lib.toInt/toIntBase10: Make more efficient by hoisting up internal strings into higher scope

1 files changed, 17 insertions, 10 deletions

diff --git a/lib/strings.nix b/lib/strings.nix
index 47ee095f1b68..32efc9bdb70e 100644
--- a/lib/strings.nix
+++ b/lib/strings.nix
@@ -1038,30 +1038,32 @@ rec {
        toInt "3.14"
        => error: floating point JSON numbers are not supported
   */
-  toInt = str:
+  toInt =
+    let
+      matchStripInput = match "[[:space:]]*(-?[[:digit:]]+)[[:space:]]*";
+      matchLeadingZero = match "0[[:digit:]]+";
+    in
+    str:
     let
       # RegEx: Match any leading whitespace, possibly a '-', one or more digits,
       # and finally match any trailing whitespace.
-      strippedInput = match "[[:space:]]*(-?[[:digit:]]+)[[:space:]]*" str;
+      strippedInput = matchStripInput str;
 
       # RegEx: Match a leading '0' then one or more digits.
-      isLeadingZero = match "0[[:digit:]]+" (head strippedInput) == [];
+      isLeadingZero = matchLeadingZero (head strippedInput) == [];
 
       # Attempt to parse input
       parsedInput = fromJSON (head strippedInput);
 
       generalError = "toInt: Could not convert ${escapeNixString str} to int.";
 
-      octalAmbigError = "toInt: Ambiguity in interpretation of ${escapeNixString str}"
-      + " between octal and zero padded integer.";
-
     in
       # Error on presence of non digit characters.
       if strippedInput == null
       then throw generalError
       # Error on presence of leading zero/octal ambiguity.
       else if isLeadingZero
-      then throw octalAmbigError
+      then throw "toInt: Ambiguity in interpretation of ${escapeNixString str} between octal and zero padded integer."
       # Error if parse function fails.
       else if !isInt parsedInput
       then throw generalError
@@ -1089,15 +1091,20 @@ rec {
        toIntBase10 "3.14"
        => error: floating point JSON numbers are not supported
   */
-  toIntBase10 = str:
+  toIntBase10 =
+    let
+      matchStripInput = match "[[:space:]]*0*(-?[[:digit:]]+)[[:space:]]*";
+      matchZero = match "0+";
+    in
+    str:
     let
       # RegEx: Match any leading whitespace, then match any zero padding,
       # capture possibly a '-' followed by one or more digits,
       # and finally match any trailing whitespace.
-      strippedInput = match "[[:space:]]*0*(-?[[:digit:]]+)[[:space:]]*" str;
+      strippedInput = matchStripInput str;
 
       # RegEx: Match at least one '0'.
-      isZero = match "0+" (head strippedInput) == [];
+      isZero = matchZero (head strippedInput) == [];
 
       # Attempt to parse input
       parsedInput = fromJSON (head strippedInput);