diff options
Diffstat (limited to 'lib/compiler')
| -rw-r--r-- | lib/compiler/src/v3_core.erl | 492 |
1 files changed, 230 insertions, 262 deletions
diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl index ec5deb6905..3435a46ca9 100644 --- a/lib/compiler/src/v3_core.erl +++ b/lib/compiler/src/v3_core.erl @@ -101,6 +101,8 @@ -record(ireceive2, {anno=#a{},clauses,timeout,action}). -record(iset, {anno=#a{},var,arg}). -record(itry, {anno=#a{},args,vars,body,evars,handler}). +-record(ifilter, {anno=#a{},arg}). +-record(igen, {anno=#a{},acc_pat,acc_guard,skip_pat,tail,tail_pat,arg}). -type iapply() :: #iapply{}. -type ibinary() :: #ibinary{}. @@ -117,10 +119,13 @@ -type ireceive2() :: #ireceive2{}. -type iset() :: #iset{}. -type itry() :: #itry{}. +-type ifilter() :: #ifilter{}. +-type igen() :: #igen{}. -type i() :: iapply() | ibinary() | icall() | icase() | icatch() | iclause() | ifun() | iletrec() | imatch() | iprimop() - | iprotect() | ireceive1() | ireceive2() | iset() | itry(). + | iprotect() | ireceive1() | ireceive2() | iset() | itry() + | ifilter() | igen(). -type warning() :: {file:filename(), [{integer(), module(), term()}]}. @@ -479,8 +484,9 @@ expr({cons,L,H0,T0}, St0) -> {T1,Tps,St2} = safe(T0, St1), A = lineno_anno(L, St2), {ann_c_cons(A, H1, T1),Hps ++ Tps,St2}; -expr({lc,L,E,Qs}, St) -> - lc_tq(L, E, Qs, #c_literal{anno=lineno_anno(L, St),val=[]}, St); +expr({lc,L,E,Qs0}, St0) -> + {Qs1,St1} = preprocess_quals(L, Qs0, St0), + lc_tq(L, E, Qs1, #c_literal{anno=lineno_anno(L, St1),val=[]}, St1); expr({bc,L,E,Qs}, St) -> bc_tq(L, E, Qs, {nil,L}, St); expr({tuple,L,Es0}, St0) -> @@ -647,7 +653,7 @@ expr({match,L,P0,E0}, St0) -> Other when not is_atom(Other) -> {#imatch{anno=#a{anno=Lanno},pat=P2,arg=E2,fc=Fc},Eps,St4} end; -expr({op,_,'++',{lc,Llc,E,Qs},More}, St0) -> +expr({op,_,'++',{lc,Llc,E,Qs0},More}, St0) -> %% Optimise '++' here because of the list comprehension algorithm. %% %% To avoid achieving quadratic complexity if there is a chain of @@ -655,7 +661,8 @@ expr({op,_,'++',{lc,Llc,E,Qs},More}, St0) -> %% evaluation of More now. Evaluating More here could also reduce the %% number variables in the environment for letrec. {Mc,Mps,St1} = safe(More, St0), - {Y,Yps,St} = lc_tq(Llc, E, Qs, Mc, St1), + {Qs,St2} = preprocess_quals(Llc, Qs0, St1), + {Y,Yps,St} = lc_tq(Llc, E, Qs, Mc, St2), {Y,Mps++Yps,St}; expr({op,L,'andalso',E1,E2}, St0) -> {#c_var{name=V0},St} = new_var(L, St0), @@ -889,136 +896,45 @@ fun_tq({_,_,Name}=Id, Cs0, L, St0, NameInfo) -> %% lc_tq(Line, Exp, [Qualifier], Mc, State) -> {LetRec,[PreExp],State}. %% This TQ from Simon PJ pp 127-138. -%% This gets a bit messy as we must transform all directly here. We -%% recognise guard