%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
-\section[MatchLit]{Pattern-matching literal and n+k patterns}
+\section[MatchLit]{Pattern-matching literal patterns}
\begin{code}
+module MatchLit ( matchLiterals ) where
+
#include "HsVersions.h"
-module MatchLit (
- matchLiterals
- ) where
+import {-# SOURCE #-} Match ( match )
+import {-# SOURCE #-} DsExpr ( dsExpr )
-import AbsSyn -- the stuff being desugared
-import PlainCore -- the output of desugaring;
- -- importing this module also gets all the
- -- CoreSyn utility functions
-import DsMonad -- the monadery used in the desugarer
+import HsSyn ( HsLit(..), OutPat(..), HsExpr(..) )
+import TcHsSyn ( TypecheckedPat )
+import CoreSyn ( Expr(..), Bind(..) )
+import Id ( Id )
-import AbsUniType ( isPrimType, getUniDataTyCon, kindFromType )
-import BasicLit ( mkMachInt, BasicLit(..), PrimKind )
-import DsExpr ( dsExpr )
+import DsMonad
import DsUtils
-import Maybes ( Maybe(..), catMaybes )
-import Match ( match )
-import Id ( getIdUniType, eqId )
-import Util
+
+import Literal ( mkMachInt, Literal(..) )
+import Maybes ( catMaybes )
+import Type ( isUnLiftedType )
+import Panic ( panic, assertPanic )
\end{code}
\begin{code}
matchLiterals :: [Id]
-> [EquationInfo]
- -> [EquationInfo] -- Shadows
-> DsM MatchResult
\end{code}
the alts---here we use @match_prims_used@.
\begin{code}
-matchLiterals all_vars@(var:vars) eqns_info@(EqnInfo (LitPat literal lit_ty : ps1) _ : eqns) shadows
+matchLiterals all_vars@(var:vars) eqns_info@(EqnInfo n ctx (LitPat literal lit_ty : ps1) _ : eqns)
= -- GENERATE THE ALTS
- match_prims_used vars eqns_info shadows `thenDs` \ prim_alts ->
+ match_prims_used vars eqns_info `thenDs` \ prim_alts ->
-- MAKE THE PRIMITIVE CASE
- mkCoPrimCaseMatchResult var prim_alts
+ returnDs (mkCoPrimCaseMatchResult var prim_alts)
where
- match_prims_used _ [{-no more eqns-}] _ = returnDs []
+ match_prims_used _ [{-no more eqns-}] = returnDs []
- match_prims_used vars eqns_info@(EqnInfo ((LitPat literal _):ps1) _ : eqns) shadows
+ match_prims_used vars eqns_info@(EqnInfo n ctx (pat@(LitPat literal lit_ty):ps1) _ : eqns)
= let
(shifted_eqns_for_this_lit, eqns_not_for_this_lit)
- = partitionEqnsByLit Nothing literal eqns_info
- (shifted_shadows_for_this_lit, shadows_not_for_this_lit)
- = partitionEqnsByLit Nothing literal shadows
+ = partitionEqnsByLit pat eqns_info
in
-- recursive call to make other alts...
- match_prims_used vars eqns_not_for_this_lit shadows_not_for_this_lit `thenDs` \ rest_of_alts ->
+ match_prims_used vars eqns_not_for_this_lit `thenDs` \ rest_of_alts ->
-- (prim pats have no args; no selectMatchVars as in match_cons_used)
-- now do the business to make the alt for _this_ LitPat ...
