gnu.lists

Class SeqPosition<E,ESEQ extends AbstractSequence<E>>

java.lang.Object

gnu.lists.SeqPosition<E,ESEQ>

All Implemented Interfaces:

java.util.Enumeration<E>, java.util.Iterator<E>, java.util.ListIterator<E>

Direct Known Subclasses:

ExtPosition, KNode, Marker, TreePosition

public class SeqPosition<E,ESEQ extends AbstractSequence<E>>
extends java.lang.Object
implements java.util.ListIterator<E>, java.util.Enumeration<E>

A position in a sequence (list). Conceptually similar to Java2's ListIterator, but we use the name "Position" to indicate that it can be used to both indicate a position in a sequence and to iterate through a sequence. If you use a SeqPosition as a "position", you would not modify if (though it is possible the offset of the position in the sequence may change due to other update operations on the sequence). If you use a SeqPosition as an "iterator", you would initialize it to some beginnning position, and then modify the current position of the SeqPosition so it refers to successive elements. See the package overview for more information.

Field Summary

Fields

Modifier and Type	Field and Description
int	ipos An integer that (together with xpos) indicates the current position.
ESEQ	sequence The Sequence relative to which ipos and xpos have meaning.

Constructor Summary

Constructors

Constructor and Description
SeqPosition()
SeqPosition(ESEQ seq)
SeqPosition(ESEQ seq, int ipos)
SeqPosition(ESEQ seq, int offset, boolean isAfter)

Method Summary

Methods

Modifier and Type	Method and Description
void	add(E o)
SeqPosition<E,ESEQ>	copy()
void	finalize()
int	fromEndIndex()
int	getContainingSequenceSize()
java.lang.Object	getNext() Get element following current position.
int	getNextKind() Return a code (defined in Sequence) for the type of the next element.
java.lang.String	getNextTypeName() Get the "tag name" for the next element, if any.
E	getNextTypeObject() Get the "tag object" for the next element, if any.
int	getPos() Get a position int "cookie" for this SeqPosition.
java.lang.Object	getPrevious() Get element before the current position.
boolean	gotoChildrenStart() Set position before first child (of the element following position).
void	gotoEnd(ESEQ seq)
boolean	gotoNext() Move one element forwards, if possible.
boolean	gotoPrevious() Move backwards one element.
void	gotoStart(ESEQ seq)
boolean	hasMoreElements() True if there is an element following the current position.
boolean	hasNext() See java.util.Iterator.
boolean	hasPrevious() See java.util.Iterator.
boolean	isAfter() Tests whether the position pair has the "isAfter" property.
static <E,ESEQ extends AbstractSequence<E>> SeqPosition<E,ESEQ>	make(ESEQ seq, int ipos) Creates a new SeqPosition, from a position pair.
E	next() See java.util.ListIterator.
E	nextElement() See java.util.Enumeration.
int	nextIndex() See java.util.Iterator.
E	previous() See java.util.ListIterator.
int	previousIndex() See java.util.Iterator.
void	release()
void	remove()
void	set(E value)
void	set(ESEQ seq, int index, boolean isAfter)
void	set(SeqPosition<E,ESEQ> pos)
void	setNext(E value)
void	setPos(ESEQ seq, int ipos)
void	setPos(int ipos)
void	setPrevious(E value)
java.lang.String	toInfo()
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

sequence

public ESEQ extends AbstractSequence<E> sequence

The Sequence relative to which ipos and xpos have meaning. This is normally the same as the Sequence we iterate through. However, if this is a TreePosition, it may an ancestor instead.

ipos

public int ipos

An integer that (together with xpos) indicates the current position. The actual value has no meaning, except as interpreted by sequence.

Constructor Detail

SeqPosition

public SeqPosition()

SeqPosition

public SeqPosition(ESEQ seq)

SeqPosition

public SeqPosition(ESEQ seq,
           int offset,
           boolean isAfter)

SeqPosition

public SeqPosition(ESEQ seq,
           int ipos)

Method Detail

make

public static <E,ESEQ extends AbstractSequence<E>> SeqPosition<E,ESEQ> make(ESEQ seq,
                                                            int ipos)

Creates a new SeqPosition, from a position pair. The position pair is copied (using copyPos).

copy

public SeqPosition<E,ESEQ> copy()

gotoStart

public final void gotoStart(ESEQ seq)

gotoEnd

public final void gotoEnd(ESEQ seq)

gotoChildrenStart

public boolean gotoChildrenStart()

Set position before first child (of the element following position).

