iOS Team / CNliveBBASMModule · Files

//
//  BBAJSBindingBase.h
//  SWAN
//
//  Created by baidu on 2018/7/19.
//  Copyright © 2018年 baidu. All rights reserved.
//

#import <Foundation/Foundation.h>
#import <JavaScriptCore/JavaScriptCore.h>
#import "JSValue+JSBinding.h"
#include <objc/message.h>
#include <objc/runtime.h>
#import "BBAJSBindingError.h"
#import "BBAJSBindingTools.h"
#import "BBAJSBContext.h"

NS_ASSUME_NONNULL_BEGIN


/**
 绑定实现层数据类型
 
 在JSB_PARAM_DESCRIPTOR宏中使用
 绑定实现层实际需要的数据类型，框架层会自动将JSValue对象转为实现层需要的数据类型，不支持int等基本数据类型
 如果类型转换失败（如实现层希望是NSSting，js实际传入Array），将会抛出js异常，不会向实现层转发消息
 */
typedef NS_OPTIONS(NSUInteger, JSBNativeDataType) {
    /// OC id类型, 默认类型, 直接传入[JSValue toObject]结果（可能是OC任意对象类型）
    JSBNativeDataTypeObject = (1 << 0),
    /// OC NSNumber类型
    JSBNativeDataTypeNSNumber = (1 << 1),
    /// OC NSString类型
    JSBNativeDataTypeNSString = (1 << 2),
    /// OC NSDictionary类型
    JSBNativeDataTypeNSDictionary = (1 << 3),
    /// OC NSArray类型
    JSBNativeDataTypeNSArray = (1 << 4),
    /// OC NSData类型, 对应js的ArrayBuffer类型
    JSBNativeDataTypeNSData = (1 << 5),
    /// OC NSDate类型
    JSBNativeDataTypeNSDate = (1 << 6),
    /// OC Block, 即BBAJSBindingCallbackType类型block, 有callback时可以使用，同步或者异步回调，以数组形式传入callback参数，如果有js回调情况一定使用该类型
    JSBNativeDataTypeCallBack = (1 << 7),
    /// OC CGFloat, NSInteger, NSUInteger, BOOL
    JSBNativeDataTypeBasicDataType = (1 << 8),
    /// OC 框架中的JSBinding对象，这些对象，我们需要特殊处理，直接从JSValue->JSBinding对象找到相对应的imp层对象
    JSBNativeDataTypeJSBindingObject = (1 << 9),
};


/**
 绑定实现层数据能否为空
 
 在JSB_PARAM_DESCRIPTOR宏中使用
 如果实现层不能为空，js传入空，框架层直接抛出js异常
 */
typedef NS_ENUM(NSUInteger, JSBNativeParamsCanNull) {
    /// 数据能为空
    JSBNativeParamsCanNullable,
    /// 数据不能为空
    JSBNativeParamsCanNullnon
};



/**
 * 绑定所属的域
 */
typedef NS_OPTIONS(NSUInteger, JSBDomainType) {
    /// default, 主域
    JSBDomainTypeMaster = (1 << 0),
    /// 开放域
    JSBDomainTypeOpenData = (1 << 1),
    /// worker 域
    JSBDomainTypeWorker = (1 << 2),
    /// 以上所有域, 添加新的域时注意加进来
    JSBDomainTypeAll = JSBDomainTypeMaster | JSBDomainTypeOpenData,
};


/**
 有js回调时实现层使用该类型

 @param callBackParams js回调参数，按顺序以数组形式传入
 返回给js的值
 */
typedef void (^ _Nullable BBAJSBindingCallbackType)(NSArray* _Nullable callBackParams);
// 附Demo一个
// - (void)copyFileWithSrcPath:(NSString *)srcPath destPath:(NSString *)destPath success:(BBAJSBindingCallbackType)success fail:(BBAJSBindingCallbackType)fail complete:(BBAJSBindingCallbackType)complete {
//    if (!srcPath) {
//        if (fail) {
//            fail(@[@"fail"]);
//        }
//        return;
//    }
//    // 拷贝文件操作
//    if (success) {
//        success(@[@"sucess"]);
//    }
//    if (complete) {
//        success(@[@"complete"]);
//    }
//}


