Package org.drools.base.rule.accessor

Interface Evaluator

All Superinterfaces:
Evaluator, Serializable
public interface Evaluator extends Serializable, Evaluator
A public interface to be implemented by all evaluators

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    evaluate(ValueResolver valueResolver, ReadAccessor extractor, FactHandle factHandle, FieldValue value)
    Evaluates the expression using the provided parameters.
    boolean
    evaluate(ValueResolver valueResolver, ReadAccessor leftExtractor, FactHandle left, ReadAccessor rightExtractor, FactHandle right)
    Evaluates the expression using the provided parameters.
    ValueType
    getCoercedValueType()
    Returns the value type this evaluator will coerce operands to, during evaluation.
    Interval
    getInterval()
    In case this is a temporal evaluator, returns the interval in which this evaluator may match the target fact
    Operator
    getOperator()
    Returns the operator representation object for this evaluator
    ValueType
    getValueType()
    Returns the type of the values this evaluator operates upon.
    boolean
    isTemporal()
    Returns true if this evaluator implements a temporal evaluation, i.e., a time sensitive evaluation whose properties of matching only events within an specific time interval can be used for determining event expirations automatically.

  • Method Details

    • getValueType

      ValueType getValueType()
      Returns the type of the values this evaluator operates upon.
      Returns:

    • getOperator

      Operator getOperator()
      Returns the operator representation object for this evaluator
      Specified by:
      getOperator in interface Evaluator
      Returns:

    • getCoercedValueType

      ValueType getCoercedValueType()
      Returns the value type this evaluator will coerce operands to, during evaluation. This is useful for operators like "memberOf", that always convert to Object when evaluating, independently of the source operand value type.
      Returns:

    • evaluate

      boolean evaluate(ValueResolver valueResolver, ReadAccessor extractor, FactHandle factHandle, FieldValue value)
      Evaluates the expression using the provided parameters. This method is used when evaluating alpha-constraints, i.e., a fact attribute against a constant value. For instance: Person( name == "Bob" ) So, it uses a constant value "Bob" that is sent into the method as the FieldValue (value), and compares it to the value of the name field, read by using the extractor on the fact instance (object1).
      Parameters:
      valueResolver - The current working memory
      extractor - The extractor used to get the field value from the object
      factHandle - The source object to evaluate, i.e., the fact
      value - The actual value to compare to, i.e., the constant value.
      Returns:
      Returns true if evaluation is successful. false otherwise.

    • evaluate

      boolean evaluate(ValueResolver valueResolver, ReadAccessor leftExtractor, FactHandle left, ReadAccessor rightExtractor, FactHandle right)
      Evaluates the expression using the provided parameters. This method is used for internal indexing and hashing, when drools needs to extract and evaluate both left and right values at once. For instance: Person( name == $someName ) This method will be used to extract and evaluate both the "name" attribute and the "$someName" variable at once.
      Parameters:
      valueResolver - The current working memory
      leftExtractor - The extractor to read the left value. In the above example, the "$someName" variable value.
      left - The source object from where the value of the variable is extracted.
      rightExtractor - The extractor to read the right value. In the above example, the "name" attribute value.
      right - The right object from where to extract the value. In the above example, that is the "Person" instance from where to extract the "name" attribute.
      Returns:
      Returns true if evaluation is successful. false otherwise.

    • isTemporal

      boolean isTemporal()
      Returns true if this evaluator implements a temporal evaluation, i.e., a time sensitive evaluation whose properties of matching only events within an specific time interval can be used for determining event expirations automatically.
      Specified by:
      isTemporal in interface Evaluator
      Returns:
      true if the evaluator is a temporal evaluator.

    • getInterval

      Interval getInterval()
      In case this is a temporal evaluator, returns the interval in which this evaluator may match the target fact
      Returns: