ItemKind.hs

{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE DerivingVia #-}

module Scrod.Core.ItemKind where

import qualified GHC.Generics as Generics
import qualified Scrod.Json.ToJson as ToJson
import qualified Scrod.Schema as Schema

-- | The kind of Haskell declaration an Item represents.
--
-- This type must remain a simple enumeration: no constructor should
-- carry arguments. Renderers and predicates pattern-match on it
-- exhaustively, and keeping it argument-free avoids coupling the
-- core representation to presentation details.
data ItemKind
  = -- | Function binding: @f x = expr@
    Function
  | -- | Operator binding: @(+) x y = expr@
    Operator
  | -- | Pattern binding: @(x, y) = tuple@
    PatternBinding
  | -- | Pattern synonym: @pattern P x = Just x@
    PatternSynonym
  | -- | Data type declaration: @data T = C@
    DataType
  | -- | Newtype declaration: @newtype T = C@
    Newtype
  | -- | Type data declaration: @type data T = C@
    TypeData
  | -- | Type synonym: @type T = U@
    TypeSynonym
  | -- | Data constructor (Haskell 98 style)
    DataConstructor
  | -- | GADT constructor
    GADTConstructor
  | -- | Record field
    RecordField
  | -- | Type class: @class C a@
    Class
  | -- | Class method signature
    ClassMethod
  | -- | Class instance: @instance C T@
    ClassInstance
  | -- | Standalone deriving: @deriving instance C T@
    StandaloneDeriving
  | -- | Derived instance from deriving clause
    DerivedInstance
  | -- | Open type family (standalone or associated)
    OpenTypeFamily
  | -- | Closed type family
    ClosedTypeFamily
  | -- | Data family (standalone or associated)
    DataFamily
  | -- | Type family instance: @type instance F T = U@
    TypeFamilyInstance
  | -- | Data family instance: @data instance D T = C@
    DataFamilyInstance
  | -- | Foreign import declaration
    ForeignImport
  | -- | Foreign export declaration
    ForeignExport
  | -- | Fixity signature: @infixl 6 +@
    FixitySignature
  | -- | Inline/noinline signature
    InlineSignature
  | -- | Specialise signature
    SpecialiseSignature
  | -- | Standalone kind signature: @type T :: Type@
    StandaloneKindSig
  | -- | Rewrite rule: @{-# RULES ... #-}@
    Rule
  | -- | Default declaration: @default (Integer, Double)@
    Default
  | -- | Annotation: @{-# ANN ... #-}@
    Annotation
  | -- | Template Haskell splice or quasi-quote: @$(expr)@ or @[quoter|...|]@
    Splice
  | -- | Warning pragma: @{-# WARNING x "msg" #-}@
    Warning
  | -- | Minimal pragma: @{-# MINIMAL size #-}@
    MinimalPragma
  | -- | Complete pragma: @{-# COMPLETE Nil, Cons #-}@
    CompletePragma
  | -- | Default method signature: @default m :: Show a => a -> String@
    DefaultMethodSignature
  | -- | Role annotation: @type role T nominal@
    RoleAnnotation
  | -- | Named documentation chunk: @-- $name@
    DocumentationChunk
  | -- | Positional argument of a function or constructor
    Argument
  | -- | Return type of a function
    ReturnType
  | -- | Export list entry with no matching declaration in this module
    -- (e.g. a module re-export or an unresolved name).
    UnresolvedExport
  deriving (Eq, Generics.Generic, Ord, Show)
  deriving (ToJson.ToJson, Schema.ToSchema) via Generics.Generically ItemKind

-- | Whether an item kind is a traditional subordinate that can be
-- filtered by export subordinate restrictions (e.g. @Foo(Bar)@ or
-- @Foo(..)@).
isTraditionalSubordinate :: ItemKind -> Bool
isTraditionalSubordinate k = case k of
  DataConstructor -> True
  GADTConstructor -> True
  RecordField -> True
  ClassMethod -> True
  DefaultMethodSignature -> True
  _ -> False