scriptruntime.java

這是一個javascript 的 interpreter是了解 web browser的好材料

            return result.toString();
        }

    }

    static String uneval(Context cx, Scriptable scope, Object value)
    {
        if (value == null) {
            return "null";
        }
        if (value == Undefined.instance) {
            return "undefined";
        }
        if (value instanceof String) {
            String escaped = escapeString((String)value);
            StringBuffer sb = new StringBuffer(escaped.length() + 2);
            sb.append('\"');
            sb.append(escaped);
            sb.append('\"');
            return sb.toString();
        }
        if (value instanceof Number) {
            double d = ((Number)value).doubleValue();
            if (d == 0 && 1 / d < 0) {
                return "-0";
            }
            return toString(d);
        }
        if (value instanceof Boolean) {
            return toString(value);
        }
        if (value instanceof Scriptable) {
            Scriptable obj = (Scriptable)value;
            // Wrapped Java objects won't have "toSource" and will report
            // errors for get()s of nonexistent name, so use has() first
            if (ScriptableObject.hasProperty(obj, "toSource")) {
                Object v = ScriptableObject.getProperty(obj, "toSource");
                if (v instanceof Function) {
                    Function f = (Function)v;
                    return toString(f.call(cx, scope, obj, emptyArgs));
                }
            }
            return toString(value);
        }
        warnAboutNonJSObject(value);
        return value.toString();
    }

    static String defaultObjectToSource(Context cx, Scriptable scope,
                                        Scriptable thisObj, Object[] args)
    {
        boolean toplevel, iterating;
        if (cx.iterating == null) {
            toplevel = true;
            iterating = false;
            cx.iterating = new ObjToIntMap(31);
        } else {
            toplevel = false;
            iterating = cx.iterating.has(thisObj);
        }

        StringBuffer result = new StringBuffer(128);
        if (toplevel) {
            result.append("(");
        }
        result.append('{');

        // Make sure cx.iterating is set to null when done
        // so we don't leak memory
        try {
            if (!iterating) {
                cx.iterating.intern(thisObj); // stop recursion.
                Object[] ids = thisObj.getIds();
                for (int i=0; i < ids.length; i++) {
                    Object id = ids[i];
                    Object value;
                    if (id instanceof Integer) {
                        int intId = ((Integer)id).intValue();
                        value = thisObj.get(intId, thisObj);
                        if (value == Scriptable.NOT_FOUND)
                            continue;   // a property has been removed
                        if (i > 0)
                            result.append(", ");
                        result.append(intId);
                    } else {
                        String strId = (String)id;
                        value = thisObj.get(strId, thisObj);
                        if (value == Scriptable.NOT_FOUND)
                            continue;   // a property has been removed
                        if (i > 0)
                            result.append(", ");
                        if (ScriptRuntime.isValidIdentifierName(strId)) {
                            result.append(strId);
                        } else {
                            result.append('\'');
                            result.append(
                                ScriptRuntime.escapeString(strId, '\''));
                            result.append('\'');
                        }
                    }
                    result.append(':');
                    result.append(ScriptRuntime.uneval(cx, scope, value));
                }
            }
        } finally {
            if (toplevel) {
                cx.iterating = null;
            }
        }

        result.append('}');
        if (toplevel) {
            result.append(')');
        }
        return result.toString();
    }

    public static Scriptable toObject(Scriptable scope, Object val)
    {
        if (val instanceof Scriptable) {
            return (Scriptable)val;
        }
        return toObject(Context.getContext(), scope, val);
    }

    public static Scriptable toObjectOrNull(Context cx, Object obj)
    {
        if (obj instanceof Scriptable) {
            return (Scriptable)obj;
        } else if (obj != null && obj != Undefined.instance) {
            return toObject(cx, getTopCallScope(cx), obj);
        }
        return null;
    }

    /**
     * @deprecated Use {@link #toObject(Scriptable, Object)} instead.
     */
    public static Scriptable toObject(Scriptable scope, Object val,
                                      Class staticClass)
    {
        if (val instanceof Scriptable) {
            return (Scriptable)val;
        }
        return toObject(Context.getContext(), scope, val);
    }

    /**
     * Convert the value to an object.
     *
     * See ECMA 9.9.
     */
    public static Scriptable toObject(Context cx, Scriptable scope, Object val)
    {
        if (val instanceof Scriptable) {
            return (Scriptable) val;
        }
        if (val == null) {
            throw typeError0("msg.null.to.object");
        }
        if (val == Undefined.instance) {
            throw typeError0("msg.undef.to.object");
        }
        String className = val instanceof String ? "String" :
                           val instanceof Number ? "Number" :
                           val instanceof Boolean ? "Boolean" :
                           null;
        if (className != null) {
            Object[] args = { val };
            scope = ScriptableObject.getTopLevelScope(scope);
            return newObject(cx, scope, className, args);
        }

        // Extension: Wrap as a LiveConnect object.
        Object wrapped = cx.getWrapFactory().wrap(cx, scope, val, null);
        if (wrapped instanceof Scriptable)
            return (Scriptable) wrapped;
        throw errorWithClassName("msg.invalid.type", val);
    }

    /**
     * @deprecated Use {@link #toObject(Context, Scriptable, Object)} instead.
     */
    public static Scriptable toObject(Context cx, Scriptable scope, Object val,
                                      Class staticClass)
    {
        return toObject(cx, scope, val);
    }

