util: deduplicate stripStr implementation

lib/pep508.nix

@@ -3,7 +3,7 @@
 let
   inherit (builtins) match elemAt split foldl' substring stringLength typeOf fromJSON isString head mapAttrs elem length;
   inherit (lib) stringToCharacters fix;
-  inherit (import ./util.nix { inherit lib; }) splitComma;
+  inherit (import ./util.nix { inherit lib; }) splitComma stripStr;
 
   re = {
     operators = "([=><!~^]+)";
@@ -34,9 +34,6 @@ let
     }
   );
 
-  # Strip leading/trailing whitespace from string
-  stripStr = s: let t = match "[\t ]*(.*[^\t ])[\t ]*" s; in if t == null then "" else head t;
-
   # Remove groupings ( ) from expression
   unparen = expr':
     let

lib/pip.nix

@@ -4,14 +4,7 @@
 }:
 let
   inherit (builtins) match head tail typeOf split filter foldl' readFile dirOf hasContext unsafeDiscardStringContext;
-
-  stripStr = s:
-    let
-      t = match "[\t ]*(.*[^\t ])[\t ]*" s;
-    in
-    if t == null
-    then ""
-    else head t;
+  inherit (import ./util.nix { inherit lib; }) stripStr;
 
   uncomment = l: head (match " *([^#]*).*" l);
 

lib/util.nix

@@ -1,11 +1,19 @@
 # Small utilities for internal reuse, not exposed externally
 { lib }:
 let
-  inherit (builtins) filter match split;
+  inherit (builtins) filter match split head;
   inherit (lib) isString;
 
   isEmptyStr = s: isString s && match " *" s == null;
 in
 {
   splitComma = s: if s == "" then [ ] else filter isEmptyStr (split " *, *" s);
+
+  stripStr = s:
+    let
+      t = match "[\t ]*(.*[^\t ])[\t ]*" s;
+    in
+    if t == null
+    then ""
+    else head t;
 }