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0e3beb028d
### Description There were several places in the codebase where we would either implement a generic container, or express the need for one. This PR extracts / creates all relevant containers, and adapts the relevant parts of the code to make use of said new generic containers. More specifically, it introduces the following modules: - `Data.Set.Extended`, for new functions on `Data.Set` - `Data.HashMap.Strict.Multi`, for hash maps that accept multiple values - `Data.HashMap.Strict.NonEmpty`, for hash maps that can never be constructed as empty - `Data.Trie`, for a generic implementation of a prefix tree This PR makes use of those new containers in the following parts of the code: - `Hasura.GraphQL.Execute.RemoteJoin.Types` - `Hasura.RQL.Types.Endpoint*` PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3828 GitOrigin-RevId: e6c1b971bcb3f5ab66bc91d0fa4d0e9df7a0c6c6
93 lines
2.9 KiB
Haskell
93 lines
2.9 KiB
Haskell
-- | HashMap to multiple values.
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module Data.HashMap.Strict.Multi
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( -- * Type
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MultiMap,
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-- * Construction and conversions
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singleton,
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fromMap,
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toMap,
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fromList,
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toList,
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-- * Basic interface
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lookup,
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insert,
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keys,
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elems,
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)
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where
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import Data.Aeson (ToJSON)
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import Data.HashMap.Strict qualified as M
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import Data.Hashable (Hashable)
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import Data.Maybe (fromMaybe)
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import Data.Set qualified as S
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import Prelude hiding (lookup)
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-------------------------------------------------------------------------------
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-- | Map from keys to sets of values
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newtype MultiMap k v = MultiMap
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{ unMultiMap :: M.HashMap k (S.Set v)
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}
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deriving newtype (Eq, Show, ToJSON)
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instance (Eq k, Hashable k, Ord v) => Semigroup (MultiMap k v) where
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MultiMap m0 <> MultiMap m1 = MultiMap $ M.unionWith S.union m0 m1
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instance (Eq k, Hashable k, Ord v) => Monoid (MultiMap k v) where
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mempty = MultiMap mempty
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-------------------------------------------------------------------------------
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-- | Construct a 'MmultiMap' with a single key, to which only one
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-- value is associated.
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singleton :: Hashable k => k -> v -> MultiMap k v
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singleton k v = MultiMap $ M.singleton k (S.singleton v)
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-- | Construct a 'MultiMap' with the supplied mappings.
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fromMap :: M.HashMap k (S.Set v) -> MultiMap k v
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fromMap = MultiMap
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-- | Convert a 'MultiMap' to a 'HashMap'.
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toMap :: MultiMap k v -> M.HashMap k (S.Set v)
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toMap = unMultiMap
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-- | Creates a 'MultiMap' from an association list.
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--
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-- If the provided list constains duplicate mappings, the resulting
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-- 'MultiMap' will store the set of all mapped values for each
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-- duplicate key.
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fromList :: (Eq k, Hashable k, Ord v) => [(k, v)] -> MultiMap k v
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fromList l = MultiMap $ M.fromListWith (S.union) $ map (fmap S.singleton) l
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-- | Creates an association list from a 'MultiMap'.
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--
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-- Each set of values associated with a given key is transformed back
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-- into a list.
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toList :: MultiMap k v -> [(k, [v])]
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toList (MultiMap m) = M.toList $ fmap (S.toList) m
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-------------------------------------------------------------------------------
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-- | Return the value to which the specified key is mapped, or 'Nothing' if
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-- this map contains no mapping for the key.
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lookup :: (Eq k, Hashable k) => k -> MultiMap k v -> S.Set v
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lookup k (MultiMap m) = fromMaybe S.empty $ M.lookup k m
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-- | Associate the specified value with the specified key in this map.
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--
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-- If this map previously contained a mapping for the key, the new value is
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-- inserted in the set, and does not replace the previous mapping.
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insert :: (Eq k, Hashable k, Ord v) => k -> v -> MultiMap k v -> MultiMap k v
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insert k v (MultiMap m) = MultiMap $ M.insertWith (S.union) k (S.singleton v) m
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-- | Returns a list of this map's keys.
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keys :: MultiMap k v -> [k]
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keys = M.keys . unMultiMap
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-- | Returns a list of this map's set of values.
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elems :: MultiMap k v -> [S.Set v]
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elems = M.elems . unMultiMap
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