{-
-- The "real" main program for cpphs, a simple C pre-processor written in Haskell.
--
-- This module exports function "runCpps", which performs all of the functions of
-- the main program of Cpphs, and which can be called from a stand-alone command line
-- program or from some other program (such as a test harness).

-- Copyright (c) 2004 Malcolm Wallace
-- This file is placed in the public domain, but the library modules it
-- refers to are either standard Haskell'98, or distributed under the LGPL.

-- Modified:
--   18-May-2004, Graham Klyne:
--      separated main program logic from cpphs main program module;
--      added -O option, and arranged that output is written to a
--      specified stream (retaining stdout as the default);
--      strip any trailing '/' and '\' characters from -I options.
-}
module RunCpphs
    ( runCpphs )
where

import IO       (stdout, IOMode(WriteMode), openFile, hClose, hPutStr )                 -- [[[GK]]]
import List     (isPrefixOf)
import Monad    (when,unless)                                                           -- [[[GK]]]
import CppIfdef (cppIfdef, preDefine)
import Position (newfile)
import MacroPass(macroPass)

--  Callable form of main program, for testing [[[GK]]]
--  Also, add -O option to specify output file
runCpphs :: String -> [String] -> IO ()
runCpphs prog args = do
  let ds    = map (drop 2) (filter ("-D"`isPrefixOf`) args)
      is    = map ((dropTrailing "/\\") . (drop 2)) (filter ("-I"`isPrefixOf`) args)    -- [[[GK]]]
      os    = map (drop 2) (filter ("-O"`isPrefixOf`) args)                             -- [[[GK]]]
      macro = not ("--nomacro" `elem` args)
      locat = not ("--noline" `elem` args)
      files = filter (not . isPrefixOf "-") args
  when (null files)
       (error ("Usage: "++prog++" file ... [-Dsym]* |-Dsym=val]* [-Ipath]* [-Ofile]"    -- [[[GK]]]
                              ++" [--nomacro] [--noline]"))
  oh <- if null os then return stdout else openFile (head os) WriteMode                 -- [[[GK]]]
  mapM_ (\f-> do c <- readFile f
                 let pass1 = cppIfdef (newfile f) (preDefine ds)
                                      is macro locat c
                     pass2 = macroPass ds pass1
                     putResult = hPutStr oh                                             -- [[[GK]]]
                 if not macro then putResult pass1 else putResult pass2                 -- [[[GK]]]
        ) files
  unless (null os) (hClose oh)                                                          -- [[[GK]]]

dropTrailing :: (Eq a) => [a] -> [a] -> [a]                                             -- [[[GK]]]
dropTrailing dropVals = reverse . dropWhile (`elem` dropVals) . reverse                 -- [[[GK]]]