jsj_javaobject.c

caffeine-monkey java实现的js模拟引擎

JavaObject_convert(JSContext *cx, JSObject *obj, JSType type, jsval *vp)
{
    JavaObjectWrapper *java_wrapper;
    JavaClassDescriptor *class_descriptor;
    jobject java_obj;
    JNIEnv *jEnv;
    JSJavaThreadState *jsj_env;
    JSBool result;

    java_wrapper = JS_GetPrivate(cx, obj);
    if (!java_wrapper) {
        if (type == JSTYPE_OBJECT) {
            *vp = OBJECT_TO_JSVAL(obj);
            return JS_TRUE;
        }

        JS_ReportErrorNumber(cx, jsj_GetErrorMessage, NULL,
                             JSJMSG_BAD_OP_JOBJECT);
        return JS_FALSE;
    }

    java_obj = java_wrapper->java_obj;
    class_descriptor = java_wrapper->class_descriptor;

    switch (type) {
    case JSTYPE_OBJECT:
        *vp = OBJECT_TO_JSVAL(obj);
        return JS_TRUE;

    case JSTYPE_FUNCTION:
        JS_ReportErrorNumber(cx, jsj_GetErrorMessage, NULL,
                             JSJMSG_CONVERT_TO_FUNC);
        return JS_FALSE;

    case JSTYPE_VOID:
    case JSTYPE_STRING:
        /* Get the Java per-thread environment pointer for this JSContext */
        jsj_env = jsj_EnterJava(cx, &jEnv);
        if (!jEnv)
            return JS_FALSE;

        /* Either extract a C-string from the java.lang.String object
           or call the Java toString() method */
        result = jsj_ConvertJavaObjectToJSString(cx, jEnv, class_descriptor, java_obj, vp);
        jsj_ExitJava(jsj_env);
        return result;

    case JSTYPE_NUMBER:
        /* Get the Java per-thread environment pointer for this JSContext */
        jsj_env = jsj_EnterJava(cx, &jEnv);
        if (!jEnv)
            return JS_FALSE;

        /* Call Java doubleValue() method, if applicable */
        result = jsj_ConvertJavaObjectToJSNumber(cx, jEnv, class_descriptor, java_obj, vp);
        jsj_ExitJava(jsj_env);
        return result;

    case JSTYPE_BOOLEAN:
        /* Get the Java per-thread environment pointer for this JSContext */
        jsj_env = jsj_EnterJava(cx, &jEnv);
        if (!jEnv)
            return JS_FALSE;

        /* Call booleanValue() method, if applicable */
        result = jsj_ConvertJavaObjectToJSBoolean(cx, jEnv, class_descriptor, java_obj, vp);
        jsj_ExitJava(jsj_env);
        return result;

    default:
        JS_ASSERT(0);
        return JS_FALSE;
    }
}

/*
 * Get a property from the prototype object of a native ECMA object, i.e.
 * return <js_constructor_name>.prototype.<member_name>
 * This is used to allow Java objects to inherit methods from Array.prototype
 * and String.prototype.
 */
static JSBool
inherit_props_from_JS_natives(JSContext *cx, const char *js_constructor_name,
                              const char *member_name, jsval *vp)
{
    JSObject *global_obj, *constructor_obj, *prototype_obj;
    jsval constructor_val, prototype_val;

    global_obj = JS_GetGlobalObject(cx);
    JS_ASSERT(global_obj);
    if (!global_obj)
        return JS_FALSE;

    JS_GetProperty(cx, global_obj, js_constructor_name, &constructor_val);
    JS_ASSERT(JSVAL_IS_OBJECT(constructor_val));
    constructor_obj = JSVAL_TO_OBJECT(constructor_val);

    JS_GetProperty(cx, constructor_obj, "prototype", &prototype_val);
    JS_ASSERT(JSVAL_IS_OBJECT(prototype_val));
    prototype_obj = JSVAL_TO_OBJECT(prototype_val);

    return JS_GetProperty(cx, prototype_obj, member_name, vp) && *vp != JSVAL_VOID;
}

struct JSJPropertyInfo {
    JSBool wantProp;            /* input param tells whether prop is returned */
    const char* name;           /* output param, name of property (XXX ASCII) */
    uintN attributes;           /* output param, attributes of property */
    JSProperty *prop;           /* output param, if wantProp, held pointer that
                                   must be released via OBJ_DROP_PROPERTY */
};
typedef struct JSJPropertyInfo JSJPropertyInfo;

static JSBool
lookup_member_by_id(JSContext *cx, JNIEnv *jEnv, JSObject *obj,
                    JavaObjectWrapper **java_wrapperp, jsid id,
                    JavaMemberDescriptor **member_descriptorp,
                    jsval *vp, JSObject **proto_chainp,
                    JSJPropertyInfo *prop_infop)
{
    jsval idval;
    JavaObjectWrapper *java_wrapper;
    JavaMemberDescriptor *member_descriptor;
    const char *member_name;
    JavaClassDescriptor *class_descriptor;
    JSObject *proto_chain;
    JSBool found_in_proto;

    found_in_proto = JS_FALSE;
    member_descriptor = NULL;
    java_wrapper = JS_GetPrivate(cx, obj);

