net.sf.saxon.expr

Class BigRangeIterator

java.lang.Object

net.sf.saxon.tree.iter.RangeIterator

net.sf.saxon.expr.BigRangeIterator

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, LastPositionFinder, SequenceIterator, AtomicIterator, GroundedIterator, LookaheadIterator

public class BigRangeIterator
extends RangeIterator
implements AtomicIterator, LastPositionFinder, LookaheadIterator

An Iterator that produces numeric values in a monotonic ascending or descending sequence, where the integers may exceed the range of a Long

Constructor Summary

Constructors

Constructor and Description
BigRangeIterator(java.math.BigInteger start, java.math.BigInteger step, java.math.BigInteger end) Create an iterator over a range of monotonically increasing integers

Method Summary

Modifier and Type	Method and Description
IntegerValue	getFirst()
IntegerValue	getLast()
int	getLength() Get the last position (that is, the number of items in the sequence).
IntegerValue	getMax()
IntegerValue	getMin()
GroundedValue	getResidue() Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position.
IntegerValue	getStep() Get the increment between successive values.
boolean	hasNext() Determine whether there are more items to come.
boolean	isActuallyGrounded() Ask if the iterator is actually grounded.
IntegerValue	next() Get the next atomic value in the sequence.
boolean	supportsGetLength() Ask whether this iterator supports use of the LastPositionFinder.getLength() method.
boolean	supportsHasNext() Ask whether the hasNext() method can be called.

Methods inherited from class net.sf.saxon.tree.iter.RangeIterator

containsEq

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.sf.saxon.om.SequenceIterator

close, discharge

Methods inherited from interface net.sf.saxon.tree.iter.GroundedIterator

materialize

Constructor Detail

BigRangeIterator

public BigRangeIterator(java.math.BigInteger start,
                        java.math.BigInteger step,
                        java.math.BigInteger end)
                 throws XPathException

Create an iterator over a range of monotonically increasing integers

Parameters:

start - the first integer in the sequence

step - the increment: negative for descending sequence

end - the last integer in the sequence. Must be >= start if ascending, or <= if descending.

Throws:

XPathException - if the max sequence length is exceeded

Method Detail

getResidue

public GroundedValue getResidue()

Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position. This should be an "in-memory" value, not a Closure. This method does not change the state of the iterator (in particular, it does not consume the iterator).

Specified by:

getResidue in interface GroundedIterator

Specified by:

getResidue in class RangeIterator

Returns:

the corresponding Value

Throws:

UncheckedXPathException - in the cases of subclasses (such as the iterator over a MemoClosure) which cause evaluation of expressions while materializing the value.

getFirst

public IntegerValue getFirst()

Specified by:

getFirst in class RangeIterator

getLast

public IntegerValue getLast()

Specified by:

getLast in class RangeIterator

getMin

public IntegerValue getMin()

Specified by:

getMin in class RangeIterator

getMax

public IntegerValue getMax()

Specified by:

getMax in class RangeIterator

getStep

public IntegerValue getStep()

Get the increment between successive values. For a descending iterator this will be negative value.

Specified by:

getStep in class RangeIterator

Returns:

the increment between successive values

supportsHasNext

public boolean supportsHasNext()

Description copied from interface: LookaheadIterator

Ask whether the hasNext() method can be called. This method must be called before calling hasNext(), because some iterators implement this interface, but only support look-ahead under particular circumstances (this is usually because they delegate to another iterator)

Specified by:

supportsHasNext in interface LookaheadIterator

Returns:

true if the LookaheadIterator.hasNext() method is available

hasNext

public boolean hasNext()

Description copied from interface: LookaheadIterator

Determine whether there are more items to come. Note that this operation is stateless and it is not necessary (or usual) to call it before calling next(). It is used only when there is an explicit need to tell if we are at the last element.

This method must not be called unless the result of LookaheadIterator.supportsHasNext() is true.

Specified by:

hasNext in interface LookaheadIterator

Returns:

true if there are more items in the sequence

next

public IntegerValue next()

Description copied from interface: AtomicIterator

Get the next atomic value in the sequence.

Specified by:

next in interface SequenceIterator

Specified by:

next in interface AtomicIterator

Returns:

the next Item. If there are no more items, return null.

supportsGetLength

public boolean supportsGetLength()

Description copied from interface: LastPositionFinder

Ask whether this iterator supports use of the LastPositionFinder.getLength() method. This method should always be called before calling LastPositionFinder.getLength(), because an iterator that implements this interface may support use of LastPositionFinder.getLength() in some situations and not in others

Specified by:

supportsGetLength in interface LastPositionFinder

Returns:

true if the LastPositionFinder.getLength() method can be called to determine the length of the underlying sequence.

getLength

public int getLength()

Description copied from interface: LastPositionFinder

Get the last position (that is, the number of items in the sequence). This method is non-destructive: it does not change the state of the iterator. The result is undefined if the next() method of the iterator has already returned null. This method must not be called unless the LastPositionFinder.supportsGetLength() has been called and has returned true.

Specified by:

getLength in interface LastPositionFinder

Returns:

the number of items in the sequence

isActuallyGrounded

public boolean isActuallyGrounded()

Description copied from interface: GroundedIterator

Ask if the iterator is actually grounded. This method must be called before calling GroundedIterator.materialize() or GroundedIterator.getResidue(), because the iterator might be grounded under some conditions and not others (usually when it delegates to another iterator)

Specified by:

isActuallyGrounded in interface GroundedIterator

Returns:

true if this iterator is grounded