From ff432e262e65243cbc983fcb002527f8fae8c78b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Fri, 9 Apr 2010 15:50:17 +0200 Subject: EEP-23: Allow variables in fun M:F/A Currently, the external fun syntax "fun M:F/A" only supports literals. That is, "fun lists:reverse/1" is allowed but not "fun M:F/A". In many real-life situations, some or all of M, F, A are not known until run-time, and one is forced to either use the undocumented erlang:make_fun/3 BIF or to use a "tuple fun" (which is deprecated). EEP-23 suggests that the parser (erl_parse) should immediately transform "fun M:F/A" to "erlang:make_fun(M, F, A)". We have not followed that approach in this implementation, because we want the abstract code to mirror the source code as closely as possible, and we also consider erlang:make_fun/3 to be an implementation detail that we might want to remove in the future. Instead, we will change the abstract format for "fun M:F/A" (in a way that is not backwards compatible), and while we are at it, we will move the translation from "fun M:F/A" to "erlang:make_fun(M, F, A)" from sys_pre_expand down to the v3_core pass. We will also update the debugger and xref to use the new format. We did consider making the abstract format backward compatible if no variables were used in the fun, but decided against it. Keeping it backward compatible would mean that there would be different abstract formats for the no-variable and variable case, and tools would have to handle both formats, probably forever. Reference: http://www.erlang.org/eeps/eep-0023.html --- lib/stdlib/src/erl_eval.erl | 3 ++- lib/stdlib/src/erl_lint.erl | 9 +++++++-- lib/stdlib/src/erl_parse.yrl | 12 +++++++++--- lib/stdlib/src/erl_pp.erl | 10 +++++++++- lib/stdlib/src/qlc.erl | 5 ++++- 5 files changed, 31 insertions(+), 8 deletions(-) (limited to 'lib/stdlib/src') diff --git a/lib/stdlib/src/erl_eval.erl b/lib/stdlib/src/erl_eval.erl index 4f4fa16040..88a0094d57 100644 --- a/lib/stdlib/src/erl_eval.erl +++ b/lib/stdlib/src/erl_eval.erl @@ -256,7 +256,8 @@ expr({'receive',_,Cs}, Bs, Lf, Ef, RBs) -> expr({'receive',_, Cs, E, TB}, Bs0, Lf, Ef, RBs) -> {value,T,Bs} = expr(E, Bs0, Lf, Ef, none), receive_clauses(T, Cs, {TB,Bs}, Bs0, Lf, Ef, [], RBs); -expr({'fun',_Line,{function,Mod,Name,Arity}}, Bs, _Lf, _Ef, RBs) -> +expr({'fun',_Line,{function,Mod0,Name0,Arity0}}, Bs0, Lf, Ef, RBs) -> + {[Mod,Name,Arity],Bs} = expr_list([Mod0,Name0,Arity0], Bs0, Lf, Ef), F = erlang:make_fun(Mod, Name, Arity), ret_expr(F, Bs, RBs); expr({'fun',_Line,{function,Name,Arity}}, _Bs0, _Lf, _Ef, _RBs) -> % R8 diff --git a/lib/stdlib/src/erl_lint.erl b/lib/stdlib/src/erl_lint.erl index 78b996d94b..5d45260fe9 100644 --- a/lib/stdlib/src/erl_lint.erl +++ b/lib/stdlib/src/erl_lint.erl @@ -2127,8 +2127,13 @@ expr({'fun',Line,Body}, Vt, St) -> true -> {[],St}; false -> {[],call_function(Line, F, A, St)} end; - {function,_M,_F,_A} -> - {[],St} + {function,M,F,A} when is_atom(M), is_atom(F), is_integer(A) -> + %% Compatibility with pre-R15 