Use memchr in indices

Author: Lysxia

src/Data/Text/Internal/ArrayUtils.hs

@@ -14,6 +14,8 @@ import System.Posix.Types (CSsize(..))
 import GHC.Exts (ByteArray#)
 import Data.Word (Word8)
 
+-- | Find index of next occurrence of given byte,
+-- relative to the starting offset, or @-1@ if not found.
 memchr :: ByteArray# -> Int -> Int -> Word8 -> Int
 #if defined(PURE_HASKELL)
 memchr arr# off len w =

src/Data/Text/Internal/Lazy/Search.hs

@@ -111,12 +111,11 @@ indicesOne c = chunk
   where
     chunk :: Int64 -> Text -> [Int64]
     chunk !_ Empty = []
-    chunk !i (Chunk (T.Text oarr ooff olen) os) = go 0
+    chunk !i (Chunk (T.Text (A.ByteArray oarr#) ooff olen) os) = go 0
       where
-        go h | h >= olen = chunk (i+intToInt64 olen) os
-             | on == c = i + intToInt64 h : go (h+1)
-             | otherwise = go (h+1)
-             where on = A.unsafeIndex oarr (ooff+h)
+        go h = case memchr oarr# (ooff+h) (olen-h) c of
+          -1 -> chunk (i+intToInt64 olen) os
+          x  -> i + intToInt64 h + intToInt64 x : go (h + x + 1)
 
 -- | First argument is a strict Text, and second is a lazy one.
 isPrefixOf :: T.Text -> Text -> Bool

src/Data/Text/Internal/Search.hs

@@ -91,12 +91,11 @@ indices' (Text narr noff nlen) (Text harr@(A.ByteArray harr#) hoff hlen) = loop
 {-# INLINE indices' #-}
 
 scanOne :: Word8 -> Text -> [Int]
-scanOne c (Text harr hoff hlen) = loop 0
+scanOne c (Text (A.ByteArray harr#) hoff hlen) = loop 0
   where
-    loop !i
-      | i >= hlen                        = []
-      | A.unsafeIndex harr (hoff+i) == c = i : loop (i+1)
-      | otherwise                        = loop (i+1)
+    loop !i = case memchr harr# (hoff + i) (hlen - i) c of
+      -1 -> []
+      x  -> i + x : loop (i + x + 1)
 {-# INLINE scanOne #-}
 
 word8ToInt :: Word8 -> Int