public class StartsEvaluatorDefinition extends Object implements EvaluatorDefinition
The implementation of the starts
evaluator definition.
The starts
evaluator correlates two events and matches when the current event's
end timestamp happens before the correlated event's end timestamp, but both start timestamps occur at
the same time.
Lets look at an example:
$eventA : EventA( this starts $eventB )
The previous pattern will match if and only if the $eventA finishes before $eventB finishes and starts at the same time $eventB starts. In other words:
$eventA.startTimestamp == $eventB.startTimestamp && $eventA.endTimestamp < $eventB.endTimestamp
The starts
evaluator accepts one optional parameter. If it is defined, it determines
the maximum distance between the start timestamp of both events in order for the operator to match. Example:
$eventA : EventA( this starts[ 5s ] $eventB )Will match if and only if:
abs( $eventA.startTimestamp - $eventB.startTimestamp ) <= 5s && $eventA.endTimestamp < $eventB.endTimestamp
NOTE: it makes no sense to use a negative interval value for the parameter and the engine will raise an exception if that happens.
Modifier and Type | Class and Description |
---|---|
static class |
StartsEvaluatorDefinition.StartsEvaluator
Implements the 'starts' evaluator itself
|
EvaluatorDefinition.Target
Modifier and Type | Field and Description |
---|---|
static Operator |
STARTS |
static Operator |
STARTS_NOT |
protected static String |
startsOp |
Constructor and Description |
---|
StartsEvaluatorDefinition() |
Modifier and Type | Method and Description |
---|---|
Evaluator |
getEvaluator(ValueType type,
Operator operator)
Returns the evaluator instance for the given type and the
defined parameterText
|
Evaluator |
getEvaluator(ValueType type,
Operator operator,
String parameterText)
Returns the evaluator instance for the given type and the
defined parameterText
|
Evaluator |
getEvaluator(ValueType type,
String operatorId,
boolean isNegated,
String parameterText)
Returns the evaluator instance for the given type and the
defined parameterText
|
Evaluator |
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 parameterText
|
String[] |
getEvaluatorIds()
Returns the list of identifies this
evaluator implementation supports
|
EvaluatorDefinition.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) |
protected static final String startsOp
public static Operator STARTS
public static Operator STARTS_NOT
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException
readExternal
in interface Externalizable
IOException
ClassNotFoundException
public void writeExternal(ObjectOutput out) throws IOException
writeExternal
in interface Externalizable
IOException
public Evaluator getEvaluator(ValueType type, Operator operator)
EvaluatorDefinition
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 evaluatorpublic Evaluator getEvaluator(ValueType type, Operator operator, String parameterText)
EvaluatorDefinition
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.public Evaluator getEvaluator(ValueType type, String operatorId, boolean isNegated, String parameterText)
EvaluatorDefinition
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.public Evaluator getEvaluator(ValueType type, String operatorId, boolean isNegated, String parameterText, EvaluatorDefinition.Target left, EvaluatorDefinition.Target right)
EvaluatorDefinition
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.public String[] getEvaluatorIds()
EvaluatorDefinition
public boolean isNegatable()
EvaluatorDefinition
public EvaluatorDefinition.Target getTarget()
EvaluatorDefinition
public boolean supportsType(ValueType type)
EvaluatorDefinition
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