Class AfterEvaluatorDefinition
- java.lang.Object
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- org.drools.core.base.evaluators.AfterEvaluatorDefinition
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- All Implemented Interfaces:
Externalizable
,Serializable
,EvaluatorDefinition
,org.kie.api.runtime.rule.EvaluatorDefinition
public class AfterEvaluatorDefinition extends Object implements EvaluatorDefinition
The implementation of the 'after' evaluator definition.
The
after
evaluator correlates two events and matches when the temporal distance from the current event to the event being correlated belongs to the distance range declared for the operator.Lets look at an example:
$eventA : EventA( this after[ 3m30s, 4m ] $eventB )
The previous pattern will match if and only if the temporal distance between the time when $eventB finished and the time when $eventA started is between ( 3 minutes and 30 seconds ) and ( 4 minutes ). In other words:
3m30s <= $eventA.startTimestamp - $eventB.endTimeStamp <= 4m
The temporal distance interval for the
after
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, 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 after[ -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 after[ -3m30s, -2m ] $eventB ) $eventA : EventA( this after[ -2m, -3m30s ] $eventB )
- See Also:
- Serialized Form
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
AfterEvaluatorDefinition.AfterEvaluator
Implements the 'after' evaluator itself-
Nested classes/interfaces inherited from interface org.drools.core.base.evaluators.EvaluatorDefinition
EvaluatorDefinition.Target
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Constructor Summary
Constructors Constructor Description AfterEvaluatorDefinition()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description Evaluator
getEvaluator(ValueType type, String operatorId, boolean isNegated, String parameterText)
Returns the evaluator instance for the given type and the defined parameterTextEvaluator
getEvaluator(ValueType type, String operatorId, boolean isNegated, String parameterText, EvaluatorDefinition.Target left, EvaluatorDefinition.Target right)
Returns the evaluator instance for the given type and the defined parameterTextEvaluator
getEvaluator(ValueType type, Operator operator)
Returns the evaluator instance for the given type and the defined parameterTextEvaluator
getEvaluator(ValueType type, Operator operator, String parameterText)
Returns the evaluator instance for the given type and the defined parameterTextString[]
getEvaluatorIds()
Returns the list of identifies this evaluator implementation supportsEvaluatorDefinition.Target
getTarget()
There are evaluators that operate on *fact* attributes, evaluators that operate on *fact handle* attributes, and evaluators that operate on both.boolean
isNegatable()
My apologies to English speakers if the word "negatable" does not exist. :) This method returns true if this evaluator supports negation.void
readExternal(ObjectInput in)
boolean
supportsType(ValueType type)
Returns true in case this evaluator supports operations over values of that specific type.void
writeExternal(ObjectOutput out)
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Field Detail
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afterOp
protected static final String afterOp
- See Also:
- Constant Field Values
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AFTER
public static Operator AFTER
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NOT_AFTER
public static Operator NOT_AFTER
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Method Detail
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readExternal
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException
- Specified by:
readExternal
in interfaceExternalizable
- Throws:
IOException
ClassNotFoundException
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writeExternal
public void writeExternal(ObjectOutput out) throws IOException
- Specified by:
writeExternal
in interfaceExternalizable
- Throws:
IOException
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getEvaluator
public Evaluator getEvaluator(ValueType type, Operator operator)
Description copied from interface:EvaluatorDefinition
Returns the evaluator instance for the given type and the defined parameterText- Specified by:
getEvaluator
in interfaceEvaluatorDefinition
- Parameters:
type
- the type of the attributes this evaluator will operate on. This is important because the evaluator may do optimisations and type coercion based on the types it is evaluating. It is also possible that this evaluator does not support a given type.operator
- the operator implemented by the evaluator- Returns:
- an Evaluator instance capable of evaluating expressions between values of the given type, or null in case the type is not supported.
