nativejavaobject.java

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

                    return 4;
                }
            }
            break;

        case JSTYPE_JAVA_CLASS:
            if (to == ScriptRuntime.ClassClass) {
                return 1;
            }
            else if (to == ScriptRuntime.ObjectClass) {
                return 3;
            }
            else if (to == ScriptRuntime.StringClass) {
                return 4;
            }
            break;

        case JSTYPE_JAVA_OBJECT:
        case JSTYPE_JAVA_ARRAY:
            Object javaObj = fromObj;
            if (javaObj instanceof Wrapper) {
                javaObj = ((Wrapper)javaObj).unwrap();
            }
            if (to.isInstance(javaObj)) {
                return CONVERSION_NONTRIVIAL;
            }
            if (to == ScriptRuntime.StringClass) {
                return 2;
            }
            else if (to.isPrimitive() && to != Boolean.TYPE) {
                return (fromCode == JSTYPE_JAVA_ARRAY)
                       ? CONVERSION_NONE : 2 + getSizeRank(to);
            }
            break;

        case JSTYPE_OBJECT:
            // Other objects takes #1-#3 spots
            if (to == fromObj.getClass()) {
                // No conversion required
                return 1;
            }
            if (to.isArray()) {
                if (fromObj instanceof NativeArray) {
                    // This is a native array conversion to a java array
                    // Array conversions are all equal, and preferable to object
                    // and string conversion, per LC3.
                    return 1;
                }
            }
            else if (to == ScriptRuntime.ObjectClass) {
                return 2;
            }
            else if (to == ScriptRuntime.StringClass) {
                return 3;
            }
            else if (to == ScriptRuntime.DateClass) {
                if (fromObj instanceof NativeDate) {
                    // This is a native date to java date conversion
                    return 1;
                }
            }
            else if (to.isInterface()) {
                if (fromObj instanceof Function) {
                    // See comments in coerceType
                    if (to.getMethods().length == 1) {
                        return 1;
                    }
                }
                return 11;
            }
            else if (to.isPrimitive() && to != Boolean.TYPE) {
                return 3 + getSizeRank(to);
            }
            break;
        }

        return CONVERSION_NONE;
    }

    static int getSizeRank(Class aType) {
        if (aType == Double.TYPE) {
            return 1;
        }
        else if (aType == Float.TYPE) {
            return 2;
        }
        else if (aType == Long.TYPE) {
            return 3;
        }
        else if (aType == Integer.TYPE) {
            return 4;
        }
        else if (aType == Short.TYPE) {
            return 5;
        }
        else if (aType == Character.TYPE) {
            return 6;
        }
        else if (aType == Byte.TYPE) {
            return 7;
        }
        else if (aType == Boolean.TYPE) {
            return CONVERSION_NONE;
        }
        else {
            return 8;
        }
    }

    private static int getJSTypeCode(Object value) {
        if (value == null) {
            return JSTYPE_NULL;
        }
        else if (value == Undefined.instance) {
            return JSTYPE_UNDEFINED;
        }
        else if (value instanceof String) {
            return JSTYPE_STRING;
        }
        else if (value instanceof Number) {
            return JSTYPE_NUMBER;
        }
        else if (value instanceof Boolean) {
            return JSTYPE_BOOLEAN;
        }
        else if (value instanceof Scriptable) {
            if (value instanceof NativeJavaClass) {
                return JSTYPE_JAVA_CLASS;
            }
            else if (value instanceof NativeJavaArray) {
                return JSTYPE_JAVA_ARRAY;
            }
            else if (value instanceof Wrapper) {
                return JSTYPE_JAVA_OBJECT;
            }
            else {
                return JSTYPE_OBJECT;
            }
        }
        else if (value instanceof Class) {
            return JSTYPE_JAVA_CLASS;
        }
        else {
            Class valueClass = value.getClass();
            if (valueClass.isArray()) {
                return JSTYPE_JAVA_ARRAY;
            }
            else {
                return JSTYPE_JAVA_OBJECT;
            }
        }
    }

    /**
     * Not intended for public use. Callers should use the
     * public API Context.toType.
     * @deprecated as of 1.5 Release 4
     * @see org.mozilla.javascript.Context#jsToJava(Object, Class)
     */
    public static Object coerceType(Class type, Object value)
    {
        return coerceTypeImpl(type, value);
    }

