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

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{-# LANGUAGE LambdaCase #-}
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{-# LANGUAGE OverloadedStrings #-}
-- | @GraphQL@ document parser.
module Language.GraphQL.AST.Parser
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( document
) where
import Control.Applicative (Alternative(..), optional)
import Control.Applicative.Combinators (sepBy1)
import qualified Control.Applicative.Combinators.NonEmpty as NonEmpty
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import Data.List.NonEmpty (NonEmpty)
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import Data.Text (Text)
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import qualified Language.GraphQL.AST.DirectiveLocation as Directive
import Language.GraphQL.AST.DirectiveLocation
( DirectiveLocation
, ExecutableDirectiveLocation
, TypeSystemDirectiveLocation
)
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import Language.GraphQL.AST.Document
import Language.GraphQL.AST.Lexer
import Text.Megaparsec (lookAhead, option, try, (<?>))
-- | Parser for the GraphQL documents.
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document :: Parser Document
document = unicodeBOM
>> spaceConsumer
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>> lexeme (NonEmpty.some definition)
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definition :: Parser Definition
definition = ExecutableDefinition <$> executableDefinition
<|> TypeSystemDefinition <$> typeSystemDefinition
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<|> TypeSystemExtension <$> typeSystemExtension
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<?> "Definition"
executableDefinition :: Parser ExecutableDefinition
executableDefinition = DefinitionOperation <$> operationDefinition
<|> DefinitionFragment <$> fragmentDefinition
<?> "ExecutableDefinition"
typeSystemDefinition :: Parser TypeSystemDefinition
typeSystemDefinition = schemaDefinition
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<|> TypeDefinition <$> typeDefinition
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<|> directiveDefinition
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<?> "TypeSystemDefinition"
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typeSystemExtension :: Parser TypeSystemExtension
typeSystemExtension = SchemaExtension <$> schemaExtension
<?> "TypeSystemExtension"
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directiveDefinition :: Parser TypeSystemDefinition
directiveDefinition = DirectiveDefinition
<$> description
<* symbol "directive"
<* at
<*> name
<*> argumentsDefinition
<* symbol "on"
<*> directiveLocations
directiveLocations :: Parser (NonEmpty DirectiveLocation)
directiveLocations = optional pipe
*> directiveLocation `NonEmpty.sepBy1` pipe
directiveLocation :: Parser DirectiveLocation
directiveLocation
= Directive.ExecutableDirectiveLocation <$> executableDirectiveLocation
<|> Directive.TypeSystemDirectiveLocation <$> typeSystemDirectiveLocation
executableDirectiveLocation :: Parser ExecutableDirectiveLocation
executableDirectiveLocation = Directive.Query <$ symbol "QUERY"
<|> Directive.Mutation <$ symbol "MUTATION"
<|> Directive.Subscription <$ symbol "SUBSCRIPTION"
<|> Directive.Field <$ symbol "FIELD"
<|> Directive.FragmentDefinition <$ "FRAGMENT_DEFINITION"
<|> Directive.FragmentSpread <$ "FRAGMENT_SPREAD"
<|> Directive.InlineFragment <$ "INLINE_FRAGMENT"
typeSystemDirectiveLocation :: Parser TypeSystemDirectiveLocation
typeSystemDirectiveLocation = Directive.Schema <$ symbol "SCHEMA"
<|> Directive.Scalar <$ symbol "SCALAR"
<|> Directive.Object <$ symbol "OBJECT"
<|> Directive.FieldDefinition <$ symbol "FIELD_DEFINITION"
<|> Directive.ArgumentDefinition <$ symbol "ARGUMENT_DEFINITION"
<|> Directive.Interface <$ symbol "INTERFACE"
<|> Directive.Union <$ symbol "UNION"
<|> Directive.Enum <$ symbol "ENUM"
<|> Directive.EnumValue <$ symbol "ENUM_VALUE"
<|> Directive.InputObject <$ symbol "INPUT_OBJECT"
<|> Directive.InputFieldDefinition <$ symbol "INPUT_FIELD_DEFINITION"
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typeDefinition :: Parser TypeDefinition
typeDefinition = scalarTypeDefinition
<|> objectTypeDefinition
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<|> interfaceTypeDefinition
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<|> unionTypeDefinition
<|> enumTypeDefinition
<|> inputObjectTypeDefinition
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<?> "TypeDefinition"
scalarTypeDefinition :: Parser TypeDefinition
scalarTypeDefinition = ScalarTypeDefinition
<$> description
<* symbol "scalar"
<*> name
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<*> directives
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<?> "ScalarTypeDefinition"
objectTypeDefinition :: Parser TypeDefinition
objectTypeDefinition = ObjectTypeDefinition
<$> description
<* symbol "type"
<*> name
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<*> option (ImplementsInterfaces []) (implementsInterfaces sepBy1)
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<*> directives
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<*> braces (many fieldDefinition)
<?> "ObjectTypeDefinition"
description :: Parser Description
description = Description
<$> optional (string <|> blockString)
<?> "Description"
