org.jboss.byteman.rule.expression

Class NullLiteral

java.lang.Object

org.jboss.byteman.rule.RuleElement

org.jboss.byteman.rule.expression.Expression

org.jboss.byteman.rule.expression.NullLiteral

public class NullLiteral
extends Expression

an expression which identifies a null value

Field Summary

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

charPos, line, rule, token, type

Constructor Summary

Constructors

Constructor and Description
NullLiteral(Rule rule, ParseNode token)

Method Summary

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	compile(org.objectweb.asm.MethodVisitor mv, CompileContext compileContext)
Object	interpret(HelperAdapter helper) evaluate the expression by interpreting the expression tree
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, rebox, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

NullLiteral

public NullLiteral(Rule rule,
                   ParseNode token)

Method Detail

bind

public 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

Specified by:

bind in class Expression

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

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 - 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

writeTo

public void writeTo(StringWriter stringWriter)

Specified by:

writeTo in class Expression