Move AST to AST.Document

src/Language/GraphQL/AST/Document.hs

@@ -1,34 +1,46 @@
 -- | This module defines an abstract syntax tree for the @GraphQL@ language. It
---   follows closely the structure given in the specification. Please refer to
---   <https://facebook.github.io/graphql/ Facebook's GraphQL Specification>.
---   for more information.
+-- follows closely the structure given in the specification. Please refer to
+-- <https://facebook.github.io/graphql/ Facebook's GraphQL Specification>.
+-- for more information.
 module Language.GraphQL.AST.Document
-    ( Definition(..)
+    ( Alias
+    , Argument(..)
+    , Definition(ExecutableDefinition)
+    , Directive(..)
     , Document
     , ExecutableDefinition(..)
+    , FragmentDefinition(..)
+    , 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)
-import Language.GraphQL.AST
-    ( ExecutableDefinition(..)
-    , Directive
-    , Name
-    , OperationType
-    , Type
-    , Value
-    )
 import Language.GraphQL.AST.DirectiveLocation
 
 -- * Language
 
+-- ** Source Text
+
+-- | Name.
+type Name = Text
+
 -- ** Document
 
 -- | GraphQL document.
 type Document = NonEmpty Definition
 
-type NamedType = Name
-
 -- | All kinds of definitions that can occur in a GraphQL document.
 data Definition
     = ExecutableDefinition ExecutableDefinition
@@ -36,12 +48,190 @@ data Definition
     | TypeSystemExtension TypeSystemExtension
     deriving (Eq, Show)
 
+-- | Top-level definition of a document, either an operation or a fragment.
+data ExecutableDefinition
+    = DefinitionOperation OperationDefinition
+    | DefinitionFragment FragmentDefinition
+    deriving (Eq, Show)
+
+-- ** Operations
+
+-- | Operation definition.
+data OperationDefinition
+    = SelectionSet SelectionSet
+    | OperationDefinition
+        OperationType
+        (Maybe Name)
+        [VariableDefinition]
+        [Directive]
+        SelectionSet
+    deriving (Eq, Show)
+
+-- | GraphQL has 3 operation types:
+--
+-- * query - a read-only fetch.
+-- * mutation - a write operation followed by a fetch.
+-- * subscription - a long-lived request that fetches data in response to
+-- source events.
+--
+-- Currently only queries and mutations are supported.
+data OperationType = Query | Mutation deriving (Eq, Show)
+
+-- ** Selection Sets
+
+-- | "Top-level" selection, selection on an operation or fragment.
+type SelectionSet = NonEmpty Selection
+
+-- | Field selection.
+type SelectionSetOpt = [Selection]
+
+-- | Selection is a single entry in a selection set. It can be a single field,
+-- fragment spread or inline fragment.
+--
+-- The only required property of a field is its name. Optionally it can also
+-- have an alias, arguments, directives and a list of subfields.
+--
+-- In the following query "user" is a field with two subfields, "id" and "name":
+--
+-- @
+-- {
+--   user {
+--     id
+--     name
+--   }
+-- }
+-- @
+--
+-- A fragment spread refers to a fragment defined outside the operation and is
+-- expanded at the execution time.
+--
+-- @
+-- {
+--   user {
+--     ...userFragment
+--   }
+-- }
+--
+-- fragment userFragment on UserType {
+--   id
+--   name
+-- }
+-- @
+--
+-- Inline fragments are similar but they don't have any name and the type
+-- condition ("on UserType") is optional.
+--
+-- @
+-- {
+--   user {
+--     ... on UserType {
+--       id
+--       name
+--     }
+-- }
+-- @
+data Selection
+    = Field (Maybe Alias) Name [Argument] [Directive] SelectionSetOpt
+    | FragmentSpread Name [Directive]
+    | InlineFragment (Maybe TypeCondition) [Directive] SelectionSet
+    deriving (Eq, Show)
+
+-- ** Arguments
+
+-- | 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)
+
+-- ** Field Alias
+
+-- | 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
+
+-- ** Fragments
+
+-- | Fragment definition.
+data FragmentDefinition
+    = FragmentDefinition Name TypeCondition [Directive] SelectionSet
+    deriving (Eq, Show)
+
+-- | Type condition.
+type TypeCondition = Name
+
+-- ** Input Values
+
+-- | 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)
+
+-- ** Variables
+
+-- | Variable definition.
+data VariableDefinition = VariableDefinition Name Type (Maybe Value)
+    deriving (Eq, Show)
+
+-- ** Type References
+
+-- | Type representation.
+data Type
+    = TypeNamed Name
+    | TypeList Type
+    | TypeNonNull NonNullType
+    deriving (Eq, Show)
+
+type NamedType = Name
+
+-- | Helper type to represent Non-Null types and lists of such types.
+data NonNullType
+    = NonNullTypeNamed Name
+    | NonNullTypeList Type
+    deriving (Eq, Show)
+
+-- ** Directives
+
+-- | Directive.
+data Directive = Directive Name [Argument] deriving (Eq, Show)
+
 -- * Type System
 
 data TypeSystemDefinition
     = SchemaDefinition [Directive] RootOperationTypeDefinitions
     | TypeDefinition TypeDefinition
-    | DirectiveDefinition Description Name ArgumentsDefinition DirectiveLocation
+    | DirectiveDefinition
+        Description Name ArgumentsDefinition DirectiveLocation
     deriving (Eq, Show)
 
 -- ** Type System Extensions
@@ -109,7 +299,8 @@ newtype ImplementsInterfaces = ImplementsInterfaces (NonEmpty NamedType)
 newtype ImplementsInterfacesOpt = ImplementsInterfacesOpt [NamedType]
     deriving (Eq, Show)
 
-data FieldDefinition = FieldDefinition Description Name ArgumentsDefinition Type
+data FieldDefinition
+    = FieldDefinition Description Name ArgumentsDefinition Type
     deriving (Eq, Show)
 
 newtype ArgumentsDefinition = ArgumentsDefinition [InputValueDefinition]