-- |
-- #name_types#
-- GHC uses several kinds of name internally:
--
-- * 'OccName.OccName': see "OccName#name_types"
--
-- * 'RdrName.RdrName': see "RdrName#name_types"
--
-- *  'Name.Name' is the type of names that have had their scoping and binding resolved. They
--   have an 'OccName.OccName' but also a 'Unique.Unique' that disambiguates Names that have
--   the same 'OccName.OccName' and indeed is used for all 'Name.Name' comparison. Names
--   also contain information about where they originated from, see "Name#name_sorts"
--
-- * 'Id.Id': see "Id#name_types"
--
-- * 'Var.Var': see "Var#name_types"
--
-- #name_sorts#
-- Names are one of:
--
--  * External, if they name things declared in other modules. Some external
--    Names are wired in, i.e. they name primitives defined in the compiler itself
--
--  * Internal, if they name things in the module being compiled. Some internal
--    Names are system names, if they are names manufactured by the compiler

module Name (
        -- * The main types
        Name,                                   -- Abstract
        BuiltInSyntax(..),

        -- ** Creating 'Name's
        mkSystemName, mkSystemNameAt,
        mkInternalName, mkClonedInternalName, mkDerivedInternalName,
        mkSystemVarName, mkSysTvName,
        mkFCallName,
        mkExternalName, mkWiredInName,

        -- ** Manipulating and deconstructing 'Name's
        nameUnique, setNameUnique,
        nameOccName, nameModule, nameModule_maybe,
        tidyNameOcc,
        hashName, localiseName,
        mkLocalisedOccName,

        nameSrcLoc, nameSrcSpan, pprNameDefnLoc, pprDefinedAt,

        -- ** Predicates on 'Name's
        isSystemName, isInternalName, isExternalName,
        isTyVarName, isTyConName, isDataConName,
        isValName, isVarName,
        isWiredInName, isBuiltInSyntax,
        wiredInNameTyThing_maybe,
        nameIsLocalOrFrom, stableNameCmp,

        -- * Class 'NamedThing' and overloaded friends
        NamedThing(..),
        getSrcLoc, getSrcSpan, getOccString,

        pprInfixName, pprPrefixName, pprModulePrefix,

        -- Re-export the OccName stuff
        module OccName
    ) where

#include "Typeable.h"

import {-# SOURCE #-} TypeRep( TyThing )
import {-# SOURCE #-} PrelNames( liftedTypeKindTyConKey )

import OccName
import Module
import SrcLoc
import Unique
import Util
import Maybes
import Binary
import DynFlags
import FastTypes
import FastString
import Outputable

import Data.Data

-- | A unique, unambigious name for something, containing information about where
-- that thing originated.
data Name = Name {
                n_sort :: NameSort,     -- What sort of name it is
                n_occ  :: !OccName,     -- Its occurrence name
                n_uniq :: FastInt,      -- UNPACK doesn't work, recursive type
--(note later when changing Int# -> FastInt: is that still true about UNPACK?)
                n_loc  :: !SrcSpan      -- Definition site
            }
    deriving Typeable

-- NOTE: we make the n_loc field strict to eliminate some potential
-- (and real!) space leaks, due to the fact that we don't look at
-- the SrcLoc in a Name all that often.

data NameSort
  = External Module

  | WiredIn Module TyThing BuiltInSyntax
        -- A variant of External, for wired-in things

  | Internal            -- A user-defined Id or TyVar
                        -- defined in the module being compiled

  | System              -- A system-defined Id or TyVar.  Typically the
                        -- OccName is very uninformative (like 's')

