Package org.eclipse.rdf4j.repository.sparql.federation

## Class SPARQLCrossProductIteration

- java.lang.Object
- - org.eclipse.rdf4j.common.iteration.AbstractCloseableIteration<E,​X>
  - - org.eclipse.rdf4j.common.iteration.LookAheadIteration<BindingSet,​QueryEvaluationException>
    - - org.eclipse.rdf4j.repository.sparql.federation.SPARQLCrossProductIteration

- All Implemented Interfaces:
    `AutoCloseable`, `CloseableIteration<BindingSet,​QueryEvaluationException>`, `Iteration<BindingSet,​QueryEvaluationException>`

      public class SPARQLCrossProductIteration
      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 Note that this class is a fully equivalent copy of `CrossProductIteration`, and is only included here to avoid a circular dependency between the algebra-evaluation module and the sparql-repository module.
  Author:
    Andreas Schwarte

- - ### Field Summary

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

  - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `SPARQLCrossProductIteration​(CloseableIteration<BindingSet,​QueryEvaluationException> resultIteration, List<BindingSet> inputBindings)` |

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method | 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`

    - ### Methods inherited from interface org.eclipse.rdf4j.common.iteration.Iteration

      `stream`

- - ### 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

    - #### SPARQLCrossProductIteration

          public SPARQLCrossProductIteration​(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`