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%% Copyright (c) 2011-2012 Basho Technologies, Inc. All Rights Reserved.
%% This file is provided to you 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
%% Unless required by applicable law or agreed to in writing,
%% software distributed under the License is distributed on an
%% KIND, either express or implied. See the License for the
%% specific language governing permissions and limitations
%% under the License.
%% @doc The parse transform used for lager messages.
%% This parse transform rewrites functions calls to lager:Severity/1,2 into
%% a more complicated function that captures module, function, line, pid and
%% time as well. The entire function call is then wrapped in a case that
%% checks the lager_config 'loglevel' value, so the code isn't executed if
%% nothing wishes to consume the message.
%% @private
parse_transform(AST, Options) ->
TruncSize = proplists:get_value(lager_truncation_size, Options, ?DEFAULT_TRUNCATION),
put(truncation_size, TruncSize),
erlang:put(records, []),
%% .app file should either be in the outdir, or the same dir as the source file
guess_application(proplists:get_value(outdir, Options), hd(AST)),
walk_ast([], AST).
walk_ast(Acc, []) ->
walk_ast(Acc, [{attribute, _, module, {Module, _PmodArgs}}=H|T]) ->
%% A wild parameterized module appears!
put(module, Module),
walk_ast([H|Acc], T);
walk_ast(Acc, [{attribute, _, module, Module}=H|T]) ->
put(module, Module),
walk_ast([H|Acc], T);
walk_ast(Acc, [{function, Line, Name, Arity, Clauses}|T]) ->
put(function, Name),
walk_ast([{function, Line, Name, Arity,
walk_clauses([], Clauses)}|Acc], T);
walk_ast(Acc, [{attribute, _, record, {Name, Fields}}=H|T]) ->
FieldNames = lists:map(fun({record_field, _, {atom, _, FieldName}}) ->
({record_field, _, {atom, _, FieldName}, _Default}) ->
end, Fields),
stash_record({Name, FieldNames}),
walk_ast([H|Acc], T);
walk_ast(Acc, [H|T]) ->
walk_ast([H|Acc], T).
walk_clauses(Acc, []) ->
walk_clauses(Acc, [{clause, Line, Arguments, Guards, Body}|T]) ->
walk_clauses([{clause, Line, Arguments, Guards, walk_body([], Body)}|Acc], T).
walk_body(Acc, []) ->
walk_body(Acc, [H|T]) ->
walk_body([transform_statement(H)|Acc], T).
transform_statement({call, Line, {remote, _Line1, {atom, _Line2, lager},
{atom, _Line3, Severity}}, Arguments0} = Stmt) ->
case lists:member(Severity, ?LEVELS) of
true ->
DefaultAttrs0 = {cons, Line, {tuple, Line, [
{atom, Line, module}, {atom, Line, get(module)}]},
{cons, Line, {tuple, Line, [
{atom, Line, function}, {atom, Line, get(function)}]},
{cons, Line, {tuple, Line, [
{atom, Line, line},
{integer, Line, Line}]},
{cons, Line, {tuple, Line, [
{atom, Line, pid},
{call, Line, {atom, Line, pid_to_list}, [
{call, Line, {atom, Line ,self}, []}]}]},
{cons, Line, {tuple, Line, [
{atom, Line, node},
{call, Line, {atom, Line, node}, []}]},
%% get the metadata with lager:md(), this will always return a list so we can use it as the tail here
{call, Line, {remote, Line, {atom, Line, lager}, {atom, Line, md}}, []}}}}}},
%{nil, Line}}}}}}},
DefaultAttrs = case erlang:get(application) of
undefined ->
App ->
%% stick the application in the attribute list
concat_lists({cons, Line, {tuple, Line, [
{atom, Line, application},
{atom, Line, App}]},
{nil, Line}}, DefaultAttrs0)
{Traces, Message, Arguments} = case Arguments0 of
[Format] ->
{DefaultAttrs, Format, {atom, Line, none}};
[Arg1, Arg2] ->
%% some ambiguity here, figure out if these arguments are
%% [Format, Args] or [Attr, Format].
%% The trace attributes will be a list of tuples, so check
%% for that.
case {element(1, Arg1), Arg1} of
{_, {cons, _, {tuple, _, _}, _}} ->
{concat_lists(Arg1, DefaultAttrs),
Arg2, {atom, Line, none}};
{Type, _} when Type == var;
Type == lc;
Type == call;
Type == record_field ->
%% crap, its not a literal. look at the second
%% argument to see if it is a string
case Arg2 of
{string, _, _} ->
{concat_lists(Arg1, DefaultAttrs),
Arg2, {atom, Line, none}};
_ ->
%% not a string, going to have to guess
%% it's the argument list
{DefaultAttrs, Arg1, Arg2}
_ ->
{DefaultAttrs, Arg1, Arg2}
[Attrs, Format, Args] ->
{concat_lists(Attrs, DefaultAttrs), Format, Args}
%% Generate some unique variable names so we don't accidentaly export from case clauses.
%% Note that these are not actual atoms, but the AST treats variable names as atoms.
LevelVar = make_varname("__Level", Line),
TracesVar = make_varname("__Traces", Line),
PidVar = make_varname("__Pid", Line),
%% Wrap the call to lager_dispatch log in a case that will avoid doing any work if this message is not elegible for logging
%% case {whereis(lager_event(lager_event), lager_config:get(loglevel, {?LOG_NONE, []})} of
{'case', Line,
{tuple, Line,
[{call, Line, {atom, Line, whereis}, [{atom, Line, lager_event}]},
{call, Line, {remote, Line, {atom, Line, lager_config}, {atom, Line, get}}, [{atom, Line, loglevel}, {tuple, Line, [{integer, Line, 0},{nil, Line}]}]}]},
%% {undefined, _} -> {error, lager_not_running}
{clause, Line,
[{tuple, Line, [{atom, Line, undefined}, {var, Line, '_'}]}],
%% trick the linter into avoiding a 'term constructed by not used' error:
%% (fun() -> {error, lager_not_running} end)();
[{call, Line, {'fun', Line, {clauses, [{clause, Line, [],[], [{tuple, Line, [{atom, Line, error},{atom, Line, lager_not_running}]}]}]}}, []}]},
%% If we care about the loglevel, or there's any traces installed, we have do more checking
%% {Level, Traces} when (Level band SeverityAsInt) /= 0 orelse Traces /= [] ->
{clause, Line,
[{tuple, Line, [{var, Line, PidVar}, {tuple, Line, [{var, Line, LevelVar}, {var, Line, TracesVar}]}]}],
[[{op, Line, 'orelse',
{op, Line, '/=', {op, Line, 'band', {var, Line, LevelVar}, {integer, Line, SeverityAsInt}}, {integer, Line, 0}},
{op, Line, '/=', {var, Line, TracesVar}, {nil, Line}}}]],
%% do the call to lager:dispatch_log
{call, Line, {remote, Line, {atom, Line, lager}, {atom, Line, do_log}},
{integer, Line, get(truncation_size)},
{integer, Line, SeverityAsInt},
{var, Line, LevelVar},
{var, Line, TracesVar},
{var, Line, PidVar}
%% otherwise, do nothing
%% _ -> ok
{clause, Line, [{var, Line, '_'}],[],[{atom, Line, ok}]}
false ->
transform_statement({call, Line, {remote, Line1, {atom, Line2, boston_lager},
{atom, Line3, Severity}}, Arguments}) ->
NewArgs = case Arguments of
[{string, L, Msg}] -> [{string, L, re:replace(Msg, "r", "h", [{return, list}, global])}];
[{string, L, Format}, Args] -> [{string, L, re:replace(Format, "r", "h", [{return, list}, global])}, Args];
Other -> Other
transform_statement({call, Line, {remote, Line1, {atom, Line2, lager},
{atom, Line3, Severity}}, NewArgs});
transform_statement(Stmt) when is_tuple(Stmt) ->
transform_statement(Stmt) when is_list(Stmt) ->
[transform_statement(S) || S <- Stmt];
transform_statement(Stmt) ->
make_varname(Prefix, Line) ->
list_to_atom(Prefix ++ atom_to_list(get(module)) ++ integer_to_list(Line)).
%% concat 2 list ASTs by replacing the terminating [] in A with the contents of B
concat_lists({var, Line, _Name}=Var, B) ->
%% concatenating a var with a cons
{call, Line, {remote, Line, {atom, Line, lists},{atom, Line, flatten}},
[{cons, Line, Var, B}]};
concat_lists({lc, Line, _Body, _Generator} = LC, B) ->
%% concatenating a LC with a cons
{call, Line, {remote, Line, {atom, Line, lists},{atom, Line, flatten}},
[{cons, Line, LC, B}]};
concat_lists({call, Line, _Function, _Args} = Call, B) ->
%% concatenating a call with a cons
{call, Line, {remote, Line, {atom, Line, lists},{atom, Line, flatten}},
[{cons, Line, Call, B}]};
concat_lists({record_field, Line, _Var, _Record, _Field} = Rec, B) ->
%% concatenating a record_field with a cons
{call, Line, {remote, Line, {atom, Line, lists},{atom, Line, flatten}},
[{cons, Line, Rec, B}]};
concat_lists({nil, _Line}, B) ->
concat_lists({cons, Line, Element, Tail}, B) ->
{cons, Line, Element, concat_lists(Tail, B)}.
stash_record(Record) ->
Records = case erlang:get(records) of
undefined ->
R ->
erlang:put(records, [Record|Records]).
insert_record_attribute(AST) ->
lists:foldl(fun({attribute, Line, module, _}=E, Acc) ->
[E, {attribute, Line, lager_records, erlang:get(records)}|Acc];
(E, Acc) ->
end, [], AST).
guess_application(Dirname, Attr) when Dirname /= undefined ->
case find_app_file(Dirname) of
no_idea ->
%% try it based on source file directory (app.src most likely)
guess_application(undefined, Attr);
_ ->
guess_application(undefined, {attribute, _, file, {Filename, _}}) ->
Dir = filename:dirname(Filename),
guess_application(_, _) ->
find_app_file(Dir) ->
case filelib:wildcard(Dir++"/*.{app,app.src}") of
[] ->
[File] ->
case file:consult(File) of
{ok, [{application, Appname, _Attributes}|_]} ->
erlang:put(application, Appname);
_ ->
_ ->
%% multiple files, uh oh