From ab61be26a9643b779aca54585273585e72dbf9ec Mon Sep 17 00:00:00 2001
From: yanyongyu <yanyongyu_1@126.com>
Date: Mon, 28 Dec 2020 17:39:33 +0800
Subject: [PATCH] :zap: improve radd support for messagesegment

---
 nonebot/adapters/__init__.py       | 57 ++++++++++++++++++++----------
 nonebot/adapters/cqhttp/message.py |  4 +++
 2 files changed, 43 insertions(+), 18 deletions(-)

diff --git a/nonebot/adapters/__init__.py b/nonebot/adapters/__init__.py
index 1d4d971a..22c6f587 100644
--- a/nonebot/adapters/__init__.py
+++ b/nonebot/adapters/__init__.py
@@ -9,7 +9,7 @@ import abc
 from typing_extensions import Literal
 from functools import reduce, partial
 from dataclasses import dataclass, field
-from typing import Any, Dict, Union, Optional, Callable, Iterable, Awaitable, TYPE_CHECKING
+from typing import Any, Dict, Union, TypeVar, Optional, Callable, Iterable, Awaitable, TYPE_CHECKING
 
 from pydantic import BaseModel
 
@@ -267,6 +267,10 @@ class Event(abc.ABC, BaseModel):
         raise NotImplementedError
 
 
+T_Message = TypeVar("T_Message", bound="Message")
+T_MessageSegment = TypeVar("T_MessageSegment", bound="MessageSegment")
+
+
 @dataclass
 class MessageSegment(abc.ABC):
     """消息段基类"""
@@ -282,19 +286,34 @@ class MessageSegment(abc.ABC):
     """
 
     @abc.abstractmethod
-    def __str__(self) -> str:
+    def __str__(self: T_MessageSegment) -> str:
         """该消息段所代表的 str，在命令匹配部分使用"""
         raise NotImplementedError
 
     @abc.abstractmethod
-    def __add__(self, other) -> "Message":
+    def __add__(self: T_MessageSegment, other: Union[str, T_MessageSegment,
+                                                     T_Message]) -> "T_Message":
         """你需要在这里实现不同消息段的合并：
         比如：
             if isinstance(other, str):
                 ...
             elif isinstance(other, MessageSegment):
                 ...
-        注意：不能返回 self，需要返回一个新生成的对象
+        注意：需要返回一个新生成的对象
+        """
+        raise NotImplementedError
+
+    @abc.abstractmethod
+    def __radd__(
+        self: T_MessageSegment, other: Union[str, dict, list, T_MessageSegment,
+                                             T_Message]) -> "T_Message":
+        """你需要在这里实现不同消息段的合并：
+        比如：
+            if isinstance(other, str):
+                ...
+            elif isinstance(other, MessageSegment):
+                ...
+        注意：需要返回一个新生成的对象
         """
         raise NotImplementedError
 
@@ -316,17 +335,17 @@ class Message(list, abc.ABC):
     """消息数组"""
 
     def __init__(self,
-                 message: Union[str, dict, list, BaseModel, MessageSegment,
-                                "Message"] = None,
+                 message: Union[str, dict, list, T_MessageSegment,
+                                T_Message] = None,
                  *args,
                  **kwargs):
         """
         :参数:
 
-          * ``message: Union[str, dict, list, BaseModel, MessageSegment, Message]``: 消息内容
+          * ``message: Union[str, dict, list, MessageSegment, Message]``: 消息内容
         """
         super().__init__(*args, **kwargs)
-        if isinstance(message, (str, dict, list, BaseModel)):
+        if isinstance(message, (str, dict, list)):
             self.extend(self._construct(message))
         elif isinstance(message, Message):
             self.extend(message)
@@ -347,11 +366,12 @@ class Message(list, abc.ABC):
     @staticmethod
     @abc.abstractmethod
     def _construct(
-            msg: Union[str, dict, list, BaseModel]) -> Iterable[MessageSegment]:
+            msg: Union[str, dict, list,
+                       BaseModel]) -> Iterable[T_MessageSegment]:
         raise NotImplementedError
 
-    def __add__(self, other: Union[str, MessageSegment,
-                                   "Message"]) -> "Message":
+    def __add__(self: T_Message, other: Union[str, T_MessageSegment,
+                                              T_Message]) -> T_Message:
         result = self.__class__(self)
         if isinstance(other, str):
             result.extend(self._construct(other))
@@ -361,11 +381,12 @@ class Message(list, abc.ABC):
             result.extend(other)
         return result
 
-    def __radd__(self, other: Union[str, MessageSegment, "Message"]):
+    def __radd__(self: T_Message, other: Union[str, T_MessageSegment,
+                                               T_Message]):
         result = self.__class__(other)
         return result.__add__(self)
 
-    def append(self, obj: Union[str, MessageSegment]) -> "Message":
+    def append(self: T_Message, obj: Union[str, T_MessageSegment]) -> T_Message:
         """
         :说明:
 
@@ -383,8 +404,8 @@ class Message(list, abc.ABC):
             raise ValueError(f"Unexpected type: {type(obj)} {obj}")
         return self
 
-    def extend(self, obj: Union["Message",
-                                Iterable[MessageSegment]]) -> "Message":
+    def extend(self: T_Message,
+               obj: Union[T_Message, Iterable[T_MessageSegment]]) -> T_Message:
         """
         :说明:
 
@@ -398,7 +419,7 @@ class Message(list, abc.ABC):
             self.append(segment)
         return self
 
-    def reduce(self) -> None:
+    def reduce(self: T_Message) -> None:
         """
         :说明:
 
@@ -413,14 +434,14 @@ class Message(list, abc.ABC):
             else:
                 index += 1
 
-    def extract_plain_text(self) -> str:
+    def extract_plain_text(self: T_Message) -> str:
         """
         :说明:
 
           提取消息内纯文本消息
         """
 
-        def _concat(x: str, y: MessageSegment) -> str:
+        def _concat(x: str, y: T_MessageSegment) -> str:
             return f"{x} {y}" if y.is_text() else x
 
         plain_text = reduce(_concat, self, "")
diff --git a/nonebot/adapters/cqhttp/message.py b/nonebot/adapters/cqhttp/message.py
index fae867ac..466da970 100644
--- a/nonebot/adapters/cqhttp/message.py
+++ b/nonebot/adapters/cqhttp/message.py
@@ -35,6 +35,10 @@ class MessageSegment(BaseMessageSegment):
     def __add__(self, other) -> "Message":
         return Message(self) + other
 
+    @overrides(BaseMessageSegment)
+    def __radd__(self, other) -> "Message":
+        return Message(other) + self
+
     @overrides(BaseMessageSegment)
     def is_text(self) -> bool:
         return self.type == "text"