWindow() Destroys the connection to the window buffer and gives the used item free for garbage collection
abstract boolean	equals(java.lang.Object other)
int	getEndPosition()
Window	getNewEarlyParallelWindowInterface(int startPosition, WindowVariable[] startVars, VariableHolder[] startVarHolders, XDMIterator endExpr, WindowVariable[] endVars, VariableHolder[] endVarHolders)
Window	getNewEarlyWindowInterface(int startPosition, XDMIterator startExpr, WindowVariable[] startVars, VariableHolder[] startVarHolders, XDMIterator endExpr, WindowVariable[] endVars, VariableHolder[] endVarHolders)
abstract Window	getNewItemWindow(IntegerList values) Returns a new iterator consisting of the given items in the integer list.
abstract Window	getNewWindow(int startPosition, int endPosition) Returns a new iterator for a given start and end position.
int	getNextWindowStartPosition()
abstract int	getPosition()
abstract int	getStartNode() Returns the first node id of the window
abstract Source	getStore()
Window	getUnderlyingWindow()
abstract int	getWindowId() Every window has a unique id given by the buffer the window is working on.
void	increasePosition()
boolean	isExprParameter(int valueToCheck, boolean recursive) Optimization check
boolean	isWindow()
abstract boolean	isWindowInUse() If a window is not in use it is a schema for other windows.
Token	jumpToNextAttribute(java.lang.String attributeName) Jumps to the next attribute if possible in the form of /@attributeName If the jump is not possible, -1 is returned
void	setPosition(int p)
abstract void	setWindowInUse(boolean windowInUse) Specifies if a window can be used again.

Methods inherited from class ch.ethz.mxquery.model.Iterator

addPredicates, close, copy, copyInts, copyIterators, copyQNames, copyStrings, copyTypeInfos, getAllSubIters, getAllSubItersRecursive, getContext, getExpressionCategoryType, getLoc, getPendingUpdateList, getPredicates, getStaticType, getSubIters, hasPredicates, isConstModePreserve, isOpen, isResettable, removePredicates, reset, setConstModePreserve, setContext, setLoc, setOrderByExpr, setParam, setResettable, setReturnExpr, setSubIters, setSubIters, setSubIters, setWhereExpr, traverse, traverseIteratorTree

Methods inherited from class java.lang.Object

getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface ch.ethz.mxquery.model.IndexIterator

getItem, hasItem, hasNextItem, nextItem

Methods inherited from interface ch.ethz.mxquery.model.XDMIterator

next

Field Detail

END_OF_STREAM_POSITION

public static final int END_OF_STREAM_POSITION

See Also:

Constant Field Values

END_OF_STREAM_NODE

public static final int END_OF_STREAM_NODE

See Also:

Constant Field Values

Constructor Detail

Window

public Window()

Method Detail

getUnderlyingWindow

public Window getUnderlyingWindow()
                           throws MXQueryException

Throws:

MXQueryException

getNewItemWindow

public abstract Window getNewItemWindow(IntegerList values)
                                 throws MXQueryException

Returns a new iterator consisting of the given items in the integer list. If a position is outside the underlying sequence, the position is skipped.

Parameters:

values - Each value in the integer list has to be a position

Returns:

a new Window for the given list of positions

Throws:

MXQueryException

getNewEarlyWindowInterface

public Window getNewEarlyWindowInterface(int startPosition,
                                         XDMIterator startExpr,
                                         WindowVariable[] startVars,
                                         VariableHolder[] startVarHolders,
                                         XDMIterator endExpr,
                                         WindowVariable[] endVars,
                                         VariableHolder[] endVarHolders)

getNewEarlyParallelWindowInterface

public Window getNewEarlyParallelWindowInterface(int startPosition,
                                                 WindowVariable[] startVars,
                                                 VariableHolder[] startVarHolders,
                                                 XDMIterator endExpr,
                                                 WindowVariable[] endVars,
                                                 VariableHolder[] endVarHolders)

jumpToNextAttribute

public Token jumpToNextAttribute(java.lang.String attributeName)
                          throws MXQueryException

Jumps to the next attribute if possible in the form of /@attributeName If the jump is not possible, -1 is returned

Parameters:

attributeName -

Returns:

The event id

Throws:

MXQueryException

getNewWindow

public abstract Window getNewWindow(int startPosition,
                                    int endPosition)
                             throws MXQueryException

Returns a new iterator for a given start and end position. If the end is outside the underlying sequence the iterator throws no error but only returns items until the sequence ends

Parameters:

startPosition -

endPosition -

Returns:

a new window for the given start and end positions

Throws:

MXQueryException

getStartNode

public abstract int getStartNode()
                          throws MXQueryException

Returns the first node id of the window

Returns:

returns the first node id of this window

Throws:

MXQueryException

destroyWindow

public abstract void destroyWindow()

Destroys the connection to the window buffer and gives the used item free for garbage collection

equals

public abstract boolean equals(java.lang.Object other)

Overrides:

equals in class java.lang.Object

getWindowId

public abstract int getWindowId()

Every window has a unique id given by the buffer the window is working on.

Returns:

the identifier of this window

isWindowInUse

public abstract boolean isWindowInUse()

If a window is not in use it is a schema for other windows. E.g. a LET/FOR/FORSEQ binds a window to a variable the window is not in use yet. But in the moment the first variable reference is using the window the window is in used

Returns:

true if the window is use, false otherwise

setWindowInUse

public abstract void setWindowInUse(boolean windowInUse)

Specifies if a window can be used again. This method is normally only used by the variable iterator. Be carefully with it, as it is mainly responsible to allow proper garbage collection.

Parameters:

windowInUse -

increasePosition

public void increasePosition()

setPosition

public void setPosition(int p)

getPosition

public abstract int getPosition()

isWindow

public boolean isWindow()

isExprParameter

public boolean isExprParameter(int valueToCheck,
                               boolean recursive)

Description copied from interface: XDMIterator

Optimization check

Specified by:

isExprParameter in interface XDMIterator

Overrides:

isExprParameter in class Iterator

Returns:

if iterator fulfills the requested criteria

getEndPosition

public int getEndPosition()

getNextWindowStartPosition

public int getNextWindowStartPosition()

getStore

public abstract Source getStore()