Package org.jboss.byteman.rule.expression

Class DollarExpression

java.lang.Object

org.jboss.byteman.rule.RuleElement

org.jboss.byteman.rule.expression.Expression

org.jboss.byteman.rule.expression.AssignableExpression

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

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	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

Fields inherited from class org.jboss.byteman.rule.expression.Expression

charPos, line, rule, token, type

Constructor Summary

Constructors

Constructor	Description
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

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 org.jboss.byteman.rule.expression.Expression

getPos, getType

Methods inherited from class org.jboss.byteman.rule.RuleElement

getBindings, getTypeGroup, rebox, 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

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

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

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.

Returns:

the type of the expression

Throws:

TypeException - if a type check failure occurs

typeCheckAssign

public Type typeCheckAssign(Type expected)
                     throws TypeException

Description copied from class: AssignableExpression

typecheck the expression as an lvalue of an assignment operation

Specified by:

typeCheckAssign in class AssignableExpression

Parameters:

expected - the expected type for the expression

Returns:

the expression type

Throws:

TypeException - if a type check error 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

compile

public void compile(org.objectweb.asm.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", ...)

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

compileAssign

public void compileAssign(org.objectweb.asm.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

Parameters:

mv - the current method visitor

compileContext - the current compile context

Throws:

CompileException - if a compile error occurs

writeTo

public void writeTo(java.io.StringWriter stringWriter)

Specified by:

writeTo in class Expression