Interface FSIterator<T extends FeatureStructure>
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- All Superinterfaces:
Iterator<T>
- All Known Implementing Classes:
FSIndexFlat.FSIteratorFlat
,FSIteratorImplBase
,FSIteratorWrapper
,FSIteratorWrapperDoubleCheck
,Subiterator
public interface FSIterator<T extends FeatureStructure> extends Iterator<T>
Iterator over feature structures.This iterator interface extends
Iterator
, and supports the standardhasNext
andnext
methods. 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()
andhasNext()
. 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 methodsget()
,moveToNext()
,moveToPrevious()
methods. With these methods, retrieving the current element (get
) is a separate operation from moving the iterator (moveToNext
andmoveToPrevious
. 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 tonext()
would return, but does not advance the iterator.Implementations of this interface are not required to be fail-fast. That is, if the iterator's collection is modified, the effects on the iterator are in general undefined. Some collections may handle this more gracefully than others, but in general, concurrent modification of the collection you're iterating over is a bad idea.
If the iterator is moved past the boundaries of the collection, the behavior of subsequent calls to
moveToNext()
ormoveToPrevious()
is undefined. For example, if a previously valid iterator is invalidated by a call tomoveToNext()
, a subsequent call tomoveToPrevious()
is not guaranteed to set the iterator back to the last element in the collection. Always usemoveToLast()
in such cases.
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description FSIterator<T>
copy()
Copy this iterator.T
get()
Get the structure the iterator is pointing at.boolean
isValid()
Check if this iterator is valid.void
moveTo(FeatureStructure fs)
Move the iterator to the first Feature Structure that is equal tofs
.void
moveToFirst()
Move the iterator to the first element.void
moveToLast()
Move the iterator to the last element.void
moveToNext()
Advance the iterator.void
moveToPrevious()
Move the iterator one element back.-
Methods inherited from interface java.util.Iterator
forEachRemaining, hasNext, next, remove
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Method Detail
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isValid
boolean isValid()
Check if this iterator is valid.- Returns:
true
if the iterator is valid.
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get
T get() throws NoSuchElementException
Get the structure the iterator is pointing at.- Returns:
- The structure the iterator is pointing at.
- Throws:
NoSuchElementException
- If the iterator is not valid.
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moveToNext
void moveToNext()
Advance the iterator. This may invalidate the iterator.- Throws:
ConcurrentModificationException
- if the underlying indexes being iterated over were modified
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moveToPrevious
void moveToPrevious()
Move the iterator one element back. This may invalidate the iterator.- Throws:
ConcurrentModificationException
- if the underlying indexes being iterated over were modified
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moveToFirst
void moveToFirst()
Move the iterator to the first element. The iterator will be valid iff the underlying collection is non-empty. Allowed even if the underlying indexes being iterated over were modified.
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moveToLast
void moveToLast()
Move the iterator to the last element. The iterator will be valid iff the underlying collection is non-empty. Allowed even if the underlying indexes being iterated over were modified.
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moveTo
void moveTo(FeatureStructure fs)
Move the iterator to the first Feature Structure that is equal tofs
. First means the earliest one occurring in the index, in case multiple FSs that are "equal" to fs are in the index. If no such feature structure exists in the underlying collection, set the iterator to the "insertion point" forfs
, i.e., to a point where the current feature structure is greater thanfs
, and the previous one is less thanfs
.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 bag index, no ordering is present, and the moveTo operation moves to the fs which is the same identical fs as the key. If no such fs is in the index, the iterator is marked invalid.
- Parameters:
fs
- The feature structure the iterator that supplies the comparison information. It must be of type T or a subtype of T.- Throws:
ConcurrentModificationException
- if the underlying indexes being iterated over were modified
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copy
FSIterator<T> copy()
Copy this iterator.- Returns:
- A copy of this iterator, pointing at the same element.
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