tests and try to fold them together and join to a -%% preceding generators, this should give us better and more compact -%% code. -lc_tq(Line, E, [{generate,Lg,P,G}|Qs0], Mc, St0) -> - {Gs,Qs1} = splitwith(fun is_guard_test/1, Qs0), +lc_tq(Line, E, [#igen{anno=GAnno,acc_pat=AccPat,acc_guard=AccGuard, + skip_pat=SkipPat,tail=Tail,tail_pat=TailPat, + arg={Pre,Arg}}|Qs], Mc, St0) -> {Name,St1} = new_fun_name("lc", St0), - {Head,St2} = new_var(St1), - {Tname,St3} = new_var_name(St2), - LA = lineno_anno(Line, St3), - CGAnno = #a{anno=[list_comprehension|LA]}, - LAnno = #a{anno=LA}, - Tail = #c_var{anno=LA,name=Tname}, - {Arg,St4} = new_var(St3), - {Nc,[],St5} = expr({call,Lg,{atom,Lg,Name},[{var,Lg,Tname}]}, St4), - {Guardc,St6} = lc_guard_tests(Gs, St5), %These are always flat! - {Lc,Lps,St7} = lc_tq(Line, E, Qs1, Nc, St6), - {Pc,St8} = list_gen_pattern(P, Line, St7), - {Gc,Gps,St9} = safe(G, St8), %Will be a function argument! - Fc = function_clause([Arg], LA, {Name,1}), - - %% Avoid constructing a default clause if the list comprehension - %% only has a variable as generator and there are no guard - %% tests. In other words, if the comprehension is equivalent to - %% lists:map/2. - Cs0 = case {Guardc, Pc} of - {[], #c_var{}} -> - [#iclause{anno=LAnno, - pats=[#c_literal{anno=LA,val=[]}],guard=[], - body=[Mc]}]; - _ -> - [#iclause{anno=#a{anno=[compiler_generated|LA]}, - pats=[ann_c_cons(LA, Head, Tail)], - guard=[], - body=[Nc]}, - #iclause{anno=LAnno, - pats=[#c_literal{anno=LA,val=[]}],guard=[], - body=[Mc]}] - end, - Cs = case Pc of - nomatch -> Cs0; - _ -> - [#iclause{anno=LAnno, - pats=[ann_c_cons(LA, Pc, Tail)], - guard=Guardc, - body=Lps ++ [Lc]}|Cs0] - end, - Fun = #ifun{anno=LAnno,id=[],vars=[Arg],clauses=Cs,fc=Fc}, - {#iletrec{anno=CGAnno,defs=[{{Name,1},Fun}], - body=Gps ++ [#iapply{anno=LAnno, - op=#c_var{anno=LA,name={Name,1}}, - args=[Gc]}]}, - [],St9}; -lc_tq(Line, E, [{b_generate,Lg,P,G}|Qs0], Mc, St0) -> - {Gs,Qs1} = splitwith(fun is_guard_test/1, Qs0), - {Name,St1} = new_fun_name("blc", St0), LA = lineno_anno(Line, St1), LAnno = #a{anno=LA}, - CGAnno = #a{anno=[list_comprehension|LA]}, - HeadBinPattern = pattern(P, St1), - #c_binary{segments=Ps0} = HeadBinPattern, - {Ps,Tail,St2} = append_tail_segment(Ps0, St1), - {EPs,St3} = emasculate_segments(Ps, St2), - Pattern = HeadBinPattern#c_binary{segments=Ps}, - EPattern = HeadBinPattern#c_binary{segments=EPs}, - {Arg,St4} = new_var(St3), - {Guardc,St5} = lc_guard_tests(Gs, St4), %These are always flat! - Tname = Tail#c_var.name, - {Nc,[],St6} = expr({call,Lg,{atom,Lg,Name},[{var,Lg,Tname}]}, St5), - {Bc,Bps,St7} = lc_tq(Line, E, Qs1, Nc, St6), - {Gc,Gps,St10} = safe(G, St7), %Will be a function