/**
 抛出js错误回调

 @param errorType BBAJSErrorTypes, 错误类型
 @param errorMessage 错误信息
 */
typedef void(^JSBindingThowJSErrorCallBack)(BBAJSErrorTypes errorType ,NSString* _Nullable errorMessage);


/**
 保护JSBingingObejct回调
 */
typedef void(^JSBindingProtectJSBObjectCallback)(void);


/**
 取消保护JSBingingObejct回调
 */
typedef void(^JSBindingUnProtectJSBObjectCallback)(void);


FOUNDATION_EXPORT NSString *const kJSBParamDescriptorNativeDataTypeKey; // JSB_PARAM_DESCRIPTOR 描述JSBNativeDataType的键值
FOUNDATION_EXPORT NSString *const kJSBParamDescriptorNativeParamsCanNullKey; // JSB_PARAM_DESCRIPTOR 描述JSBNativeParamsCanNull的键值
FOUNDATION_EXPORT NSString *const kJSBParamDescriptorJSObjectPropertyKey; // JSB_PARAM_DESCRIPTOR 描述js传入的object的preoperty的键值

FOUNDATION_EXPORT NSString *const kJSBExportToJSFunctionPrefix;
FOUNDATION_EXPORT NSString *const kJSBExportToJSFunctionDomainPrefix;


/**
 JSBinding基协议，所有绑定接口层定义协议遵守该协议
 */
#define JSB_EXPORT BBAJSBExportProtocol, JSExport


/**
 绑定实现层类到框架层

 @param CLASS 实现层Class，type:Class
 */
#define JSB_IMPLEMENT_CLASS(CLASS) JSB_IMPLEMENT_CLASS_WITH_DOMAIN(CLASS, JSBDomainTypeMaster)

#define JSB_IMPLEMENT_CLASS_WITH_DOMAIN(CLASS, DOMAIN_TYPE) \
    + (NSString *)jsb_implement_map_classname { \
        if (CLASS) { \
            return NSStringFromClass(CLASS); \
        } \
        return @""; \
    } \
    \
    + (JSBDomainType)jsb_implement_map_classname_domain { \
        NSAssert(DOMAIN_TYPE & JSBDomainTypeAll, @"JSB_IMPLEMENT_CLASS_WITH_DOMAIN must intput valid DOMAIN_TYPE."); \
        return DOMAIN_TYPE; \
    } \

/**
 绑定接口层selector和实现层selector

 @param JS_FUNCTION_NAME js调用函数名
 @param JS_BIND_SELECTOR 接口层selector 以@selector（selectorname）传入
 @param FORWARD_INSTANCE_SELECTOR 实现层selector，参数只支持JSBNativeDataType中定义的，不支持基础数据类型，以@selector（selectorname）传入
 @param ... 使用JSB_PARAM_DESCRIPTOR宏生成FORWARD_INSTANCE_SELECTOR参数的一一描述
 */
#define JSB_SELECTOR_MAP(JS_FUNCTION_NAME, JS_BIND_SELECTOR, FORWARD_INSTANCE_SELECTOR, ...) \
    + (NSString *)_jsb_export_selector_##JS_FUNCTION_NAME { \
        return [NSString stringWithFormat:@"%@|%@", NSStringFromSelector(JS_BIND_SELECTOR), NSStringFromSelector(FORWARD_INSTANCE_SELECTOR)]; \
    } \
    + (NSArray *)_jsb_selector_descriptor_##JS_FUNCTION_NAME { \
        return @[__VA_ARGS__]; \
    }


/**
 JSB_SELECTOR_MAP宏中FORWARD_INSTANCE_SELECTOR的参数描述符

 @param JSBNativeDataType JSBNativeDataType枚举中一种
 @param JSBNativeParamsCanNull JSBNativeParamsCanNull枚举中一种
 @param JSObjectPropertyName js传入参数的property name
 */
#define JSB_PARAM_DESCRIPTOR(JSBNativeDataType, JSBNativeParamsCanNull, JSObjectPropertyName) [NSDictionary dictionaryWithObjectsAndKeys:@(JSBNativeDataType), kJSBParamDescriptorNativeDataTypeKey, @(JSBNativeParamsCanNull), kJSBParamDescriptorNativeParamsCanNullKey, JSObjectPropertyName, kJSBParamDescriptorJSObjectPropertyKey ,nil]


