95 lines
2.9 KiB
Java
95 lines
2.9 KiB
Java
/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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*
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* The contents of this file are subject to the Netscape Public License
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* Version 1.0 (the "NPL"); you may not use this file except in
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* compliance with the NPL. You may obtain a copy of the NPL at
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* http://www.mozilla.org/NPL/
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*
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* Software distributed under the NPL is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
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* for the specific language governing rights and limitations under the
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* NPL.
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*
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* The Initial Developer of this code under the NPL is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 1998 Netscape Communications Corporation. All Rights
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* Reserved.
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*/
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package netscape.jsdebug;
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/**
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* This interface provides access to the execution stack of a thread.
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* It has several subclasses to distinguish between different kinds of
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* stack frames: these currently include activations of Java methods
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* or JavaScript functions.
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* It is possible that synchronize blocks and try blocks deserve their own
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* stack frames - to allow for later extensions a debugger should skip over
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* stack frames it doesn't understand.
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* Note that this appears very Java-specific. However, multiple threads and
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* exceptions are relevant to JavaScript as well because of its
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* interoperation with Java.
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*
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* @author John Bandhauer
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* @author Nick Thompson
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* @version 1.0
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* @since 1.0
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*/
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public abstract class StackFrameInfo {
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ThreadStateBase threadState;
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StackFrameInfo caller;
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protected StackFrameInfo(ThreadStateBase threadState) {
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this.threadState = threadState;
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}
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/**
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* Return true if this stack frame is still valid. Stack frames
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* may become invalid when the thread is resumed (this is more
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* conservative than invalidating the frame only when it actually
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* returns).
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*/
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public boolean isValid() {
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return threadState.isValid();
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}
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/**
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* Get the stack frame where this one was built, or null for the
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* start of the stack.
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*/
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public synchronized StackFrameInfo getCaller()
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throws InvalidInfoException {
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if (caller == null)
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caller = getCaller0();
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if (!isValid())
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throw new InvalidInfoException("invalid StackFrameInfo");
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return caller;
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}
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protected abstract StackFrameInfo getCaller0()
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throws InvalidInfoException;
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/**
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* Get the thread that this stack frame is a part of.
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*/
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public Thread getThread() {
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return threadState.getThread();
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}
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/**
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* Get the 'enclosing' thread state
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*/
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public ThreadStateBase getThreadState() {
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return threadState;
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}
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/**
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* Get the current program counter value. Note that the
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* class JavaPC supports the getMethod() operation.
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*/
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public abstract PC getPC()
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throws InvalidInfoException;
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}
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