Standardized code and add comments

maker/python/xdb/util.py

@@ -1,42 +1,47 @@
-#  Created by leolin49 on 2022/7/7.
-#  Copyright (C) 2022 leolin49. All rights reserved.
-
-shift_index = (24, 16, 8, 0)
-# Util function
+# Copyright 2022 The Ip2Region Authors. All rights reserved.
+# Use of this source code is governed by a Apache2.0-style
+# license that can be found in the LICENSE file.
+#
+# Author: leolin49 <leolin49@foxmail.com>
+#
+_SHIFT_INDEX = (24, 16, 8, 0)
 
 
-def checkip(ip: str) -> int:
-    """Convert ip string to integer."""
+def check_ip(ip: str) -> int:
+    """
+    Convert ip string to integer.
+    Return -1 if ip is not the correct ipv4 address.
+    """
     if not is_ipv4(ip):
         return -1
     ps = ip.split(".")
-    if len(ps) != 4:
-        return 0
     val = 0
     for i in range(len(ps)):
         d = int(ps[i])
-        if d < 0 or d > 255:
-            return 0
-        val |= d << shift_index[i]
+        val |= d << _SHIFT_INDEX[i]
     return val
 
 
 def long2ip(num: int) -> str:
-    """Convert integer to ip string."""
-    return "{}.{}.{}.{}".format((num >> 24) & 0xFF, (num >> 16) & 0xFF, (num >> 8) & 0xFF, num & 0xFF)
-
-
-def mid_ip(sip: int, eip: int):
-    """Get the middle ip between sip and eip."""
-    return (sip + eip) >> 1
+    """
+    Convert integer to ip string.
+    Return empty string if the num greater than UINT32_MAX or less than 0.
+    """
+    if num < 0 or num > 0xFFFFFFFF:
+        return ""
+    return "{}.{}.{}.{}".format(
+        (num >> 24) & 0xFF, (num >> 16) & 0xFF, (num >> 8) & 0xFF, num & 0xFF
+    )
 
 
 def is_ipv4(ip: str) -> bool:
-    """Determine whether it is an ipv4 address."""
-    p = ip.split(".")
-    if len(p) != 4:
+    """
+    Determine whether it is an ipv4 address.
+    """
+    ps = ip.split(".")
+    if len(ps) != 4:
         return False
-    for pp in p:
-        if not pp.isdigit() or len(pp) > 3 or int(pp) > 255:
+    for p in ps:
+        if not p.isdigit() or len(p) > 3 or (int(p) < 0 or int(p) > 255):
             return False
     return True