Returns:

true if there is a child sequence (which might be empty); false if current position is end of sequence or following element is atomic (cannot have children).

hasMoreElements

public final boolean hasMoreElements()

True if there is an element following the current position. False if we are at the end. See java.util.Enumeration.

Specified by:

hasMoreElements in interface java.util.Enumeration<E>

hasNext

public boolean hasNext()

See java.util.Iterator.

Specified by:

hasNext in interface java.util.Iterator<E>

Specified by:

hasNext in interface java.util.ListIterator<E>

getNextKind

public int getNextKind()

Return a code (defined in Sequence) for the type of the next element.

getNextTypeName

public java.lang.String getNextTypeName()

Get the "tag name" for the next element, if any.

getNextTypeObject

public E getNextTypeObject()

Get the "tag object" for the next element, if any.

hasPrevious

public boolean hasPrevious()

See java.util.Iterator.

Specified by:

hasPrevious in interface java.util.ListIterator<E>

next

public E next()

See java.util.ListIterator.

Specified by:

next in interface java.util.Iterator<E>

Specified by:

next in interface java.util.ListIterator<E>

gotoNext

public boolean gotoNext()

Move one element forwards, if possible.

Returns:

if we succeeded in moving forwards (i.e. not at end of sequence).

gotoPrevious

public boolean gotoPrevious()

Move backwards one element.

Returns:

false iff already at beginning.

previous

public E previous()

See java.util.ListIterator.

Specified by:

previous in interface java.util.ListIterator<E>

nextElement

public final E nextElement()

See java.util.Enumeration.

Specified by:

nextElement in interface java.util.Enumeration<E>

getNext

public java.lang.Object getNext()

Get element following current position. Does not move the position, in contrast to next() method.

Returns:

EOF if at end of sequence, otherwise the value following.

getPrevious

public java.lang.Object getPrevious()

Get element before the current position. Does not move the position, in contrast to previous() method.

Returns:

EOF if at beginning of sequence, otherwise the value prior.

nextIndex

public int nextIndex()

See java.util.Iterator.

Specified by:

nextIndex in interface java.util.ListIterator<E>

fromEndIndex

public final int fromEndIndex()

getContainingSequenceSize

public int getContainingSequenceSize()

previousIndex

public final int previousIndex()

See java.util.Iterator.

Specified by:

previousIndex in interface java.util.ListIterator<E>

isAfter

public boolean isAfter()

Tests whether the position pair has the "isAfter" property. I.e. if something is inserted at the position, will the iterator end up being after the new data? A toNext() or next() command should set isAfter() to true; a toPrevious or previous command should set isAfter() to false.

set

public final void set(E value)

Specified by:

set in interface java.util.ListIterator<E>

setNext

public void setNext(E value)

setPrevious

public void setPrevious(E value)

remove

public void remove()

Specified by:

remove in interface java.util.Iterator<E>

Specified by:

remove in interface java.util.ListIterator<E>

add

public void add(E o)

Specified by:

add in interface java.util.ListIterator<E>

getPos

public int getPos()

Get a position int "cookie" for this SeqPosition. The result can be passed to AbstractSequence's getPosNext(int), createRelativePos, and other methods. By default this is the value of ipos, but for sequences that need emore state than an ipos for efficient position, we use a PositionManager index. So this gets over-ridden in ExtPosition.

setPos

public void setPos(ESEQ seq,
          int ipos)

setPos

public void setPos(int ipos)

set

public void set(ESEQ seq,
       int index,
       boolean isAfter)

set

public void set(SeqPosition<E,ESEQ> pos)

release

public void release()

finalize

public void finalize()

Overrides:

finalize in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

toInfo

public java.lang.String toInfo()