| it.unimi.dsi.mg4j.search.IntervalIterator
| IntervalIterator | | public interface IntervalIterator extends Iterator<Interval>(Code) | | An iterator over
.
Apart for the usual methods of a (type-specific) iterator, it
has a special (optional)
IntervalIterator.reset() method that allows one to reset
the iterator: the exact meaning of this operation is decided by the
implementing classes. Typically, after a
IntervalIterator.reset() , one can
iterate over a new sequence.
Warning: from MG4J 1.2, most methods throw an
IOException (such exceptions used to be catched and wrapped into a
RuntimeException ).
This interface also specifies a method
IntervalIterator.extent() returning
a positive integer that is supposed to approximate the minimum possible
length of an interval returned by this iterator. This method returns -1
if this extent cannot be computed.
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| Method Summary | |
| public int | extent()
Returns an approximation of a lower bound for the length of an interval
returned by this iterator. | | public void | intervalTerms(IntSet terms)
Provides the set of terms that span the current interval.
For each interval returned by MG4J, there is a set of terms that caused the interval to be returned.
The terms appear inside the interval, and certainly at its extremes.
Note that the results of this method must be taken with a grain of salt: there might be different sets of terms
causing the current interval, and only one will be returned. | | public Interval | next()
Returns the next interval. | | public Interval | nextInterval()
Returns the next interval provided by this interval iterator, or null if no more intervals are available.
This method has been reintroduced in MG4J 1.2 with a different semantics.
The special return value null is used to mark the end of iteration. | | public void | reset()
Resets the internal state of this iterator for a new document. |
| extent | | public int extent()(Code) | | Returns an approximation of a lower bound for the length of an interval
returned by this iterator.
an approximation of a lower bound for the length of an interval. |
| intervalTerms | | public void intervalTerms(IntSet terms)(Code) | | Provides the set of terms that span the current interval.
For each interval returned by MG4J, there is a set of terms that caused the interval to be returned.
The terms appear inside the interval, and certainly at its extremes.
Note that the results of this method must be taken with a grain of salt: there might be different sets of terms
causing the current interval, and only one will be returned.
Parameters:
terms - a set of integers that will be filled with the terms spanning the current interval. |
| nextInterval | | public Interval nextInterval() throws IOException(Code) | | Returns the next interval provided by this interval iterator, or null if no more intervals are available.
This method has been reintroduced in MG4J 1.2 with a different semantics.
The special return value null is used to mark the end of iteration. The reason
for this change is providing fully lazy iteration over intervals. Fully lazy iteration
does not provide an hasNext() method—you have to actually ask for the next
element and check the return value. Fully lazy iteration is much lighter on method calls (half) and
in most (if not all) MG4J classes leads to a much simpler logic. Moreover,
IntervalIterator.nextInterval() can be specified as throwing an
IOException , which avoids the pernicious proliferation
of try/catch blocks in very short, low-level methods (it was having a detectable impact on performance).
the next interval, or null if no more intervals are available. |
| reset | | public void reset() throws IOException(Code) | | Resets the internal state of this iterator for a new document.
To reduce object creation, interval iterators are usually created in a lazy
fashion by document iterator when they are needed. However, this implies that
every time the document iterator is moved, some internal state of the interval iterator must be reset
(e.g., because on the new document some of the component interval iterators are now
IntervalIterators.TRUE ).
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