docs: add typing in packet.py

Author: heehehe

Diff for: pymysqlreplication/packet.py

@@ -3,6 +3,7 @@
 import struct
 
 from pymysqlreplication import constants, event, row_event
+from typing import List, Tuple, Any, Dict, Optional, Union
 
 # Constants from PyMYSQL source code
 NULL_COLUMN = 251
@@ -36,24 +37,24 @@
 JSONB_LITERAL_FALSE = 0x2
 
 
-def read_offset_or_inline(packet, large):
+def read_offset_or_inline(packet, large: bool) -> Tuple[Any, Any, Any]:
     t = packet.read_uint8()
 
     if t in (JSONB_TYPE_LITERAL,
              JSONB_TYPE_INT16, JSONB_TYPE_UINT16):
-        return (t, None, packet.read_binary_json_type_inlined(t, large))
+        return t, None, packet.read_binary_json_type_inlined(t, large)
     if large and t in (JSONB_TYPE_INT32, JSONB_TYPE_UINT32):
-        return (t, None, packet.read_binary_json_type_inlined(t, large))
+        return t, None, packet.read_binary_json_type_inlined(t, large)
 
     if large:
-        return (t, packet.read_uint32(), None)
-    return (t, packet.read_uint16(), None)
+        return t, packet.read_uint32(), None
+    return t, packet.read_uint16(), None
 
 
 class BinLogPacketWrapper(object):
     """
-    Bin Log Packet Wrapper. It uses an existing packet object, and wraps
-    around it, exposing useful variables while still providing access
+    Bin Log Packet Wrapper uses an existing packet object and wraps around it,
+    exposing useful variables while still providing access
     to the original packet objects variables and methods.
     """
 
@@ -155,7 +156,7 @@ def __init__(self, from_packet, table_map,
         if self.event._processed == False:
             self.event = None
 
-    def read(self, size):
+    def read(self, size: int) -> Union[int, bytes]:
         size = int(size)
         self.read_bytes += size
         if len(self.__data_buffer) > 0:
@@ -167,14 +168,15 @@ def read(self, size):
                 return data + self.packet.read(size - len(data))
         return self.packet.read(size)
 
-    def unread(self, data):
-        '''Push again data in data buffer. It's use when you want
-        to extract a bit from a value a let the rest of the code normally
-        read the datas'''
+    def unread(self, data: str):
+        """
+        Push again data in data buffer.
+        Use to extract a bit from a value and ensure that the rest of the code reads data normally
+        """
         self.read_bytes -= len(data)
         self.__data_buffer += data
 
-    def advance(self, size):
+    def advance(self, size: int):
         size = int(size)
         self.read_bytes += size
         buffer_len = len(self.__data_buffer)
@@ -185,13 +187,11 @@ def advance(self, size):
         else:
             self.packet.advance(size)
 
-    def read_length_coded_binary(self):
-        """Read a 'Length Coded Binary' number from the data buffer.
-
+    def read_length_coded_binary(self) -> Optional[str]:
+        """
+        Read a 'Length Coded Binary' number from the data buffer.
         Length coded numbers can be anywhere from 1 to 9 bytes depending
-        on the value of the first byte.
-
-        From PyMYSQL source code
+        on the value of the first byte. (From PyMYSQL source code)
         """
         c = struct.unpack("!B", self.read(1))[0]
         if c == NULL_COLUMN:
@@ -205,14 +205,12 @@ def read_length_coded_binary(self):
         elif c == UNSIGNED_INT64_COLUMN:
             return self.unpack_int64(self.read(UNSIGNED_INT64_LENGTH))
 