abstract format. + {[],St}; + {function,M,F,A} -> + %% New in R15. + {Bvt, St1} = expr_list([M,F,A], Vt, St), + {vtupdate(Bvt, Vt),St1} end; expr({call,_Line,{atom,_Lr,is_record},[E,{atom,Ln,Name}]}, Vt, St0) -> {Rvt,St1} = expr(E, Vt, St0), diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl index 709bd83e6f..928c10f7f2 100644 --- a/lib/stdlib/src/erl_parse.yrl +++ b/lib/stdlib/src/erl_parse.yrl @@ -35,7 +35,7 @@ tuple %struct record_expr record_tuple record_field record_fields if_expr if_clause if_clauses case_expr cr_clause cr_clauses receive_expr -fun_expr fun_clause fun_clauses +fun_expr fun_clause fun_clauses atom_or_var integer_or_var try_expr try_catch try_clause try_clauses query_expr function_call argument_list exprs guard @@ -395,11 +395,17 @@ receive_expr -> 'receive' cr_clauses 'after' expr clause_body 'end' : fun_expr -> 'fun' atom '/' integer : {'fun',?line('$1'),{function,element(3, '$2'),element(3, '$4')}}. -fun_expr -> 'fun' atom ':' atom '/' integer : - {'fun',?line('$1'),{function,element(3, '$2'),element(3, '$4'),element(3,'$6')}}. +fun_expr -> 'fun' atom_or_var ':' atom_or_var '/' integer_or_var : + {'fun',?line('$1'),{function,'$2','$4','$6'}}. fun_expr -> 'fun' fun_clauses 'end' : build_fun(?line('$1'), '$2'). +atom_or_var -> atom : '$1'. +atom_or_var -> var : '$1'. + +integer_or_var -> integer : '$1'. +integer_or_var -> var : '$1'. + fun_clauses -> fun_clause : ['$1']. fun_clauses -> fun_clause ';' fun_clauses : ['$1' | '$3']. diff --git a/lib/stdlib/src/erl_pp.erl b/lib/stdlib/src/erl_pp.erl index 7dc19f2e9b..6b5aa951cf 100644 --- a/lib/stdlib/src/erl_pp.erl +++ b/lib/stdlib/src/erl_pp.erl @@ -457,8 +457,16 @@ lexpr({'fun',_,{function,F,A}}, _Prec, _Hook) -> leaf(format("fun ~w/~w", [F,A])); lexpr({'fun',_,{function,F,A},Extra}, _Prec, _Hook) -> {force_nl,fun_info(Extra),leaf(format("fun ~w/~w", [F,A]))}; -lexpr({'fun',_,{function,M,F,A}}, _Prec, _Hook) -> +lexpr({'fun',_,{function,M,F,A}}, _Prec, _Hook) + when is_atom(M), is_atom(F), is_integer(A) -> + %% For backward compatibility with pre-R15 abstract format. leaf(format("fun ~w:~w/~w", [M,F,A])); +lexpr({'fun',_,{function,M,F,A}}, _Prec, Hook) -> + %% New format in R15. + NameItem = lexpr(M, Hook), + CallItem = lexpr(F, Hook), + ArityItem = lexpr(A, Hook), + ["fun ",NameItem,$:,CallItem,$/,ArityItem]; lexpr({'fun',_,{clauses,Cs}}, _Prec, Hook) -> {list,[{first,'fun',fun_clauses(Cs, Hook)},'end']}; lexpr({'fun',_,{clauses,Cs},Extra}, _Prec, Hook) -> diff --git a/lib/stdlib/src/qlc.erl b/lib/stdlib/src/qlc.erl index f5e180b4bd..2b691e6abf 100644 --- a/lib/stdlib/src/qlc.erl +++ b/lib/stdlib/src/qlc.erl @@ -1272,7 +1272,10 @@ abstr_term(Fun, Line) when is_function(Fun) -> case erlang:fun_info(Fun, type) of {type, external} -> {module, Module} = erlang:fun_info(Fun, module), - {'fun', Line, {function,Module,Name,Arity}}; + {'fun', Line, {function, + {atom,Line,Module}, + {atom,Line,Name}, + {integer,Line,Arity}}}; {type, local} -> {'fun', Line, {function,Name,Arity}} end -- cgit v1.2.3