org.jboss.byteman.rule.expression
Class DollarExpression

java.lang.Object
  extended by org.jboss.byteman.rule.RuleElement
      extended by org.jboss.byteman.rule.expression.Expression
          extended by org.jboss.byteman.rule.expression.AssignableExpression
              extended by org.jboss.byteman.rule.expression.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
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 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
 
Fields inherited from class org.jboss.byteman.rule.expression.Expression
charPos, line, rule, token, type
 
Constructor Summary
DollarExpression(Rule rule, Type type, ParseNode token, int index)
          constructor for param bindings or special bindings
DollarExpression(Rule rule, Type type, ParseNode token, java.lang.String name)
          constructor for local var bindings
 
Method Summary
 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(MethodVisitor mv, CompileContext compileContext)
           
 void compileAssign(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.
 void writeTo(java.io.StringWriter stringWriter)
           
 
Methods inherited from class org.jboss.byteman.rule.expression.Expression
getPos, getType
 
Methods inherited from class org.jboss.byteman.rule.RuleElement
compileBooleanConversion, compileBox, compileNumericConversion, compileObjectConversion, compilePrimitiveConversion, compileStringConversion, compileTypeConversion, compileUnbox, getBindings, getTypeGroup, toString
 
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


binding

private Binding binding

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
Constructor Detail

DollarExpression

public DollarExpression(Rule rule,
                        Type type,
                        ParseNode token,
                        int index)
constructor for param bindings or special bindings

Parameters:
rule -
type -
token -
index -

DollarExpression

public DollarExpression(Rule rule,
                        Type type,
                        ParseNode token,
                        java.lang.String name)
constructor for local var bindings

Parameters:
rule -
type -
token -
name -
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

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

bind

public void bind(boolean isUpdateable)
          throws TypeException
Throws:
TypeException

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.
Throws:
TypeException

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

compile

public void compile(MethodVisitor mv,
                    CompileContext compileContext)
             throws CompileException
Specified by:
compile in class RuleElement
Throws:
CompileException

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", ...)
Returns:
the result of evaluation as an Object
Throws:
ExecuteException

compileAssign

public void compileAssign(MethodVisitor mv,
                          CompileContext compileContext)
                   throws CompileException
Description copied from class: AssignableExpression
compile an assignment to the referenced location using the value on the top of the Java stack.

Specified by:
compileAssign in class AssignableExpression
Throws:
CompileException

writeTo

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