-    def read_length_coded_string(self):
-        """Read a 'Length Coded String' from the data buffer.
-
-        A 'Length Coded String' consists first of a length coded
-        (unsigned, positive) integer represented in 1-9 bytes followed by
-        that many bytes of binary data.  (For example "cat" would be "3cat".)
-
-        From PyMYSQL source code
+    def read_length_coded_string(self) -> Optional[str]:
+        """
+        Read a 'Length Coded String' from the data buffer.
+        A 'Length Coded String' consists first of a length coded (unsigned, positive) integer
+        represented in 1-9 bytes followed by that many bytes of binary data.
+        (For example, "cat" would be "3cat". - From PyMYSQL source code)
         """
         length = self.read_length_coded_binary()
         if length is None:
@@ -226,8 +224,10 @@ def __getattr__(self, key):
         raise AttributeError("%s instance has no attribute '%s'" %
                              (self.__class__, key))
 
-    def read_int_be_by_size(self, size):
-        '''Read a big endian integer values based on byte number'''
+    def read_int_be_by_size(self, size: int):
+        """
+        Read a big endian integer values based on byte number
+        """
         if size == 1:
             return struct.unpack('>b', self.read(size))[0]
         elif size == 2:
@@ -241,8 +241,10 @@ def read_int_be_by_size(self, size):
         elif size == 8:
             return struct.unpack('>l', self.read(size))[0]
 
-    def read_uint_by_size(self, size):
-        '''Read a little endian integer values based on byte number'''
+    def read_uint_by_size(self, size: int) -> str:
+        """
+        Read a little endian integer values based on byte number
+        """
         if size == 1:
             return self.read_uint8()
         elif size == 2:
@@ -260,19 +262,18 @@ def read_uint_by_size(self, size):
         elif size == 8:
             return self.read_uint64()
 
-    def read_length_coded_pascal_string(self, size):
-        """Read a string with length coded using pascal style.
+    def read_length_coded_pascal_string(self, size: int) -> Union[int, bytes]:
+        """
+        Read a string with length coded using pascal style.
         The string start by the size of the string
         """
         length = self.read_uint_by_size(size)
         return self.read(length)
 
-    def read_variable_length_string(self):
-        """Read a variable length string where the first 1-5 bytes stores the
-        length of the string.
-
-        For each byte, the first bit being high indicates another byte must be
-        read.
+    def read_variable_length_string(self) -> Union[int, bytes]:
+        """
+        Read a variable length string where the first 1-5 bytes stores the length of the string.
+        For each byte, the first bit being high indicates another byte must be read.
         """
         byte = 0x80
         length = 0
@@ -283,65 +284,65 @@ def read_variable_length_string(self):
             bits_read = bits_read + 7
         return self.read(length)
 
-    def read_int24(self):
+    def read_int24(self) -> str:
         a, b, c = struct.unpack("BBB", self.read(3))
         res = a | (b << 8) | (c << 16)
         if res >= 0x800000:
             res -= 0x1000000
         return res
 
-    def read_int24_be(self):
+    def read_int24_be(self) -> str:
         a, b, c = struct.unpack('BBB', self.read(3))
         res = (a << 16) | (b << 8) | c
         if res >= 0x800000:
             res -= 0x1000000
         return res
 
-    def read_uint8(self):
+    def read_uint8(self) -> str:
         return struct.unpack('<B', self.read(1))[0]
 
-    def read_int16(self):
+    def read_int16(self) -> str:
         return struct.unpack('<h', self.read(2))[0]
 
-    def read_uint16(self):
+    def read_uint16(self) -> str:
         return struct.unpack('<H', self.read(2))[0]
 
-    def read_uint24(self):
+    def read_uint24(self) -> str:
         a, b, c = struct.unpack("<BBB", self.read(3))
         return a + (b << 8) + (c << 16)
 
-    def read_uint32(self):
+    def read_uint32(self) -> str:
         return struct.unpack('<I', self.read(4))[0]
 
-    def read_int32(self):
+    def read_int32(self) -> str:
         return struct.unpack('<i', self.read(4))[0]
 
-    def read_uint40(self):
+    def read_uint40(self) -> str:
         a, b = struct.unpack("<BI", self.read(5))
         return a + (b << 8)
 