    /**
     * Type-munging for field setting and method invocation.
     * Conforms to LC3 specification
     */
    static Object coerceTypeImpl(Class type, Object value)
    {
        if (value != null && value.getClass() == type) {
            return value;
        }

        switch (getJSTypeCode(value)) {

        case JSTYPE_NULL:
            // raise error if type.isPrimitive()
            if (type.isPrimitive()) {
                reportConversionError(value, type);
            }
            return null;

        case JSTYPE_UNDEFINED:
            if (type == ScriptRuntime.StringClass ||
                type == ScriptRuntime.ObjectClass) {
                return "undefined";
            }
            else {
                reportConversionError("undefined", type);
            }
            break;

        case JSTYPE_BOOLEAN:
            // Under LC3, only JS Booleans can be coerced into a Boolean value
            if (type == Boolean.TYPE ||
                type == ScriptRuntime.BooleanClass ||
                type == ScriptRuntime.ObjectClass) {
                return value;
            }
            else if (type == ScriptRuntime.StringClass) {
                return value.toString();
            }
            else {
                reportConversionError(value, type);
            }
            break;

        case JSTYPE_NUMBER:
            if (type == ScriptRuntime.StringClass) {
                return ScriptRuntime.toString(value);
            }
            else if (type == ScriptRuntime.ObjectClass) {
                return coerceToNumber(Double.TYPE, value);
            }
            else if ((type.isPrimitive() && type != Boolean.TYPE) ||
                     ScriptRuntime.NumberClass.isAssignableFrom(type)) {
                return coerceToNumber(type, value);
            }
            else {
                reportConversionError(value, type);
            }
            break;

        case JSTYPE_STRING:
            if (type == ScriptRuntime.StringClass || type.isInstance(value)) {
                return value;
            }
            else if (type == Character.TYPE
                     || type == ScriptRuntime.CharacterClass)
            {
                // Special case for converting a single char string to a
                // character
                // Placed here because it applies *only* to JS strings,
                // not other JS objects converted to strings
                if (((String)value).length() == 1) {
                    return new Character(((String)value).charAt(0));
                }
                else {
                    return coerceToNumber(type, value);
                }
            }
            else if ((type.isPrimitive() && type != Boolean.TYPE)
                     || ScriptRuntime.NumberClass.isAssignableFrom(type))
            {
                return coerceToNumber(type, value);
            }
            else {
                reportConversionError(value, type);
            }
            break;

        case JSTYPE_JAVA_CLASS:
            if (value instanceof Wrapper) {
                value = ((Wrapper)value).unwrap();
            }

            if (type == ScriptRuntime.ClassClass ||
                type == ScriptRuntime.ObjectClass) {
                return value;
            }
            else if (type == ScriptRuntime.StringClass) {
                return value.toString();
            }
            else {
                reportConversionError(value, type);
            }
            break;

        case JSTYPE_JAVA_OBJECT:
        case JSTYPE_JAVA_ARRAY:              
            if (value instanceof Wrapper) {
              value = ((Wrapper)value).unwrap();
            }
            if (type.isPrimitive()) {
                if (type == Boolean.TYPE) {
                    reportConversionError(value, type);
                }
                return coerceToNumber(type, value);
            }
            else { 
              if (type == ScriptRuntime.StringClass) {
                    return value.toString();
                }
                else {
                    if (type.isInstance(value)) {
                        return value;
                    }
                    else {
                        reportConversionError(value, type);
                    }
                }
            }
            break;

        case JSTYPE_OBJECT:
            if (type == ScriptRuntime.StringClass) {
                return ScriptRuntime.toString(value);
            }
            else if (type.isPrimitive()) {
                if (type == Boolean.TYPE) {
                    reportConversionError(value, type);
                }
                return coerceToNumber(type, value);
            }
            else if (type.isInstance(value)) {
                return value;
            }
            else if (type == ScriptRuntime.DateClass
                     && value instanceof NativeDate)
            {
                double time = ((NativeDate)value).getJSTimeValue();
                // XXX: This will replace NaN by 0
                return new Date((long)time);
            }
            else if (type.isArray() && value instanceof NativeArray) {
                // Make a new java array, and coerce the JS array components
                // to the target (component) type.
                NativeArray array = (NativeArray) value;
                long length = array.getLength();
                Class arrayType = type.getComponentType();
                Object Result = Array.newInstance(arrayType, (int)length);
                for (int i = 0 ; i < length ; ++i) {
                    try  {
                        Array.set(Result, i, coerceType(arrayType,
                                                        array.get(i, array)));
                    }
                    catch (EvaluatorException ee) {
                        reportConversionError(value, type);
                    }
                }

                return Result;
            }
            else if (value instanceof Wrapper) {