From 0edb6a4d2d76960846fd04ecce3aa00b3348691b Mon Sep 17 00:00:00 2001 From: Stavros Aronis Date: Sun, 30 May 2010 20:02:39 +0300 Subject: Add '-callback' attribute to language syntax Behaviours may define specs for their callbacks using the familiar spec syntax, replacing the '-spec' keyword with '-callback'. Simple lint checks are performed to ensure that no callbacks are defined twice and all types referred are declared. These attributes can be then used by tools to provide documentation to the behaviour or find discrepancies in the callback definitions in the callback module. --- lib/compiler/src/compile.erl | 2 ++ lib/stdlib/src/erl_lint.erl | 25 +++++++++++++++++++++++-- lib/stdlib/src/erl_parse.yrl | 10 +++++++--- 3 files changed, 32 insertions(+), 5 deletions(-) (limited to 'lib') diff --git a/lib/compiler/src/compile.erl b/lib/compiler/src/compile.erl index 15849957e7..bfa7c6cedd 100644 --- a/lib/compiler/src/compile.erl +++ b/lib/compiler/src/compile.erl @@ -1512,6 +1512,8 @@ restore_expand_module([{attribute,Line,opaque,[Type]}|Fs]) -> [{attribute,Line,opaque,Type}|restore_expand_module(Fs)]; restore_expand_module([{attribute,Line,spec,[Arg]}|Fs]) -> [{attribute,Line,spec,Arg}|restore_expand_module(Fs)]; +restore_expand_module([{attribute,Line,callback,[Arg]}|Fs]) -> + [{attribute,Line,callback,Arg}|restore_expand_module(Fs)]; restore_expand_module([F|Fs]) -> [F|restore_expand_module(Fs)]; restore_expand_module([]) -> []. diff --git a/lib/stdlib/src/erl_lint.erl b/lib/stdlib/src/erl_lint.erl index dd0b9bc2ab..0d8773ff0d 100644 --- a/lib/stdlib/src/erl_lint.erl +++ b/lib/stdlib/src/erl_lint.erl @@ -123,6 +123,7 @@ value_option(Flag, Default, On, OnVal, Off, OffVal, Opts) -> called= [] :: [{fa(),line()}], %Called functions usage = #usage{} :: #usage{}, specs = dict:new() :: dict(), %Type specifications + callbacks = dict:new() :: dict(), %Callback types types = dict:new() :: dict(), %Type definitions exp_types=gb_sets:empty():: gb_set() %Exported types }). @@ -310,8 +311,6 @@ format_error({conflicting_behaviours,{Name,Arity},B,FirstL,FirstB}) -> format_error({undefined_behaviour_func, {Func,Arity}, Behaviour}) -> io_lib:format("undefined callback function ~w/~w (behaviour '~w')", [Func,Arity,Behaviour]); -format_error({undefined_behaviour_func, {Func,Arity,_Spec}, Behaviour}) -> - format_error({undefined_behaviour_func, {Func,Arity}, Behaviour}); format_error({undefined_behaviour,Behaviour}) -> io_lib:format("behaviour ~w undefined", [Behaviour]); format_error({undefined_behaviour_callbacks,Behaviour}) -> @@ -348,12 +347,16 @@ format_error({type_syntax, Constr}) -> io_lib:format("bad ~w type", [Constr]); format_error({redefine_spec, {M, F, A}}) -> io_lib:format("spec for ~w:~w/~w already defined", [M, F, A]); +format_error({redefine_callback, {M, F, A}}) -> + io_lib:format("callback ~w:~w/~w already defined", [M, F, A]); format_error({spec_fun_undefined, {M, F, A}}) -> io_lib:format("spec for undefined function ~w:~w/~w", [M, F, A]); format_error({missing_spec, {F,A}}) -> io_lib:format("missing specification for function ~w/~w", [F, A]); format_error(spec_wrong_arity) -> "spec has the wrong arity"; +format_error(callback_wrong_arity) -> + "callback has the wrong arity"; format_error({imported_predefined_type, Name}) -> io_lib:format("referring to built-in type ~w as a remote type; " "please take out the module name", [Name]); @@ -747,6 +750,8 @@ attribute_state({attribute,L,opaque,{TypeName,TypeDef,Args}}, St) -> type_def(opaque, L, TypeName, TypeDef, Args, St); attribute_state({attribute,L,spec,{Fun,Types}}, St) -> spec_decl(L, Fun, Types, St); +attribute_state({attribute,L,callback,{Fun,Types}}, St) -> + callback_decl(L, Fun, Types, St); attribute_state({attribute,L,on_load,Val}, St) -> on_load(L, Val, St); attribute_state({attribute,_L,_Other,_Val}, St) -> % Ignore others @@ -2770,6 +2775,20 @@ spec_decl(Line, MFA0, TypeSpecs, St0 = #lint{specs = Specs, module = Mod}) -> false -> check_specs(TypeSpecs, Arity, St1) end. +%% callback_decl(Line, Fun, Types, State) -> State. + +callback_decl(Line, MFA0, TypeSpecs, + St0 = #lint{callbacks = Callbacks, module = Mod}) -> + MFA = case MFA0 of + {F, Arity} -> {Mod, F, Arity}; + {_M, _F, Arity} -> MFA0 + end, + St1 = St0#lint{callbacks = dict:store(MFA, Line, Callbacks)}, + case dict:is_key(MFA, Callbacks) of + true -> add_error(Line, {redefine_callback, MFA}, St1); + false -> check_specs(TypeSpecs, Arity, St1) + end. + check_specs([FunType|Left], Arity, St0) -> {FunType1, CTypes} = case FunType of @@ -3275,6 +3294,8 @@ modify_line1({attribute,L,record,{Name,Fields}}, Mf) -> {attribute,Mf(L),record,{Name,modify_line1(Fields, Mf)}}; modify_line1({attribute,L,spec,{Fun,Types}}, Mf) -> {attribute,Mf(L),spec,{Fun,modify_line1(Types, Mf)}}; +modify_line1({attribute,L,callback,{Fun,Types}}, Mf) -> + {attribute,Mf(L),callback,{Fun,modify_line1(Types, Mf)}}; modify_line1({attribute,L,type,{TypeName,TypeDef,Args}}, Mf) -> {attribute,Mf(L),type,{TypeName,modify_line1(TypeDef, Mf), modify_line1(Args, Mf)}}; diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl index bd5d65a1e1..709bd83e6f 100644 --- a/lib/stdlib/src/erl_parse.yrl +++ b/lib/stdlib/src/erl_parse.yrl @@ -62,7 +62,7 @@ char integer float atom string var '==' '/=' '=<' '<' '>=' '>' '=:=' '=/=' '<=' '<<' '>>' '!' '=' '::' '..' '...' -'spec' % helper +'spec' 'callback' % helper dot. Expect 2. @@ -77,6 +77,7 @@ attribute -> '-' atom attr_val : build_attribute('$2', '$3'). attribute -> '-' atom typed_attr_val : build_typed_attribute('$2','$3'). attribute -> '-' atom '(' typed_attr_val ')' : build_typed_attribute('$2','$4'). attribute -> '-' 'spec' type_spec : build_type_spec('$2', '$3'). +attribute -> '-' 'callback' type_spec : build_type_spec('$2', '$3'). type_spec -> spec_fun type_sigs : {'$1', '$2'}. type_spec -> '(' spec_fun type_sigs ')' : {'$2', '$3'}. @@ -549,6 +550,8 @@ Erlang code. ErrorInfo :: error_info(). parse_form([{'-',L1},{atom,L2,spec}|Tokens]) -> parse([{'-',L1},{'spec',L2}|Tokens]); +parse_form([{'-',L1},{atom,L2,callback}|Tokens]) -> + parse([{'-',L1},{'callback',L2}|Tokens]); parse_form(Tokens) -> parse(Tokens). @@ -603,7 +606,8 @@ build_typed_attribute({atom,La,Attr},_) -> _ -> ret_err(La, "bad attribute") end. -build_type_spec({spec,La}, {SpecFun, TypeSpecs}) -> +build_type_spec({Kind,La}, {SpecFun, TypeSpecs}) + when (Kind =:= spec) or (Kind =:= callback) -> NewSpecFun = case SpecFun of {atom, _, Fun} -> @@ -617,7 +621,7 @@ build_type_spec({spec,La}, {SpecFun, TypeSpecs}) -> %% Old style spec. Allow this for now. {Mod,Fun,Arity} end, - {attribute,La,spec,{NewSpecFun, TypeSpecs}}. + {attribute,La,Kind,{NewSpecFun, TypeSpecs}}. find_arity_from_specs([Spec|_]) -> %% Use the first spec to find the arity. If all are not the same, -- cgit v1.2.3