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authorBjörn Gustavsson <[email protected]>2014-02-19 09:50:08 +0100
committerBjörn Gustavsson <[email protected]>2014-02-19 10:15:06 +0100
commitf2b3aa8c6a73137e26f95fb8b1c7102126af30af (patch)
tree2d21b53298646b65721e5b150d2271a18cf0acb4
parent6c9002f9174d40b69b3a5bcd5ef219ce4ceb3622 (diff)
parent78ce8917d580e9eb1fead2e6b9a9ec2840347f4e (diff)
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Merge branch 'nox/compiler/v3_core-comprehensions-cleanup'
* nox/compiler/v3_core-comprehensions-cleanup: Simplify comprehension compilation in v3_core OTP-11720
-rw-r--r--lib/compiler/src/v3_core.erl492
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) ->