Class DollarExpression


  • public class DollarExpression
    extends AssignableExpression
    an expression which refers either to a builtin variable or to a bound parameter of the triggering method for an ECA rule. builtin variables are written as a dollar sign followed by a leading alpha-underscore, trailing alpha-numeric-underscore string. bound parameters are written as a dollar sign followed by a non-negativeinteger parameter index e.g. if the rule applies to method foo.bar(int baz, Mumble mumble) then an occurrence of $2 appearing as an expression in a rule would have type Mumble and evaluate to the value of mumble at the point when the rule was triggered. At present there are no special variables but we may need to add some later
    • Field Summary

      Fields 
      Modifier and Type Field Description
      static int BIND_IDX
      index for any variable introduced in a BINDS clause
      private Binding binding  
      static int HELPER_IDX
      index of $$ variable which is bound to the current helper instance
      private int index
      index is positive or zero if this is a reference to a method param and negative if this is a reference to the current helper, the return value on the stack in an AT EXIT rule or a local or BIND variable
      static int INVOKE_PARAM_ARRAY_IDX
      index of $@ variable which is bound to an array of the invoked method params in an AT INVOKE rule
      static int LOCAL_IDX
      index for any local variable which must be further identified via its name
      private java.lang.String name  
      static int NEW_CLASS_IDX
      index of $METHOD variable which is bound to a String identifying the trigger method and signature
      static int PARAM_ARRAY_IDX
      index of $* variable which is bound to an array of the trigger method params
      static int PARAM_COUNT_IDX
      index of $# variable which is bound to the count of number of trigger method params
      static int RETURN_VALUE_IDX
      index of $! variable which is bound to the current return value on stack in AT RETURN rule
      static int THROWABLE_VALUE_IDX
      index of $@ variable which is bound to the current throwable on stack in AT THROW rule
      static int TRIGGER_CLASS_IDX
      index of $CLASS variable which is bound to a String identifying the package-qualified trigger class
      static int TRIGGER_METHOD_IDX
      index of $METHOD variable which is bound to a String identifying the trigger method and signature
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void bind()
      verify that variables mentioned in this expression are actually available in the supplied bindings list and infer/validate the type of this expression or its subexpressions where possible
      void bind​(boolean isUpdateable)  
      void bindAssign()
      verify that variables mentioned in this expression are actually available in the supplied bindings list.
      void compile​(org.objectweb.asm.MethodVisitor mv, CompileContext compileContext)  
      void compileAssign​(org.objectweb.asm.MethodVisitor mv, CompileContext compileContext)
      compile an assignment to the referenced location using the value on the top of the Java stack.
      java.lang.Object interpret​(HelperAdapter helper)
      evaluate the expression by interpreting the expression tree
      java.lang.Object interpretAssign​(HelperAdapter helperAdapter, java.lang.Object value)
      execute an assignment to the referenced location by interpretation of the expression, using the object passed in this call
      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.
      private void typeCheckAny()  
      Type typeCheckAssign​(Type expected)
      typecheck the expression as an lvalue of an assignment operation
      void writeTo​(java.io.StringWriter stringWriter)  
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
    • Field Detail

      • name

        private java.lang.String name
      • index

        private int index
        index is positive or zero if this is a reference to a method param and negative if this is a reference to the current helper, the return value on the stack in an AT EXIT rule or a local or BIND variable
      • HELPER_IDX

        public static final int HELPER_IDX
        index of $$ variable which is bound to the current helper instance
        See Also:
        Constant Field Values
      • BIND_IDX

        public static final int BIND_IDX
        index for any variable introduced in a BINDS clause
        See Also:
        Constant Field Values
      • LOCAL_IDX

        public static final int LOCAL_IDX
        index for any local variable which must be further identified via its name
        See Also:
        Constant Field Values
      • RETURN_VALUE_IDX

