com.scriptbasic.hooks

Class NullHook

java.lang.Object

com.scriptbasic.hooks.NullHook

All Implemented Interfaces:

InterpreterHook

public class NullHook
extends Object
implements InterpreterHook

The simplest implementation of the InterfaceHook interface. This implements each of the methods of the interface, each doing nothing.

This hook is used to chain into the hook chain first so that hook classes need not check if there is a next hook object in the chain.

Author:

Peter Verhas

Constructor Summary

Constructors

Constructor and Description
NullHook()

Method Summary

Methods

Modifier and Type	Method and Description
Object	afterCallJavaFunction(Method method, Object result) This method is called when the interpreter was calling a Java static method.
void	afterExecute(Command command) This method is called after the interpreter executed a command.
void	afterPop(Command command)
void	afterPush(Command command)
void	beforeCallJavaFunction(Method method)
void	beforeExecute(Command command) This method is called before the interpreter executes a command.
void	beforePop()
void	beforePush(Command command)
void	beforeRegisteringJavaMethod(String alias, Class<?> klass, String methodName, Class<?>[] argumentTypes) This method is called before registering a java method into the interpreter.
void	beforeSubroutineCall(String subroutineName, LeftValueList arguments, RightValue[] argumentValues) This method is called before the interpreter invokes a subroutine.
void	init() This method is called at the end of the hook registering.
void	setInterpreter(ExtendedInterpreter interpreter) During registration the interpreter calls this method to make the interpreter accessible for the hook objects.
void	setNext(InterpreterHook next) When a hook is registered the registering process calls this method and passes the next element in the hook chain.
void	setReturnValue(RightValue returnValue) This method is called after a subroutine has set its return value.
RightValue	variableRead(String variableName, RightValue value) This hook is called when the interpreter accesses a variable.

Methods inherited from class java.lang.Object

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

Constructor Detail

NullHook

public NullHook()

Method Detail

init

public void init()

Description copied from interface: InterpreterHook

This method is called at the end of the hook registering. When this method is called the hook does have interpreter and the field 'next' already set. The method should do its initialization and then call the same method of the next hook in the chain.

Specified by:

init in interface InterpreterHook

setNext

public void setNext(InterpreterHook next)

Description copied from interface: InterpreterHook

When a hook is registered the registering process calls this method and passes the next element in the hook chain. The hook object should remember this object and call the appropriate methods when that is called not to break the chain.

Specified by:

setNext in interface InterpreterHook

Parameters:

next - the next element in the chain.

setInterpreter

public void setInterpreter(ExtendedInterpreter interpreter)

Description copied from interface: InterpreterHook

During registration the interpreter calls this method to make the interpreter accessible for the hook objects.

Specified by:

setInterpreter in interface InterpreterHook

beforeExecute

public void beforeExecute(Command command)

Description copied from interface: InterpreterHook

This method is called before the interpreter executes a command.

Specified by:

beforeExecute in interface InterpreterHook

Parameters:

command - the command object to be executed

afterExecute

public void afterExecute(Command command)

Description copied from interface: InterpreterHook

This method is called after the interpreter executed a command.

Specified by:

afterExecute in interface InterpreterHook

Parameters:

command - the command just executed.

beforeRegisteringJavaMethod

public void beforeRegisteringJavaMethod(String alias,
                               Class<?> klass,
                               String methodName,
                               Class<?>[] argumentTypes)

Description copied from interface: InterpreterHook

This method is called before registering a java method into the interpreter.

Specified by:

beforeRegisteringJavaMethod in interface InterpreterHook

Parameters:

alias - the name of the function as it will be known to the BASIC program.

klass - the Java class where the static method is.

methodName - the Java name of the method

argumentTypes - the argument types of the methods. This, together with the name of the method and the class identifies the actual method that will be available to the BASIC programs to be called through the name alias.

beforePush

public void beforePush(Command command)

Specified by:

beforePush in interface InterpreterHook

afterPush

public void afterPush(Command command)

Specified by:

afterPush in interface InterpreterHook

beforePop

public void beforePop()

Specified by:

beforePop in interface InterpreterHook

afterPop

public void afterPop(Command command)

Specified by:

afterPop in interface InterpreterHook

setReturnValue

public void setReturnValue(RightValue returnValue)

Description copied from interface: InterpreterHook

This method is called after a subroutine has set its return value. It is possible to modify the return value calling back to the interpreter but it has to be only invoked together with ExtendedInterpreter.disableHook() and ExtendedInterpreter.enableHook().

Specified by:

setReturnValue in interface InterpreterHook

See Also:

ExtendedInterpreter.disableHook()

beforeSubroutineCall

public void beforeSubroutineCall(String subroutineName,
                        LeftValueList arguments,
                        RightValue[] argumentValues)

Description copied from interface: InterpreterHook

This method is called before the interpreter invokes a subroutine. At this point the local variables are those of the subroutine to be called.

Specified by:

beforeSubroutineCall in interface InterpreterHook

Parameters:

subroutineName - the symbolic name of the subroutine

arguments - the argument left values

argumentValues - the argument evaluated values that were assigned to the local variable table to the arguments

beforeCallJavaFunction

public void beforeCallJavaFunction(Method method)

Specified by:

beforeCallJavaFunction in interface InterpreterHook

afterCallJavaFunction

public Object afterCallJavaFunction(Method method,
                           Object result)

Description copied from interface: InterpreterHook

This method is called when the interpreter was calling a Java static method. The

Specified by:

afterCallJavaFunction in interface InterpreterHook

Parameters:

method - the method that was called

result - the result that the static method returned

Returns:

the modified result or just the same object if the hook does not want to modify the result

variableRead

public RightValue variableRead(String variableName,
                      RightValue value)

Description copied from interface: InterpreterHook

This hook is called when the interpreter accesses a variable.

Specified by:

variableRead in interface InterpreterHook

Parameters:

variableName - the name of the variable

value - the value of the variable when accessed

Returns:

the value that will be used. The implementation may decide to alter the value used. Returning a modified value will not, however alterthe value of the variable itself.