Add generic Parsers file

Extract the utility functions of Diskstats's collector
Parser so other collector Parsers can be able to use them.
Signed-off-by: Spyros Trigazis <strigazi@gmail.com>
Signed-off-by: Michele Tartara <mtartara@google.com>
Reviewed-by: Michele Tartara <mtartara@google.com>

Makefile.am

@@ -608,6 +608,7 @@ HS_LIB_SRCS = \
 	src/Ganeti/OpCodes.hs \
 	src/Ganeti/OpParams.hs \
 	src/Ganeti/Path.hs \
+	src/Ganeti/Parsers.hs \
 	src/Ganeti/Query/Cluster.hs \
 	src/Ganeti/Query/Common.hs \
 	src/Ganeti/Query/Export.hs \

src/Ganeti/Parsers.hs

+{-# LANGUAGE OverloadedStrings #-}
+{-| Utility functions for several parsers
+
+This module holds the definition for some utility functions for two
+parsers.  The parser for the @/proc/stat@ file and the parser for the
+@/proc/diskstats@ file.
+
+-}
+{-
+
+Copyright (C) 2013 Google Inc.
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301, USA.
+
+-}
+module Ganeti.Parsers where
+
+import Control.Applicative ((*>))
+import qualified Data.Attoparsec.Text as A
+import Data.Attoparsec.Text (Parser)
+import Data.Text (unpack)
+
+-- * Utility functions
+
+-- | Our own space-skipping function, because A.skipSpace also skips
+-- newline characters. It skips ZERO or more spaces, so it does not
+-- fail if there are no spaces.
+skipSpaces :: Parser ()
+skipSpaces = A.skipWhile A.isHorizontalSpace
+
+-- | A parser recognizing a number preceeded by spaces.
+numberP :: Parser Int
+numberP = skipSpaces *> A.decimal
+
+-- | A parser recognizing a word preceded by spaces, and closed by a space.
+stringP :: Parser String
+stringP = skipSpaces *> fmap unpack (A.takeWhile $ not . A.isHorizontalSpace)