processing a .tar.gz file

process-hoogle.hs

{-# LANGUAGE OverloadedStrings #-}

-- build-depends: tar, bytestring, zlib

-- Example of how to iterate through a .tar.gz file

module Lib
where

import qualified Codec.Archive.Tar as Tar
import Codec.Archive.Tar
import qualified Data.ByteString.Lazy.Char8 as LBS
import qualified Codec.Compression.GZip as GZip
import Control.Monad
import Data.Monoid
import System.Environment
import Data.List

someFunc :: IO ()
someFunc = putStrLn "someFunc"

test1 = do
  contents <- fmap GZip.decompress $ LBS.readFile "hoogle.tar.gz"
  let entries = Tar.read contents
      files = selectFiles entries
  forM_ files $ \entry-> do
    let ePath    = entryPath entry
        NormalFile bytes size = entryContent entry
    -- putStrLn $ show size ++ " " ++ ePath
    processFile bytes
  return ()

selectFiles :: Entries FormatError -> [Entry]
selectFiles Done = []
selectFiles (Fail e) = error $ "some format error: " ++ show e
selectFiles (Next entry next)
  = case entryContent entry of
      NormalFile _ _ -> entry : selectFiles next
      _              -> selectFiles next

processFile bytes = do
  let lns = LBS.lines bytes
  forM_ lns processLine

processLine str
  | LBS.isPrefixOf  "@package " str = emit
  | LBS.isPrefixOf  "@version " str = emit
  | LBS.isPrefixOf  "module " str   = emit
  | otherwise                       = return ()
  where emit = LBS.putStrLn str

----------

processTarArchive path = do
  contents <- fmap GZip.decompress $ LBS.readFile path
  let entries = Tar.read contents
      files = selectFiles entries
  forM_ files $ \entry-> do
    let ePath    = entryPath entry
        NormalFile bytes size = entryContent entry
    -- putStrLn $ show size ++ " " ++ ePath
    processFile2 ("???", "???") (LBS.lines bytes)
  return ()

processTxtFile path = do
  contents <- LBS.readFile path
  processFile2 ("???", "???") (LBS.lines contents)

processFile2 (package, version) [] = return ()
processFile2 (package, version) (a:as) =
  case LBS.words a of
    ("@package" : pkg : _)  -> processFile2 (pkg, version) as
    ("@version" : vers : _) -> processFile2 (package, vers) as
    ("module" : mod : _)    -> do LBS.putStrLn $ mod <> " " <> package <> " " <> version
                                  processFile2 (package, version) as
    _                       -> processFile2 (package, version) as

processArg path
  | isSuffixOf ".tar.gz" path = processTarArchive path
  | isSuffixOf ".txt" path    = processTxtFile path
  | otherwise                 = error $ "unknown file type: " ++ path

main = getArgs >>= mapM_ processArg