        public static final int RETURN_VALUE_IDX
        index of $! variable which is bound to the current return value on stack in AT RETURN rule
        See Also:
        Constant Field Values
      • THROWABLE_VALUE_IDX

        public static final int THROWABLE_VALUE_IDX
        index of $@ variable which is bound to the current throwable on stack in AT THROW rule
        See Also:
        Constant Field Values
      • PARAM_COUNT_IDX

        public static final int PARAM_COUNT_IDX
        index of $# variable which is bound to the count of number of trigger method params
        See Also:
        Constant Field Values
      • PARAM_ARRAY_IDX

        public static final int PARAM_ARRAY_IDX
        index of $* variable which is bound to an array of the trigger method params
        See Also:
        Constant Field Values
      • INVOKE_PARAM_ARRAY_IDX

        public static final int INVOKE_PARAM_ARRAY_IDX
        index of $@ variable which is bound to an array of the invoked method params in an AT INVOKE rule
        See Also:
        Constant Field Values
      • TRIGGER_CLASS_IDX

        public static final int TRIGGER_CLASS_IDX
        index of $CLASS variable which is bound to a String identifying the package-qualified trigger class
        See Also:
        Constant Field Values
      • TRIGGER_METHOD_IDX

        public static final int TRIGGER_METHOD_IDX
        index of $METHOD variable which is bound to a String identifying the trigger method and signature
        See Also:
        Constant Field Values
      • NEW_CLASS_IDX

        public static final int NEW_CLASS_IDX
        index of $METHOD variable which is bound to a String identifying the trigger method and signature
        See Also:
        Constant Field Values
    • Constructor Detail

      • DollarExpression

        public DollarExpression​(Rule rule,
                                Type type,
                                ParseNode token,
                                int index)
        constructor for param bindings or special bindings
        Parameters:
        rule - the rule for this expression
        type - the type for this expression
        token - the token for this expression
        index - the type of DollarExpression this is
      • DollarExpression

        public DollarExpression​(Rule rule,
                                Type type,
                                ParseNode token,
                                java.lang.String name)
        constructor for local var bindings
        Parameters:
        rule - the rule for this expression
        type - the type for this expression
        token - the token for this expression
        name - the name of the local var referenced by this DollarVariable
    • Method Detail

      • bind

        public void bind()
                  throws TypeException
        verify that variables mentioned in this expression are actually available in the supplied bindings list and infer/validate the type of this expression or its subexpressions where possible
        Specified by:
        bind in class Expression
        Throws:
        TypeException - if any variable is missing or has the wrong type
      • bindAssign

        public void bindAssign()
                        throws TypeException
        verify that variables mentioned in this expression are actually available in the supplied bindings list. infer/validate the type of this expression or its subexpressions where possible
        Specified by:
        bindAssign in class AssignableExpression
        Throws:
        TypeException - if any variable is missing or has the wrong type
      • typeCheck

        public Type typeCheck​(Type expected)
                       throws TypeException
        Description copied from class: Expression
        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 Expression
        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
      • typeCheckAny

        private void typeCheckAny()
      • interpret

        public java.lang.Object interpret​(HelperAdapter helper)
                                   throws ExecuteException
        Description copied from class: Expression
        evaluate the expression by interpreting the expression tree
        Specified by:
        interpret in class Expression
        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
      • interpretAssign

        public java.lang.Object interpretAssign​(HelperAdapter helperAdapter,
                                                java.lang.Object value)
                                         throws ExecuteException
        Description copied from class: AssignableExpression
        execute an assignment to the referenced location by interpretation of the expression, using the object passed in this call
        Specified by:
        interpretAssign in class AssignableExpression
        Parameters:
        helperAdapter - 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", ...)
        value - the value to be assigned to this object
        Returns:
        the result of evaluation as an Object
        Throws:
        ExecuteException - if an error occurs during execution
      • writeTo

        public void writeTo​(java.io.StringWriter stringWriter)
        Specified by:
        writeTo in class Expression