Improve dollar IpAddress (#20729)

* Improve dollar

* Improve dollar

* Simplify, remove 1 if in for loop

* ci

* Update lib/pure/net.nim

* Update lib/pure/net.nim

Co-authored-by: Andreas Rumpf <rumpf_a@web.de>

changelog.md

@@ -116,6 +116,9 @@
 - `std/uri.Uri` dollar `$` improved, precalculates the `string` result length from the `Uri`.
 
 
+- `std/net.IpAddress` dollar `$` improved, uses a fixed capacity for the `string` result based from the `IpAddressFamily`.
+
+
 [//]: # "Additions:"
 - Added ISO 8601 week date utilities in `times`:
   - Added `IsoWeekRange`, a range type for weeks in a week-based year.

lib/pure/net.nim

@@ -1898,14 +1898,18 @@ proc `==`*(lhs, rhs: IpAddress): bool =
 
 proc `$`*(address: IpAddress): string =
   ## Converts an IpAddress into the textual representation
-  result = ""
   case address.family
   of IpAddressFamily.IPv4:
-    for i in 0 .. 3:
-      if i != 0:
-        result.add('.')
-      result.add($address.address_v4[i])
+    result = newStringOfCap(16)
+    result.addInt address.address_v4[0]
+    result.add '.'
+    result.addInt address.address_v4[1]
+    result.add '.'
+    result.addInt address.address_v4[2]
+    result.add '.'
+    result.addInt address.address_v4[3]
   of IpAddressFamily.IPv6:
+    result = newStringOfCap(48)
     var
       currentZeroStart = -1
       currentZeroCount = 0