Class Expression
- java.lang.Object
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- org.jboss.byteman.rule.RuleElement
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- org.jboss.byteman.rule.expression.Expression
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- Direct Known Subclasses:
ArrayInitExpression
,AssignableExpression
,BooleanLiteral
,ClassLiteralExpression
,MethodExpression
,NewExpression
,NullLiteral
,NumericLiteral
,OperExpression
,ReturnExpression
,StringLiteral
,ThrowExpression
public abstract class Expression extends RuleElement
abstract class representing an evaluable expression. this is used in all 3 elements of ECA rules: as the value part of each of the event bindings in the binding list comprising an ECA rule event; as the condition expression of an ECA rule condition;and as an element of the actions list in an ECA rule action.
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Constructor Summary
Constructors Modifier Constructor Description protected
Expression(Rule rule, Type type, ParseNode token)
Create a new expression.
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description abstract void
bind()
verify that variables mentioned in this expression are actually available in the rule bindings listjava.lang.String
getPos()
Type
getType()
abstract java.lang.Object
interpret(HelperAdapter helper)
evaluate the expression by interpreting the expression treeabstract Type
typeCheck(Type expected)
ensure that all type references in the expression and its component expressions can be resolved, that the type of the expression is well-defined and that it is compatible with the type expected in the context in which it occurs.abstract void
writeTo(java.io.StringWriter stringWriter)
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Methods inherited from class org.jboss.byteman.rule.RuleElement
compile, getBindings, getTypeGroup, rebox, toString
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Method Detail
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bind
public abstract void bind() throws TypeException
verify that variables mentioned in this expression are actually available in the rule bindings list- Throws:
TypeException
- if any variable is missing or has the wrong type
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getPos
public java.lang.String getPos()
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getType
public Type getType()
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typeCheck
public abstract Type typeCheck(Type expected) throws TypeException
ensure that all type references in the expression and its component expressions can be resolved, that the type of the expression is well-defined and that it is compatible with the type expected in the context in which it occurs.- Specified by:
typeCheck
in classRuleElement
- Parameters:
expected
- the type expected for the expression in the contxet in which it occurs. this may be void but should not be undefined at the point where type checking is performed.- Returns:
- the type of the expression
- Throws:
TypeException
- if a type check failure occurs
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interpret
public abstract java.lang.Object interpret(HelperAdapter helper) throws ExecuteException
evaluate the expression by interpreting the expression tree- Specified by:
interpret
in classRuleElement
- Parameters:
helper
- an execution context associated with the rule which contains a map of current bindings for rule variables and another map of their declared types both of which are indexed by variable name. This includes entries for the helper (name "-1"), the recipient if the trigger method is not static (name "0") and the trigger method arguments (names "1", ...)- Returns:
- the result of evaluation as an Object
- Throws:
ExecuteException
- if an error occurs during execution
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writeTo
public abstract void writeTo(java.io.StringWriter stringWriter)
- Specified by:
writeTo
in classRuleElement
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