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

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{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ExplicitForAll #-}
-- | 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)
import Data.Monoid ((<>))
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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)
import qualified Language.GraphQL.AST as Full
-- | 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
-- | Converts a 'Full.Document' into a string.
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document :: Formatter -> Full.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 = NonEmpty.toList $ definition formatter <$> defs
-- | Converts a 'Full.Definition' into a string.
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definition :: Formatter -> Full.Definition -> Lazy.Text
definition formatter x
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| Pretty _ <- formatter = Lazy.Text.snoc (encodeDefinition x) '\n'
| Minified <- formatter = encodeDefinition x
where
encodeDefinition (Full.DefinitionOperation operation)
= operationDefinition formatter operation
encodeDefinition (Full.DefinitionFragment fragment)
= fragmentDefinition formatter fragment
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operationDefinition :: Formatter -> Full.OperationDefinition -> Lazy.Text
operationDefinition formatter (Full.OperationSelectionSet sels)
= selectionSet formatter sels
operationDefinition formatter (Full.OperationDefinition Full.Query name vars dirs sels)
= "query " <> node formatter name vars dirs sels
operationDefinition formatter (Full.OperationDefinition Full.Mutation name vars dirs sels)
= "mutation " <> node formatter name vars dirs sels
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node :: Formatter ->
Maybe Full.Name ->
[Full.VariableDefinition] ->
[Full.Directive] ->
Full.SelectionSet ->
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 -> [Full.VariableDefinition] -> Lazy.Text
variableDefinitions formatter
= parensCommas formatter $ variableDefinition formatter
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variableDefinition :: Formatter -> Full.VariableDefinition -> Lazy.Text
variableDefinition formatter (Full.VariableDefinition var ty dv)
= variable var
<> eitherFormat formatter ": " ":"
<> type' ty
<> maybe mempty (defaultValue formatter) dv
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defaultValue :: Formatter -> Full.Value -> Lazy.Text
defaultValue formatter val
= eitherFormat formatter " = " "="
<> value formatter val
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variable :: Full.Name -> Lazy.Text
variable var = "$" <> Lazy.Text.fromStrict var
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selectionSet :: Formatter -> Full.SelectionSet -> Lazy.Text
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selectionSet formatter
= bracesList formatter (selection formatter)
. NonEmpty.toList
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selectionSetOpt :: Formatter -> Full.SelectionSetOpt -> Lazy.Text
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selectionSetOpt formatter = bracesList formatter $ selection formatter
indent :: (Integral a) => a -> Lazy.Text
indent indentation = Lazy.Text.replicate (fromIntegral indentation) " "
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selection :: Formatter -> Full.Selection -> Lazy.Text
selection formatter = Lazy.Text.append indent' . encodeSelection
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where
encodeSelection (Full.SelectionField field') = field incrementIndent field'
encodeSelection (Full.SelectionInlineFragment fragment) =
inlineFragment incrementIndent fragment
encodeSelection (Full.SelectionFragmentSpread spread) =
fragmentSpread incrementIndent spread
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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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field :: Formatter -> Full.Field -> Lazy.Text
field formatter (Full.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 -> [Full.Argument] -> Lazy.Text
arguments formatter = parensCommas formatter $ argument formatter
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argument :: Formatter -> Full.Argument -> Lazy.Text
argument formatter (Full.Argument name value')
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= Lazy.Text.fromStrict name
<> colon formatter
<> value formatter value'
-- * Fragments
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fragmentSpread :: Formatter -> Full.FragmentSpread -> Lazy.Text
fragmentSpread formatter (Full.FragmentSpread name ds)
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= "..." <> Lazy.Text.fromStrict name <> optempty (directives formatter) ds
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inlineFragment :: Formatter -> Full.InlineFragment -> Lazy.Text
inlineFragment formatter (Full.InlineFragment tc dirs sels)
= "... on "
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<> Lazy.Text.fromStrict (fold tc)
<> directives formatter dirs
<> eitherFormat formatter " " mempty
<> selectionSet formatter sels
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fragmentDefinition :: Formatter -> Full.FragmentDefinition -> Lazy.Text
fragmentDefinition formatter (Full.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
-- | Converts a 'Full.Directive' into a string.
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directive :: Formatter -> Full.Directive -> Lazy.Text
directive formatter (Full.Directive name args)
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= "@" <> Lazy.Text.fromStrict name <> optempty (arguments formatter) args
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directives :: Formatter -> [Full.Directive] -> Lazy.Text
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directives Minified = spaces (directive Minified)
directives formatter = Lazy.Text.cons ' ' . spaces (directive formatter)
-- | Converts a 'Full.Value' into a string.
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value :: Formatter -> Full.Value -> Lazy.Text
value _ (Full.Variable x) = variable x
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value _ (Full.Int x) = Builder.toLazyText $ decimal x
value _ (Full.Float x) = Builder.toLazyText $ realFloat x
value _ (Full.Boolean x) = booleanValue x
value _ Full.Null = mempty
value formatter (Full.String string) = stringValue formatter string
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value _ (Full.Enum x) = Lazy.Text.fromStrict x
value formatter (Full.List x) = listValue formatter x
value formatter (Full.Object x) = objectValue formatter x
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booleanValue :: Bool -> Lazy.Text
booleanValue True = "true"
booleanValue False = "false"
stringValue :: Formatter -> Text -> Lazy.Text
stringValue Minified string = Builder.toLazyText
$ quote <> Text.foldr (mappend . escape') quote string
where
quote = Builder.singleton '\"'
escape' '\n' = Builder.fromString "\\n"
escape' char = escape char
stringValue (Pretty indentation) string = byStringType $ Text.lines string
where
byStringType [] = "\"\""
byStringType [line] = Builder.toLazyText
$ quote <> Text.foldr (mappend . escape) quote line
byStringType lines' = "\"\"\"\n"
<> Lazy.Text.unlines (transformLine <$> lines')
<> indent indentation
<> "\"\"\""
transformLine = (indent (indentation + 1) <>)
. Lazy.Text.fromStrict
. Text.replace "\"\"\"" "\\\"\"\""
quote = Builder.singleton '\"'
escape :: Char -> Builder
escape char'
| char' == '\\' = Builder.fromString "\\\\"
| char' == '\"' = Builder.fromString "\\\""
| char' == '\b' = Builder.fromString "\\b"
| char' == '\f' = Builder.fromString "\\f"
| char' == '\r' = Builder.fromString "\\r"
| 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 -> [Full.Value] -> Lazy.Text
listValue formatter = bracketsCommas formatter $ value formatter
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objectValue :: Formatter -> [Full.ObjectField] -> 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 -> Full.ObjectField -> Lazy.Text
objectField formatter (Full.ObjectField name value') =
Lazy.Text.fromStrict name <> colon formatter <> value formatter value'
-- | Converts a 'Full.Type' a type into a string.
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type' :: Full.Type -> Lazy.Text
type' (Full.TypeNamed x) = Lazy.Text.fromStrict x
type' (Full.TypeList x) = listType x
type' (Full.TypeNonNull x) = nonNullType x
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listType :: Full.Type -> Lazy.Text
listType x = brackets (type' x)
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nonNullType :: Full.NonNullType -> Lazy.Text
nonNullType (Full.NonNullTypeNamed x) = Lazy.Text.fromStrict x <> "!"
nonNullType (Full.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