Interface FSIterator<T extends FeatureStructure>
- All Superinterfaces:
Iterator<T>
- All Known Implementing Classes:
FilteredIterator
,FSIndexFlat.FSIteratorFlat
,FSIteratorAggregate
,FSIteratorImplBase
,FSIteratorWrapper
,FSIteratorWrapperDoubleCheck
,Subiterator
This iterator interface extends Iterator
, and supports the
standard hasNext
and next
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()
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.
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()
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.
-
Method Summary
Modifier and TypeMethodDescriptioncopy()
Copy this iterator.get()
Get the structure the iterator is pointing at.boolean
isValid()
Check if this iterator is valid.void
Move the iterator to the first Feature Structure that is equal tofs
.void
Move the iterator to the first element.void
Move the iterator to the last element.void
Advance the iterator.void
Move the iterator one element back.Methods inherited from interface java.util.Iterator
forEachRemaining, hasNext, next, remove
-
Method Details
-
isValid
boolean isValid()Check if this iterator is valid.- Returns:
true
if the iterator is valid.
-
get
Get the structure the iterator is pointing at.- Returns:
- The structure the iterator is pointing at.
- Throws:
NoSuchElementException
- If the iterator is not valid.
-
moveToNext
void moveToNext()Advance the iterator. This may invalidate the iterator.- Throws:
ConcurrentModificationException
- if the underlying indexes being iterated over were modified
-
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
-
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. -
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. -
moveTo
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
-
copy
FSIterator<T> copy()Copy this iterator.- Returns:
- A copy of this iterator, pointing at the same element.
-