argument! - Fc = function_clause([Arg], LA, {Name,1}), - {TailSegList,_,St} = append_tail_segment([], St10), - Cs = [#iclause{anno=#a{anno=[compiler_generated|LA]}, - pats=[Pattern], - guard=Guardc, - body=Bps ++ [Bc]}, - #iclause{anno=#a{anno=[compiler_generated|LA]}, - pats=[EPattern], - guard=[], - body=[#iapply{anno=LAnno, - op=#c_var{anno=LA,name={Name,1}}, - args=[Tail]}]}, - #iclause{anno=LAnno, - pats=[#c_binary{anno=LA,segments=TailSegList}],guard=[], - body=[Mc]}], - Fun = #ifun{anno=LAnno,id=[],vars=[Arg],clauses=Cs,fc=Fc}, - {#iletrec{anno=CGAnno,defs=[{{Name,1},Fun}], - body=Gps ++ [#iapply{anno=LAnno, - op=#c_var{anno=LA,name={Name,1}}, - args=[Gc]}]}, - [],St}; -lc_tq(Line, E, [Fil0|Qs0], Mc, St0) -> - %% Special case sequences guard tests. - LA = lineno_anno(element(2, Fil0), St0), - LAnno = #a{anno=LA}, - CGAnno = #a{anno=[list_comprehension|LA]}, - case is_guard_test(Fil0) of - true -> - {Gs0,Qs1} = splitwith(fun is_guard_test/1, Qs0), - {Lc,Lps,St1} = lc_tq(Line, E, Qs1, Mc, St0), - {Gs,St2} = lc_guard_tests([Fil0|Gs0], St1), %These are always flat! - {#icase{anno=CGAnno, - args=[], - clauses=[#iclause{anno=LAnno,pats=[], - guard=Gs,body=Lps ++ [Lc]}], - fc=#iclause{anno=LAnno#a{anno=[compiler_generated|LA]}, - pats=[],guard=[],body=[Mc]}}, - [],St2}; - false -> - {Lc,Lps,St1} = lc_tq(Line, E, Qs0, Mc, St0), - {Fpat,St2} = new_var(St1), - Fc = fail_clause([Fpat], LA, - c_tuple([#c_literal{val=case_clause},Fpat])), - %% Do a novars little optimisation here. - {Filc,Fps,St3} = novars(Fil0, St2), - {#icase{anno=CGAnno, - args=[Filc], - clauses=[#iclause{anno=LAnno, - pats=[#c_literal{anno=LA,val=true}], - guard=[], - body=Lps ++ [Lc]}, - #iclause{anno=LAnno#a{anno=[compiler_generated|LA]}, - pats=[#c_literal{anno=LA,val=false}], - guard=[], - body=[Mc]}], - fc=Fc}, - Fps,St3} - end; + F = #c_var{anno=LA,name={Name,1}}, + Nc = #iapply{anno=GAnno,op=F,args=[Tail]}, + {Var,St2} = new_var(St1), + Fc = function_clause([Var], LA, {Name,1}), + TailClause = #iclause{anno=LAnno,pats=[TailPat],guard=[],body=[Mc]}, + Cs0 = case {AccPat,AccGuard} of + {SkipPat,[]} -> + %% Skip and accumulator patterns are the same and there is + %% no guard, no need to generate a skip clause. + [TailClause]; + _ -> + [#iclause{anno=#a{anno=[compiler_generated|LA]}, + pats=[SkipPat],guard=[],body=[Nc]}, + TailClause] + end, + {Cs,St4} = case AccPat of + nomatch -> + %% The accumulator pattern never matches, no need + %% for an accumulator clause. + {Cs0,St2}; + _ -> + {Lc,Lps,St3} = lc_tq(Line, E, Qs, Nc, St2), + {[#iclause{anno=LAnno,pats=[AccPat],guard=AccGuard, + body=Lps ++ [Lc]}|Cs0], + St3} + end, + Fun = #ifun{anno=LAnno,id=[],vars=[Var],clauses=Cs,fc=Fc}, + {#iletrec{anno=LAnno#a{anno=[list_comprehension|LA]},defs=[{{Name,1},Fun}], + body=Pre ++ [#iapply{anno=LAnno,op=F,args=[Arg]}]}, + [],St4}; +lc_tq(Line, E, [#ifilter{}=Filter|Qs], Mc, St) -> + filter_tq(Line, E, Filter, Mc, St, Qs, fun lc_tq/5); lc_tq(Line, E0, [], Mc0, St0) -> {H1,Hps,St1} = safe(E0, St0), {T1,Tps,St} = force_safe(Mc0, St1), @@ -1028,146 +944,60 @@ lc_tq(Line, E0, [], Mc0, St0) -> %% bc_tq(Line, Exp, [Qualifier], More, State) -> {LetRec,[PreExp],State}. %% This TQ from Gustafsson ERLANG'05. -%% This gets a bit messy as we must transform all directly here. We -%% recognise guard tests and try to fold them together and join to a -%% preceding generators, this should give us better and more compact -%% code. %% More could be transformed before calling bc_tq. -bc_tq(Line, Exp, Qualifiers, _, St0) -> +bc_tq(Line, Exp, Qs0, _, St0) -> {BinVar,St1} = new_var(St0), - {Sz,SzPre,St2} = bc_initial_size(Exp, Qualifiers, St1), - {E,BcPre,St} = bc_tq1(Line, Exp, Qualifiers, BinVar, St2), + {Sz,SzPre,St2} = bc_initial_size(Exp, Qs0, St1), + {Qs,St3} = preprocess_quals(Line, Qs0, St2), + {E,BcPre,St} = bc_tq1(Line, Exp, Qs, BinVar, St3), Pre = SzPre ++ [#iset{var=BinVar, arg=#iprimop{name=#c_literal{val=bs_init_writable}, args=[Sz]}}] ++ BcPre, {E,Pre,St}. -bc_tq1(Line, E, [{generate,Lg,P,G}|Qs0], AccExpr, St0) -> - {Gs,Qs1} = splitwith(fun is_guard_test/1, Qs0), - {Name,St1} = new_fun_name("lbc", St0), - LA = lineno_anno(Line, St1), - {[Head,Tail,AccVar],St2} = new_vars(LA, 3, St1), - LAnno = #a{anno=LA}, - CGAnno = #a{anno=[list_comprehension|LA]}, - {Arg,St3} = new_var(St2), - NewMore = {call,Lg,{atom,Lg,Name},[{var,Lg,Tail#c_var.name}, - {var,Lg,AccVar#c_var.name}]}, - {Guardc,St4} = lc_guard_tests(Gs, St3), %These are always flat! - {Lc,Lps,St5} = bc_tq1(Line, E, Qs1, AccVar, St4), - {Nc,Nps,St6} = expr(NewMore, St5), - {Pc,St7} = list_gen_pattern(P, Line, St6), - {Gc,Gps,St8} = safe(G, St7), %Will be a function argument! - Fc = function_clause([Arg,AccVar], LA, {Name,2}), - Cs0 = case {Guardc, Pc} of - {[], #c_var{}} -> - [#iclause{anno=LAnno, - pats=[#c_literal{anno=LA,val=[]},AccVar],guard=[], - body=[AccVar]}]; - _ -> - [#iclause{anno=#a{anno=[compiler_generated|LA]}, - pats=[ann_c_cons(LA, Head, Tail),AccVar], - guard=[], - body=Nps ++ [Nc]}, - #iclause{anno=LAnno, - pats=[#c_literal{anno=LA,val=[]},AccVar],guard=[], - body=[AccVar]}] - end, - Cs = case Pc of - nomatch -> Cs0; - _ -> - Body = Lps ++ Nps ++ [#iset{var=AccVar,arg=Lc},Nc], - [#iclause{anno=LAnno, - pats=[ann_c_cons(LA,Pc,Tail),AccVar], - guard=Guardc, - body=Body}|Cs0] - end, - Fun = #ifun{anno=LAnno,id=[],vars=[Arg,AccVar],clauses=Cs,fc=Fc}, - {#iletrec{anno=CGAnno,defs=[{{Name,2},Fun}], - body=Gps ++ [#iapply{anno=LAnno, - op=#c_var{anno=LA,name={Name,2}}, - args=[Gc,AccExpr]}]}, - [],St8}; -bc_tq1(Line, E, [{b_generate,Lg,P,G}|Qs0], AccExpr, St0) -> - {Gs,Qs1} = splitwith(fun is_guard_test/1, Qs0), +bc_tq1(Line, E, [#igen{anno=GAnno,acc_pat=AccPat,acc_guard=AccGuard, + skip_pat=SkipPat,tail=Tail,tail_pat=TailPat, + arg={Pre,Arg}}|Qs], Mc, St0) -> {Name,St1} = new_fun_name("lbc", St0), LA = lineno_anno(Line, St1), - {AccVar,St2} = new_var(LA, St1), LAnno = #a{anno=LA}, - CGAnno = #a{anno=[list_comprehension|LA]}, - HeadBinPattern = pattern(P, St2), - #c_binary{segments=Ps0} = HeadBinPattern, - {Ps,Tail,St3} = append_tail_segment(Ps0, St2), - {EPs,St4} = emasculate_segments(Ps, St3), - Pattern = HeadBinPattern#c_binary{segments=Ps}, - EPattern = HeadBinPattern#c_binary{segments=EPs}, - {Arg,St5} = new_var(St4), - NewMore = {call,Lg,{atom,Lg,Name},[{var,Lg,Tail#c_var.name}, - {var,Lg,AccVar#c_var.name}]}, - {Guardc,St6} = lc_guard_tests(Gs, St5), %These are always flat! - {Bc,Bps,St7} = bc_tq1(Line, E, Qs1, AccVar, St6), - {Nc,Nps,St8} = expr(NewMore, St7), - {Gc,Gps,St9} = safe(G, St8), %Will be a function argument! - Fc = function_clause([Arg,AccVar], LA, {Name,2}), - Body = Bps ++ Nps ++ [#iset{var=AccVar,arg=Bc},Nc], - {TailSegList,_,St} = append_tail_segment([], St9), - Cs = [#iclause{anno=LAnno, - pats=[Pattern,AccVar], - guard=Guardc, - body=Body}, - #iclause{anno=#a{anno=[compiler_generated|LA]}, - pats=[EPattern,AccVar], - guard=[], - body=Nps ++ [Nc]}, - #iclause{anno=LAnno, - pats=[#c_binary{anno=LA,segments=TailSegList},AccVar], - guard=[], - body=[AccVar]}], - Fun = #ifun{anno=CGAnno,id=[],vars=[Arg,AccVar],clauses=Cs,fc=Fc}, - {#iletrec{anno=LAnno,defs=[{{Name,2},Fun}], - body=Gps ++ [#iapply{anno=LAnno, - op=#c_var{anno=LA,name={Name,2}}, - args=[Gc,AccExpr]}]}, - [],St}; -bc_tq1(Line, E, [Fil0|Qs0], AccVar, St0) -> - %% Special case sequences guard tests. - LA = lineno_anno(element(2, Fil0), St0), - LAnno = #a{anno=LA}, - CGAnno = #a{anno=[list_comprehension|LA]}, - case is_guard_test(Fil0) of - true -> - {Gs0,Qs1} = splitwith(fun is_guard_test/1, Qs0), - {Bc,Bps,St1} = bc_tq1(Line, E, Qs1, AccVar, St0), - {Gs,St} = lc_guard_tests([Fil0|Gs0], St1), %These are always flat! - {#icase{anno=CGAnno, - args=[], - clauses=[#iclause{anno=LAnno, - pats=[], - guard=Gs,body=Bps ++ [Bc]}], - fc=#iclause{anno=LAnno#a{anno=[compiler_generated|LA]}, - pats=[],guard=[],body=[AccVar]}}, - [],St}; - false -> - {Bc,Bps,St1} = bc_tq1(Line, E, Qs0, AccVar, St0), - {Fpat,St2} = new_var(St1), - Fc = fail_clause([Fpat], LA, - c_tuple([#c_literal{val=case_clause},Fpat])), - %% Do a novars little optimisation