public interface FSIterator<T extends FeatureStructure> extends ListIterator<T>
This iterator interface extends ListIterator which, in turn,
extends Iterator. It supports all the methods of those APIs
except nextIndex, previousIndex, set, and add. remove meaning is changed to mean
remove the item obtained by a get() from all the indexes in this view.
If finer control, including reverse iteration, is needed, see below.
Note: do not use the APIs described below *together* with the standard Java iterator methods
next() and hasNext(). On any given iterator, use either the one or the
other, but not both together. Otherwise, next/hasNext may exhibit incorrect
behavior.
The FSIterator interface introduces the methods get(),
moveToNext(), moveToPrevious() methods. With these methods, retrieving the
current element (get) is a separate operation from moving the iterator (moveToNext
and moveToPrevious. This makes the user's code less compact, but allows for finer
control.
Specifically the get method is defined to return the same element that a call to
next() would return, but does not advance the iterator.
If the iterator's underlying UIMA Indexes are modified, the iterator continues as if it doesn't see these modifications. Three operations cause the iterator to "see" any modifications: moveToFirst, moveToLast, and moveTo(featureStructure).
If the iterator is moved past the boundaries of the collection, the behavior of subsequent calls
to moveToNext() or
moveToPrevious() is undefined. For example, if a previously
valid iterator is invalidated by a call to moveToNext(), a
subsequent call to moveToPrevious() is not guaranteed to set
the iterator back to the last element in the collection. Always use
moveToLast() in such cases.
| Modifier and Type | Method and Description |
|---|---|
default void |
add(T e) |
FSIterator<T> |
copy()
Copy this iterator.
|
default T |
get()
Get the structure the iterator is pointing at.
|
T |
getNvc()
Get the structure the iterator is pointing at.
|
default Type |
getType() |
default boolean |
hasNext()
DEFAULT implementations of Iterator interface
in terms of FSIterator methods
|
default boolean |
hasPrevious() |
boolean |
isValid()
Check if this iterator is valid.
|
void |
moveTo(FeatureStructure fs)
Move the iterator to the first Feature Structure that matches the
fs. |
void |
moveToFirst()
Move the iterator to the first element.
|
void |
moveToLast()
Move the iterator to the last element.
|
default void |
moveToNext()
Advance the iterator.
|
void |
moveToNextNvc()
version of moveToNext which bypasses the isValid check - call only if you've just done this check yourself
|
default void |
moveToPrevious()
Move the iterator one element back.
|
void |
moveToPreviousNvc()
version of moveToPrevious which bypasses the isValid check - call only if you've just done this check yourself
|
default T |
next() |
default int |
nextIndex() |
default T |
nextNvc() |
default T |
previous() |
default int |
previousIndex() |
default T |
previousNvc() |
default void |
remove()
Removes from all the indexes associated with this view, the
"current" Feature Structure (the one that would be returned by a
"get()" operation).
|
default void |
set(T e) |
default Spliterator<T> |
spliterator()
Don't use this directly, use select()...
|
default Stream<T> |
stream() |
forEachRemainingboolean isValid()
true if the iterator is valid.default T get() throws NoSuchElementException
NoSuchElementException - If the iterator is not valid.T getNvc()
default void moveToNext()
ConcurrentModificationException - if the underlying indexes being iterated over were modifiedvoid moveToNextNvc()
default void moveToPrevious()
ConcurrentModificationException - if the underlying indexes being iterated over were modifiedvoid moveToPreviousNvc()
void moveToFirst()
void moveToLast()
void moveTo(FeatureStructure fs)
fs.
First means the earliest one occurring in the index, in case multiple FSs matching the fs
are in the index. If no
such feature structure exists in the underlying collection, and the iterator is over a sorted index,
set the iterator to the "insertion point" for fs, i.e.,
to a point where the current feature structure compares greater
than fs, and the previous one compares less than fs, using this
sorted index's comparator.
If the fs is greater than all of the entries in the index, the moveTo cannot set the iterator to an insertion point where the current feature structure is greater than fs, so it marks the iterator "invalid".
If the underlying index is a set or bag index, or an unordered form of iteration
is configured (for example using the select API,
no ordering is present, and the moveTo operation moves to a matching item,
if one exists. The match is done using the index's comparator.
If none exist, the index is left if possible in some valid (but non-matching) position.
When the iterator is over a sorted index whose keys include the typeOrder key, this can cause unexpected operation, depending on type priorities. For example, consider the Annotation Index, which includes this key. If there are many indexed instances of the type "Foo" with the same begin and end, and a moveTo operation is specified using an Annotation instance with the same begin and end, then the Foo elements might or might not be seen going forwards, depending on the relative type priorities of "Foo" and "Annotation".
If you are not making use of typeOrdering, the "select" APIs can create iterators which will ignore the typeOrdering key when doing the moveTo operation, which will result in all the instances of type "Foo" being seen going forwards, independent of the type priorities. See the select documentation in the version 3 users guide.
fs - The feature structure the iterator that supplies the
comparison information. It doesn't need to be in the index; it is just being
used as a comparison template. It can be a supertype of T as long as it can supply the keys needed.
A typical example is a subtype of Annotation, and using an annotation instance to specify
the begin / end.FSIterator<T> copy()
default Type getType()
default boolean hasNext()
hasNext in interface Iterator<T extends FeatureStructure>hasNext in interface ListIterator<T extends FeatureStructure>default T next()
next in interface Iterator<T extends FeatureStructure>next in interface ListIterator<T extends FeatureStructure>default T nextNvc()
default boolean hasPrevious()
hasPrevious in interface ListIterator<T extends FeatureStructure>default T previous()
previous in interface ListIterator<T extends FeatureStructure>default T previousNvc()
default int nextIndex()
nextIndex in interface ListIterator<T extends FeatureStructure>default int previousIndex()
previousIndex in interface ListIterator<T extends FeatureStructure>default void set(T e)
set in interface ListIterator<T extends FeatureStructure>default void add(T e)
add in interface ListIterator<T extends FeatureStructure>default Spliterator<T> spliterator()
default Stream<T> stream()
default void remove()
remove in interface Iterator<T extends FeatureStructure>remove in interface ListIterator<T extends FeatureStructure>NoSuchElementException - if the iterator is invalid.Copyright © 2006–2017 The Apache Software Foundation. All rights reserved.