%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2000-2009. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
%% Purpose: Core Erlang abstract syntax functions.
-module(core_lib).
-export([get_anno/1,set_anno/2]).
-export([is_literal/1,is_literal_list/1]).
-export([literal_value/1]).
-export([make_values/1]).
-export([is_var_used/2]).
-include("core_parse.hrl").
%%
%% Generic get/set annotation that should be used only with cerl() structures.
%%
-spec get_anno(cerl:cerl()) -> term().
get_anno(C) -> element(2, C).
-spec set_anno(cerl:cerl(), term()) -> cerl:cerl().
set_anno(C, A) -> setelement(2, C, A).
-spec is_literal(cerl:cerl()) -> boolean().
is_literal(#c_literal{}) -> true;
is_literal(#c_cons{hd=H,tl=T}) ->
is_literal(H) andalso is_literal(T);
is_literal(#c_tuple{es=Es}) -> is_literal_list(Es);
is_literal(#c_binary{segments=Es}) -> is_lit_bin(Es);
is_literal(_) -> false.
-spec is_literal_list([cerl:cerl()]) -> boolean().
is_literal_list(Es) -> lists:all(fun is_literal/1, Es).
is_lit_bin(Es) ->
lists:all(fun (#c_bitstr{val=E,size=S}) ->
is_literal(E) andalso is_literal(S)
end, Es).
%% Return the value of LitExpr.
-spec literal_value(cerl:c_literal() | cerl:c_binary() |
cerl:c_cons() | cerl:c_tuple()) -> term().
literal_value(#c_literal{val=V}) -> V;
literal_value(#c_binary{segments=Es}) ->
list_to_binary([literal_value_bin(Bit) || Bit <- Es]);
literal_value(#c_cons{hd=H,tl=T}) ->
[literal_value(H)|literal_value(T)];
literal_value(#c_tuple{es=Es}) ->
list_to_tuple(literal_value_list(Es)).
literal_value_list(Vals) -> [literal_value(V) || V <- Vals].
literal_value_bin(#c_bitstr{val=Val,size=Sz,unit=U,type=T,flags=Fs}) ->
%% We will only handle literals constructed by make_literal/1.
%% Could be made more general in the future if the need arises.
8 = literal_value(Sz),
1 = literal_value(U),
integer = literal_value(T),
[unsigned,big] = literal_value(Fs),
literal_value(Val).
%% Make a suitable values structure, expr or values, depending on Expr.
-spec make_values([cerl:cerl()] | cerl:cerl()) -> cerl:cerl().
make_values([E]) -> E;
make_values([H|_]=Es) -> #c_values{anno=get_anno(H),es=Es};
make_values([]) -> #c_values{es=[]};
make_values(E) -> E.
%% Test if the variable VarName is used in Expr.
-spec is_var_used(cerl:var_name(), cerl:cerl()) -> boolean().
is_var_used(V, B) -> vu_expr(V, B).
vu_expr(V, #c_values{es=Es}) ->
vu_expr_list(V, Es);
vu_expr(V, #c_var{name=V2}) -> V =:= V2;
vu_expr(V, #c_alias{var=V2,pat=Pat}) ->
%% XXX Must handle aliases in expressions because of sys_core_fold:kill_types/2,
%% that uses a pattern as if it was an expression.
V =:= V2 orelse vu_expr(V, Pat);
vu_expr(_, #c_literal{}) -> false;
vu_expr(V, #c_cons{hd=H,tl=T}) ->
vu_expr(V, H) orelse vu_expr(V, T);
vu_expr(V, #c_tuple{es=Es}) ->
vu_expr_list(V, Es);
vu_expr(V, #c_binary{segments=Ss}) ->
vu_seg_list(V, Ss);
vu_expr(V, #c_fun{vars=Vs,body=B}) ->
%% Variables in fun shadow previous variables
case vu_var_list(V, Vs) of
true -> false;
false -> vu_expr(V, B)
end;
vu_expr(V, #c_let{vars=Vs,arg=Arg,body=B}) ->
case vu_expr(V, Arg) of
true -> true;
false ->
%% Variables in let shadow previous variables.