/**
 绑定属性的getter方法

 @param JS_BIND_PROPERTY_GETTER_NAME 接口层的getter方法名
 @param MAP_PROPERTY_GETTER_NAME 实现层的getter方法名字
 */
#define JSB_PROPERTY_GETTER_MAP(JS_BIND_PROPERTY_GETTER_NAME, MAP_PROPERTY_GETTER_NAME) \
@synthesize JS_BIND_PROPERTY_GETTER_NAME = _##JS_BIND_PROPERTY_GETTER_NAME; \
- (JSValue *)JS_BIND_PROPERTY_GETTER_NAME { \
    NSError *errorHappened = nil; \
    return [[self class] forwardMessageBindingParams:@[] \
                            forwardTarget:self.impInstance?self.impInstance:self \
                                        forwardSel:@selector(MAP_PROPERTY_GETTER_NAME) \
                            forwardParamDescriptors:@[] \
                                        jsContext:self.currentJSContext \
                                    errorHappened:&errorHappened]; \
} \


/**
 绑定属性的setter方法
 
 @param JS_BIND_PROPERTY_SETTER_NAME 接口层的setter方法名
 @param MAP_PROPERTY_SETTER_NAME 实现层的setter方法名字
 */
#define JSB_PROPERTY_SETTER_MAP(JS_BIND_PROPERTY_SETTER_NAME, MAP_PROPERTY_SETTER_NAME, ...) \
- (void)JS_BIND_PROPERTY_SETTER_NAME:(JSValue *)pValue { \
    if (!pValue) { \
        return; \
    } \
    NSError *errorHappened = nil; \
    [[self class] forwardMessageBindingParams:@[pValue] \
                                 forwardTarget:self.impInstance?self.impInstance:self \
                                    forwardSel:@selector(MAP_PROPERTY_SETTER_NAME:) \
                       forwardParamDescriptors:@[__VA_ARGS__] \
                                     jsContext:self.currentJSContext \
                                 errorHappened:&errorHappened]; \
} \


// 下面形式的宏定义其作用是将__LINE__展开为实际行号, 以便在下面使用##, 如果直接使用__LINE__将会得到"__LINE__"
//#define A(X) B(X, __LINE__)
//#define B(X, LINE) C(X, LINE)  
//#define C(X, LINE)


#define __JSB_FUNCTION_DOMAIN_FLAG(JS_FUNCTION_NAME, DOMAIN_TYPE) \
+ (JSBDomainType)_jsb_function_domain_export_to_js_##JS_FUNCTION_NAME { \
    NSAssert(DOMAIN_TYPE & JSBDomainTypeAll, @"JSB_FUNCTION_EXPORT_TO_JS must intput valid DOMAIN_TYPE.");\
    return DOMAIN_TYPE; \
}


/**
 绑定一个block作为js函数, block可以随意定义, 可以传入任意参数等, 完全自己掌控，绑定在JSBDomainTypeMaster域下
 
 @param JS_FUNCTION_NAME 绑定的js函数名
 @param BLOCK 绑定的native block
 */
#define JSB_FUNCTION_EXPORT_TO_JS(JS_FUNCTION_NAME, BLOCK) \
JSB_DOMAIN_FUNCTION_EXPORT_TO_JS(JS_FUNCTION_NAME, JSBDomainTypeMaster, BLOCK)


