org.eclipse.rdf4j.query.algebra.evaluation.iterator

## Class CrossProductIteration

- java.lang.Object
- - org.eclipse.rdf4j.common.iteration.AbstractCloseableIteration<E,X>
  - - org.eclipse.rdf4j.common.iteration.LookAheadIteration<BindingSet,QueryEvaluationException>
    - - org.eclipse.rdf4j.query.algebra.evaluation.iterator.CrossProductIteration

- All Implemented Interfaces:
    AutoCloseable, CloseableIteration<BindingSet,QueryEvaluationException>, Iteration<BindingSet,QueryEvaluationException>
  Direct Known Subclasses:
    ServiceCrossProductIteration

      public class CrossProductIteration
      extends LookAheadIteration<BindingSet,QueryEvaluationException>

  Iteration which forms the cross product of a list of materialized input bindings with each result obtained from the inner iteration. Example: inputBindings := {b1, b2, ...} resultIteration := {r1, r2, ...} getNextElement() returns (r1,b1), (r1, b2), ..., (r2, b1), (r2, b2), ... i.e. compute the cross product per result binding
  Author:
    Andreas Schwarte

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected BindingSet` | `currentInputBinding`
    `protected List<BindingSet>` | `inputBindings`
    `protected Iterator<BindingSet>` | `inputBindingsIterator`
    `protected CloseableIteration<BindingSet,QueryEvaluationException>` | `resultIteration`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `CrossProductIteration(CloseableIteration<BindingSet,QueryEvaluationException> resultIteration, List<BindingSet> inputBindings)`

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected BindingSet` | `getNextElement()` Gets the next element.
    `protected void` | `handleClose()` Called by `AbstractCloseableIteration.close()` when it is called for the first time.

    - ### Methods inherited from class org.eclipse.rdf4j.common.iteration.LookAheadIteration

      `hasNext, next, remove`

    - ### Methods inherited from class org.eclipse.rdf4j.common.iteration.AbstractCloseableIteration

      `close, isClosed`

    - ### Methods inherited from class java.lang.Object

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

- - ### Field Detail

    - #### inputBindings

          protected final List<BindingSet> inputBindings

    - #### resultIteration

          protected final CloseableIteration<BindingSet,QueryEvaluationException> resultIteration

    - #### inputBindingsIterator

          protected Iterator<BindingSet> inputBindingsIterator

    - #### currentInputBinding

          protected BindingSet currentInputBinding

  - ### Constructor Detail

    - #### CrossProductIteration

          public CrossProductIteration(CloseableIteration<BindingSet,QueryEvaluationException> resultIteration,
                                       List<BindingSet> inputBindings)

  - ### Method Detail

    - #### getNextElement

          protected BindingSet getNextElement()
                                       throws QueryEvaluationException

      Description copied from class: `LookAheadIteration`
      Gets the next element. Subclasses should implement this method so that it returns the next element.
      Specified by:
        `getNextElement` in class `LookAheadIteration<BindingSet,QueryEvaluationException>`
      Returns:
        The next element, or `null` if no more elements are available.
      Throws:
        `QueryEvaluationException`

    - #### handleClose

          protected void handleClose()
                              throws QueryEvaluationException

      Description copied from class: `AbstractCloseableIteration`
      Called by `AbstractCloseableIteration.close()` when it is called for the first time. This method is only called once on each iteration. By default, this method does nothing.
      Overrides:
        `handleClose` in class `LookAheadIteration<BindingSet,QueryEvaluationException>`
      Throws:
        `QueryEvaluationException`

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