    /**
     * @deprecated The method is only present for compatibility.
     */
    public static Object call(Context cx, Object fun, Object thisArg,
                              Object[] args, Scriptable scope)
    {
        if (!(fun instanceof Function)) {
            throw notFunctionError(toString(fun));
        }
        Function function = (Function)fun;
        Scriptable thisObj = toObjectOrNull(cx, thisArg);
        if (thisObj == null) {
            throw undefCallError(thisObj, "function");
        }
        return function.call(cx, scope, thisObj, args);
    }

    public static Scriptable newObject(Context cx, Scriptable scope,
                                       String constructorName, Object[] args)
    {
        scope = ScriptableObject.getTopLevelScope(scope);
        Function ctor = getExistingCtor(cx, scope, constructorName);
        if (args == null) { args = ScriptRuntime.emptyArgs; }
        return ctor.construct(cx, scope, args);
    }

    /**
     *
     * See ECMA 9.4.
     */
    public static double toInteger(Object val) {
        return toInteger(toNumber(val));
    }

    // convenience method
    public static double toInteger(double d) {
        // if it's NaN
        if (d != d)
            return +0.0;

        if (d == 0.0 ||
            d == Double.POSITIVE_INFINITY ||
            d == Double.NEGATIVE_INFINITY)
            return d;

        if (d > 0.0)
            return Math.floor(d);
        else
            return Math.ceil(d);
    }

    public static double toInteger(Object[] args, int index) {
        return (index < args.length) ? toInteger(args[index]) : +0.0;
    }

    /**
     *
     * See ECMA 9.5.
     */
    public static int toInt32(Object val)
    {
        // short circuit for common integer values
        if (val instanceof Integer)
            return ((Integer)val).intValue();

        return toInt32(toNumber(val));
    }

    public static int toInt32(Object[] args, int index) {
        return (index < args.length) ? toInt32(args[index]) : 0;
    }

    public static int toInt32(double d) {
        int id = (int)d;
        if (id == d) {
            // This covers -0.0 as well
            return id;
        }

        if (d != d
            || d == Double.POSITIVE_INFINITY
            || d == Double.NEGATIVE_INFINITY)
        {
            return 0;
        }

        d = (d >= 0) ? Math.floor(d) : Math.ceil(d);

        double two32 = 4294967296.0;
        d = Math.IEEEremainder(d, two32);
        // (double)(long)d == d should hold here

        long l = (long)d;
        // returning (int)d does not work as d can be outside int range
        // but the result must always be 32 lower bits of l
        return (int)l;
    }

    /**
     * See ECMA 9.6.
     * @return long value representing 32 bits unsigned integer
     */
    public static long toUint32(double d) {
        long l = (long)d;
        if (l == d) {
            // This covers -0.0 as well
            return l & 0xffffffffL;
        }

        if (d != d
            || d == Double.POSITIVE_INFINITY
            || d == Double.NEGATIVE_INFINITY)
        {
            return 0;
        }

        d = (d >= 0) ? Math.floor(d) : Math.ceil(d);

        // 0x100000000 gives me a numeric overflow...
        double two32 = 4294967296.0;
        l = (long)Math.IEEEremainder(d, two32);

        return l & 0xffffffffL;
    }

    public static long toUint32(Object val) {
        return toUint32(toNumber(val));
    }

    /**
     *
     * See ECMA 9.7.
     */
    public static char toUint16(Object val) {
        double d = toNumber(val);

        int i = (int)d;
        if (i == d) {
            return (char)i;
        }

        if (d != d
            || d == Double.POSITIVE_INFINITY
            || d == Double.NEGATIVE_INFINITY)
        {
            return 0;
        }

        d = (d >= 0) ? Math.floor(d) : Math.ceil(d);

        int int16 = 0x10000;
        i = (int)Math.IEEEremainder(d, int16);

        return (char)i;
    }

    // XXX: this is until setDefaultNamespace will learn how to store NS
    // properly and separates namespace form Scriptable.get etc.
    private static final String DEFAULT_NS_TAG = "__default_namespace__";

    public static Object setDefaultNamespace(Object namespace, Context cx)
    {
        Scriptable scope = cx.currentActivationCall;
        if (scope == null) {
            scope = getTopCallScope(cx);
        }

        XMLLib xmlLib = currentXMLLib(cx);
        Object ns = xmlLib.toDefaultXmlNamespace(cx, namespace);

        // XXX : this should be in separated namesapce from Scriptable.get/put
        if (!scope.has(DEFAULT_NS_TAG, scope)) {
            // XXX: this is racy of cause
            ScriptableObject.defineProperty(scope, DEFAULT_NS_TAG, ns,
                                            ScriptableObject.PERMANENT
                                            | ScriptableObject.DONTENUM);
        } else {
            scope.put(DEFAULT_NS_TAG, scope, ns);
        }

        return Undefined.instance;
    }

    public static Object searchDefaultNamespace(Context cx)
    {
        Scriptable scope = cx.currentActivationCall;
        if (scope == null) {
            scope = getTopCallScope(cx);
        }
        Object nsObject;
        for (;;) {
            Scriptable parent = scope.getParentScope();
            if (parent == null) {
                nsObject = ScriptableObject.getProperty(scope, DEFAULT_NS_TAG);
                if (nsObject == Scriptable.NOT_FOUND) {