[commit: ghc] wip/nfs-locking: Move chunksOfSize to Settings/Builders/Ar.hs, add comments. (5e3f91f)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : wip/nfs-locking
Link       : http://ghc.haskell.org/trac/ghc/changeset/5e3f91f9d050c91f8fd842b9548093c0d8d8e532/ghc

>---------------------------------------------------------------

commit 5e3f91f9d050c91f8fd842b9548093c0d8d8e532
Author: Andrey Mokhov <andrey.mokhov at gmail.com>
Date:   Sat Jan 9 16:57:49 2016 +0000

    Move chunksOfSize to Settings/Builders/Ar.hs, add comments.
    
    See #130. [skip ci]


>---------------------------------------------------------------

5e3f91f9d050c91f8fd842b9548093c0d8d8e532
 src/Base.hs                 | 19 +++----------------
 src/Settings/Builders/Ar.hs | 28 ++++++++++++++++++++++++----
 2 files changed, 27 insertions(+), 20 deletions(-)

diff --git a/src/Base.hs b/src/Base.hs
index fb33907..65a2d1d 100644
--- a/src/Base.hs
+++ b/src/Base.hs
@@ -22,9 +22,9 @@ module Base (
     putColoured, putOracle, putBuild, putSuccess, putError, renderBox,
 
     -- * Miscellaneous utilities
-    bimap, minusOrd, intersectOrd, replaceEq, quote, chunksOfSize,
-    replaceSeparators, decodeModule, encodeModule, unifyPath, (-/-),
-    versionToInt, removeFileIfExists, removeDirectoryIfExists
+    bimap, minusOrd, intersectOrd, replaceEq, quote, replaceSeparators,
+    decodeModule, encodeModule, unifyPath, (-/-), versionToInt,
+    removeFileIfExists, removeDirectoryIfExists
     ) where
 
 import Control.Applicative
@@ -90,19 +90,6 @@ replaceSeparators = replaceWhen isPathSeparator
 replaceWhen :: (a -> Bool) -> a -> [a] -> [a]
 replaceWhen p to = map (\from -> if p from then to else from)
 
--- | @chunksOfSize size strings@ splits a given list of strings into chunks not
--- exceeding the given @size at .
-chunksOfSize :: Int -> [String] -> [[String]]
-chunksOfSize _    [] = []
-chunksOfSize size strings = reverse chunk : chunksOfSize size rest
-  where
-    (chunk, rest) = go [] 0 strings
-    go res _         []     = (res, [])
-    go res chunkSize (s:ss) =
-        if newSize > size then (res, s:ss) else go (s:res) newSize ss
-      where
-        newSize = chunkSize + length s
-
 -- | Add quotes to a String
 quote :: String -> String
 quote s = "\"" ++ s ++ "\""
diff --git a/src/Settings/Builders/Ar.hs b/src/Settings/Builders/Ar.hs
index 18ce802..86f4310 100644
--- a/src/Settings/Builders/Ar.hs
+++ b/src/Settings/Builders/Ar.hs
@@ -5,6 +5,7 @@ import Expression
 import Oracles
 import Predicates (builder)
 
+-- | Default arguments for 'Ar' builder
 arBuilderArgs :: Args
 arBuilderArgs = builder Ar ? mconcat [ arg "q"
                                      , arg =<< getOutput
@@ -15,10 +16,15 @@ arBuilderArgs = builder Ar ? mconcat [ arg "q"
 arFlagsCount :: Int
 arFlagsCount = 2
 
--- Ar needs to be invoked in a special way: we pass the list of files to be
--- archived via a temporary file as otherwise Ar (or rather Windows command
--- line) chokes up. Alternatively, we split argument list into chunks and call
--- ar multiple times (when passing files via a separate file is not supported).
+-- | Invoke 'Ar' builder given a path to it and a list of arguments. Take care
+-- not to exceed the limit on command line length, which differs across
+-- supported operating systems (see 'cmdLineLengthLimit'). 'Ar' needs to be
+-- handled in a special way because we sometimes need to archive __a lot__ of
+-- files (in Cabal package, for example, command line length can reach 2MB!).
+-- To work around the limit on the command line length we pass the list of files
+-- to be archived via a temporary file, or alternatively, we split argument list
+-- into chunks and call 'Ar' multiple times (when passing arguments via a
+-- temporary file is not supported).
 arCmd :: FilePath -> [String] -> Action ()
 arCmd path argList = do
     arSupportsAtFile <- flag ArSupportsAtFile
@@ -38,3 +44,17 @@ useSuccessiveInvocations path flagArgs fileArgs = do
     maxChunk <- cmdLineLengthLimit
     forM_ (chunksOfSize maxChunk fileArgs) $ \argsChunk ->
         unit . cmd [path] $ flagArgs ++ argsChunk
+
+-- | @chunksOfSize size strings@ splits a given list of strings into chunks not
+-- exceeding the given @size at .
+chunksOfSize :: Int -> [String] -> [[String]]
+chunksOfSize _    [] = []
+chunksOfSize size strings = reverse chunk : chunksOfSize size rest
+  where
+    (chunk, rest) = go [] 0 strings
+    go res _         []     = (res, [])
+    go res chunkSize (s:ss) =
+        if newSize > size then (res, s:ss) else go (s:res) newSize ss
+      where
+        newSize = chunkSize + length s
+