src/Ormolu/Diff.hs · ormolu

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1{-# LANGUAGE DeriveDataTypeable #-}

2{-# LANGUAGE RankNTypes #-}

3{-# LANGUAGE RecordWildCards #-}

5-- | Diffing GHC ASTs modulo span positions.

7module Ormolu.Diff

8 ( diff

9 )

10where

12import Data.Generics

13import GHC

14import Ormolu.CommentStream

15import Ormolu.Imports (sortImports)

17-- | Return 'False' if two annotated ASTs are the same modulo span

18-- positions.

20diff

21 :: (CommentStream, ParsedSource) -- ^ First comment stream and AST

22 -> (CommentStream, ParsedSource) -- ^ Second comment stream and AST

23 -> Bool

24diff (cstream0, ps0) (cstream1, ps1) =

25 not (matchIgnoringSrcSpans cstream0 cstream1)

26 || not (matchIgnoringSrcSpans ps0 ps1)

28-- | Compare two values for equality disregarding differences in 'SrcSpan's

29-- and the ordering of import lists.

31matchIgnoringSrcSpans :: Data a => a -> a -> Bool

32matchIgnoringSrcSpans = genericQuery

33 where

34 genericQuery :: GenericQ (GenericQ Bool)

35 genericQuery x y = (toConstr x == toConstr y)

36 && and (gzipWithQ (genericQuery `extQ` srcSpanEq `extQ` hsModuleEq) x y)

38 srcSpanEq :: SrcSpan -> GenericQ Bool

39 srcSpanEq _ _ = True

41 hsModuleEq :: HsModule GhcPs -> GenericQ Bool

42 hsModuleEq hs0 hs1' =

43 case cast hs1' :: Maybe (HsModule GhcPs) of

44 Nothing -> False

45 Just hs1 ->

46 matchIgnoringSrcSpans

47 hs0 { hsmodImports = sortImports (hsmodImports hs0) }

48 hs1 { hsmodImports = sortImports (hsmodImports hs1) }