Package net.sf.saxon.tree.iter

## Interface ConstrainedIterator<T extends Item>

- All Superinterfaces:
    `java.lang.AutoCloseable`, `java.io.Closeable`, `GroundedIterator`, `LastPositionFinder`, `LookaheadIterator`, `ReversibleIterator`, `SequenceIterator`, `UnfailingIterator`

      public interface ConstrainedIterator<T extends Item>
      extends SequenceIterator, UnfailingIterator, ReversibleIterator, LastPositionFinder, GroundedIterator, LookaheadIterator

  SingletonIterator: an iterator over a sequence of zero or one values

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from interface net.sf.saxon.om.SequenceIterator

      `SequenceIterator.Property`

  - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `int` | `getLength()` | Get the last position (that is, the number of items in the sequence).
    `boolean` | `hasNext()` | Determine whether there are more items to come.
    `GroundedValue` | `materialize()` | Create a GroundedValue (a sequence materialized in memory) containing all the values delivered by this SequenceIterator.
    `T` | `next()` | Get the next item in the sequence.

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

      `getResidue`

    - ### Methods inherited from interface net.sf.saxon.tree.iter.ReversibleIterator

      `getReverseIterator`

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

      `close, forEachOrFail, getProperties`

    - ### Methods inherited from interface net.sf.saxon.tree.iter.UnfailingIterator

      `forEach, toList`

- - ### Method Detail

    - #### hasNext

          boolean hasNext()

      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.
      Specified by:
        `hasNext` in interface `LookaheadIterator`
      Returns:
        true if there are more items

    - #### next

          T next()

      Description copied from interface: `SequenceIterator`
      Get the next item in the sequence. This method changes the state of the iterator.
      Specified by:
        `next` in interface `SequenceIterator`
      Specified by:
        `next` in interface `UnfailingIterator`
      Returns:
        the next item, or null if there are no more items. Once a call on next() has returned null, no further calls should be made. The preferred action for an iterator if subsequent calls on next() are made is to return null again, and all implementations within Saxon follow this rule.

    - #### getLength

          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 result of getProperties() on the iterator includes the bit setting `SequenceIterator.Property.LAST_POSITION_FINDER`
      Specified by:
        `getLength` in interface `LastPositionFinder`
      Returns:
        the number of items in the sequence

    - #### materialize

          GroundedValue materialize()

      Description copied from interface: `SequenceIterator`
      Create a GroundedValue (a sequence materialized in memory) containing all the values delivered by this SequenceIterator. The method must only be used when the SequenceIterator is positioned at the start. If it is not positioned at the start, then it is implementation-dependant whether the returned sequence contains all the nodes delivered by the SequenceIterator from the beginning, or only those delivered starting at the current position.

      It is implementation-dependant whether this method consumes the SequenceIterator. (More specifically, in the current implementation: if the iterator is backed by a `GroundedValue`, then that value is returned and the iterator is not consumed; otherwise, the iterator is consumed and the method returns the remaining items after the current position only).

      Specified by:
        `materialize` in interface `GroundedIterator`
      Specified by:
        `materialize` in interface `SequenceIterator`
      Returns:
        a sequence containing all the items delivered by this SequenceIterator.