178 lines
5.0 KiB
Haskell
178 lines
5.0 KiB
Haskell
{-# LANGUAGE OverloadedStrings #-}
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-- | This module defines a printer for the @GraphQL@ language.
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module Language.GraphQL.Encoder where
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import Data.Foldable (fold)
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import Data.Monoid ((<>))
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import qualified Data.List.NonEmpty as NonEmpty (toList)
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import Data.Text (Text, cons, intercalate, pack, snoc)
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import Language.GraphQL.AST
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-- * Document
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document :: Document -> Text
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document defs = (`snoc` '\n') . mconcat . NonEmpty.toList $ definition <$> defs
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definition :: Definition -> Text
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definition (DefinitionOperation x) = operationDefinition x
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definition (DefinitionFragment x) = fragmentDefinition x
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operationDefinition :: OperationDefinition -> Text
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operationDefinition (OperationSelectionSet sels) = selectionSet sels
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operationDefinition (OperationDefinition Query name vars dirs sels) =
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"query " <> node (fold name) vars dirs sels
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operationDefinition (OperationDefinition Mutation name vars dirs sels) =
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"mutation " <> node (fold name) vars dirs sels
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node :: Name -> VariableDefinitions -> Directives -> SelectionSet -> Text
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node name vars dirs sels =
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name
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<> optempty variableDefinitions vars
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<> optempty directives dirs
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<> selectionSet sels
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variableDefinitions :: [VariableDefinition] -> Text
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variableDefinitions = parensCommas variableDefinition
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variableDefinition :: VariableDefinition -> Text
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variableDefinition (VariableDefinition var ty dv) =
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variable var <> ":" <> type_ ty <> maybe mempty defaultValue dv
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defaultValue :: DefaultValue -> Text
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defaultValue val = "=" <> value val
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variable :: Variable -> Text
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variable var = "$" <> var
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selectionSet :: SelectionSet -> Text
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selectionSet = bracesCommas selection . NonEmpty.toList
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selectionSetOpt :: SelectionSetOpt -> Text
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selectionSetOpt = bracesCommas selection
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selection :: Selection -> Text
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selection (SelectionField x) = field x
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selection (SelectionInlineFragment x) = inlineFragment x
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selection (SelectionFragmentSpread x) = fragmentSpread x
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field :: Field -> Text
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field (Field alias name args dirs selso) =
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optempty (`snoc` ':') (fold alias)
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<> name
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<> optempty arguments args
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<> optempty directives dirs
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<> optempty selectionSetOpt selso
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arguments :: [Argument] -> Text
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arguments = parensCommas argument
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argument :: Argument -> Text
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argument (Argument name v) = name <> ":" <> value v
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-- * Fragments
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fragmentSpread :: FragmentSpread -> Text
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fragmentSpread (FragmentSpread name ds) =
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"..." <> name <> optempty directives ds
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inlineFragment :: InlineFragment -> Text
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inlineFragment (InlineFragment tc dirs sels) =
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"... on " <> fold tc
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<> directives dirs
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<> selectionSet sels
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fragmentDefinition :: FragmentDefinition -> Text
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fragmentDefinition (FragmentDefinition name tc dirs sels) =
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"fragment " <> name <> " on " <> tc
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<> optempty directives dirs
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<> selectionSet sels
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-- * Values
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value :: Value -> Text
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value (ValueVariable x) = variable x
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-- TODO: This will be replaced with `decimal` Builder
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value (ValueInt x) = pack $ show x
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-- TODO: This will be replaced with `decimal` Builder
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value (ValueFloat x) = pack $ show x
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value (ValueBoolean x) = booleanValue x
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value ValueNull = mempty
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value (ValueString x) = stringValue x
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value (ValueEnum x) = x
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value (ValueList x) = listValue x
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value (ValueObject x) = objectValue x
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booleanValue :: Bool -> Text
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booleanValue True = "true"
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booleanValue False = "false"
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-- TODO: Escape characters
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stringValue :: Text -> Text
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stringValue = quotes
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listValue :: ListValue -> Text
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listValue = bracketsCommas value
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objectValue :: ObjectValue -> Text
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objectValue = bracesCommas objectField
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objectField :: ObjectField -> Text
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objectField (ObjectField name v) = name <> ":" <> value v
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-- * Directives
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directives :: [Directive] -> Text
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directives = spaces directive
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directive :: Directive -> Text
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directive (Directive name args) = "@" <> name <> optempty arguments args
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-- * Type Reference
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type_ :: Type -> Text
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type_ (TypeNamed x) = x
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type_ (TypeList x) = listType x
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type_ (TypeNonNull x) = nonNullType x
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listType :: Type -> Text
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listType x = brackets (type_ x)
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nonNullType :: NonNullType -> Text
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nonNullType (NonNullTypeNamed x) = x <> "!"
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nonNullType (NonNullTypeList x) = listType x <> "!"
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-- * Internal
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spaced :: Text -> Text
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spaced = cons '\SP'
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between :: Char -> Char -> Text -> Text
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between open close = cons open . (`snoc` close)
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parens :: Text -> Text
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parens = between '(' ')'
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brackets :: Text -> Text
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brackets = between '[' ']'
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braces :: Text -> Text
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braces = between '{' '}'
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quotes :: Text -> Text
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quotes = between '"' '"'
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spaces :: (a -> Text) -> [a] -> Text
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spaces f = intercalate "\SP" . fmap f
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parensCommas :: (a -> Text) -> [a] -> Text
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parensCommas f = parens . intercalate "," . fmap f
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bracketsCommas :: (a -> Text) -> [a] -> Text
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bracketsCommas f = brackets . intercalate "," . fmap f
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bracesCommas :: (a -> Text) -> [a] -> Text
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bracesCommas f = braces . intercalate "," . fmap f
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optempty :: (Eq a, Monoid a, Monoid b) => (a -> b) -> a -> b
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optempty f xs = if xs == mempty then mempty else f xs
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