Fixed an issue where compressing CSS expressions involving clamp wo…

…uld return invalid CSS (fixes #1021)

CHANGELOG.md

@@ -4,6 +4,11 @@ title: Releases
 
 # Releases
 
+## Unreleased
+
+- Fixed an issue where compressing CSS with `clamp` expressions would 
+    result in invalid CSS (#1021) (contribution by Laurent P. René de Cotret)
+
 ## Hakyll 4.16.3.0 (2024-10-24)
 
 - Bump `pandoc` upper bound to include up to version 3.5

lib/Hakyll/Web/CompressCss.hs

@@ -42,14 +42,17 @@ compressSeparators =
     replaceAll " *[{};,>+~!] *" (take 1 . dropWhile isSpace) .
     replaceAll ": *" (take 1) -- not destroying pseudo selectors (#323)
 
--- | Uses `compressCalcExpression` on all parenthesised calc expressions
--- and applies `transform` to all parts outside of them
+-- | Uses `compressExpression` on all parenthesised calc and 
+-- clamp expressions, and applies `transform` to all parts 
+-- outside of them
 handleCalcExpressions :: (String -> String) -> String -> String
 handleCalcExpressions transform = top transform
   where
-    top f ""                             = f ""
-    top f str | "calc(" `isPrefixOf` str = f "calc" ++ nested 0 compressCalcExpression (drop 4 str)
-    top f (x:xs)                         = top (f . (x:)) xs
+    top f ""                              = f ""
+    top f str | "calc(" `isPrefixOf` str  = f "calc"  ++ nested 0 compressExpression (drop 4 str)
+              -- See issue #1021
+              | "clamp(" `isPrefixOf` str = f "clamp" ++ nested 0 compressExpression (drop 5 str) 
+    top f (x:xs)                          = top (f . (x:)) xs
 
     -- when called with depth=0, the first character must be a '('
     nested :: Int -> (String -> String) -> String -> String
@@ -62,9 +65,10 @@ handleCalcExpressions transform = top transform
                                                       _   -> depth
                                                     ) (f . (x:)) xs
 
--- | does not remove whitespace around + and -, which is important in calc() expressions
-compressCalcExpression :: String -> String
-compressCalcExpression =
+-- | does not remove whitespace around + and -, which is important 
+-- in calc() and clamp() expressions
+compressExpression :: String -> String
+compressExpression =
     replaceAll " *[*/] *| *\\)|\\( *" (take 1 . dropWhile isSpace)
 
 --------------------------------------------------------------------------------

tests/Hakyll/Web/CompressCss/Tests.hs

@@ -43,6 +43,8 @@ tests = testGroup "Hakyll.Web.CompressCss.Tests" $ concat
         , "a!b"           @=? compressCss "a ! b"
           -- compress calc()
         , "calc(1px + 100%/(5 + 3) - (3px + 2px)*5)" @=? compressCss "calc( 1px + 100% / ( 5 +  3) - calc( 3px + 2px ) * 5 )"
+          -- compress clamp() (issue #1021)
+        , "clamp(2.25rem, 2vw + 1.5rem, 3.25rem)" @=? compressCss "clamp(2.25rem,  2vw  +     1.5rem, 3.25rem)"
           -- compress whitespace even after this curly brace
         , "}"             @=? compressCss ";   }  "
           -- but do not compress separators inside string tokens