Use hyphen in character range in IPv4 regex, make more readable

Author: krzysztofwos

api/net/ip4/addr.hpp

@@ -107,10 +107,9 @@ struct Addr {
 
     const static std::regex ipv4_address_pattern
     {
-      "^\\s*(25[0–5]|2[0–4]\\d|[01]?\\d\\d?)\\."
-        "(25[0–5]|2[0–4]\\d|[01]?\\d\\d?)\\."
-        "(25[0–5]|2[0–4]\\d|[01]?\\d\\d?)\\."
-        "(25[0–5]|2[0–4]\\d|[01]?\\d\\d?)\\s*$"
+#define OCTET_PATTERN "(25[0-5]|2[0-4]\\d|[01]?\\d\\d?)"
+      "^\\s*" OCTET_PATTERN "\\." OCTET_PATTERN "\\." OCTET_PATTERN "\\." OCTET_PATTERN "\\s*$"
+#undef OCTET_PATTERN
     };
 
     std::smatch ipv4_parts;