AST.Transform: Pass down a reader

The reader contains variable substitution functions and fragments.
This commit is contained in:
Eugen Wissner 2019-11-06 06:34:36 +01:00
parent 73fc334bf8
commit b77da3d492
4 changed files with 79 additions and 89 deletions

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@ -66,7 +66,7 @@ data OperationType = Query | Mutation deriving (Eq, Show)
-- * Selections
-- | "Top-level" selection, selection on a operation.
-- | "Top-level" selection, selection on an operation or fragment.
type SelectionSet = NonEmpty Selection
-- | Field selection.
@ -100,7 +100,7 @@ data Selection
-- * "user", "id" and "name" are field names.
-- * "user" has two subfields, "id" and "name".
-- * "zuck" is an alias for "user". "id" and "name" have no aliases.
-- * "id: 4" is an argument for "name". "id" and "name don't have any
-- * "id: 4" is an argument for "user". "id" and "name" don't have any
-- arguments.
data Field
= Field (Maybe Alias) Name [Argument] [Directive] SelectionSetOpt

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@ -39,7 +39,7 @@ pretty = Pretty 0
minified :: Formatter
minified = Minified
-- | Converts a 'Document' into a string.
-- | Converts a 'Full.Document' into a string.
document :: Formatter -> Full.Document -> Text
document formatter defs
| Pretty _ <- formatter = Text.Lazy.intercalate "\n" encodeDocument
@ -47,7 +47,7 @@ document formatter defs
where
encodeDocument = NonEmpty.toList $ definition formatter <$> defs
-- | Converts a 'Definition' into a string.
-- | Converts a 'Full.Definition' into a string.
definition :: Formatter -> Full.Definition -> Text
definition formatter x
| Pretty _ <- formatter = Text.Lazy.snoc (encodeDefinition x) '\n'
@ -165,7 +165,7 @@ fragmentDefinition formatter (Full.FragmentDefinition name tc dirs sels)
-- * Miscellaneous
-- | Converts a 'Directive' into a string.
-- | Converts a 'Full.Directive' into a string.
directive :: Formatter -> Full.Directive -> Text
directive formatter (Full.Directive name args)
= "@" <> Text.Lazy.fromStrict name <> optempty (arguments formatter) args
@ -174,7 +174,7 @@ directives :: Formatter -> [Full.Directive] -> Text
directives formatter@(Pretty _) = Text.Lazy.cons ' ' . spaces (directive formatter)
directives Minified = spaces (directive Minified)
-- | Converts a 'Value' into a string.
-- | Converts a 'Full.Value' into a string.
value :: Formatter -> Full.Value -> Text
value _ (Full.Variable x) = variable x
value _ (Full.Int x) = toLazyText $ decimal x
@ -216,7 +216,7 @@ objectField formatter (Full.ObjectField name v)
| Pretty _ <- formatter = ": "
| Minified <- formatter = ":"
-- | Converts a 'Type' a type into a string.
-- | Converts a 'Full.Type' a type into a string.
type' :: Full.Type -> Text
type' (Full.TypeNamed x) = Text.Lazy.fromStrict x
type' (Full.TypeList x) = listType x