-- | BuiltInSyntax is for things like @(:)@, @[]@ and tuples,
-- which have special syntactic forms.  They aren't in scope
-- as such.
data BuiltInSyntax = BuiltInSyntax | UserSyntax

instance HasOccName Name where
  occName = nameOccName

nameUnique              :: Name -> Unique
nameOccName             :: Name -> OccName
nameModule              :: Name -> Module
nameSrcLoc              :: Name -> SrcLoc
nameSrcSpan             :: Name -> SrcSpan

nameUnique  name = mkUniqueGrimily (iBox (n_uniq name))
nameOccName name = n_occ  name
nameSrcLoc  name = srcSpanStart (n_loc name)
nameSrcSpan name = n_loc  name

nameIsLocalOrFrom :: Module -> Name -> Bool
isInternalName    :: Name -> Bool
isExternalName    :: Name -> Bool
isSystemName      :: Name -> Bool
isWiredInName     :: Name -> Bool

isWiredInName (Name {n_sort = WiredIn _ _ _}) = True
isWiredInName _                               = False

wiredInNameTyThing_maybe :: Name -> Maybe TyThing
wiredInNameTyThing_maybe (Name {n_sort = WiredIn _ thing _}) = Just thing
wiredInNameTyThing_maybe _                                   = Nothing

isBuiltInSyntax :: Name -> Bool
isBuiltInSyntax (Name {n_sort = WiredIn _ _ BuiltInSyntax}) = True
isBuiltInSyntax _                                           = False

isExternalName (Name {n_sort = External _})    = True
isExternalName (Name {n_sort = WiredIn _ _ _}) = True
isExternalName _                               = False

isInternalName name = not (isExternalName name)

nameModule name = nameModule_maybe name `orElse` pprPanic "nameModule" (ppr name)
nameModule_maybe :: Name -> Maybe Module
nameModule_maybe (Name { n_sort = External mod})    = Just mod
nameModule_maybe (Name { n_sort = WiredIn mod _ _}) = Just mod
nameModule_maybe _                                  = Nothing

nameIsLocalOrFrom from name
  | isExternalName name = from == nameModule name
  | otherwise           = True

isTyVarName :: Name -> Bool
isTyVarName name = isTvOcc (nameOccName name)

isTyConName :: Name -> Bool
isTyConName name = isTcOcc (nameOccName name)

isDataConName :: Name -> Bool
isDataConName name = isDataOcc (nameOccName name)

isValName :: Name -> Bool
isValName name = isValOcc (nameOccName name)

isVarName :: Name -> Bool
isVarName = isVarOcc . nameOccName

isSystemName (Name {n_sort = System}) = True
isSystemName _                        = False

-- | Create a name which is (for now at least) local to the current module and hence
-- does not need a 'Module' to disambiguate it from other 'Name's
mkInternalName :: Unique -> OccName -> SrcSpan -> Name
mkInternalName uniq occ loc = Name { n_uniq = getKeyFastInt uniq
                                   , n_sort = Internal
                                   , n_occ = occ
                                   , n_loc = loc }
        -- NB: You might worry that after lots of huffing and
        -- puffing we might end up with two local names with distinct
        -- uniques, but the same OccName.  Indeed we can, but that's ok
        --      * the insides of the compiler don't care: they use the Unique
        --      * when printing for -ddump-xxx you can switch on -dppr-debug to get the
        --        uniques if you get confused
        --      * for interface files we tidyCore first, which makes
        --        the OccNames distinct when they need to be

mkClonedInternalName :: Unique -> Name -> Name
mkClonedInternalName uniq (Name { n_occ = occ, n_loc = loc })
  = Name { n_uniq = getKeyFastInt uniq, n_sort = Internal
         , n_occ = occ, n_loc = loc }

mkDerivedInternalName :: (OccName -> OccName) -> Unique -> Name -> Name
mkDerivedInternalName derive_occ uniq (Name { n_occ = occ, n_loc = loc })
  = Name { n_uniq = getKeyFastInt uniq, n_sort = Internal
         , n_occ = derive_occ occ, n_loc = loc }

-- | Create a name which definitely originates in the given module
mkExternalName :: Unique -> Module -> OccName -> SrcSpan -> Name
-- WATCH OUT! External Names should be in the Name Cache
-- (see Note [The Name Cache] in IfaceEnv), so don't just call mkExternalName
-- with some fresh unique without populating the Name Cache
mkExternalName uniq mod occ loc
  = Name { n_uniq = getKeyFastInt uniq, n_sort = External mod,
           n_occ = occ, n_loc = loc }

