Class Expression

java.lang.Object
org.jboss.byteman.rule.RuleElement
org.jboss.byteman.rule.expression.Expression
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.
  • Field Details

    • rule

      protected Rule rule
    • type

      protected Type type
    • charPos

      protected int charPos
    • line

      protected int line
    • token

      protected ParseNode token
  • Constructor Details

    • Expression

      protected Expression(Rule rule, Type type, ParseNode token)
      Create a new expression.
      Parameters:
      rule - the rule for this expression
      type - the type for this expression
      token - the token for this expression
  • Method Details

    • 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
    • getPos

      public String getPos()
    • getType

      public Type getType()
    • 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 class RuleElement
      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
    • interpret

      public abstract Object interpret(HelperAdapter helper) throws ExecuteException
      evaluate the expression by interpreting the expression tree
      Specified by:
      interpret in class RuleElement
      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
    • writeTo

      public abstract void writeTo(StringWriter stringWriter)
      Specified by:
      writeTo in class RuleElement