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@ -7,7 +7,9 @@ module Language.GraphQL.AST.Transform
( document
) where
import Data.Foldable (fold)
import Control.Monad (foldM)
import Control.Monad.Trans.Class (lift)
import Control.Monad.Trans.Reader (ReaderT, asks, runReaderT)
import Data.HashMap.Strict (HashMap)
import qualified Data.HashMap.Strict as HashMap
import Data.List.NonEmpty (NonEmpty)
@ -19,59 +21,54 @@ import qualified Language.GraphQL.Schema as Schema
-- | Associates a fragment name with a list of 'Core.Field's.
type Fragments = HashMap Core.Name (NonEmpty Core.Field)
data Replacement = Replacement
{ substitute :: Schema.Subs
, fragments :: Fragments
}
type TransformT a = ReaderT Replacement Maybe a
-- | Rewrites the original syntax tree into an intermediate representation used
-- for query execution.
document :: Schema.Subs -> Full.Document -> Maybe Core.Document
document subs doc =
case fragments of
Just fragments' -> operations subs fragments' operations'
Nothing -> Nothing
(runReaderT (operations operations') . Replacement subs) =<< fragments'
where
(fragments, operations') = foldr (defrag subs) (Just HashMap.empty, [])
(fragments', operations') = foldr (defrag subs) (Just HashMap.empty, [])
$ NonEmpty.toList doc
-- * Operation
-- TODO: Replace Maybe by MonadThrow CustomError
operations ::
Schema.Subs ->
Fragments ->
[Full.OperationDefinition] ->
Maybe Core.Document
operations subs fragments operations' = do
coreOperations <- traverse (operation subs fragments) operations'
NonEmpty.nonEmpty coreOperations
operations :: [Full.OperationDefinition] -> TransformT Core.Document
operations operations' = do
coreOperations <- traverse operation operations'
lift $ NonEmpty.nonEmpty coreOperations
operation ::
Schema.Subs ->
Fragments ->
Full.OperationDefinition ->
Maybe Core.Operation
operation subs fragments (Full.OperationSelectionSet sels) =
operation subs fragments $ Full.OperationDefinition Full.Query mempty mempty mempty sels
operation :: Full.OperationDefinition -> TransformT Core.Operation
operation (Full.OperationSelectionSet sels) =
operation $ Full.OperationDefinition Full.Query mempty mempty mempty sels
-- TODO: Validate Variable definitions with substituter
operation subs fragments (Full.OperationDefinition Full.Query name _vars _dirs sels) =
Core.Query name <$> appendSelection subs fragments sels
operation subs fragments (Full.OperationDefinition Full.Mutation name _vars _dirs sels) =
Core.Mutation name <$> appendSelection subs fragments sels
operation (Full.OperationDefinition Full.Query name _vars _dirs sels) =
Core.Query name <$> appendSelection sels
operation (Full.OperationDefinition Full.Mutation name _vars _dirs sels) =
Core.Mutation name <$> appendSelection sels
selection ::
Schema.Subs ->
Fragments ->
Full.Selection ->
Maybe (Either (NonEmpty Core.Selection) Core.Selection)
selection subs fragments (Full.SelectionField fld)
= Right . Core.SelectionField <$> field subs fragments fld
selection _ fragments (Full.SelectionFragmentSpread (Full.FragmentSpread name _))
= Left . fmap Core.SelectionField <$> HashMap.lookup name fragments
selection subs fragments (Full.SelectionInlineFragment fragment)
TransformT (Either (NonEmpty Core.Selection) Core.Selection)
selection (Full.SelectionField fld) = Right . Core.SelectionField <$> field fld
selection (Full.SelectionFragmentSpread (Full.FragmentSpread name _)) = do
fragments' <- asks fragments
lift $ Left . fmap Core.SelectionField <$> HashMap.lookup name fragments'
selection (Full.SelectionInlineFragment fragment)
| (Full.InlineFragment (Just typeCondition) _ selectionSet) <- fragment
= Right
. Core.SelectionFragment
. Core.Fragment typeCondition
<$> appendSelection subs fragments selectionSet
<$> appendSelection selectionSet
| (Full.InlineFragment Nothing _ selectionSet) <- fragment
= Left <$> appendSelection subs fragments selectionSet
= Left <$> appendSelection selectionSet
-- * Fragment replacement
@ -81,74 +78,67 @@ defrag ::
Full.Definition ->
(Maybe Fragments, [Full.OperationDefinition]) ->
(Maybe Fragments, [Full.OperationDefinition])
defrag _ (Full.DefinitionOperation op) (fragments, operations') =
(fragments, op : operations')
defrag subs (Full.DefinitionFragment fragDef) (Just fragments, operations') =
(fragmentDefinition subs fragments fragDef, operations')