/**
 * @brief 绑定一个block作为js函数
 *
 * @param JS_FUNCTION_NAME 绑定的js函数名
 * @param DOMAIN_TYPE 绑定所属的域, JSBDomainType
 * @param BLOCK 绑定的native block
 */
#define JSB_DOMAIN_FUNCTION_EXPORT_TO_JS(JS_FUNCTION_NAME, DOMAIN_TYPE, BLOCK) __JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_0(__LINE__, JS_FUNCTION_NAME, DOMAIN_TYPE, BLOCK)
#define __JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_0(LINE, JS_FUNCTION_NAME, DOMAIN_TYPE, BLOCK) __JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_1(LINE, JS_FUNCTION_NAME, DOMAIN_TYPE, BLOCK)
#define __JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_1(LINE, JS_FUNCTION_NAME, DOMAIN_TYPE, BLOCK) \
__JSB_FUNCTION_DOMAIN_FLAG(JS_FUNCTION_NAME##_##LINE, DOMAIN_TYPE) \
 \
+ (id)_jsb_function_export_to_js_##JS_FUNCTION_NAME##_##LINE { \
    id funcBlock = BLOCK; \
    return funcBlock; \
} \


/**
 绑定没有参数的js函数，绑定在JSBDomainTypeMaster域下

 @param JS_FUNCTION_NAME js 函数名
 @param FORWARD_CLASS_SELECTOR 转发selector（必须是类方法），转发到宏JSB_IMPLEMENT_CLASS绑定的类
 */
#define JSB_FUNCTION_EXPORT_TO_JS_WITH_0_JSPARAM_FORWARD(JS_FUNCTION_NAME, FORWARD_CLASS_SELECTOR) \
JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_WITH_0_JSPARAM_FORWARD(JS_FUNCTION_NAME, JSBDomainTypeMaster,  FORWARD_CLASS_SELECTOR)


/**
 * @brief 绑定一个转发的类方法（无参数）作为js函数
 *
 * @param JS_FUNCTION_NAME 绑定的js函数名
 * @param DOMAIN_TYPE 绑定所属的域, JSBDomainType
 * @param FORWARD_CLASS_SELECTOR js函数对转发到的类方法
 */
#define JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_WITH_0_JSPARAM_FORWARD(JS_FUNCTION_NAME, DOMAIN_TYPE, FORWARD_CLASS_SELECTOR) __JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_WITH_0_JSPARAM_FORWARD_0(__LINE__, JS_FUNCTION_NAME, DOMAIN_TYPE, FORWARD_CLASS_SELECTOR)
#define __JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_WITH_0_JSPARAM_FORWARD_0(LINE, JS_FUNCTION_NAME, DOMAIN_TYPE, FORWARD_CLASS_SELECTOR) __JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_WITH_0_JSPARAM_FORWARD_1(LINE, JS_FUNCTION_NAME, DOMAIN_TYPE, FORWARD_CLASS_SELECTOR)
#define __JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_WITH_0_JSPARAM_FORWARD_1(LINE, JS_FUNCTION_NAME, DOMAIN_TYPE, FORWARD_CLASS_SELECTOR) \
__JSB_FUNCTION_DOMAIN_FLAG(JS_FUNCTION_NAME##_##LINE, DOMAIN_TYPE) \
 \
+ (id)_jsb_function_export_to_js_##JS_FUNCTION_NAME##_##LINE { \
    id funcBlock = ^JSValue *(void) { \
        SEL mapClsSel = NSSelectorFromString(@"jsb_implement_map_classname"); \
        if (!mapClsSel || ![self respondsToSelector:mapClsSel]) { \
            return [JSValue valueWithNullInContext:[self currentJSContext]]; \
        } \
        NSString *impClsName = ((NSString *(*)(id, SEL))objc_msgSend)(self , mapClsSel); \
        return [self forwardMessageBindingParams:@[] \
                                forwardTarget:NSClassFromString(impClsName) \
                                forwardSel:FORWARD_CLASS_SELECTOR \
                                forwardParamDescriptors:@[] \
                                jsContext:[self currentJSContext] \
                                errorHappened:nil]; \
    }; \
    return funcBlock; \
}


/**
 绑定带有1个js参数的函数，绑定在JSBDomainTypeMaster域下

 @param JS_FUNCTION_NAME js函数名
 @param FORWARD_CLASS_SELECTOR 转发selector（必须是类方法），转发到宏JSB_IMPLEMENT_CLASS绑定的类
 @param ... 参数描述
 */
#define JSB_FUNCTION_EXPORT_TO_JS_WITH_1_JSPARAM_FORWARD(JS_FUNCTION_NAME, FORWARD_CLASS_SELECTOR, ...) \
JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_WITH_1_JSPARAM_FORWARD(JS_FUNCTION_NAME, JSBDomainTypeMaster, FORWARD_CLASS_SELECTOR, __VA_ARGS__)


