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machine: optimize ifThenElse on constant
[haskell/symantic-parser.git] / src / Symantic / Parser / Grammar / ObserveSharing.hs
1 {-# OPTIONS_GHC -fno-warn-orphans #-}
2 module Symantic.Parser.Grammar.ObserveSharing
3 ( module Symantic.Typed.Letable
4 , module Symantic.Parser.Grammar.ObserveSharing
5 ) where
6
7 import Control.Monad (mapM)
8 import Data.Function (($), (.))
9 import Data.Hashable (Hashable, hashWithSalt)
10 import Text.Show (Show(..))
11 import qualified Control.Applicative as Functor
12
13 import Symantic.Parser.Grammar.Combinators
14 import Symantic.Typed.Letable hiding (observeSharing)
15 import qualified Symantic.Typed.Letable as Letable
16 import qualified Language.Haskell.TH.Syntax as TH
17 import qualified Symantic.Typed.Trans as Sym
18
19 -- | Like 'Letable.observeSharing'
20 -- but type-binding @(letName)@ to 'TH.Name'
21 -- to avoid the trouble to always set it.
22 observeSharing :: Letsable TH.Name repr => ObserveSharing TH.Name repr a -> repr a
23 observeSharing os = lets defs body
24 where (body, defs) = Letable.observeSharing os
25
26 -- | Needed by 'observeSharing'.
27 instance Hashable TH.Name where
28 hashWithSalt s = hashWithSalt s . show
29 instance MakeLetName TH.Name where
30 makeLetName _ = TH.qNewName "name"
31
32 -- Combinators semantics for the 'ObserveSharing' interpreter.
33 instance (Letable TH.Name repr, CombAlternable repr) =>
34 CombAlternable (ObserveSharing TH.Name repr)
35 instance (Letable TH.Name repr, CombApplicable repr) =>
36 CombApplicable (ObserveSharing TH.Name repr)
37 instance
38 ( Letable TH.Name repr
39 , CombFoldable repr
40 {- TODO: the following constraints are for the current CombFoldable,
41 - they will have to be removed when CombFoldable will have Sym.lift2 as defaults
42 -}
43 , CombApplicable repr
44 , CombAlternable repr
45 ) => CombFoldable (ObserveSharing TH.Name repr)
46 instance (Letable TH.Name repr, CombLookable repr) =>
47 CombLookable (ObserveSharing TH.Name repr)
48 instance (Letable TH.Name repr, CombMatchable repr) =>
49 CombMatchable (ObserveSharing TH.Name repr) where
50 -- Here the default definition does not fit
51 -- since there is no lift* for the type of 'conditional'
52 -- and its default definition does not handles 'bs'
53 -- as needed by the 'ObserveSharing' transformation.
54 conditional a cs bs b = observeSharingNode $ ObserveSharing $
55 conditional
56 Functor.<$> unObserveSharing a
57 Functor.<*> Functor.pure cs
58 Functor.<*> mapM unObserveSharing bs
59 Functor.<*> unObserveSharing b
60 instance (Letable TH.Name repr, CombSelectable repr) =>
61 CombSelectable (ObserveSharing TH.Name repr)
62 instance (Letable TH.Name repr, CombSatisfiable tok repr) =>
63 CombSatisfiable tok (ObserveSharing TH.Name repr)
64
65 -- Combinators semantics for the 'FinalizeSharing' interpreter.
66 instance CombApplicable repr => CombApplicable (FinalizeSharing TH.Name repr)
67 instance CombAlternable repr => CombAlternable (FinalizeSharing TH.Name repr)
68 instance CombFoldable repr => CombFoldable (FinalizeSharing TH.Name repr) where
69 chainPre = Sym.lift2 chainPre
70 chainPost = Sym.lift2 chainPost
71 instance CombLookable repr => CombLookable (FinalizeSharing TH.Name repr)
72 instance CombMatchable repr => CombMatchable (FinalizeSharing TH.Name repr) where
73 conditional a cs bs b = FinalizeSharing $
74 conditional
75 Functor.<$> unFinalizeSharing a
76 Functor.<*> Functor.pure cs
77 Functor.<*> mapM unFinalizeSharing bs
78 Functor.<*> unFinalizeSharing b
79 instance CombSatisfiable tok repr => CombSatisfiable tok (FinalizeSharing TH.Name repr)
80 instance CombSelectable repr => CombSelectable (FinalizeSharing TH.Name repr)