-- Copyright (c) 2014 Eric McCorkle.  All rights reserved.
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{-# OPTIONS_GHC -Wall -Werror #-}

-- | Definition of a class for traversals.
module Data.Enumeration.Traversal.Class(
       Traversal(..)
       ) where

import Data.Enumeration

-- | A typeclass representing a traversal scheme over an enumeration.
class Traversal trav where
  -- | Create a @Traversal@ from an @Enumeration@.
  mkTraversal :: Enumeration ty -> trav ty
  -- | Get the next item in the traversal.
  getNext :: trav ty -> Maybe (ty, Path, trav ty)

  -- | Get all items in the traversal as a list.
  getAll :: trav ty -> [(ty, Path)]
  getAll trav =
    case getNext trav of
      Just (item, path, next) -> (item, path) : getAll next
      Nothing -> []