-    def read_int40_be(self):
+    def read_int40_be(self) -> str:
         a, b = struct.unpack(">IB", self.read(5))
         return b + (a << 8)
 
-    def read_uint48(self):
+    def read_uint48(self) -> str:
         a, b, c = struct.unpack("<HHH", self.read(6))
         return a + (b << 16) + (c << 32)
 
-    def read_uint56(self):
+    def read_uint56(self) -> str:
         a, b, c = struct.unpack("<BHI", self.read(7))
         return a + (b << 8) + (c << 24)
 
-    def read_uint64(self):
+    def read_uint64(self) -> str:
         return struct.unpack('<Q', self.read(8))[0]
 
-    def read_int64(self):
+    def read_int64(self) -> str:
         return struct.unpack('<q', self.read(8))[0]
 
-    def unpack_uint16(self, n):
+    def unpack_uint16(self, n: bytes) -> str:
         return struct.unpack('<H', n[0:2])[0]
 
-    def unpack_int24(self, n):
+    def unpack_int24(self, n: bytes) -> Optional[str, int]:
         try:
             return struct.unpack('B', n[0])[0] \
                 + (struct.unpack('B', n[1])[0] << 8) \
@@ -358,7 +359,7 @@ def unpack_int32(self, n):
         except TypeError:
             return n[0] + (n[1] << 8) + (n[2] << 16) + (n[3] << 24)
 
-    def read_binary_json(self, size):
+    def read_binary_json(self, size: int) -> Optional[str]:
         length = self.read_uint_by_size(size)
         if length == 0:
             # handle NULL value
@@ -369,7 +370,7 @@ def read_binary_json(self, size):
 
         return self.read_binary_json_type(t, length)
 
-    def read_binary_json_type(self, t, length):
+    def read_binary_json_type(self, t: bytes, length: int) -> Optional[bool, str]:
         large = (t in (JSONB_TYPE_LARGE_OBJECT, JSONB_TYPE_LARGE_ARRAY))
         if t in (JSONB_TYPE_SMALL_OBJECT, JSONB_TYPE_LARGE_OBJECT):
             return self.read_binary_json_object(length - 1, large)
@@ -402,7 +403,7 @@ def read_binary_json_type(self, t, length):
 
         raise ValueError('Json type %d is not handled' % t)
 
-    def read_binary_json_type_inlined(self, t, large):
+    def read_binary_json_type_inlined(self, t: bytes, large: bool) -> Optional[bool, str]:
         if t == JSONB_TYPE_LITERAL:
             value = self.read_uint32() if large else self.read_uint16()
             if value == JSONB_LITERAL_NULL:
@@ -422,7 +423,7 @@ def read_binary_json_type_inlined(self, t, large):
 
         raise ValueError('Json type %d is not handled' % t)
 
-    def read_binary_json_object(self, length, large):
+    def read_binary_json_object(self, length: int, large: bool) -> Dict[str, str]:
         if large:
             elements = self.read_uint32()
             size = self.read_uint32()
@@ -460,7 +461,7 @@ def read_binary_json_object(self, length, large):
 
         return out
 
-    def read_binary_json_array(self, length, large):
+    def read_binary_json_array(self, length: int, large: bool) -> List:
         if large:
             elements = self.read_uint32()
             size = self.read_uint32()
@@ -482,13 +483,11 @@ def _read(x):
 
         return [_read(x) for x in values_type_offset_inline]
 
-    def read_string(self):
-        """Read a 'Length Coded String' from the data buffer.
-
+    def read_string(self) -> bytes:
+        """
+        Read a 'Length Coded String' from the data buffer.
         Read __data_buffer until NULL character (0 = \0 = \x00)
-
-        Returns:
-            Binary string parsed from __data_buffer
+        :return string: Binary string parsed from __data_buffer
         """
         string = b''
         while True: