graphql/src/Language/GraphQL/AST/Encoder.hs

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{-# LANGUAGE ExplicitForAll #-}
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{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE LambdaCase #-}
-- | This module defines a minifier and a printer for the @GraphQL@ language.
module Language.GraphQL.AST.Encoder
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( Formatter
, definition
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, directive
, document
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, minified
, pretty
, type'
, value
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) where
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import Data.Char (ord)
import Data.Foldable (fold)
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import qualified Data.List.NonEmpty as NonEmpty
import Data.Text (Text)
import qualified Data.Text as Text
import qualified Data.Text.Lazy as Lazy (Text)
import qualified Data.Text.Lazy as Lazy.Text
import Data.Text.Lazy.Builder (Builder)
import qualified Data.Text.Lazy.Builder as Builder
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import Data.Text.Lazy.Builder.Int (decimal, hexadecimal)
import Data.Text.Lazy.Builder.RealFloat (realFloat)
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import Language.GraphQL.AST.Document
-- | Instructs the encoder whether the GraphQL document should be minified or
-- pretty printed.
--
-- Use 'pretty' or 'minified' to construct the formatter.
data Formatter
= Minified
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| Pretty Word
-- | Constructs a formatter for pretty printing.
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pretty :: Formatter
pretty = Pretty 0
-- | Constructs a formatter for minifying.
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minified :: Formatter
minified = Minified
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-- | Converts a Document' into a string.
document :: Formatter -> Document -> Lazy.Text
document formatter defs
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| Pretty _ <- formatter = Lazy.Text.intercalate "\n" encodeDocument
| Minified <-formatter = Lazy.Text.snoc (mconcat encodeDocument) '\n'
where
encodeDocument = foldr executableDefinition [] defs
executableDefinition (ExecutableDefinition executableDefinition') acc =
definition formatter executableDefinition' : acc
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executableDefinition _ acc = acc
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-- | Converts a t'ExecutableDefinition' into a string.
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definition :: Formatter -> ExecutableDefinition -> Lazy.Text
definition formatter x
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| Pretty _ <- formatter = Lazy.Text.snoc (encodeDefinition x) '\n'
| Minified <- formatter = encodeDefinition x
where
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encodeDefinition (DefinitionOperation operation)
= operationDefinition formatter operation
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encodeDefinition (DefinitionFragment fragment)
= fragmentDefinition formatter fragment
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-- | Converts a 'OperationDefinition into a string.
operationDefinition :: Formatter -> OperationDefinition -> Lazy.Text
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operationDefinition formatter = \case
SelectionSet sels _ -> selectionSet formatter sels
OperationDefinition Query name vars dirs sels _ ->
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"query " <> node formatter name vars dirs sels
OperationDefinition Mutation name vars dirs sels _ ->
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"mutation " <> node formatter name vars dirs sels
OperationDefinition Subscription name vars dirs sels _ ->
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"subscription " <> node formatter name vars dirs sels
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-- | Converts a Query or Mutation into a string.
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node :: Formatter ->
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Maybe Name ->
[VariableDefinition] ->
[Directive] ->
SelectionSet ->
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Lazy.Text
node formatter name vars dirs sels
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= Lazy.Text.fromStrict (fold name)
<> optempty (variableDefinitions formatter) vars
<> optempty (directives formatter) dirs
<> eitherFormat formatter " " mempty
<> selectionSet formatter sels
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variableDefinitions :: Formatter -> [VariableDefinition] -> Lazy.Text
variableDefinitions formatter
= parensCommas formatter $ variableDefinition formatter
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variableDefinition :: Formatter -> VariableDefinition -> Lazy.Text
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variableDefinition formatter (VariableDefinition var ty defaultValue' _)
= variable var
<> eitherFormat formatter ": " ":"
<> type' ty
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<> maybe mempty (defaultValue formatter) defaultValue'
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defaultValue :: Formatter -> ConstValue -> Lazy.Text
defaultValue formatter val
= eitherFormat formatter " = " "="
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<> value formatter (fromConstValue val)
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variable :: Name -> Lazy.Text
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variable var = "$" <> Lazy.Text.fromStrict var
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selectionSet :: Formatter -> SelectionSet -> Lazy.Text
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selectionSet formatter
= bracesList formatter (selection formatter)
. NonEmpty.toList
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selectionSetOpt :: Formatter -> SelectionSetOpt -> Lazy.Text
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selectionSetOpt formatter = bracesList formatter $ selection formatter
indentSymbol :: Lazy.Text
indentSymbol = " "
indent :: (Integral a) => a -> Lazy.Text
indent indentation = Lazy.Text.replicate (fromIntegral indentation) indentSymbol
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selection :: Formatter -> Selection -> Lazy.Text
selection formatter = Lazy.Text.append indent' . encodeSelection
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where
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encodeSelection (FieldSelection fieldSelection) =
field incrementIndent fieldSelection
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encodeSelection (InlineFragmentSelection fragmentSelection) =
inlineFragment incrementIndent fragmentSelection
encodeSelection (FragmentSpreadSelection fragmentSelection) =
fragmentSpread incrementIndent fragmentSelection
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incrementIndent
| Pretty indentation <- formatter = Pretty $ indentation + 1
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| otherwise = Minified
indent'
| Pretty indentation <- formatter = indent $ indentation + 1
| otherwise = ""
colon :: Formatter -> Lazy.Text
colon formatter = eitherFormat formatter ": " ":"
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-- | Converts Field into a string.
field :: Formatter -> Field -> Lazy.Text
field formatter (Field alias name args dirs set _)
= optempty prependAlias (fold alias)
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<> Lazy.Text.fromStrict name
<> optempty (arguments formatter) args
<> optempty (directives formatter) dirs
<> optempty selectionSetOpt' set
where
prependAlias aliasName = Lazy.Text.fromStrict aliasName <> colon formatter
selectionSetOpt' = (eitherFormat formatter " " "" <>)
. selectionSetOpt formatter
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arguments :: Formatter -> [Argument] -> Lazy.Text
arguments formatter = parensCommas formatter $ argument formatter
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argument :: Formatter -> Argument -> Lazy.Text
argument formatter (Argument name value' _)
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= Lazy.Text.fromStrict name
<> colon formatter
<> value formatter value'
-- * Fragments
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fragmentSpread :: Formatter -> FragmentSpread -> Lazy.Text
fragmentSpread formatter (FragmentSpread name directives' _)
= "..." <> Lazy.Text.fromStrict name
<> optempty (directives formatter) directives'
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inlineFragment :: Formatter -> InlineFragment -> Lazy.Text
inlineFragment formatter (InlineFragment typeCondition directives' selections _)
= "... on "
<> Lazy.Text.fromStrict (fold typeCondition)
<> directives formatter directives'
<> eitherFormat formatter " " mempty
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<> selectionSet formatter selections
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fragmentDefinition :: Formatter -> FragmentDefinition -> Lazy.Text
fragmentDefinition formatter (FragmentDefinition name tc dirs sels _)
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= "fragment " <> Lazy.Text.fromStrict name
<> " on " <> Lazy.Text.fromStrict tc
<> optempty (directives formatter) dirs
<> eitherFormat formatter " " mempty
<> selectionSet formatter sels
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-- * Miscellaneous
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-- | Converts a 'Directive' into a string.
directive :: Formatter -> Directive -> Lazy.Text
directive formatter (Directive name args _)
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= "@" <> Lazy.Text.fromStrict name <> optempty (arguments formatter) args
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directives :: Formatter -> [Directive] -> Lazy.Text
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directives Minified = spaces (directive Minified)
directives formatter = Lazy.Text.cons ' ' . spaces (directive formatter)
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-- | Converts a 'Value' into a string.
value :: Formatter -> Value -> Lazy.Text
value _ (Variable x) = variable x
value _ (Int x) = Builder.toLazyText $ decimal x
value _ (Float x) = Builder.toLazyText $ realFloat x
value _ (Boolean x) = booleanValue x
value _ Null = "null"
value formatter (String string) = stringValue formatter string
value _ (Enum x) = Lazy.Text.fromStrict x
value formatter (List x) = listValue formatter x
value formatter (Object x) = objectValue formatter x
fromConstValue :: ConstValue -> Value
fromConstValue (ConstInt x) = Int x
fromConstValue (ConstFloat x) = Float x
fromConstValue (ConstBoolean x) = Boolean x
fromConstValue ConstNull = Null
fromConstValue (ConstString string) = String string
fromConstValue (ConstEnum x) = Enum x
fromConstValue (ConstList x) = List $ fromConstValue <$> x
fromConstValue (ConstObject x) = Object $ fromConstObjectField <$> x
where
fromConstObjectField (ObjectField key value') =
ObjectField key $ fromConstValue value'
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booleanValue :: Bool -> Lazy.Text
booleanValue True = "true"
booleanValue False = "false"
quote :: Builder.Builder
quote = Builder.singleton '\"'
oneLine :: Text -> Builder
oneLine string = quote <> Text.foldr (mappend . escape) quote string
stringValue :: Formatter -> Text -> Lazy.Text
stringValue Minified string = Builder.toLazyText
$ quote <> Text.foldr (mappend . escape) quote string
stringValue (Pretty indentation) string =
if hasEscaped string
then stringValue Minified string
else Builder.toLazyText $ encoded lines'
where
isWhiteSpace char = char == ' ' || char == '\t'
isNewline char = char == '\n' || char == '\r'
hasEscaped = Text.any (not . isAllowed)
isAllowed char =
char == '\t' || isNewline char || (char >= '\x0020' && char /= '\x007F')
tripleQuote = Builder.fromText "\"\"\""
newline = Builder.singleton '\n'
strip = Text.dropWhile isWhiteSpace . Text.dropWhileEnd isWhiteSpace
lines' = map Builder.fromText $ Text.split isNewline (Text.replace "\r\n" "\n" $ strip string)
encoded [] = oneLine string
encoded [_] = oneLine string
encoded lines'' = tripleQuote <> newline
<> transformLines lines''
<> Builder.fromLazyText (indent indentation) <> tripleQuote
transformLines = foldr transformLine mempty
transformLine "" acc = newline <> acc
transformLine line' acc
= Builder.fromLazyText (indent (indentation + 1))
<> line' <> newline <> acc
escape :: Char -> Builder
escape char'
| char' == '\\' = Builder.fromString "\\\\"
| char' == '\"' = Builder.fromString "\\\""
| char' == '\b' = Builder.fromString "\\b"
| char' == '\f' = Builder.fromString "\\f"
| char' == '\n' = Builder.fromString "\\n"
| char' == '\r' = Builder.fromString "\\r"
| char' == '\t' = Builder.fromString "\\t"
| char' < '\x0010' = unicode "\\u000" char'
| char' < '\x0020' = unicode "\\u00" char'
| otherwise = Builder.singleton char'
where
unicode prefix = mappend (Builder.fromString prefix) . (hexadecimal . ord)
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listValue :: Formatter -> [Value] -> Lazy.Text
listValue formatter = bracketsCommas formatter $ value formatter
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objectValue :: Formatter -> [ObjectField Value] -> Lazy.Text
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objectValue formatter = intercalate $ objectField formatter
where
intercalate f
= braces
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. Lazy.Text.intercalate (eitherFormat formatter ", " ",")
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. fmap f
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objectField :: Formatter -> ObjectField Value -> Lazy.Text
objectField formatter (ObjectField name value') =
Lazy.Text.fromStrict name <> colon formatter <> value formatter value'
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-- | Converts a 'Type' a type into a string.
type' :: Type -> Lazy.Text
type' (TypeNamed x) = Lazy.Text.fromStrict x
type' (TypeList x) = listType x
type' (TypeNonNull x) = nonNullType x
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listType :: Type -> Lazy.Text
listType x = brackets (type' x)
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nonNullType :: NonNullType -> Lazy.Text
nonNullType (NonNullTypeNamed x) = Lazy.Text.fromStrict x <> "!"
nonNullType (NonNullTypeList x) = listType x <> "!"
-- * Internal
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between :: Char -> Char -> Lazy.Text -> Lazy.Text
between open close = Lazy.Text.cons open . (`Lazy.Text.snoc` close)
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parens :: Lazy.Text -> Lazy.Text
parens = between '(' ')'
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brackets :: Lazy.Text -> Lazy.Text
brackets = between '[' ']'
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braces :: Lazy.Text -> Lazy.Text
braces = between '{' '}'
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spaces :: forall a. (a -> Lazy.Text) -> [a] -> Lazy.Text
spaces f = Lazy.Text.intercalate "\SP" . fmap f
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parensCommas :: forall a. Formatter -> (a -> Lazy.Text) -> [a] -> Lazy.Text
parensCommas formatter f
= parens
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. Lazy.Text.intercalate (eitherFormat formatter ", " ",")
. fmap f
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bracketsCommas :: Formatter -> (a -> Lazy.Text) -> [a] -> Lazy.Text
bracketsCommas formatter f
= brackets
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. Lazy.Text.intercalate (eitherFormat formatter ", " ",")
. fmap f
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bracesList :: forall a. Formatter -> (a -> Lazy.Text) -> [a] -> Lazy.Text
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bracesList (Pretty intendation) f xs
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= Lazy.Text.snoc (Lazy.Text.intercalate "\n" content) '\n'
<> (Lazy.Text.snoc $ Lazy.Text.replicate (fromIntegral intendation) " ") '}'
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where
content = "{" : fmap f xs
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bracesList Minified f xs = braces $ Lazy.Text.intercalate "," $ fmap f xs
optempty :: (Eq a, Monoid a, Monoid b) => (a -> b) -> a -> b
optempty f xs = if xs == mempty then mempty else f xs
eitherFormat :: forall a. Formatter -> a -> a -> a
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eitherFormat (Pretty _) x _ = x
eitherFormat Minified _ x = x