-- | Create a name which is actually defined by the compiler itself
mkWiredInName :: Module -> OccName -> Unique -> TyThing -> BuiltInSyntax -> Name
mkWiredInName mod occ uniq thing built_in
  = Name { n_uniq = getKeyFastInt uniq,
           n_sort = WiredIn mod thing built_in,
           n_occ = occ, n_loc = wiredInSrcSpan }

-- | Create a name brought into being by the compiler
mkSystemName :: Unique -> OccName -> Name
mkSystemName uniq occ = mkSystemNameAt uniq occ noSrcSpan

mkSystemNameAt :: Unique -> OccName -> SrcSpan -> Name
mkSystemNameAt uniq occ loc = Name { n_uniq = getKeyFastInt uniq, n_sort = System
                                   , n_occ = occ, n_loc = loc }

mkSystemVarName :: Unique -> FastString -> Name
mkSystemVarName uniq fs = mkSystemName uniq (mkVarOccFS fs)

mkSysTvName :: Unique -> FastString -> Name
mkSysTvName uniq fs = mkSystemName uniq (mkOccNameFS tvName fs)

-- | Make a name for a foreign call
mkFCallName :: Unique -> String -> Name
mkFCallName uniq str = mkInternalName uniq (mkVarOcc str) noSrcSpan
   -- The encoded string completely describes the ccall

-- When we renumber/rename things, we need to be
-- able to change a Name's Unique to match the cached
-- one in the thing it's the name of.  If you know what I mean.
setNameUnique :: Name -> Unique -> Name
setNameUnique name uniq = name {n_uniq = getKeyFastInt uniq}

tidyNameOcc :: Name -> OccName -> Name
-- We set the OccName of a Name when tidying
-- In doing so, we change System --> Internal, so that when we print
-- it we don't get the unique by default.  It's tidy now!
tidyNameOcc name@(Name { n_sort = System }) occ = name { n_occ = occ, n_sort = Internal}
tidyNameOcc name                            occ = name { n_occ = occ }

-- | Make the 'Name' into an internal name, regardless of what it was to begin with
localiseName :: Name -> Name
localiseName n = n { n_sort = Internal }

-- |Create a localised variant of a name.
--
-- If the name is external, encode the original's module name to disambiguate.
--
mkLocalisedOccName :: Module -> (Maybe String -> OccName -> OccName) -> Name -> OccName
mkLocalisedOccName this_mod mk_occ name = mk_occ origin (nameOccName name)
  where
    origin
      | nameIsLocalOrFrom this_mod name = Nothing
      | otherwise                       = Just (moduleNameColons . moduleName . nameModule $ name)

hashName :: Name -> Int         -- ToDo: should really be Word
hashName name = getKey (nameUnique name) + 1
        -- The +1 avoids keys with lots of zeros in the ls bits, which
        -- interacts badly with the cheap and cheerful multiplication in
        -- hashExpr

cmpName :: Name -> Name -> Ordering
cmpName n1 n2 = iBox (n_uniq n1) `compare` iBox (n_uniq n2)

stableNameCmp :: Name -> Name -> Ordering
-- Compare lexicographically
stableNameCmp (Name { n_sort = s1, n_occ = occ1 })
              (Name { n_sort = s2, n_occ = occ2 })
  = (s1 `sort_cmp` s2) `thenCmp` (occ1 `compare` occ2)
    -- The ordinary compare on OccNames is lexicogrpahic
  where
    -- Later constructors are bigger
    sort_cmp (External m1) (External m2)       = m1 `stableModuleCmp` m2
    sort_cmp (External {}) _                   = LT
    sort_cmp (WiredIn {}) (External {})        = GT
    sort_cmp (WiredIn m1 _ _) (WiredIn m2 _ _) = m1 `stableModuleCmp` m2
    sort_cmp (WiredIn {})     _                = LT
    sort_cmp Internal         (External {})    = GT
    sort_cmp Internal         (WiredIn {})     = GT
    sort_cmp Internal         Internal         = EQ
    sort_cmp Internal         System           = LT
    sort_cmp System           System           = EQ
    sort_cmp System           _                = GT