- match vars shifted_eqns_for_this_lit shifted_shadows_for_this_lit `thenDs` \ match_result ->
+ match vars shifted_eqns_for_this_lit `thenDs` \ match_result ->
returnDs (
(mk_core_lit literal, match_result)
: rest_of_alts
)
where
- mk_core_lit :: Literal -> BasicLit
-
- mk_core_lit (IntPrimLit i) = mkMachInt i
- mk_core_lit (CharPrimLit c) = MachChar c
- mk_core_lit (StringPrimLit s) = MachStr s
- mk_core_lit (FloatPrimLit f) = MachFloat f
- mk_core_lit (DoublePrimLit d) = MachDouble d
- mk_core_lit (LitLitLit s t) = ASSERT(isPrimType t)
- MachLitLit s (kindFromType t)
- mk_core_lit other = panic "matchLiterals:mk_core_lit:unhandled"
+ mk_core_lit :: HsLit -> Literal
+
+ mk_core_lit (HsIntPrim i) = mkMachInt i
+ mk_core_lit (HsCharPrim c) = MachChar c
+ mk_core_lit (HsStringPrim s) = MachStr s
+ mk_core_lit (HsFloatPrim f) = MachFloat f
+ mk_core_lit (HsDoublePrim d) = MachDouble d
+ mk_core_lit (HsLitLit s ty) = ASSERT(isUnLiftedType ty)
+ MachLitLit s ty
+ mk_core_lit other = panic "matchLiterals:mk_core_lit:unhandled"
\end{code}
\begin{code}
-matchLiterals all_vars@(var:vars) eqns_info@(EqnInfo ((NPat literal lit_ty eq_chk):ps1) _ : eqns) shadows
+matchLiterals all_vars@(var:vars)
+ eqns_info@(EqnInfo n ctx (pat@(NPat literal lit_ty eq_chk):ps1) _ : eqns)
= let
(shifted_eqns_for_this_lit, eqns_not_for_this_lit)
- = partitionEqnsByLit Nothing literal eqns_info
- (shifted_shadows_for_this_lit, shadows_not_for_this_lit)
- = partitionEqnsByLit Nothing literal shadows
+ = partitionEqnsByLit pat eqns_info
+ in
+ dsExpr (HsApp eq_chk (HsVar var)) `thenDs` \ pred_expr ->
+ match vars shifted_eqns_for_this_lit `thenDs` \ inner_match_result ->
+ let
+ match_result1 = mkGuardedMatchResult pred_expr inner_match_result
in
- dsExpr (App eq_chk (Var var)) `thenDs` \ pred_expr ->
- match vars shifted_eqns_for_this_lit shifted_shadows_for_this_lit `thenDs` \ inner_match_result ->
- mkGuardedMatchResult pred_expr inner_match_result `thenDs` \ match_result1 ->
-
if (null eqns_not_for_this_lit)
- then
+ then
returnDs match_result1
- else
- matchLiterals all_vars eqns_not_for_this_lit shadows_not_for_this_lit `thenDs` \ match_result2 ->
- combineMatchResults match_result1 match_result2
+ else
+ matchLiterals all_vars eqns_not_for_this_lit `thenDs` \ match_result2 ->
+ returnDs (combineMatchResults match_result1 match_result2)
\end{code}
For an n+k pattern, we use the various magic expressions we've been given.
<try-next-pattern-or-whatever>
\end{verbatim}
+
\begin{code}
-matchLiterals all_vars@(var:vars) eqns_info@(EqnInfo ((NPlusKPat master_n k ty from_lit ge sub):ps1) _ : eqns) shadows
+matchLiterals all_vars@(var:vars) eqns_info@(EqnInfo n ctx (pat@(NPlusKPat master_n k ty ge sub):ps1) _ : eqns)
= let
(shifted_eqns_for_this_lit, eqns_not_for_this_lit)
- = partitionEqnsByLit (Just master_n) k eqns_info
- (shifted_shadows_for_this_lit, shadows_not_for_this_lit)
- = partitionEqnsByLit (Just master_n) k shadows
+ = partitionEqnsByLit pat eqns_info
in
- match vars shifted_eqns_for_this_lit shifted_shadows_for_this_lit `thenDs` \ inner_match_result ->
+ match vars shifted_eqns_for_this_lit `thenDs` \ inner_match_result ->
- dsExpr from_lit `thenDs` \ core_lit ->
- dsExpr (App ge (Var var)) `thenDs` \ var_ge ->
- dsExpr (App sub (Var var)) `thenDs` \ var_sub ->
- mkCoAppDs var_ge core_lit `thenDs` \ var_ge_lit ->
- mkCoAppDs var_sub core_lit `thenDs` \ var_sub_lit ->
-
- mkGuardedMatchResult
- var_ge_lit
- (mkCoLetsMatchResult [CoNonRec master_n var_sub_lit] inner_match_result)
- `thenDs` \ match_result1 ->
+ dsExpr (HsApp ge (HsVar var)) `thenDs` \ ge_expr ->
+ dsExpr (HsApp sub (HsVar var)) `thenDs` \ nminusk_expr ->
+ let
+ match_result1 = mkGuardedMatchResult ge_expr $
+ mkCoLetsMatchResult [NonRec master_n nminusk_expr] $
+ inner_match_result
+ in
if (null eqns_not_for_this_lit)
then
returnDs match_result1
else
- matchLiterals all_vars eqns_not_for_this_lit shadows_not_for_this_lit `thenDs` \ match_result2 ->
- combineMatchResults match_result1 match_result2
+ matchLiterals all_vars eqns_not_for_this_lit `thenDs` \ match_result2 ->
+ returnDs (combineMatchResults match_result1 match_result2)
\end{code}
-Given a blob of LitPats/NPats/NPlusKPats, we want to split them into those
+Given a blob of @LitPat@s/@NPat@s, we want to split them into those
that are ``same''/different as one we are looking at. We need to know
-whether we're looking at a LitPat/NPat or NPlusKPat (initial Bool arg is
-@True@ for the latter), and what literal we're after.
