dim.java

java中比较著名的js引擎当属mozilla开源的rhino

                final String alertMessage;
                if (scriptException == null) {
                    alertMessage = null;
                } else {
                    alertMessage = scriptException.toString();
                }

                int returnValue = -1;
                if (!eventThreadFlag) {
                    synchronized (monitor) {
                        if (insideInterruptLoop) Kit.codeBug();
                        this.insideInterruptLoop = true;
                        this.evalRequest = null;
                        this.returnValue = -1;
                        callback.enterInterrupt(frame, threadTitle,
                                                alertMessage);
                        try {
                            for (;;) {
                                try {
                                    monitor.wait();
                                } catch (InterruptedException exc) {
                                    Thread.currentThread().interrupt();
                                    break;
                                }
                                if (evalRequest != null) {
                                    this.evalResult = null;
                                    try {
                                        evalResult = do_eval(cx, evalFrame,
                                                             evalRequest);
                                    } finally {
                                        evalRequest = null;
                                        evalFrame = null;
                                        monitor.notify();
                                    }
                                    continue;
                                }
                                if (this.returnValue != -1) {
                                    returnValue = this.returnValue;
                                    break;
                                }
                            }
                        } finally {
                            insideInterruptLoop = false;
                        }
                    }
                } else {
                    this.returnValue = -1;
                    callback.enterInterrupt(frame, threadTitle, alertMessage);
                    while (this.returnValue == -1) {
                        try {
                            callback.dispatchNextGuiEvent();
                        } catch (InterruptedException exc) {
                        }
                    }
                    returnValue = this.returnValue;
                }
                switch (returnValue) {
                case STEP_OVER:
                    contextData.breakNextLine = true;
                    contextData.stopAtFrameDepth = contextData.frameCount();
                    break;
                case STEP_INTO:
                    contextData.breakNextLine = true;
                    contextData.stopAtFrameDepth = -1;
                    break;
                case STEP_OUT:
                    if (contextData.frameCount() > 1) {
                        contextData.breakNextLine = true;
                        contextData.stopAtFrameDepth
                            = contextData.frameCount() -1;
                    }
                    break;
                }
            } while (false);
        } finally {
            synchronized (eventThreadMonitor) {
                interruptedContextData = null;
                eventThreadMonitor.notifyAll();
            }
        }

    }

    /**
     * Evaluates script in the given stack frame.
     */
    private static String do_eval(Context cx, StackFrame frame, String expr) {
        String resultString;
        Debugger saved_debugger = cx.getDebugger();
        Object saved_data = cx.getDebuggerContextData();
        int saved_level = cx.getOptimizationLevel();

        cx.setDebugger(null, null);
        cx.setOptimizationLevel(-1);
        cx.setGeneratingDebug(false);
        try {
            Callable script = (Callable)cx.compileString(expr, "", 0, null);
            Object result = script.call(cx, frame.scope, frame.thisObj,
                                        ScriptRuntime.emptyArgs);
            if (result == Undefined.instance) {
                resultString = "";
            } else {
                resultString = ScriptRuntime.toString(result);
            }
        } catch (Exception exc) {
            resultString = exc.getMessage();
        } finally {
            cx.setGeneratingDebug(true);
            cx.setOptimizationLevel(saved_level);
            cx.setDebugger(saved_debugger, saved_data);
        }
        if (resultString == null) {
            resultString = "null";
        }
        return resultString;
    }

    /**
     * Proxy class to implement debug interfaces without bloat of class
     * files.
     */
    private static class DimIProxy
        implements ContextAction, ContextFactory.Listener, Debugger {

        /**
         * The debugger.
         */
        private Dim dim;

        /**
         * The interface implementation type.  One of the IPROXY_* constants
         * defined in {@link Dim}.
         */
        private int type;

        /**
         * The URL origin of the script to compile or evaluate.
         */
        private String url;

        /**
         * The text of the script to compile, evaluate or test for compilation.
         */
        private String text;

        /**
         * The object to convert, get a property from or enumerate.
         */
        private Object object;

        /**
         * The property to look up in {@link #object}.
         */
        private Object id;

        /**
         * The boolean result of the action.
         */
        private boolean booleanResult;

        /**
         * The String result of the action.
         */
        private String stringResult;

        /**
         * The Object result of the action.
         */
        private Object objectResult;

        /**
         * The Object[] result of the action.
         */
        private Object[] objectArrayResult;

        /**
         * Creates a new DimIProxy.
         */
        private DimIProxy(Dim dim, int type) {
            this.dim = dim;
            this.type = type;
        }