case vu_var_list(V, Vs) of
true -> false;
false -> vu_expr(V, B)
end
end;
vu_expr(V, #c_letrec{defs=Fs,body=B}) ->
lists:any(fun ({_,Fb}) -> vu_expr(V, Fb) end, Fs) orelse vu_expr(V, B);
vu_expr(V, #c_seq{arg=Arg,body=B}) ->
vu_expr(V, Arg) orelse vu_expr(V, B);
vu_expr(V, #c_case{arg=Arg,clauses=Cs}) ->
vu_expr(V, Arg) orelse vu_clauses(V, Cs);
vu_expr(V, #c_receive{clauses=Cs,timeout=T,action=A}) ->
vu_clauses(V, Cs) orelse vu_expr(V, T) orelse vu_expr(V, A);
vu_expr(V, #c_apply{op=Op,args=As}) ->
vu_expr_list(V, [Op|As]);
vu_expr(V, #c_call{module=M,name=N,args=As}) ->
vu_expr_list(V, [M,N|As]);
vu_expr(V, #c_primop{args=As}) -> %Name is an atom
vu_expr_list(V, As);
vu_expr(V, #c_catch{body=B}) ->
vu_expr(V, B);
vu_expr(V, #c_try{arg=E,vars=Vs,body=B,evars=Evs,handler=H}) ->
case vu_expr(V, E) of
true -> true;
false ->
%% Variables shadow previous ones.
case case vu_var_list(V, Vs) of
true -> false;
false -> vu_expr(V, B)
end of
true -> true;
false ->
case vu_var_list(V, Evs) of
true -> false;
false -> vu_expr(V, H)
end
end
end.
vu_expr_list(V, Es) ->
lists:any(fun(E) -> vu_expr(V, E) end, Es).
vu_seg_list(V, Ss) ->
lists:any(fun (#c_bitstr{val=Val,size=Size}) ->
vu_expr(V, Val) orelse vu_expr(V, Size)
end, Ss).
%% Have to get the pattern results right.
-spec vu_clause(cerl:var_name(), cerl:c_clause()) -> boolean().
vu_clause(V, #c_clause{pats=Ps,guard=G,body=B}) ->
case vu_pattern_list(V, Ps) of
{true,_Shad} -> true; %It is used
{false,true} -> false; %Shadowed
{false,false} -> %Not affected
%% Neither used nor shadowed. Check guard and body.
vu_expr(V, G) orelse vu_expr(V, B)
end.
-spec vu_clauses(cerl:var_name(), [cerl:c_clause()]) -> boolean().
vu_clauses(V, Cs) ->
lists:any(fun(C) -> vu_clause(V, C) end, Cs).
%% vu_pattern(VarName, Pattern) -> {Used,Shadow}.
%% vu_pattern_list(VarName, [Pattern]) -> {Used,Shadow}.
%% Binaries complicate patterns as a variable can both be properly
%% used, in a bit segment size, and shadow. They can also do both.
%% vu_pattern(V, Pat) -> vu_pattern(V, Pat, {false,false}).
vu_pattern(V, #c_var{name=V2}, {Used,_}) ->
{Used,V =:= V2};
vu_pattern(V, #c_cons{hd=H,tl=T}, St0) ->
case vu_pattern(V, H, St0) of
{true,_}=St1 -> St1; %Nothing more to know
St1 -> vu_pattern(V, T, St1)
end;
vu_pattern(V, #c_tuple{es=Es}, St) ->
vu_pattern_list(V, Es, St);
vu_pattern(V, #c_binary{segments=Ss}, St) ->
vu_pat_seg_list(V, Ss, St);
vu_pattern(V, #c_alias{var=Var,pat=P}, St0) ->
case vu_pattern(V, Var, St0) of
{true,_}=St1 -> St1;
St1 -> vu_pattern(V, P, St1)
end;
vu_pattern(_, _, St) -> St.
vu_pattern_list(V, Ps) -> vu_pattern_list(V, Ps, {false,false}).
vu_pattern_list(V, Ps, St0) ->
lists:foldl(fun(P, St) -> vu_pattern(V, P, St) end, St0, Ps).
vu_pat_seg_list(V, Ss, St) ->
lists:foldl(fun(_, {true,_}=St0) -> St0;
(#c_bitstr{val=Val,size=Size}, St0) ->
case vu_pattern(V, Val, St0) of
{true,_}=St1 -> St1;
{false,Shad} ->
{vu_expr(V, Size),Shad}
end
end, St, Ss).
-spec vu_var_list(cerl:var_name(), [cerl:c_var()]) -> boolean().
vu_var_list(V, Vs) ->
lists:any(fun (#c_var{name=V2}) -> V =:= V2 end, Vs).
