diff options
Diffstat (limited to 'lib/stdlib/src/erl_expand_records.erl')
| -rw-r--r-- | lib/stdlib/src/erl_expand_records.erl | 132 |
1 files changed, 130 insertions, 2 deletions
diff --git a/lib/stdlib/src/erl_expand_records.erl b/lib/stdlib/src/erl_expand_records.erl index a38b7639d8..18c467db81 100644 --- a/lib/stdlib/src/erl_expand_records.erl +++ b/lib/stdlib/src/erl_expand_records.erl @@ -95,8 +95,9 @@ forms([F | Fs0], St0) -> forms([], St) -> {[],St}. clauses([{clause,Line,H0,G0,B0} | Cs0], St0) -> - {H,St1} = head(H0, St0), - {G,St2} = guard(G0, St1), + {H1,St1} = head(H0, St0), + {G1,St2} = guard(G0, St1), + {H,G} = optimize_is_record(H1, G1), {B,St3} = exprs(B0, St2), {Cs,St4} = clauses(Cs0, St3), {[{clause,Line,H,G,B} | Cs],St4}; @@ -800,5 +801,132 @@ imported(F, A, St) -> error -> no end. +%%% +%%% Replace is_record/3 in guards with matching if possible. +%%% + +optimize_is_record(H0, G0) -> + case opt_rec_vars(G0) of + [] -> + {H0,G0}; + Rs0 -> + {H,Rs} = opt_pattern_list(H0, Rs0), + G = opt_remove(G0, Rs), + {H,G} + end. + + +%% opt_rec_vars(Guards) -> Vars. +%% Search through the guard expression, looking for +%% variables referenced in those is_record/3 calls that +%% will fail the entire guard if they evaluate to 'false' +%% +%% In the following code +%% +%% f(X, Y, Z) when is_record(X, r1) andalso +%% (is_record(Y, r2) orelse is_record(Z, r3)) +%% +%% the entire guard will be false if the record test for +%% X fails, and the clause can be rewritten to: +%% +%% f({r1,...}=X, Y, Z) when true andalso +%% (is_record(Y, r2) or is_record(Z, r3)) +%% +opt_rec_vars([G|Gs]) -> + Rs = opt_rec_vars_1(G, orddict:new()), + opt_rec_vars(Gs, Rs); +opt_rec_vars([]) -> orddict:new(). + +opt_rec_vars([G|Gs], Rs0) -> + Rs1 = opt_rec_vars_1(G, orddict:new()), + Rs = ordsets:intersection(Rs0, Rs1), + opt_rec_vars(Gs, Rs); +opt_rec_vars([], Rs) -> Rs. + +opt_rec_vars_1([T|Ts], Rs0) -> + Rs = opt_rec_vars_2(T, Rs0), + opt_rec_vars_1(Ts, Rs); +opt_rec_vars_1([], Rs) -> Rs. + +opt_rec_vars_2({op,_,'and',A1,A2}, Rs) -> + opt_rec_vars_1([A1,A2], Rs); +opt_rec_vars_2({op,_,'andalso',A1,A2}, Rs) -> + opt_rec_vars_1([A1,A2], Rs); +opt_rec_vars_2({op,_,'orelse',Arg,{atom,_,fail}}, Rs) -> + %% Since the second argument guarantees failure, + %% it is safe to inspect the first argument. + opt_rec_vars_2(Arg, Rs); +opt_rec_vars_2({call,_,{remote,_,{atom,_,erlang},{atom,_,is_record}}, + [{var,_,V},{atom,_,Tag},{integer,_,Sz}]}, Rs) -> + orddict:store(V, {Tag,Sz}, Rs); +opt_rec_vars_2({call,_,{atom,_,is_record}, + [{var,_,V},{atom,_,Tag},{integer,_,Sz}]}, Rs) -> + orddict:store(V, {Tag,Sz}, Rs); +opt_rec_vars_2(_, Rs) -> Rs. + +opt_pattern_list(Ps, Rs) -> + opt_pattern_list(Ps, Rs, []). + +opt_pattern_list([P0|Ps], Rs0, Acc) -> + {P,Rs} = opt_pattern(P0, Rs0), + opt_pattern_list(Ps, Rs, [P|Acc]); +opt_pattern_list([], Rs, Acc) -> + {reverse(Acc),Rs}. + +opt_pattern({var,_,V}=Var, Rs0) -> + case orddict:find(V, Rs0) of + {ok,{Tag,Sz}} -> + Rs = orddict:store(V, {remove,Tag,Sz}, Rs0), + {opt_var(Var, Tag, Sz),Rs}; + _ -> + {Var,Rs0} + end; +opt_pattern({cons,Line,H0,T0}, Rs0) -> + {H,Rs1} = opt_pattern(H0, Rs0), + {T,Rs} = opt_pattern(T0, Rs1), + {{cons,Line,H,T},Rs}; +opt_pattern({tuple,Line,Es0}, Rs0) -> + {Es,Rs} = opt_pattern_list(Es0, Rs0), + {{tuple,Line,Es},Rs}; +opt_pattern({match,Line,Pa0,Pb0}, Rs0) -> + {Pa,Rs1} = opt_pattern(Pa0, Rs0), + {Pb,Rs} = opt_pattern(Pb0, Rs1), + {{match,Line,Pa,Pb},Rs}; +opt_pattern(P, Rs) -> {P,Rs}. + +opt_var({var,Line,_}=Var, Tag, Sz) -> + Rp = record_pattern(2, -1, ignore, Sz, Line, [{atom,Line,Tag}]), + {match,Line,{tuple,Line,Rp},Var}. + +opt_remove(Gs, Rs) -> + [opt_remove_1(G, Rs) || G <- Gs]. + +opt_remove_1(Ts, Rs) -> + [opt_remove_2(T, Rs) || T <- Ts]. + +opt_remove_2({op,L,'and'=Op,A1,A2}, Rs) -> + {op,L,Op,opt_remove_2(A1, Rs),opt_remove_2(A2, Rs)}; +opt_remove_2({op,L,'andalso'=Op,A1,A2}, Rs) -> + {op,L,Op,opt_remove_2(A1, Rs),opt_remove_2(A2, Rs)}; +opt_remove_2({op,L,'orelse',A1,A2}, Rs) -> + {op,L,'orelse',opt_remove_2(A1, Rs),A2}; +opt_remove_2({call,Line,{remote,_,{atom,_,erlang},{atom,_,is_record}}, + [{var,_,V},{atom,_,Tag},{integer,_,Sz}]}=A, Rs) -> + case orddict:find(V, Rs) of + {ok,{remove,Tag,Sz}} -> + {atom,Line,true}; + _ -> + A + end; +opt_remove_2({call,Line,{atom,_,is_record}, + [{var,_,V},{atom,_,Tag},{integer,_,Sz}]}=A, Rs) -> + case orddict:find(V, Rs) of + {ok,{remove,Tag,Sz}} -> + {atom,Line,true}; + _ -> + A + end; +opt_remove_2(A, _) -> A. + neg_line(L) -> erl_parse:set_line(L, fun(Line) -> -abs(Line) end). |