/**
 * @brief 绑定一个转发的类方法（1个参数）作为js函数
 *
 * @param JS_FUNCTION_NAME 绑定的js函数名
 * @param DOMAIN_TYPE 绑定所属的域, JSBDomainType
 * @param FORWARD_CLASS_SELECTOR js函数对转发到的类方法
 * @param ... 参数描述
 */
#define JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_WITH_1_JSPARAM_FORWARD(JS_FUNCTION_NAME, DOMAIN_TYPE, FORWARD_CLASS_SELECTOR, ...) __JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_WITH_1_JSPARAM_FORWARD_0(__LINE__, JS_FUNCTION_NAME, DOMAIN_TYPE, FORWARD_CLASS_SELECTOR, __VA_ARGS__)
#define __JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_WITH_1_JSPARAM_FORWARD_0(LINE, JS_FUNCTION_NAME, DOMAIN_TYPE, FORWARD_CLASS_SELECTOR, ...) __JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_WITH_1_JSPARAM_FORWARD_1(LINE, JS_FUNCTION_NAME, DOMAIN_TYPE, FORWARD_CLASS_SELECTOR, __VA_ARGS__)
#define __JSB_DOMAIN_FUNCTION_EXPORT_TO_JS_WITH_1_JSPARAM_FORWARD_1(LINE, JS_FUNCTION_NAME, DOMAIN_TYPE, FORWARD_CLASS_SELECTOR, ...) \
__JSB_FUNCTION_DOMAIN_FLAG(JS_FUNCTION_NAME##_##LINE, DOMAIN_TYPE) \
\
+ (id)_jsb_function_export_to_js_##JS_FUNCTION_NAME##_##LINE { \
    id funcBlock = ^JSValue *(JSValue *object) { \
        if (!object) { \
            return [JSValue valueWithNullInContext:[JSContext currentContext]]; \
        } \
        SEL mapClsSel = NSSelectorFromString(@"jsb_implement_map_classname"); \
        if (!mapClsSel || ![self respondsToSelector:mapClsSel]) { \
            return [JSValue valueWithNullInContext:object.context]; \
        } \
        NSString *impClsName = ((NSString *(*)(id, SEL))objc_msgSend)(self , mapClsSel); \
        return [self forwardMessageBindingParams:@[object] \
                                   forwardTarget:NSClassFromString(impClsName) \
                                      forwardSel:FORWARD_CLASS_SELECTOR \
                         forwardParamDescriptors:@[__VA_ARGS__] \
                                       jsContext:object.context \
                                   errorHappened:nil]; \
    }; \
    return funcBlock; \
}





@protocol BBAJSBExportProtocol <JSExport>


/**
 * 添加init方法js可以通过 new Class() 方式来创建对象
 * Note: 这个初始化方法只能在JS线程中触发，NA不能创建<JSExport> 这样的对象出来
 @return Class实例
 */
- (instancetype)init;

@end

@interface BBAJSBindingBase : NSObject <BBAJSBExportProtocol>

- (instancetype)initWithJSContext:(JSContext *)jsContext instance:(id _Nullable)instance;

/**
 当前的js context
 */
@property (nonatomic, weak, readonly) BBAJSBContext *currentJSContext;

/**
 当前的appID
 */
@property (nonatomic, copy, readonly) NSString *appId;

/**
 绑定实现的实例
 */
@property (nonatomic, strong) id impInstance;

/**
 *  对象运行的线程，默认是创建对象的线程
 */
@property (nonatomic, strong, readwrite, nullable) NSThread *executeJSThread;


/**
 当前的JSContext, 必须在JS环境下执行

 @return JSContext
 */
+ (BBAJSBContext *)currentJSContext;


/**
 当前的appId, 必须在JS环境下执行

 @return appId
 */
+ (NSString *)currentAppId;
/**
 当前的appId, 获取指定的 JSContext
 
 @return appId
 */
+ (NSString *)currentAppIdWithJSContext:(JSContext *)jsContext;


