%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1998-2009. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
%% Purpose : Transform Erlang compiler attributes
-module(sys_pre_attributes).
-export([parse_transform/2]).
-define(OPTION_TAG, attributes).
-record(state, {forms,
pre_ops = [],
post_ops = [],
options}).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Inserts, deletes and replaces Erlang compiler attributes.
%%
%% Valid options are:
%%
%% {attribute, insert, AttrName, NewAttrVal}
%% {attribute, replace, AttrName, NewAttrVal} % replace first occurrence
%% {attribute, delete, AttrName}
%%
%% The transformation is performed in two passes:
%%
%% pre_transform
%% -------------
%% Searches for attributes in the list of Forms in order to
%% delete or replace them. 'delete' will delete all occurrences
%% of attributes with the given name. 'replace' will replace the
%% first occurrence of the attribute. This pass is will only be
%% performed if there are replace or delete operations stated
%% as options.
%%
%% post_transform
%% -------------
%% Looks up the module attribute and inserts the new attributes
%% directly after. This pass will only be performed if there are
%% any attributes left to be inserted after pre_transform. The left
%% overs will be those replace operations that not has been performed
%% due to that the pre_transform pass did not find the attribute plus
%% all insert operations.
parse_transform(Forms, Options) ->
S = #state{forms = Forms, options = Options},
S2 = init_transform(S),
report_verbose("Pre options: ~p~n", [S2#state.pre_ops], S2),
report_verbose("Post options: ~p~n", [S2#state.post_ops], S2),
S3 = pre_transform(S2),
S4 = post_transform(S3),
S4#state.forms.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Computes the lists of pre_ops and post_ops that are
%% used in the real transformation.
init_transform(S) ->
case S#state.options of
Options when is_list(Options) ->
init_transform(Options, S);
Option ->
init_transform([Option], S)
end.
init_transform([{attribute, insert, Name, Val} | Tail], S) ->
Op = {insert, Name, Val},
PostOps = [Op | S#state.post_ops],
init_transform(Tail, S#state{post_ops = PostOps});
init_transform([{attribute, replace, Name, Val} | Tail], S) ->
Op = {replace, Name, Val},
PreOps = [Op | S#state.pre_ops],
PostOps = [Op | S#state.post_ops],
init_transform(Tail, S#state{pre_ops = PreOps, post_ops = PostOps});
init_transform([{attribute, delete, Name} | Tail], S) ->
Op = {delete, Name},
PreOps = [Op | S#state.pre_ops],
init_transform(Tail, S#state{pre_ops = PreOps});
init_transform([], S) ->
S;
init_transform([_ | T], S) ->
init_transform(T, S);
init_transform(BadOpt, S) ->
report_error("Illegal option (ignored): ~p~n", [BadOpt], S),
S.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Handle delete and perhaps replace
pre_transform(#state{pre_ops = []} = S) ->
S;
pre_transform(S) ->
pre_transform(S#state.forms, [], S).
pre_transform([H | T], Acc, S) ->
case H of
{attribute, Line, Name, Val} ->
case lists:keyfind(Name, 2, S#state.pre_ops) of
false ->
pre_transform(T, [H | Acc], S);
{replace, Name, NewVal} ->
report_warning("Replace attribute ~p: ~p -> ~p~n",
[Name, Val, NewVal],
S),
New = {attribute, Line, Name, NewVal},
Pre = lists:keydelete(Name, 2, S#state.pre_ops),
Post = lists:keydelete(Name, 2, S#state.post_ops),
S2 = S#state{pre_ops = Pre, post_ops = Post},
if
Pre == [] ->
%% No need to search the rest of the Forms
Forms = lists:reverse(Acc, [New | T]),
S2#state{forms = Forms};
true ->
pre_transform(T, [New | Acc], S2)
end;
{delete, Name} ->
report_warning("Delete attribute ~p: ~p~n",
[Name, Val],
S),
pre_transform(T, Acc, S)
end;
_Any ->
pre_transform(T, [H | Acc], S)
end;
pre_transform([], Acc, S) ->
S#state{forms = lists:reverse(Acc)}.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Handle insert and perhaps replace
post_transform(#state{post_ops = []} = S) ->
S;
post_transform(S) ->
post_transform(S#state.forms, [], S).
post_transform([H | T], Acc, S) ->
case H of
{attribute, Line, module, _Val} = Attribute ->
Acc2 = lists:reverse([Attribute | Acc]),
Forms = Acc2 ++ attrs(S#state.post_ops, Line, S) ++ T,
S#state{forms = Forms, post_ops = []};
_Any ->
post_transform(T, [H | Acc], S)
end;
post_transform([], Acc, S) ->
S#state{forms = lists:reverse(Acc)}.
attrs([{replace, Name, NewVal} | T], Line, S) ->
report_verbose("Insert attribute ~p: ~p~n", [Name, NewVal], S),
[{attribute, Line, Name, NewVal} | attrs(T, Line, S)];
attrs([{insert, Name, NewVal} | T], Line, S) ->
report_verbose("Insert attribute ~p: ~p~n", [Name, NewVal], S),
[{attribute, Line, Name, NewVal} | attrs(T, Line, S)];
attrs([], _, _) ->
[].
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Report functions.
%%
%% Errors messages are controlled with the 'report_errors' compiler option
%% Warning messages are controlled with the 'report_warnings' compiler option
%% Verbose messages are controlled with the 'verbose' compiler option
report_error(Format, Args, S) ->
case is_error(S) of
true ->
io:format("~p: * ERROR * " ++ Format, [?MODULE | Args]);
false ->
ok
end.
report_warning(Format, Args, S) ->
case is_warning(S) of
true ->
io:format("~p: * WARNING * " ++ Format, [?MODULE | Args]);
false ->
ok
end.
report_verbose(Format, Args, S) ->
case is_verbose(S) of
true ->
io:format("~p: " ++ Format, [?MODULE | Args]);
false ->
ok
end.
is_error(S) ->
lists:member(report_errors, S#state.options) or is_verbose(S).
is_warning(S) ->
lists:member(report_warnings, S#state.options) or is_verbose(S).
is_verbose(S) ->
lists:member(verbose, S#state.options).
