Add Basename module

src/Streamly/Coreutils/Basename.hs

@@ -0,0 +1,48 @@
+-- |
+-- Module      : Streamly.Coreutils.Basename
+-- Copyright   : (c) 2022 Composewell Technologies
+-- License     : BSD-3-Clause
+-- Maintainer  : streamly@composewell.com
+-- Stability   : experimental
+-- Portability : GHC
+--
+-- Return pathe with any leading directory components removed.
+-- If specified, also remove a trailing suffix.
+
+module Streamly.Coreutils.Basename
+    ( basename
+    , basenameWith
+
+    -- * Options
+    , Basename
+    , Suffix(..)
+    , suffix
+    )
+where
+
+import Data.List (stripPrefix)
+
+data Suffix = None | Suffix [Char]
+
+newtype Basename = Basename {removeSuffix :: Suffix}
+
+suffix :: Suffix -> Basename -> Basename
+suffix opt cfg = cfg {removeSuffix = opt}
+
+defaultConfig :: Basename
+defaultConfig = Basename None
+
+basenameWith :: (Basename -> Basename) -> FilePath -> String
+basenameWith f path =
+    let opt = f defaultConfig
+        base = reverse $ takeWhile (/= '/') $ reverse path
+        in case removeSuffix opt of
+            None -> base
+            Suffix x ->
+                let suf = reverse x
+                    val0 = stripPrefix suf $ takeWhile (/= '/') $ reverse path
+                    val = maybe base reverse val0
+                    in val
+
+basename :: FilePath -> String
+basename  = basenameWith id

streamly-coreutils.cabal

@@ -108,6 +108,7 @@ library
   hs-source-dirs:      src
   exposed-modules:
       Streamly.Coreutils
+    , Streamly.Coreutils.Basename
     , Streamly.Coreutils.Common
     , Streamly.Coreutils.Cp
     , Streamly.Coreutils.Directory