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 and Description
static int	BIND_IDX index for any variable introduced in a BINDS clause
static int	HELPER_IDX index of $$ variable which is bound to the current helper instance
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
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

Constructors

Constructor and Description
DollarExpression(Rule rule, Type type, ParseNode token, int index) constructor for param bindings or special bindings
DollarExpression(Rule rule, Type type, ParseNode token, String name) constructor for local var bindings

Method Summary

Methods

Modifier and Type	Method and 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.
Object	interpret(HelperAdapter helper) evaluate the expression by interpreting the expression tree
Object	interpretAssign(HelperAdapter helperAdapter, 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(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

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,
                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 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(org.objectweb.asm.MethodVisitor mv,
           CompileContext compileContext)
             throws CompileException

Specified by:

compile in class RuleElement

Throws:

CompileException

interpretAssign

public Object interpretAssign(HelperAdapter helperAdapter,
                     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(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

Throws:

CompileException

writeTo

public void writeTo(StringWriter stringWriter)

Specified by:

writeTo in class Expression