-- |
-- #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
	mkInternalName, mkSystemName, mkDerivedInternalName, 
	mkSystemVarName, mkSysTvName, 
	mkFCallName, mkIPName,
        mkTickBoxOpName,
	mkExternalName, mkWiredInName,

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

	nameSrcLoc, nameSrcSpan, pprNameLoc,

	-- ** 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 OccName
import Module
import SrcLoc
import Unique
import Util
import Maybes
import Binary
import StaticFlags
import FastTypes
import FastString
import Outputable

import Data.Array
import Data.Data
import Data.Word        ( Word32 )

-- | 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

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 puts the uniques
	--	  into the print name (see setNameVisibility below)

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
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 = Name { n_uniq = getKeyFastInt uniq, n_sort = System, 
			       n_occ = occ, n_loc = noSrcSpan }

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
	-- The encoded string completely describes the ccall
mkFCallName uniq str =  Name { n_uniq = getKeyFastInt uniq, n_sort = Internal, 
			       n_occ = mkVarOcc str, n_loc = noSrcSpan }


mkTickBoxOpName :: Unique -> String -> Name
mkTickBoxOpName uniq str 
   = Name { n_uniq = getKeyFastInt uniq, n_sort = Internal, 
	    n_occ = mkVarOcc str, n_loc = noSrcSpan }

-- | Make the name of an implicit parameter
mkIPName :: Unique -> OccName -> Name
mkIPName uniq occ
  = Name { n_uniq = getKeyFastInt uniq,
	   n_sort = Internal,
	   n_occ  = occ,
	   n_loc = noSrcSpan }

-- 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 }

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 = do
        i <- get bh
        return $! (ud_symtab (getUserData bh) ! fromIntegral (i::Word32))

instance Outputable Name where
    ppr name = pprName name

instance OutputableBndr Name where
    pprBndr _ name = pprName name

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

pprExternal :: PprStyle -> Unique -> Module -> OccName -> Bool -> BuiltInSyntax -> SDoc
pprExternal sty uniq mod occ 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 = ppr mod <> dot <> 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 occ <> ppr_occ_name occ

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 -> OccName -> 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 occ
  | opt_SuppressModulePrefixes = empty
  
  | otherwise
  = case qualName sty mod occ 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
  | opt_SuppressUniques = empty
  | otherwise		= 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 = ftext (zEncodeFS (occNameFS occ))

-- Prints (if mod information is available) "Defined at <loc>" or 
--  "Defined in <mod>" information for a Name.
pprNameLoc :: Name -> SDoc
pprNameLoc name = case nameSrcSpan name of
                  RealSrcSpan s ->
                      pprDefnLoc s
                  UnhelpfulSpan _
                   | isInternalName name || isSystemName name ->
                      ptext (sLit "<no location info>")
                   | otherwise ->
                      ptext (sLit "Defined in ") <> 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 n = pprPrefixVar (isSymOcc (getOccName n)) (ppr n)