forked from OSS/graphql
66 lines
2.2 KiB
Haskell
66 lines
2.2 KiB
Haskell
{-# LANGUAGE CPP #-}
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module Data.GraphQL.Execute (execute) where
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#if !MIN_VERSION_base(4,8,0)
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import Control.Applicative ((<$>), pure)
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import Data.Traversable (traverse)
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#endif
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import Control.Applicative (Alternative, empty)
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import Data.Foldable (fold)
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import Data.Maybe (catMaybes)
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import qualified Data.Aeson as Aeson
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import qualified Data.HashMap.Strict as HashMap
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import qualified Data.Text as T
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import Data.GraphQL.AST
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import Data.GraphQL.Schema (Resolver, Schema(..))
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import qualified Data.GraphQL.Schema as Schema
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execute
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:: (Alternative m, Monad m)
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=> Schema m -> Schema.Subs -> Document -> m Aeson.Value
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execute (Schema resolv) f doc = selectionSet f resolv =<< query doc
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query :: Alternative f => Document -> f SelectionSet
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query (Document [DefinitionOperation (Query (Node _varDefs _ _ sels))]) = pure sels
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query _ = empty
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selectionSet
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:: Alternative f
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=> Schema.Subs -> Resolver f -> SelectionSet -> f Aeson.Value
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selectionSet f resolv = fmap (Aeson.Object . fold)
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. traverse (selection f resolv)
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selection
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:: Alternative f
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=> Schema.Subs -> Resolver f -> Selection -> f Aeson.Object
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selection f resolv (SelectionField field@(Field alias name _ _ _)) =
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fmap (HashMap.singleton aliasOrName)
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$ Aeson.toJSON
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<$> resolv (fieldToInput f field)
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where
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aliasOrName = if T.null alias then name else alias
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selection _ _ _ = empty
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-- * AST/Schema conversions
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argument :: Schema.Subs -> Argument -> Maybe Schema.Argument
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argument f (Argument n (ValueVariable (Variable v))) =
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maybe Nothing (\v' -> Just (n, v')) $ f v
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argument _ (Argument n (ValueInt v)) =
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Just (n, Schema.ScalarInt $ fromIntegral v)
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argument _ (Argument n (ValueString (StringValue v))) =
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Just (n, Schema.ScalarString v)
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argument _ _ = error "argument: not implemented yet"
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fieldToInput :: Schema.Subs -> Field -> Schema.Input
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fieldToInput f (Field _ n as _ sels) =
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-- TODO: Get rid of `catMaybes`, invalid arguments should raise an error
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Schema.InputField n (catMaybes $ argument f <$> as)
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(fieldToInput f . selectionToField <$> sels)
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selectionToField :: Selection -> Field
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selectionToField (SelectionField x) = x
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selectionToField _ = error "selectionField: not implemented yet"
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