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-module(pmod).
-export([parse_transform/2]).
-import(erl_syntax, [attribute_name/1, attribute_arguments/1,
list_elements/1,
atom_value/1, tuple_elements/1, integer_value/1]).
-record(st, {vars = [],
funs = ordsets:new()}).
parse_transform(Forms, Opts) ->
case proplists:get_bool(trace, Opts) of
true ->
dbg:tracer(),
dbg:tpl(?MODULE,x),
dbg:p(all,[c]);
false ->
ok
end,
C = parse_trans:initial_context(Forms, Opts),
St = parse_trans:do_inspect(fun inspect/4, #st{}, Forms, C),
Res = parse_trans:revert(
export_funs(wrap_funs(create_new_f(Forms, St, C), St, C), St, C)),
parse_trans:optionally_pretty_print(Res, Opts, C),
Res.
inspect(attribute, Form, _C, Acc) ->
case attr_name(Form) of
pmod_vars ->
[] = Acc#st.vars, %% assertion - should be a proper check
VarNames = [atom_value(V) ||
V <- list_elements(hd(attribute_arguments(Form)))],
{false, Acc#st{vars = VarNames}};
pmod_funs ->
Fs = lists:foldl(fun(E, Acc1) ->
[Fun,Ay] = tuple_elements(E),
ordsets:add_element(
{atom_value(Fun), integer_value(Ay)},
Acc1)
end, Acc#st.funs,
list_elements(hd(attribute_arguments(Form)))),
{false, Acc#st{funs = Fs}};
_ ->
{false, Acc}
end;
inspect(_, _, _, Acc) ->
{false, Acc}.
attr_name(F) ->
atom_value(attribute_name(F)).
create_new_f(Forms, #st{vars = Vs}, C) ->
Arity = length(Vs),
Form = {function, 1, new, Arity,
[{clause, 1,
[{var,1,V} || V <- Vs],
[],
[{tuple, 1, [{atom, 1, parse_trans:context(module, C)},
{tuple, 1, [{var,1,V} || V <- Vs]}]}
]}
]},
parse_trans:do_insert_forms(above, [Form], Forms, C).
wrap_funs(Forms, #st{vars = Vs, funs = Fs}, C) ->
Mod = parse_trans:context(module, C),
lists:foldl(
fun({F,A}, Acc) ->
{NewForms, _} =
parse_trans:do_transform(
fun(T,Form,C1,Acc1) ->
wrap_fun(T,Form,C1,Acc1,F,A,Vs,Mod)
end, false, Acc, C),
NewForms
end, Forms, Fs).
wrap_fun(function, Form, _, Acc, F, A, Vs,Mod) ->
case erl_syntax:revert(Form) of
{function, L, F, A, Cs} ->
{{function, L, F, A + 1,
[{clause, Lc,
Args ++ [{tuple,1,[{atom,1,Mod},
{tuple,1,
fix_vars(Vs, F, A, Clause)}]}], Gs, B}
|| {clause, Lc, Args, Gs, B} = Clause <- Cs]},
false, Acc};
_ ->
{Form, false, Acc}
end;
wrap_fun(_, Form, _, Acc, _, _, _, _) ->
{Form, false, Acc}.
fix_vars(Vars, F, A, Clause) ->
%% erl_syntax_lib:variables/1 doesn't seem to work with just a clause...
Used = sets:to_list(erl_syntax_lib:variables({function,1,F,A,[Clause]})),
[{var, 1, fix_var(V, Used)} || V <- Vars].
fix_var(V, Used) ->
case lists:member(V, Used) of
true -> V;
false ->
list_to_atom("_" ++ atom_to_list(V))
end.
export_funs(Forms, #st{vars = Vs, funs = Fs}, C) ->
New = [{attribute,1,export,[{new,length(Vs)}]},
{attribute,1,export,[{F,A+1} || {F,A} <- Fs]}],
parse_trans:do_insert_forms(above, New, Forms, C).
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