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unionTypeDefinition :: Parser TypeDefinition
unionTypeDefinition = UnionTypeDefinition
<$> description
<* symbol "union"
<*> name
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<*> directives
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<*> option (UnionMemberTypes []) (unionMemberTypes sepBy1)
<?> "UnionTypeDefinition"
unionMemberTypes ::
Foldable t =>
(Parser Text -> Parser Text -> Parser (t NamedType)) ->
Parser (UnionMemberTypes t)
unionMemberTypes sepBy' = UnionMemberTypes
<$ equals
<* optional pipe
<*> name `sepBy'` pipe
<?> "UnionMemberTypes"
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interfaceTypeDefinition :: Parser TypeDefinition
interfaceTypeDefinition = InterfaceTypeDefinition
<$> description
<* symbol "interface"
<*> name
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<*> directives
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<*> braces (many fieldDefinition)
<?> "InterfaceTypeDefinition"
enumTypeDefinition :: Parser TypeDefinition
enumTypeDefinition = EnumTypeDefinition
<$> description
<* symbol "enum"
<*> name
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<*> directives
<*> enumValuesDefinition
<?> "EnumTypeDefinition"
where
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enumValuesDefinition = listOptIn braces enumValueDefinition
inputObjectTypeDefinition :: Parser TypeDefinition
inputObjectTypeDefinition = InputObjectTypeDefinition
<$> description
<* symbol "input"
<*> name
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<*> directives
<*> inputFieldsDefinition
<?> "InputObjectTypeDefinition"
where
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inputFieldsDefinition = listOptIn braces inputValueDefinition
enumValueDefinition :: Parser EnumValueDefinition
enumValueDefinition = EnumValueDefinition
<$> description
<*> enumValue
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<*> directives
<?> "EnumValueDefinition"
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implementsInterfaces ::
Foldable t =>
(Parser Text -> Parser Text -> Parser (t NamedType)) ->
Parser (ImplementsInterfaces t)
implementsInterfaces sepBy' = ImplementsInterfaces
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<$ symbol "implements"
<* optional amp
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<*> name `sepBy'` amp
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<?> "ImplementsInterfaces"
inputValueDefinition :: Parser InputValueDefinition
inputValueDefinition = InputValueDefinition
<$> description
<*> name
<* colon
<*> type'
<*> defaultValue
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<*> directives
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<?> "InputValueDefinition"
argumentsDefinition :: Parser ArgumentsDefinition
argumentsDefinition = ArgumentsDefinition
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<$> listOptIn parens inputValueDefinition
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<?> "ArgumentsDefinition"
fieldDefinition :: Parser FieldDefinition
fieldDefinition = FieldDefinition
<$> description
<*> name
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<*> argumentsDefinition
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<* colon
<*> type'
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<*> directives
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<?> "FieldDefinition"
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schemaDefinition :: Parser TypeSystemDefinition
schemaDefinition = SchemaDefinition
<$ symbol "schema"
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<*> directives
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<*> operationTypeDefinitions
<?> "SchemaDefinition"
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operationTypeDefinitions :: Parser (NonEmpty OperationTypeDefinition)
operationTypeDefinitions = braces $ NonEmpty.some operationTypeDefinition
schemaExtension :: Parser SchemaExtension
schemaExtension = extend "schema"
>> try schemaOperationExtension
<|> SchemaDirectiveExtension <$> NonEmpty.some directive
<?> "SchemaExtension"
where
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schemaOperationExtension = SchemaOperationExtension
<$> directives
<*> operationTypeDefinitions
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operationTypeDefinition :: Parser OperationTypeDefinition
operationTypeDefinition = OperationTypeDefinition
<$> operationType <* colon
<*> name
<?> "OperationTypeDefinition"
operationDefinition :: Parser OperationDefinition
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operationDefinition = SelectionSet <$> selectionSet
<|> operationDefinition'
<?> "operationDefinition error"
where
operationDefinition'
= OperationDefinition <$> operationType
<*> optional name
<*> variableDefinitions
<*> directives
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<*> selectionSet
operationType :: Parser OperationType
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operationType = Query <$ symbol "query"
<|> Mutation <$ symbol "mutation"
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-- <?> Keep default error message
-- * SelectionSet
selectionSet :: Parser SelectionSet
selectionSet = braces $ NonEmpty.some selection
selectionSetOpt :: Parser SelectionSetOpt
selectionSetOpt = listOptIn braces selection
selection :: Parser Selection
selection = field
<|> try fragmentSpread
<|> inlineFragment
<?> "selection error!"
