Package org.eclipse.rdf4j.query.algebra.evaluation

## Interface QueryValueEvaluationStep

- All Known Implementing Classes:
    `QueryValueEvaluationStep.ConstantQueryValueEvaluationStep`, `QueryValueEvaluationStep.Minimal`

      public interface QueryValueEvaluationStep

  A step in the query evaluation that works on ValueExpresions.

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Interface | Description
    --- | --- | ---
    `static class` | `QueryValueEvaluationStep.ConstantQueryValueEvaluationStep` | A QueryValueEvalationStep that will return the same constant value throughout the query execution.
    `static class` | `QueryValueEvaluationStep.Minimal` | A minimal implementation that falls back to calling evaluate in the strategy.

  - ### Method Summary

    All Methods Instance Methods Abstract Methods Default Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `Value` | `evaluate​(BindingSet bindings)` |
    `default boolean` | `isConstant()` | If an value expression results in a constant then it may be executed once per query invocation.

- - ### Method Detail

    - #### evaluate

          Value evaluate​(BindingSet bindings)
                  throws ValueExprEvaluationException,
                         QueryEvaluationException

      Throws:
        `ValueExprEvaluationException`
        `QueryEvaluationException`

    - #### isConstant

          default boolean isConstant()

      If an value expression results in a constant then it may be executed once per query invocation. This can reduce computation time significantly.
      Returns:
        if this ValueExpresionStep will always return the same value