here. - {Filc,Fps,St} = novars(Fil0, St2), - {#icase{anno=CGAnno, - args=[Filc], - clauses=[#iclause{anno=LAnno, - pats=[#c_literal{anno=LA,val=true}], - guard=[], - body=Bps ++ [Bc]}, - #iclause{anno=LAnno#a{anno=[compiler_generated|LA]}, - pats=[#c_literal{anno=LA,val=false}], - guard=[], - body=[AccVar]}], - fc=Fc}, - Fps,St} - end; + {Vars=[_,AccVar],St2} = new_vars(LA, 2, St1), + F = #c_var{anno=LA,name={Name,2}}, + Nc = #iapply{anno=GAnno,op=F,args=[Tail,AccVar]}, + Fc = function_clause(Vars, LA, {Name,2}), + TailClause = #iclause{anno=LAnno,pats=[TailPat,AccVar],guard=[], + body=[AccVar]}, + Cs0 = case {AccPat,AccGuard} of + {SkipPat,[]} -> + %% Skip and accumulator patterns are the same and there is + %% no guard, no need to generate a skip clause. + [TailClause]; + _ -> + [#iclause{anno=#a{anno=[compiler_generated|LA]}, + pats=[SkipPat,AccVar],guard=[],body=[Nc]}, + TailClause] + end, + {Cs,St4} = case AccPat of + nomatch -> + %% The accumulator pattern never matches, no need + %% for an accumulator clause. + {Cs0,St2}; + _ -> + {Bc,Bps,St3} = bc_tq1(Line, E, Qs, AccVar, St2), + Body = Bps ++ [#iset{var=AccVar,arg=Bc},Nc], + {[#iclause{anno=LAnno, + pats=[AccPat,AccVar],guard=AccGuard, + body=Body}|Cs0], + St3} + end, + Fun = #ifun{anno=LAnno,id=[],vars=Vars,clauses=Cs,fc=Fc}, + {#iletrec{anno=LAnno#a{anno=[list_comprehension|LA]},defs=[{{Name,2},Fun}], + body=Pre ++ [#iapply{anno=LAnno,op=F,args=[Arg,Mc]}]}, + [],St4}; +bc_tq1(Line, E, [#ifilter{}=Filter|Qs], Mc, St) -> + filter_tq(Line, E, Filter, Mc, St, Qs, fun bc_tq1/5); bc_tq1(_, {bin,Bl,Elements}, [], AccVar, St0) -> {E,Pre,St} = expr({bin,Bl,[{bin_element,Bl, {var,Bl,AccVar#c_var.name}, @@ -1175,16 +1005,154 @@ bc_tq1(_, {bin,Bl,Elements}, [], AccVar, St0) -> [binary,{unit,1}]}|Elements]}, St0), #a{anno=A} = Anno0 = get_anno(E), Anno = Anno0#a{anno=[compiler_generated,single_use|A]}, - %%Anno = Anno0#a{anno=[compiler_generated|A]}, {set_anno(E, Anno),Pre,St}. +%% filter_tq(Line, Expr, Filter, Mc, State, [Qualifier], TqFun) -> +%% {Case,[PreExpr],State}. +%% Transform an intermediate comprehension filter to its intermediate case +%% representation. + +filter_tq(Line, E, #ifilter{anno=#a{anno=LA}=LAnno,arg={Pre,Arg}}, + Mc, St0, Qs, TqFun) -> + %% The filter is an expression, it is compiled to a case of degree 1 with + %% 3 clauses, one accumulating, one skipping and the final one throwing + %% {case_clause,Value} where Value is the result of the filter and is not a + %% boolean. + {Lc,Lps,St1} = TqFun(Line, E, Qs, Mc, St0), + {FailPat,St2} = new_var(St1), + Fc = fail_clause([FailPat], LA, + c_tuple([#c_literal{val=case_clause},FailPat])), + {#icase{anno=LAnno#a{anno=[list_comprehension|LA]},args=[Arg], + clauses=[#iclause{anno=LAnno, + pats=[#c_literal{val=true}],guard=[], + body=Lps ++ [Lc]}, + #iclause{anno=LAnno#a{anno=[compiler_generated|LA]}, + pats=[#c_literal{val=false}],guard=[], + body=[Mc]}], + fc=Fc}, + Pre,St2}; +filter_tq(Line, E, #ifilter{anno=#a{anno=LA}=LAnno,arg=Guard}, + Mc, St0, Qs, TqFun) when is_list(Guard) -> + %% Otherwise it is a guard, compiled to a case of degree 0 with 2 clauses, + %% the first matches if the guard succeeds and the comprehension continues + %% or the second one is selected and the current element is skipped. + {Lc,Lps,St1} = TqFun(Line, E, Qs, Mc, St0), + {#icase{anno=LAnno#a{anno=[list_comprehension|LA]},args=[], + clauses=[#iclause{anno=LAnno,pats=[],guard=Guard,body=Lps ++ [Lc]}], + fc=#iclause{anno=LAnno#a{anno=[compiler_generated|LA]}, + pats=[],guard=[],body=[Mc]}}, + [],St1}. + +%% preprocess_quals(Line, [Qualifier], State) -> {[Qualifier'],State}. +%% Preprocess a list of Erlang qualifiers into its intermediate representation, +%% represented as a list of #igen{} and #ifilter{} records. We recognise guard +%% tests and try to fold them together and join to a preceding generators, this +%% should give us better and more compact code. + +preprocess_quals(Line, Qs, St) -> + preprocess_quals(Line, Qs, St, []). + +preprocess_quals(Line, [Q|Qs0], St0, Acc) -> + case is_generator(Q) of + true -> + {Gs,Qs} = splitwith(fun is_guard_test/1, Qs0), + {Gen,St} = generator(Line, Q, Gs, St0), + preprocess_quals(Line, Qs, St, [Gen|Acc]); + false -> + LAnno = #a{anno=lineno_anno(get_anno(Q), St0)}, + case is_guard_test(Q) of + true -> + %% When a filter is a guard test, its argument in the + %% #ifilter{} record is a list as returned by + %% lc_guard_tests/2. + {Gs,Qs} = splitwith(fun is_guard_test/1, Qs0), + {Cg,St} = lc_guard_tests([Q|Gs], St0), + Filter = #ifilter{anno=LAnno,arg=Cg}, + preprocess_quals(Line, Qs, St, [Filter|Acc]); + false -> + %% Otherwise, it is a pair {Pre,Arg} as in a generator + %% input. + {Ce,Pre,St} = novars(Q, St0), + Filter = #ifilter{anno=LAnno,arg={Pre,Ce}}, + preprocess_quals(Line, Qs0, St, [Filter|Acc]) + end + end; +preprocess_quals(_, [], St, Acc) -> + {reverse(Acc),St}. + +is_generator({generate,_,_,_}) -> true; +is_generator({b_generate,_,_,_}) -> true; +is_generator(_) -> false. + +%% +%% Generators are abstracted as sextuplets: +%% - acc_pat is the accumulator pattern, e.g. [Pat|Tail] for Pat <- Expr. +%% - acc_guard is the list of guards immediately following the current +%% generator in the qualifier list input. +%% - skip_pat is the skip pattern, e.g. <<X,_:X,Tail/bitstring>> for +%% <<X,1:X>> <= Expr. +%% - tail is the variable used in AccPat and SkipPat bound to the rest of the +%% generator input. +%% - tail_pat is the