Compat.hs

-- |
-- Module:     Data.CSS.Properties.Compat
-- Copyright:  (c) 2013 Ertugrul Soeylemez
-- License:    BSD3
-- Maintainer: Ertugrul Soeylemez <es@ertes.de>

module Data.CSS.Properties.Compat
    ( -- * Vendor prefixes
      vendors
    )
    where

import qualified Data.ByteString as B
import Control.Lens
import Control.Monad.Writer.Class
import Data.CSS.Types


-- | Adds vendor-prefixed properties for all properties in the given
-- style sheet.  The following vendors are currently added:
--
--   * Microsoft (@-ms-@),
--
--   * Mozilla (@-moz-@),
--
--   * Opera (@-o-@),
--
--   * WebKit (@-webkit-@).
--
-- This combinator keeps the original (non-prefixed) property and does
-- not prefix properties that already have a vendor prefix.

vendors ::
    (MonadWriter CSS m)
    => m a
    -> m a
vendors =
    censoring (cssProps . mapped) . concatMap $ \(Property sel (PropName name) val imp) ->
        let prefix pfx = Property sel (PropName $ B.append pfx name) val imp
            prefixes
                | B.isPrefixOf "-" name = [""]
                | otherwise             = ["", "-moz-", "-ms-", "-o-", "-webkit-"]
        in map prefix prefixes