Interface Expression
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- All Known Implementing Classes:
AbstractAlertExpressionContext.AlertVariableExpression
,AbstractExpression
,AlarmEventPropertyExpression
,ArithmeticExpression
,BitwiseExpression
,BitwiseNot
,BoundPropertyExpression
,BoundTagExpression
,BoundVariableExpression
,ComparisonExpression
,ConstantExpression
,EqualityExpression
,FormattedExpression
,FunctionExpression
,LikeExpression
,LocaleAwareMessageParseContext.LocaleStringExpression
,LogicalExpression
,NonLocalizedToStringExpression
,NotExpression
,PropertyBasedExpressionParseContext.PropertyReferenceExpression
,SubscriptExpression
,TagPathReadExpression
,TagReferenceBinder.SubscribedTagExpression
,TagReferenceBinder.TagReadExpression
,ToStringExpression
,UMinusExpression
public interface Expression
An expression is something that can be executed to compute a result. Each instance of expression is typically some node in what amounts to a parse tree. Many expressions such as operators and function calls have child expressions.
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Method Summary
All Methods Instance Methods Abstract Methods Default Methods Modifier and Type Method Description void
connect(CommonContext context, InteractionListener updateListener)
Gives the expression a chance to connect itself to things, if necessary.void
disconnect()
Tells the expression to disconnect from anything it was connected to.QualifiedValue
execute()
Compute and return the value of this expressionExpression[]
getChildren()
The children (if any) that this expression is dependent on for its executionjava.lang.String
getOpName()
Return a human-readable name for the operation that this expression performsdefault java.lang.Class<?>
getType()
Return the type that this expression will returnvoid
shutdown()
Tells the expression to shutdown any polling operations.void
startup()
Tells the expression to startup any polling operations.
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Method Detail
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execute
@Nonnull QualifiedValue execute() throws ExpressionException
Compute and return the value of this expression- Throws:
ExpressionException
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getType
default java.lang.Class<?> getType()
Return the type that this expression will return
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getOpName
java.lang.String getOpName()
Return a human-readable name for the operation that this expression performs
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getChildren
Expression[] getChildren()
The children (if any) that this expression is dependent on for its execution
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connect
void connect(CommonContext context, InteractionListener updateListener)
Gives the expression a chance to connect itself to things, if necessary. Most expressions do not have any connections. An expression should notify the updateListener if they change.
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disconnect
void disconnect()
Tells the expression to disconnect from anything it was connected to.
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startup
void startup()
Tells the expression to startup any polling operations. Expressions that use this can remember the updateListener from connect() to feed update notification to.
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shutdown
void shutdown()
Tells the expression to shutdown any polling operations.
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