Package org.drools.mvel.evaluators

Class BeforeEvaluatorDefinition

java.lang.Object

org.drools.mvel.evaluators.BeforeEvaluatorDefinition

All Implemented Interfaces:

Externalizable, Serializable, org.drools.compiler.rule.builder.EvaluatorDefinition, org.kie.api.runtime.rule.EvaluatorDefinition

public class BeforeEvaluatorDefinition
extends Object
implements org.drools.compiler.rule.builder.EvaluatorDefinition

The implementation of the 'before' evaluator definition.

The before evaluator correlates two events and matches when the temporal distance from the event being correlated to the current correlated belongs to the distance range declared for the operator.

Lets look at an example:

$eventA : EventA( this before[ 3m30s, 4m ] $eventB )

The previous pattern will match if and only if the temporal distance between the time when $eventA finished and the time when $eventB started is between ( 3 minutes and 30 seconds ) and ( 4 minutes ). In other words:

 3m30s <= $eventB.startTimestamp - $eventA.endTimeStamp <= 4m 

The temporal distance interval for the before operator is optional:

• If two values are defined (like in the example below), the interval starts on the first value and finishes on the second.
• If only one value is defined, then the interval starts on the value and finishes on the positive infinity.
• If no value is defined, it is assumed that the initial value is 1ms and the final value is the positive infinity.

NOTE: it is allowed to define negative distances for this operator. Example:

$eventA : EventA( this before[ -3m30s, -2m ] $eventB )

NOTE: if the initial value is greater than the finish value, the engine automatically reverse them, as there is no reason to have the initial value greater than the finish value. Example: the following two patterns are considered to have the same semantics:

 $eventA : EventA( this before[ -3m30s, -2m ] $eventB )
 $eventA : EventA( this before[ -2m, -3m30s ] $eventB )
 

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	BeforeEvaluatorDefinition.BeforeEvaluator	Implements the 'before' evaluator itself

Nested classes/interfaces inherited from interface org.drools.compiler.rule.builder.EvaluatorDefinition

org.drools.compiler.rule.builder.EvaluatorDefinition.Target

Field Summary

Fields

Modifier and Type	Field	Description
static org.drools.drl.parser.impl.Operator	BEFORE
static String	beforeOp
static org.drools.drl.parser.impl.Operator	NOT_BEFORE

Constructor Summary

Constructors

Constructor	Description
BeforeEvaluatorDefinition()

Method Summary

Modifier and Type	Method	Description
org.drools.core.rule.accessor.Evaluator	getEvaluator(org.drools.core.base.ValueType type, String operatorId, boolean isNegated, String parameterText)
org.drools.core.rule.accessor.Evaluator	getEvaluator(org.drools.core.base.ValueType type, String operatorId, boolean isNegated, String parameterText, org.drools.compiler.rule.builder.EvaluatorDefinition.Target left, org.drools.compiler.rule.builder.EvaluatorDefinition.Target right)
org.drools.core.rule.accessor.Evaluator	getEvaluator(org.drools.core.base.ValueType type, org.drools.drl.parser.impl.Operator operator)
org.drools.core.rule.accessor.Evaluator	getEvaluator(org.drools.core.base.ValueType type, org.drools.drl.parser.impl.Operator operator, String parameterText)
String[]	getEvaluatorIds()
org.drools.compiler.rule.builder.EvaluatorDefinition.Target	getTarget()
boolean	isNegatable()
void	readExternal(ObjectInput in)
boolean	supportsType(org.drools.core.base.ValueType type)
void	writeExternal(ObjectOutput out)

Methods inherited from class java.lang.Object

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

Field Detail

beforeOp

public static final String beforeOp

BEFORE

public static final org.drools.drl.parser.impl.Operator BEFORE

NOT_BEFORE

public static final org.drools.drl.parser.impl.Operator NOT_BEFORE

Constructor Detail

BeforeEvaluatorDefinition

public BeforeEvaluatorDefinition()

Method Detail

readExternal

public void readExternal(ObjectInput in)
                  throws IOException,
                         ClassNotFoundException

Specified by:

readExternal in interface Externalizable

Throws:

IOException

ClassNotFoundException

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

Specified by:

writeExternal in interface Externalizable

Throws:

IOException

getEvaluator

public org.drools.core.rule.accessor.Evaluator getEvaluator(org.drools.core.base.ValueType type,
                                                            org.drools.drl.parser.impl.Operator operator)

Specified by:

getEvaluator in interface org.drools.compiler.rule.builder.EvaluatorDefinition

getEvaluator

public org.drools.core.rule.accessor.Evaluator getEvaluator(org.drools.core.base.ValueType type,
                                                            org.drools.drl.parser.impl.Operator operator,
                                                            String parameterText)

Specified by:

getEvaluator in interface org.drools.compiler.rule.builder.EvaluatorDefinition

getEvaluator

public org.drools.core.rule.accessor.Evaluator getEvaluator(org.drools.core.base.ValueType type,
                                                            String operatorId,
                                                            boolean isNegated,
                                                            String parameterText)

Specified by:

getEvaluator in interface org.drools.compiler.rule.builder.EvaluatorDefinition

getEvaluator

public org.drools.core.rule.accessor.Evaluator getEvaluator(org.drools.core.base.ValueType type,
                                                            String operatorId,
                                                            boolean isNegated,
                                                            String parameterText,
                                                            org.drools.compiler.rule.builder.EvaluatorDefinition.Target left,
                                                            org.drools.compiler.rule.builder.EvaluatorDefinition.Target right)

Specified by:

getEvaluator in interface org.drools.compiler.rule.builder.EvaluatorDefinition

getEvaluatorIds

public String[] getEvaluatorIds()

Specified by:

getEvaluatorIds in interface org.drools.compiler.rule.builder.EvaluatorDefinition

isNegatable

public boolean isNegatable()

Specified by:

isNegatable in interface org.drools.compiler.rule.builder.EvaluatorDefinition

getTarget

public org.drools.compiler.rule.builder.EvaluatorDefinition.Target getTarget()

Specified by:

getTarget in interface org.drools.compiler.rule.builder.EvaluatorDefinition

supportsType

public boolean supportsType(org.drools.core.base.ValueType type)

Specified by:

supportsType in interface org.drools.compiler.rule.builder.EvaluatorDefinition