    /* Handle accesses to prototype object */
    if (!java_wrapper) {
        if (JS_IdToValue(cx, id, &idval) && JSVAL_IS_STRING(idval) &&
            (member_name = JS_GetStringBytes(JSVAL_TO_STRING(idval))) != NULL) {
            if (!strcmp(member_name, "constructor"))
                goto done;
        }
        JS_ReportErrorNumber(cx, jsj_GetErrorMessage, NULL, JSJMSG_BAD_OP_JOBJECT);
        return JS_FALSE;
    }

    class_descriptor = java_wrapper->class_descriptor;
    JS_ASSERT(IS_REFERENCE_TYPE(class_descriptor->type));

    member_descriptor = jsj_LookupJavaMemberDescriptorById(cx, jEnv, class_descriptor, id);
    if (member_descriptor)
        goto done;

    /* Instances can reference static methods and fields */
    member_descriptor = jsj_LookupJavaStaticMemberDescriptorById(cx, jEnv, class_descriptor, id);
    if (member_descriptor)
        goto done;

    /* Ensure that the property we're searching for is string-valued. */
    JS_IdToValue(cx, id, &idval);
    if (!JSVAL_IS_STRING(idval)) {
        JS_ReportErrorNumber(cx, jsj_GetErrorMessage, NULL, JSJMSG_BAD_JOBJECT_EXPR);
        return JS_FALSE;
    }
    member_name = JS_GetStringBytes(JSVAL_TO_STRING(idval));

    /*
     * A little LC3 feature magic:
     *   + Instances of java.lang.String "inherit" the standard ECMA string methods
     *     of String.prototype.  All of the ECMA string methods convert the Java
     *     string to a JS string before performing the string operation.  For example,
     *         s = new java.lang.String("foobar");
     *         return s.slice(2);
     *   + Similarly, instances of Java arrays "inherit" the standard ECMA array
     *     methods of Array.prototype.  (Not all of these methods work properly
     *     on JavaArray objects, however, since the 'length' property is read-only.)
     */
    if (vp) {
        if ((class_descriptor->type == JAVA_SIGNATURE_JAVA_LANG_STRING) &&
            inherit_props_from_JS_natives(cx, "String", member_name, vp))
            goto done;
        if ((class_descriptor->type == JAVA_SIGNATURE_ARRAY) &&
            inherit_props_from_JS_natives(cx, "Array", member_name, vp))
            goto done;
    }

    /* Check for access to magic prototype chain property */
    if (!strcmp(member_name, "__proto__")) {
        proto_chain = JS_GetPrototype(cx, obj);
        if (vp)
            *vp = OBJECT_TO_JSVAL(proto_chain);
        goto done;
    }

    /*
     * See if the property looks like the explicit resolution of an
     * overloaded method, e.g. "max(double,double)", first as an instance method,
     * then as a static method.  If we find such a method, it will be cached
     * so future accesses won't run this code.
     */
    member_descriptor = jsj_ResolveExplicitMethod(cx, jEnv, class_descriptor, id, JS_FALSE);
    if (member_descriptor)
        goto done;
    member_descriptor = jsj_ResolveExplicitMethod(cx, jEnv, class_descriptor, id, JS_TRUE);
    if (member_descriptor)
        goto done;

    /* Is the property defined in the prototype chain? */
    if (proto_chainp && prop_infop) {
        /* If so, follow __proto__ link to search prototype chain */
        proto_chain = JS_GetPrototype(cx, obj);

        /* Use OBJ_LOOKUP_PROPERTY to determine if and where the property
           actually exists in the prototype chain. */
        if (proto_chain) {
            if (!OBJ_LOOKUP_PROPERTY(cx, proto_chain, id, proto_chainp,
                                     &prop_infop->prop)) {
                return JS_FALSE;
            }
            if (prop_infop->prop) {
                if (!OBJ_GET_ATTRIBUTES(cx, *proto_chainp, id, prop_infop->prop,
                                        &prop_infop->attributes)) {
                    OBJ_DROP_PROPERTY(cx, *proto_chainp, prop_infop->prop);
                    return JS_FALSE;
                }
                if (!prop_infop->wantProp) {
                    OBJ_DROP_PROPERTY(cx, *proto_chainp, prop_infop->prop);
                    prop_infop->prop = NULL;
                }
                prop_infop->name = member_name;
                found_in_proto = JS_TRUE;
                goto done;
            }
        }
    }