instance Eq Name where
    a == b = case (a `compare` b) of { EQ -> True;  _ -> False }
    a /= b = case (a `compare` b) of { EQ -> False; _ -> True }

instance Ord Name where
    a <= b = case (a `compare` b) of { LT -> True;  EQ -> True;  GT -> False }
    a <  b = case (a `compare` b) of { LT -> True;  EQ -> False; GT -> False }
    a >= b = case (a `compare` b) of { LT -> False; EQ -> True;  GT -> True  }
    a >  b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True  }
    compare a b = cmpName a b

instance Uniquable Name where
    getUnique = nameUnique

instance NamedThing Name where
    getName n = n

instance Data Name where
  -- don't traverse?
  toConstr _   = abstractConstr "Name"
  gunfold _ _  = error "gunfold"
  dataTypeOf _ = mkNoRepType "Name"

instance Binary Name where
   put_ bh name =
      case getUserData bh of
        UserData{ ud_put_name = put_name } -> put_name bh name

   get bh =
      case getUserData bh of
        UserData { ud_get_name = get_name } -> get_name bh

instance Outputable Name where
    ppr name = pprName name

instance OutputableBndr Name where
    pprBndr _ name = pprName name
    pprInfixOcc  = pprInfixName
    pprPrefixOcc = pprPrefixName


pprName :: Name -> SDoc
pprName n@(Name {n_sort = sort, n_uniq = u, n_occ = occ})
  = getPprStyle $ \ sty ->
    case sort of
      WiredIn mod _ builtin   -> pprExternal sty uniq mod occ n True  builtin
      External mod            -> pprExternal sty uniq mod occ n False UserSyntax
      System                  -> pprSystem sty uniq occ
      Internal                -> pprInternal sty uniq occ
  where uniq = mkUniqueGrimily (iBox u)

pprExternal :: PprStyle -> Unique -> Module -> OccName -> Name -> Bool -> BuiltInSyntax -> SDoc
pprExternal sty uniq mod occ name is_wired is_builtin
  | codeStyle sty = ppr mod <> char '_' <> ppr_z_occ_name occ
        -- In code style, always qualify
        -- ToDo: maybe we could print all wired-in things unqualified
        --       in code style, to reduce symbol table bloat?
  | debugStyle sty = pp_mod <> ppr_occ_name occ
                     <> braces (hsep [if is_wired then ptext (sLit "(w)") else empty,
                                      pprNameSpaceBrief (occNameSpace occ),
                                      pprUnique uniq])
  | BuiltInSyntax <- is_builtin = ppr_occ_name occ  -- Never qualify builtin syntax
  | otherwise                   = pprModulePrefix sty mod name <> ppr_occ_name occ
  where
    pp_mod = sdocWithDynFlags $ \dflags ->
             if gopt Opt_SuppressModulePrefixes dflags
             then empty
             else ppr mod <> dot

pprInternal :: PprStyle -> Unique -> OccName -> SDoc
pprInternal sty uniq occ
  | codeStyle sty  = pprUnique uniq
  | debugStyle sty = ppr_occ_name occ <> braces (hsep [pprNameSpaceBrief (occNameSpace occ),
                                                       pprUnique uniq])
  | dumpStyle sty  = ppr_occ_name occ <> ppr_underscore_unique uniq
                        -- For debug dumps, we're not necessarily dumping
                        -- tidied code, so we need to print the uniques.
  | otherwise      = ppr_occ_name occ   -- User style

-- Like Internal, except that we only omit the unique in Iface style
pprSystem :: PprStyle -> Unique -> OccName -> SDoc
pprSystem sty uniq occ
  | codeStyle sty  = pprUnique uniq
  | debugStyle sty = ppr_occ_name occ <> ppr_underscore_unique uniq
                     <> braces (pprNameSpaceBrief (occNameSpace occ))
  | otherwise      = ppr_occ_name occ <> ppr_underscore_unique uniq
                                -- If the tidy phase hasn't run, the OccName
                                -- is unlikely to be informative (like 's'),
                                -- so print the unique


pprModulePrefix :: PprStyle -> Module -> Name -> SDoc
-- Print the "M." part of a name, based on whether it's in scope or not
-- See Note [Printing original names] in HscTypes
pprModulePrefix sty mod name = sdocWithDynFlags $ \dflags ->
  if gopt Opt_SuppressModulePrefixes dflags
  then empty
  else
    case qualName sty name of              -- See Outputable.QualifyName:
      NameQual modname -> ppr modname <> dot       -- Name is in scope
      NameNotInScope1  -> ppr mod <> dot           -- Not in scope
      NameNotInScope2  -> ppr (modulePackageId mod) <> colon     -- Module not in
                          <> ppr (moduleName mod) <> dot         -- scope eithber
      _otherwise       -> empty

ppr_underscore_unique :: Unique -> SDoc
-- Print an underscore separating the name from its unique
-- But suppress it if we aren't printing the uniques anyway
ppr_underscore_unique uniq
  = sdocWithDynFlags $ \dflags ->
    if gopt Opt_SuppressUniques dflags
    then empty
    else char '_' <> pprUnique uniq

ppr_occ_name :: OccName -> SDoc
ppr_occ_name occ = ftext (occNameFS occ)
        -- Don't use pprOccName; instead, just print the string of the OccName;
        -- we print the namespace in the debug stuff above

-- In code style, we Z-encode the strings.  The results of Z-encoding each FastString are
-- cached behind the scenes in the FastString implementation.
ppr_z_occ_name :: OccName -> SDoc
ppr_z_occ_name occ = ztext (zEncodeFS (occNameFS occ))

-- Prints (if mod information is available) "Defined at <loc>" or
--  "Defined in <mod>" information for a Name.
pprDefinedAt :: Name -> SDoc
pprDefinedAt name = ptext (sLit "Defined") <+> pprNameDefnLoc name

pprNameDefnLoc :: Name -> SDoc
-- Prints "at <loc>" or
--     or "in <mod>" depending on what info is available
pprNameDefnLoc name
  = case nameSrcLoc name of
         -- nameSrcLoc rather than nameSrcSpan
         -- It seems less cluttered to show a location
         -- rather than a span for the definition point
       RealSrcLoc s -> ptext (sLit "at") <+> ppr s
       UnhelpfulLoc s
         | isInternalName name || isSystemName name
         -> ptext (sLit "at") <+> ftext s
         | otherwise
         -> ptext (sLit "in") <+> quotes (ppr (nameModule name))

-- | A class allowing convenient access to the 'Name' of various datatypes
class NamedThing a where
    getOccName :: a -> OccName
    getName    :: a -> Name

    getOccName n = nameOccName (getName n)      -- Default method

getSrcLoc           :: NamedThing a => a -> SrcLoc
getSrcSpan          :: NamedThing a => a -> SrcSpan
getOccString        :: NamedThing a => a -> String

getSrcLoc           = nameSrcLoc           . getName
getSrcSpan          = nameSrcSpan          . getName
getOccString        = occNameString        . getOccName

pprInfixName, pprPrefixName :: (Outputable a, NamedThing a) => a -> SDoc
-- See Outputable.pprPrefixVar, pprInfixVar;
-- add parens or back-quotes as appropriate
pprInfixName  n = pprInfixVar (isSymOcc (getOccName n)) (ppr n)

pprPrefixName thing 
 |  name `hasKey` liftedTypeKindTyConKey 
 = ppr name   -- See Note [Special treatment for kind *]
 | otherwise
 = pprPrefixVar (isSymOcc (nameOccName name)) (ppr name)
 where
   name = getName thing