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getEvaluator
public Evaluator getEvaluator(ValueType type, Operator operator, String parameterText)
Description copied from interface:EvaluatorDefinition
Returns the evaluator instance for the given type and the defined parameterText- Specified by:
getEvaluator
in interfaceEvaluatorDefinition
- Parameters:
type
- the type of the attributes this evaluator will operate on. This is important because the evaluator may do optimisations and type coercion based on the types it is evaluating. It is also possible that this evaluator does not support a given type.operator
- the operator implemented by the evaluatorparameterText
- some evaluators support parameters and these parameters are defined as a String that is parsed by the evaluator itself.- Returns:
- an Evaluator instance capable of evaluating expressions between values of the given type, or null in case the type is not supported.
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getEvaluator
public Evaluator getEvaluator(ValueType type, String operatorId, boolean isNegated, String parameterText)
Description copied from interface:EvaluatorDefinition
Returns the evaluator instance for the given type and the defined parameterText- Specified by:
getEvaluator
in interfaceEvaluatorDefinition
- Parameters:
type
- the type of the attributes this evaluator will operate on. This is important because the evaluator may do optimisations and type coercion based on the types it is evaluating. It is also possible that this evaluator does not support a given type.operatorId
- the string identifier of the evaluatorisNegated
- true if the evaluator instance to be returned is the negated version of the evaluator.parameterText
- some evaluators support parameters and these parameters are defined as a String that is parsed by the evaluator itself.- Returns:
- an Evaluator instance capable of evaluating expressions between values of the given type, or null in case the type is not supported.
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getEvaluator
public Evaluator getEvaluator(ValueType type, String operatorId, boolean isNegated, String parameterText, EvaluatorDefinition.Target left, EvaluatorDefinition.Target right)
Description copied from interface:EvaluatorDefinition
Returns the evaluator instance for the given type and the defined parameterText- Specified by:
getEvaluator
in interfaceEvaluatorDefinition
- Parameters:
type
- the type of the attributes this evaluator will operate on. This is important because the evaluator may do optimisations and type coercion based on the types it is evaluating. It is also possible that this evaluator does not support a given type.operatorId
- the string identifier of the evaluatorisNegated
- true if the evaluator instance to be returned is the negated version of the evaluator.parameterText
- some evaluators support parameters and these parameters are defined as a String that is parsed by the evaluator itself.left
- the target of the evaluator on the Left side, i.e., on Rete terms, the previous binding or the actual value on the right side of the operator.right
- the target of the evaluator on the Right side, i.e., on Rete terms, the current pattern field.- Returns:
- an Evaluator instance capable of evaluating expressions between values of the given type, or null in case the type is not supported.
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getEvaluatorIds
public String[] getEvaluatorIds()
Description copied from interface:EvaluatorDefinition
Returns the list of identifies this evaluator implementation supports- Specified by:
getEvaluatorIds
in interfaceEvaluatorDefinition
- Returns:
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isNegatable
public boolean isNegatable()
Description copied from interface:EvaluatorDefinition
My apologies to English speakers if the word "negatable" does not exist. :) This method returns true if this evaluator supports negation. Example: the "matches" operator supports "not matches" and so is "negatable" (!?)- Specified by:
isNegatable
in interfaceEvaluatorDefinition
- Returns:
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getTarget
public EvaluatorDefinition.Target getTarget()
Description copied from interface:EvaluatorDefinition
There are evaluators that operate on *fact* attributes, evaluators that operate on *fact handle* attributes, and evaluators that operate on both. This method returns the target of the current evaluator.- Specified by:
getTarget
in interfaceEvaluatorDefinition
- Returns:
- true if this evaluator operates on fact handle attributes and false if it operates on fact attributes
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supportsType
public boolean supportsType(ValueType type)
Description copied from interface:EvaluatorDefinition
Returns true in case this evaluator supports operations over values of that specific type.- Specified by:
supportsType
in interfaceEvaluatorDefinition
- Returns:
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