-- * Field
field :: Parser Selection
field = Field
<$> optional alias
<*> name
<*> arguments
<*> directives
<*> selectionSetOpt
alias :: Parser Alias
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alias = try $ name <* colon
-- * Arguments
arguments :: Parser [Argument]
arguments = listOptIn parens argument
argument :: Parser Argument
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argument = Argument <$> name <* colon <*> value
-- * Fragments
fragmentSpread :: Parser Selection
fragmentSpread = FragmentSpread
<$ spread
<*> fragmentName
<*> directives
inlineFragment :: Parser Selection
inlineFragment = InlineFragment
<$ spread
<*> optional typeCondition
<*> directives
<*> selectionSet
fragmentDefinition :: Parser FragmentDefinition
fragmentDefinition = FragmentDefinition
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<$ symbol "fragment"
<*> name
<*> typeCondition
<*> directives
<*> selectionSet
fragmentName :: Parser Name
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fragmentName = but (symbol "on") *> name
typeCondition :: Parser TypeCondition
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typeCondition = symbol "on" *> name
-- * Input Values
value :: Parser Value
value = Variable <$> variable
<|> Float <$> try float
<|> Int <$> integer
<|> Boolean <$> booleanValue
<|> Null <$ symbol "null"
<|> String <$> blockString
<|> String <$> string
<|> Enum <$> try enumValue
<|> List <$> listValue
<|> Object <$> objectValue
<?> "value error!"
where
booleanValue :: Parser Bool
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booleanValue = True <$ symbol "true"
<|> False <$ symbol "false"
listValue :: Parser [Value]
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listValue = brackets $ some value
objectValue :: Parser [ObjectField]
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objectValue = braces $ some objectField
enumValue :: Parser Name
enumValue = but (symbol "true") *> but (symbol "false") *> but (symbol "null") *> name
objectField :: Parser ObjectField
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objectField = ObjectField <$> name <* colon <*> value
-- * Variables
variableDefinitions :: Parser [VariableDefinition]
variableDefinitions = listOptIn parens variableDefinition
variableDefinition :: Parser VariableDefinition
variableDefinition = VariableDefinition
<$> variable
<* colon
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<*> type'
<*> defaultValue
<?> "VariableDefinition"
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variable :: Parser Name
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variable = dollar *> name
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defaultValue :: Parser (Maybe Value)
defaultValue = optional (equals *> value) <?> "DefaultValue"
-- * Input Types
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type' :: Parser Type
type' = try (TypeNonNull <$> nonNullType)
<|> TypeList <$> brackets type'
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<|> TypeNamed <$> name
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<?> "Type"
nonNullType :: Parser NonNullType
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nonNullType = NonNullTypeNamed <$> name <* bang
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<|> NonNullTypeList <$> brackets type' <* bang
<?> "nonNullType error!"
-- * Directives
directives :: Parser [Directive]
directives = many directive
directive :: Parser Directive
directive = Directive
<$ at
<*> name
<*> arguments
-- * Internal
listOptIn :: (Parser [a] -> Parser [a]) -> Parser a -> Parser [a]
listOptIn surround = option [] . surround . some
-- Hack to reverse parser success
but :: Parser a -> Parser ()
but pn = False <$ lookAhead pn <|> pure True >>= \case
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False -> empty
True -> pure ()