/* @brief 为对应的key值设置私有数据, 必须在JS环境下执行
*
* @param data 私有数据
* @param key 私有数据key值
*/
+ (void)setPrivateData:(id)data forKey:(NSString *)key;


/**
 * @brief 根据key值获取私有数据, 必须在JS环境下执行
 *
 * @param key 私有数据key值
 */
+ (id)getPrivateDataForKey:(NSString *)key;
/**
 * @brief 根据key值获取私有数据, 必须在JS环境下执行
 *
 * @param key 私有数据key值
 * @param jsContext JSContext
 */
+ (id)getPrivateDataForKey:(NSString *)key context:(JSContext * _Nullable)jsContext;


/**
 * @brief 根据key值删除私有数据, 必须在JS环境下执行
 *
 * @param key 私有数据key值
 */
+ (void)removePrivateDataForKey:(NSString *)key;

/**
 * @brief 根据key值删除私有数据
 *
 * @param key 私有数据key值
 * @param jsContext JS环境
 */
+ (void)removePrivateDataForKey:(NSString *)key context:(JSContext * _Nullable)jsContext;


/**
 * @brief jsbObject引用计数+1，不被GC掉，需要与unRootAnJSBObject成对使用, 必须在JS环境下执行
 *
 * @param jsbObject 私有数据key值
 */
+ (void)protectAnJSBObject:(BBAJSBindingBase *)jsbObject;


/**
 * @brief jsbObject引用计数-1，可以被GC掉（referenceCount = 0时），需要与rootAnJSBObject成对使用, 必须在JS环境下执行
 *
 * @param jsbObject 私有数据key值
 */
+ (void)unProtectAnJSBObject:(BBAJSBindingBase *)jsbObject;


/**
 * @brief 获取类需要绑定到jscontext的函数列表
 *
 * @return 需要绑定的js函数名列表，key:@(JSBDomainType), value:function list
 */
+ (NSDictionary *)jsFunctionListShouldBeBind;


+ (JSValue *)forwardMessageBindingParams:(NSArray *)bindParams
                           forwardTarget:(id)forwardTarget
                              forwardSel:(SEL)forwardSel
                 forwardParamDescriptors:(NSArray *)descriptors
                               jsContext:(JSContext *)jsContext
                           errorHappened:(NSError**)error;


/**
 将绑定方法传入的JSValue转换为转发消息使用的OC数据类型
 
 @param jsValue 绑定方法传入的JSValue
 @param nativeType 转发消息期望使用的OC数据类型
 @param canNull 是否能够为空
 @param propertyName js 属性名字, 报错使用，nullable
 @return 转发消息使用的object
 */
+ (id)convertJSValue:(JSValue *)jsValue
    toNativeDataType:(JSBNativeDataType)nativeType
   nativeDataCanNull:(JSBNativeParamsCanNull)canNull
      jsPropertyName:(NSString *_Nullable)propertyName
           jsContext:(JSContext *)jsContext;


/**
 将JSBNativeDataTypeCallBack类型传入的参数中的实现实例转化为
 
 @param callBackParams JSBNativeDataTypeCallBack 参数
 @return 新的JSBNativeDataTypeCallBack参数
 */
+ (NSArray *)packCallBackParams:(NSArray *)callBackParams jsContext:(JSContext *)jsContext;


/**
 根据selector名计算需要的参数个数
 
 @param sel selector name
 @return selector的参数个数
 */
NSInteger jsb_paramcount_from_selector(SEL sel);

/**
 将一个数组中的实现实例（如果有）转化为绑定实例
 
 @param array 数组对象
 @return 数组对象
 */
+ (NSArray *)bindingObjectArrayFromArray:(NSArray *)array jsContext:(JSContext *)jsContext;

/**
 * @brief js ArrayBuffer转为NSData
 *
 * @param arrayBuffer ArrayBuffer
 * @return NSData
 */
+ (NSData *)arrayBufferToData:(JSValue *)arrayBuffer;

@end

NS_ASSUME_NONNULL_END