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|
{-# OPTIONS_HADDOCK hide #-}
{- |
Module : Data.GraphViz.Attributes.Same
Description : Consider Attributes equal on constructors.
Copyright : (c) Ivan Lazar Miljenovic
License : 3-Clause BSD-style
Maintainer : Ivan.Miljenovic@gmail.com
This module is used when @a1 == a2@ should return @True@ if they
are the same Attribute, even if they don't have the same value
(typically for 'Set's).
-}
module Data.GraphViz.Attributes.Same
( SameAttr
, SAttrs
, toSAttr
, unSame
, unSameSet
) where
import Data.GraphViz.Attributes.Complete(Attribute, Attributes, sameAttribute)
import Data.Function(on)
import qualified Data.Set as Set
import Data.Set(Set)
-- -----------------------------------------------------------------------------
-- | Defined as a wrapper around 'Attribute' where equality is based
-- solely upon the constructor, not the contents.
newtype SameAttr = SA { getAttr :: Attribute }
deriving (Show, Read)
instance Eq SameAttr where
(==) = sameAttribute `on` getAttr
instance Ord SameAttr where
compare sa1 sa2
| sa1 == sa2 = EQ
| otherwise = (compare `on` getAttr) sa1 sa2
type SAttrs = Set SameAttr
toSAttr :: Attributes -> SAttrs
toSAttr = Set.fromList . map SA
unSame :: SAttrs -> Attributes
unSame = map getAttr . Set.toList
unSameSet :: SAttrs -> Set Attribute
unSameSet = Set.mapMonotonic getAttr
|
