feat(lexer): add numbers

main.py

@@ -6,6 +6,8 @@ def main():
     source: str = """()  {}  +- += / /= // sefs + {, )
     }:: *
     "This is a string"
+    3.1415
+    123
     "This is
      another string" """
     lexer: Lexer = Lexer()

src/lexer.py

@@ -49,6 +49,11 @@ class Lexer:
             return self.source[self.idx]
         return ""
 
+    def peek_next(self) -> str:
+        if self.idx + 1 < self.length:
+            return self.source[self.idx + 1]
+        return ""
+
     def advance(self) -> str:
         char: str = self.peek()
         self.idx += 1
@@ -122,6 +127,9 @@ class Lexer:
             case '"':
                 self.scan_string()
             case _:
+                if char.isdigit():
+                    self.scan_number()
+                else:
                     self.error("Unexpected character")
         return None
 
@@ -138,3 +146,15 @@ class Lexer:
         self.advance()
         value: str = self.source[self.start + 1:self.idx - 1]
         self.add_token(TokenType.STRING, value)
+
+    def scan_number(self):
+        while self.peek().isdigit():
+            self.advance()
+
+        if self.peek() == "." and self.peek_next().isdigit():
+            self.advance()
+            while self.peek().isdigit():
+                self.advance()
+
+        value: float = float(self.source[self.start:self.idx])
+        self.add_token(TokenType.NUMBER, value)