+whether we're looking at a @LitPat@/@NPat@, and what literal we're after.
\begin{code}
-partitionEqnsByLit :: Maybe Id -- (Just v) for N-plus-K patterns, where v
- -- is the "master" variable;
- -- Nothing for NPats and LitPats
- -> Literal
+partitionEqnsByLit :: TypecheckedPat
-> [EquationInfo]
-> ([EquationInfo], -- These ones are for this lit, AND
-- they've been "shifted" by stripping
-- are exactly as fed in.
)
-partitionEqnsByLit want_NPlusK lit eqns
+partitionEqnsByLit master_pat eqns
= ( \ (xs,ys) -> (catMaybes xs, catMaybes ys))
- (unzip (map (partition_eqn want_NPlusK lit) eqns))
+ (unzip (map (partition_eqn master_pat) eqns))
where
- partition_eqn :: Maybe Id -> Literal -> EquationInfo ->
- (Maybe EquationInfo, Maybe EquationInfo)
+ partition_eqn :: TypecheckedPat -> EquationInfo -> (Maybe EquationInfo, Maybe EquationInfo)
- partition_eqn Nothing lit (EqnInfo (LitPat k _ : remaining_pats) match_result)
- | lit `eq_lit` k = (Just (EqnInfo remaining_pats match_result), Nothing)
- -- NB the pattern is stripped off thhe EquationInfo
+ partition_eqn (LitPat k1 _) (EqnInfo n ctx (LitPat k2 _ : remaining_pats) match_result)
+ | k1 == k2 = (Just (EqnInfo n ctx remaining_pats match_result), Nothing)
+ -- NB the pattern is stripped off the EquationInfo
- partition_eqn Nothing lit (EqnInfo (NPat k _ _ : remaining_pats) match_result)
- | lit `eq_lit` k = (Just (EqnInfo remaining_pats match_result), Nothing)
- -- NB the pattern is stripped off thhe EquationInfo
+ partition_eqn (NPat k1 _ _) (EqnInfo n ctx (NPat k2 _ _ : remaining_pats) match_result)
+ | k1 == k2 = (Just (EqnInfo n ctx remaining_pats match_result), Nothing)
+ -- NB the pattern is stripped off the EquationInfo
- partition_eqn (Just master_n) lit (EqnInfo (NPlusKPat n k _ _ _ _ : remaining_pats) match_result)
- | lit `eq_lit` k = (Just (EqnInfo remaining_pats new_match_result), Nothing)
- -- NB the pattern is stripped off thhe EquationInfo
+ partition_eqn (NPlusKPat master_n k1 _ _ _)
+ (EqnInfo n ctx (NPlusKPat n' k2 _ _ _ : remaining_pats) match_result)
+ | k1 == k2 = (Just (EqnInfo n ctx remaining_pats new_match_result), Nothing)
+ -- NB the pattern is stripped off the EquationInfo
where
- new_match_result = if master_n `eqId` n then
- match_result
- else
- mkCoLetsMatchResult [CoNonRec n (CoVar master_n)] match_result
+ new_match_result | master_n == n' = match_result
+ | otherwise = mkCoLetsMatchResult
+ [NonRec n' (Var master_n)] match_result
- -- Wild-card patterns, which will only show up in the shadows, go into both groups
- partition_eqn wantNPlusK lit eqn@(EqnInfo (WildPat _ : remaining_pats) match_result)
- = (Just (EqnInfo remaining_pats match_result), Just eqn)
+ -- Wild-card patterns, which will only show up in the shadows,
+ -- go into both groups
+ partition_eqn master_pat eqn@(EqnInfo n ctx (WildPat _ : remaining_pats) match_result)
+ = (Just (EqnInfo n ctx remaining_pats match_result), Just eqn)
-- Default case; not for this pattern
- partition_eqn wantNPlusK lit eqn = (Nothing, Just eqn)
-
--- ToDo: meditate about this equality business...
-
-eq_lit (IntLit i1) (IntLit i2) = i1 == i2
-eq_lit (FracLit f1) (FracLit f2) = f1 == f2
-
-eq_lit (IntPrimLit i1) (IntPrimLit i2) = i1 == i2
-eq_lit (FloatPrimLit f1) (FloatPrimLit f2) = f1 == f2
-eq_lit (DoublePrimLit d1) (DoublePrimLit d2) = d1 == d2
-eq_lit (CharLit c1) (CharLit c2) = c1 == c2
-eq_lit (CharPrimLit c1) (CharPrimLit c2) = c1 == c2
-eq_lit (StringLit s1) (StringLit s2) = s1 == s2
-eq_lit (StringPrimLit s1) (StringPrimLit s2) = s1 == s2
-eq_lit (LitLitLit s1 _) (LitLitLit s2 _) = s1 == s2 -- ToDo: ??? (dubious)
-eq_lit other1 other2 = panic "matchLiterals:eq_lit"
+ partition_eqn master_pat eqn = (Nothing, Just eqn)
\end{code}