    /* Report lack of Java member with the given property name */
    JS_ReportErrorNumber(cx, jsj_GetErrorMessage, NULL, JSJMSG_NO_INSTANCE_NAME,
                         class_descriptor->name, member_name);
    return JS_FALSE;

done:
    /* Success.  Handle the multiple return values */
    if (java_wrapperp)
        *java_wrapperp = java_wrapper;
    if (member_descriptorp)
        *member_descriptorp = member_descriptor;
    if (proto_chainp && !found_in_proto)
        *proto_chainp = NULL;
    return JS_TRUE;
}

JS_EXPORT_API(JSBool)
JavaObject_getPropertyById(JSContext *cx, JSObject *obj, jsid id, jsval *vp)
{
    jobject java_obj;
    JavaMemberDescriptor *member_descriptor;
    JavaObjectWrapper *java_wrapper;
    JNIEnv *jEnv;
    JSObject *funobj;
    jsval field_val, method_val;
    JSBool success;
    JSJavaThreadState *jsj_env;
    JSObject *proto_chain;
    JSJPropertyInfo prop_info;

    /* printf("In JavaObject_getProperty\n"); */

    /* Get the Java per-thread environment pointer for this JSContext */
    jsj_env = jsj_EnterJava(cx, &jEnv);
    if (!jEnv)
        return JS_FALSE;

    if (vp)
        *vp = JSVAL_VOID;
    prop_info.wantProp = JS_FALSE;
    if (!lookup_member_by_id(cx, jEnv, obj, &java_wrapper, id, &member_descriptor, vp,
                             &proto_chain, &prop_info)) {
        jsj_ExitJava(jsj_env);
        return JS_FALSE;
    }

    /* Handle access to special, non-Java properties of JavaObjects, e.g. the
       "constructor" property of the prototype object */
    if (!member_descriptor) {
        jsj_ExitJava(jsj_env);
        if (proto_chain)
            return JS_GetProperty(cx, proto_chain, prop_info.name, vp);
        return JS_TRUE;
    }

    java_obj = java_wrapper->java_obj;
    field_val = method_val = JSVAL_VOID;

    if (jaApplet && (*jEnv)->IsInstanceOf(jEnv, java_obj, jaApplet)) {
        jsj_JSIsCallingApplet = JS_TRUE;
    }

    /* If a field member, get the value of the field */
    if (member_descriptor->field) {
        success = jsj_GetJavaFieldValue(cx, jEnv, member_descriptor->field, java_obj, &field_val);
        if (!success) {
            jsj_ExitJava(jsj_env);
            return JS_FALSE;
        }
    }

    /* If a method member, build a wrapper around the Java method */
    if (member_descriptor->methods) {
        /* Create a function object with this JavaObject as its parent, so that
           JSFUN_BOUND_METHOD binds it as the default 'this' for the function. */
        funobj = JS_CloneFunctionObject(cx, member_descriptor->invoke_func_obj, obj);
        if (!funobj) {
            jsj_ExitJava(jsj_env);
            return JS_FALSE;
        }
        method_val = OBJECT_TO_JSVAL(funobj);
    }

#if TEST_JAVAMEMBER
    /* Always create a JavaMember object, even though it's inefficient */
    obj = jsj_CreateJavaMember(cx, method_val, field_val);
    if (!obj) {
        jsj_ExitJava(jsj_env);
        return JS_FALSE;
    }
    *vp = OBJECT_TO_JSVAL(obj);
#else   /* !TEST_JAVAMEMBER */

    if (member_descriptor->field) {
        if (!member_descriptor->methods) {
            /* Return value of Java field */
            *vp = field_val;
        } else {
            /* Handle special case of access to a property that could refer
               to either a Java field or a method that share the same name.
               In Java, such ambiguity is not possible because the compiler
               can statically determine which is being accessed. */
            obj = jsj_CreateJavaMember(cx, method_val, field_val);
            if (!obj) {
                jsj_ExitJava(jsj_env);
                return JS_FALSE;
            }
            *vp = OBJECT_TO_JSVAL(obj);
        }

    } else {
        /* Return wrapper around Java method */
        *vp = method_val;
    }

#endif  /* !TEST_JAVAMEMBER */

    jsj_ExitJava(jsj_env);
    return JS_TRUE;
}

JS_STATIC_DLL_CALLBACK(JSBool)
JavaObject_setPropertyById(JSContext *cx, JSObject *obj, jsid id, jsval *vp)
{
    jobject java_obj;
    const char *member_name;
    JavaObjectWrapper *java_wrapper;
    JavaClassDescriptor *class_descriptor;
    JavaMemberDescriptor *member_descriptor;
    jsval idval;
    JNIEnv *jEnv;
    JSJavaThreadState *jsj_env;
    JSObject *proto_chain;