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}, []}]},
{nil, Line}}}}}}, %% 这个元组的定义乍看上去恐怖，再看还是很恐怖
%% 转换成代码后，是这样的，[{module, mod},{function, fun},{line, lin},{pid,pid_to_list(self())},{node, node()}]
DefaultAttrs = case erlang:get(application) of
undefined ->
DefaultAttrs0;
App ->
%% stick the application in the attribute list
concat_lists({cons, Line, {tuple, Line, [
{atom, Line, application},
{atom, Line, App}]},
{nil, Line}}, DefaultAttrs0)
end, %% DefaultAttrs 最终的格式嵌套的包含后面这些信息 application-module-function-line-pid-node
{Traces, Message, Arguments} = case Arguments0 of %% 处理函数调用时的参数
[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 %% 作者骂娘了？
%% 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}
end;
_ ->
{DefaultAttrs, Arg1, Arg2}
end;
[Attrs, Format, Args] ->
{concat_lists(Attrs, DefaultAttrs), Format, Args}
end,
{call, Line, {remote, Line, {atom,Line,lager},{atom,Line,dispatch_log}}, %% lager:dispatch_log()
[ %% 参数
{atom,Line,Severity},
Traces,
Message,
Arguments,
{integer, Line, get(truncation_size)}
] %% 最终的调用是： lager:dispatch_log(error, Traces, format, [], 500)
%% Traces就是上面那个复杂的列表
};
false ->
Stmt
end;
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
end,
transform_statement({call, Line, {remote, Line1, {atom, Line2, lager},
{atom, Line3, Severity}}, NewArgs});
transform_statement(Stmt) when is_tuple(Stmt) ->
list_to_tuple(transform_statement(tuple_to_list(Stmt)));
transform_statement(Stmt) when is_list(Stmt) -> %% 如果碰到case语句什么的，还是要深入进去
[transform_statement(S) || S <- Stmt];
transform_statement(Stmt) ->
Stmt.
