bsh

Class CallStack

java.lang.Object

bsh.CallStack

All Implemented Interfaces:

java.io.Serializable

public final class CallStack
extends java.lang.Object
implements java.io.Serializable

A stack of NameSpaces representing the call path. Each method invocation, for example, pushes a new NameSpace onto the stack. The top of the stack is always the current namespace of evaluation.

This is used to support the this.caller magic reference and to print script "stack traces" when evaluation errors occur.

Note: How can this be thread safe, you might ask? Wouldn't a thread executing various beanshell methods be mutating the callstack? Don't we need one CallStack per Thread in the interpreter? The answer is that we do. Any java.lang.Thread enters our script via an external (hard) Java reference via a This type interface, e.g. the Runnable interface implemented by This or an arbitrary interface implemented by XThis. In that case the This invokeMethod() method (called by any interface that it exposes) creates a new CallStack for each external call.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
CallStack()
CallStack(NameSpace namespace)

Method Summary

Modifier and Type	Method and Description
void	clear()
CallStack	copy() Occasionally we need to freeze the callstack for error reporting purposes, etc.
int	depth()
NameSpace	get(int depth) zero based.
NameSpace	pop()
void	push(NameSpace ns)
void	set(int depth, NameSpace ns) This is kind of crazy, but used by the setNameSpace command.
NameSpace	swap(NameSpace newTop) Swap in the value as the new top of the stack and return the old value.
NameSpace	top()
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

CallStack

public CallStack()

CallStack

public CallStack(NameSpace namespace)

Method Detail

clear

public void clear()

push

public void push(NameSpace ns)

top

public NameSpace top()

get

public NameSpace get(int depth)

zero based.

set

public void set(int depth,
                NameSpace ns)

This is kind of crazy, but used by the setNameSpace command. zero based.

pop

public NameSpace pop()

swap

public NameSpace swap(NameSpace newTop)

Swap in the value as the new top of the stack and return the old value.

depth

public int depth()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

copy

public CallStack copy()

Occasionally we need to freeze the callstack for error reporting purposes, etc.