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{-| Template Haskell code for Haskell to Python constants.

-}

{-

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.

-}

{-# LANGUAGE TemplateHaskell #-}

module Ganeti.Hs2Py.GenConstants (genPyConstants) where

import Language.Haskell.TH

import Ganeti.THH

fileFromModule :: Maybe String -> String

fileFromModule Nothing = ""

fileFromModule (Just name) = "src/" ++ map dotToSlash name ++ ".hs"

  where dotToSlash '.' = '/'

        dotToSlash c = c

comment :: Name -> String

comment name =

  "# Generated automatically from Haskell constant '" ++ nameBase name ++

  "' in file '" ++ fileFromModule (nameModule name) ++ "'"

genList :: Name -> [Name] -> Q [Dec]

genList name consNames = do

  let cons = listE $ map (\n -> tupE [mkString n, mkPyValueEx n]) consNames

  sig <- sigD name [t| [(String, String)] |]

  fun <- funD name [clause [] (normalB cons) []]

  return [sig, fun]

  where mkString n = stringE (comment n ++ "\n" ++ deCamelCase (nameBase n))

        mkPyValueEx n = [| showValue $(varE n) |]

genPyConstants :: String -> [Name] -> Q [Dec]

genPyConstants name = genList (mkName name)