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|
-- | This module defines an abstract syntax tree for the @GraphQL@ language based on
-- <https://facebook.github.io/graphql/ Facebook's GraphQL Specification>.
--
-- Target AST for Parser.
module Language.GraphQL.AST
( Alias
, Argument(..)
, Definition(..)
, Directive(..)
, Document
, Field(..)
, FragmentDefinition(..)
, FragmentSpread(..)
, InlineFragment(..)
, Name
, NonNullType(..)
, ObjectField(..)
, OperationDefinition(..)
, OperationType(..)
, Selection(..)
, SelectionSet
, SelectionSetOpt
, Type(..)
, TypeCondition
, Value(..)
, VariableDefinition(..)
) where
import Data.Int (Int32)
import Data.List.NonEmpty (NonEmpty)
import Data.Text (Text)
-- * Document
-- | GraphQL document.
type Document = NonEmpty Definition
-- | Name
type Name = Text
-- | Directive.
data Directive = Directive Name [Argument] deriving (Eq, Show)
-- * Operations
-- | Top-level definition of a document, either an operation or a fragment.
data Definition
= DefinitionOperation OperationDefinition
| DefinitionFragment FragmentDefinition
deriving (Eq, Show)
-- | Operation definition.
data OperationDefinition
= OperationSelectionSet SelectionSet
| OperationDefinition OperationType
(Maybe Name)
[VariableDefinition]
[Directive]
SelectionSet
deriving (Eq, Show)
-- | GraphQL has 3 operation types: queries, mutations and subscribtions.
--
-- Currently only queries and mutations are supported.
data OperationType = Query | Mutation deriving (Eq, Show)
-- * Selections
-- | "Top-level" selection, selection on a operation.
type SelectionSet = NonEmpty Selection
-- | Field selection.
type SelectionSetOpt = [Selection]
-- | Single selection element.
data Selection
= SelectionField Field
| SelectionFragmentSpread FragmentSpread
| SelectionInlineFragment InlineFragment
deriving (Eq, Show)
-- * Field
-- | Single GraphQL field.
--
-- The only required property of a field is its name. Optionally it can also
-- have an alias, arguments or a list of subfields.
--
-- Given the following query:
--
-- @
-- {
-- zuck: user(id: 4) {
-- id
-- name
-- }
-- }
-- @
--
-- * "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
-- arguments.
data Field
= Field (Maybe Alias) Name [Argument] [Directive] SelectionSetOpt
deriving (Eq, Show)
-- | Alternative field name.
--
-- @
-- {
-- smallPic: profilePic(size: 64)
-- bigPic: profilePic(size: 1024)
-- }
-- @
--
-- Here "smallPic" and "bigPic" are aliases for the same field, "profilePic",
-- used to distinquish between profile pictures with different arguments
-- (sizes).
type Alias = Name
-- | Single argument.
--
-- @
-- {
-- user(id: 4) {
-- name
-- }
-- }
-- @
--
-- Here "id" is an argument for the field "user" and its value is 4.
data Argument = Argument Name Value deriving (Eq,Show)
-- * Fragments
-- | Fragment spread.
data FragmentSpread = FragmentSpread Name [Directive] deriving (Eq, Show)
-- | Inline fragment.
data InlineFragment = InlineFragment (Maybe TypeCondition) [Directive] SelectionSet
deriving (Eq, Show)
-- | Fragment definition.
data FragmentDefinition
= FragmentDefinition Name TypeCondition [Directive] SelectionSet
deriving (Eq, Show)
-- * Inputs
-- | Input value.
data Value = Variable Name
| Int Int32
| Float Double
| String Text
| Boolean Bool
| Null
| Enum Name
| List [Value]
| Object [ObjectField]
deriving (Eq, Show)
-- | Key-value pair.
--
-- A list of 'ObjectField's represents a GraphQL object type.
data ObjectField = ObjectField Name Value deriving (Eq, Show)
-- | Variable definition.
data VariableDefinition = VariableDefinition Name Type (Maybe Value)
deriving (Eq, Show)
-- | Type condition.
type TypeCondition = Name
-- | Type representation.
data Type = TypeNamed Name
| TypeList Type
| TypeNonNull NonNullType
deriving (Eq, Show)
-- | Helper type to represent Non-Null types and lists of such types.
data NonNullType = NonNullTypeNamed Name
| NonNullTypeList Type
deriving (Eq, Show)
|