        // ContextAction

        /**
         * Performs the action given by {@link #type}.
         */
        public Object run(Context cx) {
            switch (type) {
              case IPROXY_COMPILE_SCRIPT:
                cx.compileString(text, url, 1, null);
                break;

              case IPROXY_EVAL_SCRIPT:
                {
                    Scriptable scope = null;
                    if (dim.scopeProvider != null) {
                        scope = dim.scopeProvider.getScope();
                    }
                    if (scope == null) {
                        scope = new ImporterTopLevel(cx);
                    }
                    cx.evaluateString(scope, text, url, 1, null);
                }
                break;

              case IPROXY_STRING_IS_COMPILABLE:
                booleanResult = cx.stringIsCompilableUnit(text);
                break;

              case IPROXY_OBJECT_TO_STRING:
                if (object == Undefined.instance) {
                    stringResult = "undefined";
                } else if (object == null) {
                    stringResult = "null";
                } else if (object instanceof NativeCall) {
                    stringResult = "[object Call]";
                } else {
                    stringResult = Context.toString(object);
                }
                break;

              case IPROXY_OBJECT_PROPERTY:
                objectResult = dim.getObjectPropertyImpl(cx, object, id);
                break;

              case IPROXY_OBJECT_IDS:
                objectArrayResult = dim.getObjectIdsImpl(cx, object);
                break;

              default:
                throw Kit.codeBug();
            }
            return null;
        }

        /**
         * Performs the action given by {@link #type} with the attached
         * {@link ContextFactory}.
         */
        private void withContext() {
            dim.contextFactory.call(this);
        }

        // ContextFactory.Listener

        /**
         * Called when a Context is created.
         */
        public void contextCreated(Context cx) {
            if (type != IPROXY_LISTEN) Kit.codeBug();
            ContextData contextData = new ContextData();
            Debugger debugger = new DimIProxy(dim, IPROXY_DEBUG);
            cx.setDebugger(debugger, contextData);
            cx.setGeneratingDebug(true);
            cx.setOptimizationLevel(-1);
        }

        /**
         * Called when a Context is destroyed.
         */
        public void contextReleased(Context cx) {
            if (type != IPROXY_LISTEN) Kit.codeBug();
        }

        // Debugger

        /**
         * Returns a StackFrame for the given function or script.
         */
        public DebugFrame getFrame(Context cx, DebuggableScript fnOrScript) {
            if (type != IPROXY_DEBUG) Kit.codeBug();

            FunctionSource item = dim.getFunctionSource(fnOrScript);
            if (item == null) {
                // Can not debug if source is not available
                return null;
            }
            return new StackFrame(cx, dim, item);
        }

        /**
         * Called when compilation is finished.
         */
        public void handleCompilationDone(Context cx,
                                          DebuggableScript fnOrScript,
                                          String source) {
            if (type != IPROXY_DEBUG) Kit.codeBug();

            if (!fnOrScript.isTopLevel()) {
                return;
            }
            dim.registerTopScript(fnOrScript, source);
        }
    }

    /**
     * Class to store information about a stack.
     */
    public static class ContextData {

        /**
         * The stack frames.
         */
        private ObjArray frameStack = new ObjArray();

        /**
         * Whether the debugger should break at the next line in this context.
         */
        private boolean breakNextLine;

        /**
         * The frame depth the debugger should stop at.  Used to implement
         * "step over" and "step out".
         */
        private int stopAtFrameDepth = -1;

        /**
         * Whether this context is in the event thread.
         */
        private boolean eventThreadFlag;

        /**
         * The last exception that was processed.
         */
        private Throwable lastProcessedException;

        /**
         * Returns the ContextData for the given Context.
         */
        public static ContextData get(Context cx) {
            return (ContextData) cx.getDebuggerContextData();
        }

        /**
         * Returns the number of stack frames.
         */
        public int frameCount() {
            return frameStack.size();
        }

        /**
         * Returns the stack frame with the given index.
         */
        public StackFrame getFrame(int frameNumber) {
            int num = frameStack.size() - frameNumber - 1;
            return (StackFrame) frameStack.get(num);
        }

        /**
         * Pushes a stack frame on to the stack.
         */
        private void pushFrame(StackFrame frame) {
            frameStack.push(frame);
        }

        /**
         * Pops a stack frame from the stack.
         */
        private void popFrame() {
            frameStack.pop();
        }
    }

    /**
     * Object to represent one stack frame.
     */
    public static class StackFrame implements DebugFrame {

        /**
         * The debugger.
         */
        private Dim dim;

        /**
         * The ContextData for the Context being debugged.
         */
        private ContextData contextData;

        /**
         * The scope.
         */
        private Scriptable scope;

        /**
         * The 'this' object.
         */
        private Scriptable thisObj;

        /**