Fix typing issues and improve typing completeness across the library

Co-authored-by: Danny <Rapptz@users.noreply.github.com>
Co-authored-by: Josh <josh.ja.butt@gmail.com>

discord/ext/commands/view.py

@@ -21,6 +21,11 @@ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 DEALINGS IN THE SOFTWARE.
 """
+
+from __future__ import annotations
+
+from typing import Optional
+
 from .errors import UnexpectedQuoteError, InvalidEndOfQuotedStringError, ExpectedClosingQuoteError
 
 # map from opening quotes to closing quotes
@@ -47,24 +52,24 @@ _all_quotes = set(_quotes.keys()) | set(_quotes.values())
 
 
 class StringView:
-    def __init__(self, buffer):
-        self.index = 0
-        self.buffer = buffer
-        self.end = len(buffer)
+    def __init__(self, buffer: str) -> None:
+        self.index: int = 0
+        self.buffer: str = buffer
+        self.end: int = len(buffer)
         self.previous = 0
 
     @property
-    def current(self):
+    def current(self) -> Optional[str]:
         return None if self.eof else self.buffer[self.index]
 
     @property
-    def eof(self):
+    def eof(self) -> bool:
         return self.index >= self.end
 
-    def undo(self):
+    def undo(self) -> None:
         self.index = self.previous
 
-    def skip_ws(self):
+    def skip_ws(self) -> bool:
         pos = 0
         while not self.eof:
             try:
@@ -79,7 +84,7 @@ class StringView:
         self.index += pos
         return self.previous != self.index
 
-    def skip_string(self, string):
+    def skip_string(self, string: str) -> bool:
         strlen = len(string)
         if self.buffer[self.index : self.index + strlen] == string:
             self.previous = self.index
@@ -87,19 +92,19 @@ class StringView:
             return True
         return False
 
-    def read_rest(self):
+    def read_rest(self) -> str:
         result = self.buffer[self.index :]
         self.previous = self.index
         self.index = self.end
         return result
 
-    def read(self, n):
+    def read(self, n: int) -> str:
         result = self.buffer[self.index : self.index + n]
         self.previous = self.index
         self.index += n
         return result
 
-    def get(self):
+    def get(self) -> Optional[str]:
         try:
             result = self.buffer[self.index + 1]
         except IndexError:
@@ -109,7 +114,7 @@ class StringView:
         self.index += 1
         return result
 
-    def get_word(self):
+    def get_word(self) -> str:
         pos = 0
         while not self.eof:
             try:
@@ -119,12 +124,12 @@ class StringView:
                 pos += 1
             except IndexError:
                 break
-        self.previous = self.index
+        self.previous: int = self.index
         result = self.buffer[self.index : self.index + pos]
         self.index += pos
         return result
 
-    def get_quoted_word(self):
+    def get_quoted_word(self) -> Optional[str]:
         current = self.current
         if current is None:
             return None
@@ -187,5 +192,5 @@ class StringView:
 
             result.append(current)
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return f'<StringView pos: {self.index} prev: {self.previous} end: {self.end} eof: {self.eof}>'