tail pattern, respectively [] and <<_/bitstring>> for list +%% and bit string generators. +%% - arg is a pair {Pre,Arg} where Pre is the list of expressions to be +%% inserted before the comprehension function and Arg is the expression +%% that it should be passed. +%% + +%% generator(Line, Generator, Guard, State) -> {Generator',State}. +%% Transform a given generator into its #igen{} representation. + +generator(Line, {generate,Lg,P0,E}, Gs, St0) -> + LA = lineno_anno(Line, St0), + GA = lineno_anno(Lg, St0), + {Head,St1} = list_gen_pattern(P0, Line, St0), + {[Tail,Skip],St2} = new_vars(2, St1), + {Cg,St3} = lc_guard_tests(Gs, St2), + {AccPat,SkipPat} = case Head of + #c_var{} -> + %% If the generator pattern is a variable, the + %% pattern from the accumulator clause can be + %% reused in the skip one. lc_tq and bc_tq1 takes + %% care of dismissing the latter in that case. + Cons = ann_c_cons(LA, Head, Tail), + {Cons,Cons}; + nomatch -> + %% If it never matches, there is no need for + %% an accumulator clause. + {nomatch,ann_c_cons(LA, Skip, Tail)}; + _ -> + {ann_c_cons(LA, Head, Tail), + ann_c_cons(LA, Skip, Tail)} + end, + {Ce,Pre,St4} = safe(E, St3), + Gen = #igen{anno=#a{anno=GA},acc_pat=AccPat,acc_guard=Cg,skip_pat=SkipPat, + tail=Tail,tail_pat=#c_literal{anno=LA,val=[]},arg={Pre,Ce}}, + {Gen,St4}; +generator(Line, {b_generate,Lg,P,E}, Gs, St0) -> + LA = lineno_anno(Line, St0), + GA = lineno_anno(Lg, St0), + Cp = #c_binary{segments=Segs} = pattern(P, St0), + %% The function append_tail_segment/2 keeps variable patterns as-is, making + %% it possible to have the same skip clause removal as with list generators. + {AccSegs,Tail,TailSeg,St1} = append_tail_segment(Segs, St0), + AccPat = Cp#c_binary{segments=AccSegs}, + {Cg,St2} = lc_guard_tests(Gs, St1), + {SkipSegs,St3} = emasculate_segments(AccSegs, St2), + SkipPat = Cp#c_binary{segments=SkipSegs}, + {Ce,Pre,St4} = safe(E, St3), + Gen = #igen{anno=#a{anno=GA},acc_pat=AccPat,acc_guard=Cg,skip_pat=SkipPat, + tail=Tail,tail_pat=#c_binary{anno=LA,segments=[TailSeg]}, + arg={Pre,Ce}}, + {Gen,St4}. + append_tail_segment(Segs, St0) -> {Var,St} = new_var(St0), Tail = #c_bitstr{val=Var,size=#c_literal{val=all}, unit=#c_literal{val=1}, type=#c_literal{val=binary}, flags=#c_literal{val=[unsigned,big]}}, - {Segs++[Tail],Var,St}. + {Segs++[Tail],Var,Tail,St}. emasculate_segments(Segs, St) -> emasculate_segments(Segs, St, []). @@ -1195,7 +1163,7 @@ emasculate_segments([B|Rest], St0, Acc) -> {Var,St1} = new_var(St0), emasculate_segments(Rest, St1, [B#c_bitstr{val=Var}|Acc]); emasculate_segments([], St, Acc) -> - {lists:reverse(Acc),St}. + {reverse(Acc),St}. lc_guard_tests([], St) -> {[],St}; lc_guard_tests(Gs0, St0) -> |