{-
	Copyright (C) 2018 Dr. Alistair Ward

	This file is part of BishBosh.

	BishBosh 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 3 of the License, or
	(at your option) any later version.

	BishBosh 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 BishBosh.  If not, see <http://www.gnu.org/licenses/>.
-}
{- |
 [@AUTHOR@]	Dr. Alistair Ward

 [@DESCRIPTION@]

	* <https://chessprogramming.wikispaces.com/Forsyth-Edwards+Notation>.

	* <https://en.wikipedia.org/wiki/Forsyth%E2%80%93Edwards_Notation>.
-}

module BishBosh.Property.ForsythEdwards(
-- * Type-classes
        ReadsFEN(..),
        ShowsFEN(..),
-- * Constants
        showsNullField,
        showsSeparator,
-- * Functions
        readFEN,
        showFEN
) where

-- | An alternative to 'Read'.
class ReadsFEN a where
        readsFEN        :: ReadS a      -- ^ Read a datum from FEN.

-- | An alternative to 'Show'.
class ShowsFEN a where
        showsFEN        :: a -> ShowS   -- ^ Stringify a FEN-datum.

-- | Read from FEN.
readFEN :: ReadsFEN a => String -> a
readFEN s       = case readsFEN s of
        [(a, _)]        -> a
        _               -> error . showString "BishBosh.Property.ForsythEdwards.readFEN:\tfailed to parse " $ shows s "."

-- | Display in FEN.
showFEN :: ShowsFEN a => a -> String
showFEN a       = showsFEN a ""

-- | The standard way to denote the absence of a field.
showsNullField :: ShowS
showsNullField  = showChar '-'

-- | The standard separator between fields in FEN.
showsSeparator :: ShowS
showsSeparator  = showChar ' '