    {- |
       Module      : Text.Pandoc.Readers.ODT.Generic.Namespaces
       Copyright   : Copyright (C) 2015 Martin Linnemann
       License     : GNU GPL, version 2 or above

       Maintainer  : Martin Linnemann <theCodingMarlin@googlemail.com>
       Stability   : alpha
       Portability : portable

    A class containing a set of namespace identifiers. Used to convert between
    typesafe Haskell namespace identifiers and unsafe "real world" namespaces.
    -}

    module Text.Pandoc.Readers.ODT.Generic.Namespaces where

    import qualified Data.Map as M
    import Data.Text (Text)

    --
    type NameSpaceIRI          = Text

    --
    type NameSpaceIRIs     nsID = M.Map nsID NameSpaceIRI

    --
    class (Eq nsID, Ord nsID) => NameSpaceID nsID where

      -- | Given a IRI, possibly update the map and return the id of the namespace.
      -- May fail if the namespace is unknown and the application does not
      -- allow unknown namespaces.
      getNamespaceID   :: NameSpaceIRI
                          -> NameSpaceIRIs nsID
                          -> Maybe (NameSpaceIRIs nsID, nsID)
      -- | Given a namespace id, lookup its IRI. May be overridden for performance.
      getIRI           :: nsID
                          -> NameSpaceIRIs nsID
                          -> Maybe NameSpaceIRI
      -- | The root element of an XML document has a namespace, too, and the
      -- "XML.Light-parser" is eager to remove the corresponding namespace
      -- attribute.
      -- As a result, at least this root namespace must be provided.
      getInitialIRImap :: NameSpaceIRIs nsID

      getIRI           = nsID -> NameSpaceIRIs nsID -> Maybe NameSpaceIRI
    forall k a. Ord k => k -> Map k a -> Maybe a
    M.lookup
      getInitialIRImap = NameSpaceIRIs nsID
    forall k a. Map k a
    M.empty