defrag _ (Full.DefinitionOperation op) (fragments', operations') =
(fragments', op : operations')
defrag subs (Full.DefinitionFragment fragDef) (Just fragments', operations') =
(runReaderT (fragmentDefinition fragDef) (Replacement subs fragments'), operations')
defrag _ _ (Nothing, operations') =
(Nothing, operations')
fragmentDefinition ::
Schema.Subs ->
Fragments ->
Full.FragmentDefinition ->
Maybe Fragments
fragmentDefinition subs fragments (Full.FragmentDefinition name _tc _dirs sels) = do
fragmentDefinition :: Full.FragmentDefinition -> TransformT Fragments
fragmentDefinition (Full.FragmentDefinition name _tc _dirs sels) = do
emitted <- emitValue
newValue <- traverse extractField emitted
Just $ HashMap.insert name newValue fragments
newValue <- lift $ traverse extractField emitted
fragments' <- asks fragments
lift . Just $ HashMap.insert name newValue fragments'
where
emitValue :: Maybe (NonEmpty Core.Selection)
emitValue = do
selections <- traverse (selection subs fragments) sels
selections <- traverse selection sels
pure $ selections >>= either id pure
extractField :: Core.Selection -> Maybe Core.Field
extractField (Core.SelectionField field') = Just field'
extractField _ = Nothing -- Fragments within fragments are not supported yet
field :: Schema.Subs -> Fragments -> Full.Field -> Maybe Core.Field
field subs fragments (Full.Field a n args _dirs sels) =
Core.Field a n (fold $ argument subs `traverse` args)
<$> appendSelectionOpt subs fragments sels
field :: Full.Field -> TransformT Core.Field
field (Full.Field a n args _dirs sels) = do
arguments <- traverse argument args
selection' <- appendSelectionOpt sels
return $ Core.Field a n arguments selection'
argument :: Schema.Subs -> Full.Argument -> Maybe Core.Argument
argument subs (Full.Argument n v) = Core.Argument n <$> value subs v
argument :: Full.Argument -> TransformT Core.Argument
argument (Full.Argument n v) = Core.Argument n <$> value v
value :: Schema.Subs -> Full.Value -> Maybe Core.Value
value subs (Full.Variable n) = subs n
value _ (Full.Int i) = pure $ Core.Int i
value _ (Full.Float f) = pure $ Core.Float f
value _ (Full.String x) = pure $ Core.String x
value _ (Full.Boolean b) = pure $ Core.Boolean b
value _ Full.Null = pure Core.Null
value _ (Full.Enum e) = pure $ Core.Enum e
value subs (Full.List l) =
Core.List <$> traverse (value subs) l
value subs (Full.Object o) =
Core.Object . HashMap.fromList <$> traverse (objectField subs) o
value :: Full.Value -> TransformT Core.Value
value (Full.Variable n) = do
substitute' <- asks substitute
lift $ substitute' n
value (Full.Int i) = pure $ Core.Int i
value (Full.Float f) = pure $ Core.Float f
value (Full.String x) = pure $ Core.String x
value (Full.Boolean b) = pure $ Core.Boolean b
value Full.Null = pure Core.Null
value (Full.Enum e) = pure $ Core.Enum e
value (Full.List l) =
Core.List <$> traverse value l
value (Full.Object o) =
Core.Object . HashMap.fromList <$> traverse objectField o
objectField :: Schema.Subs -> Full.ObjectField -> Maybe (Core.Name, Core.Value)
objectField subs (Full.ObjectField n v) = (n,) <$> value subs v
objectField :: Full.ObjectField -> TransformT (Core.Name, Core.Value)
objectField (Full.ObjectField n v) = (n,) <$> value v
appendSelectionOpt ::
Traversable t =>
Schema.Subs ->
Fragments ->
t Full.Selection ->
Maybe [Core.Selection]
appendSelectionOpt subs fragments = foldr go (Just [])
TransformT [Core.Selection]
appendSelectionOpt = foldM go []
where
go :: Full.Selection -> Maybe [Core.Selection] -> Maybe [Core.Selection]
go _ Nothing = Nothing
go sel (Just acc) = append acc <$> selection subs fragments sel
go acc sel = append acc <$> selection sel
append acc (Left list) = NonEmpty.toList list <> acc
append acc (Right one) = one : acc
appendSelection ::
Schema.Subs ->
Fragments ->
NonEmpty Full.Selection ->
Maybe (NonEmpty Core.Selection)
appendSelection subs fragments fullSelection = do
coreSelection <-appendSelectionOpt subs fragments fullSelection
NonEmpty.nonEmpty coreSelection
TransformT (NonEmpty Core.Selection)
appendSelection fullSelection = do
coreSelection <-appendSelectionOpt fullSelection
lift $ NonEmpty.nonEmpty coreSelection

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@ -1,4 +1,4 @@
resolver: lts-14.12
resolver: lts-14.13
packages:
- .