/
filters.erl
94 lines (74 loc) · 3.26 KB
/
filters.erl
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-module(filters).
-export([before_exec/3, after_exec/3]).
-define(before_form, {function,LineNum,Original,Arity,
[{clause,
LineNum,
OriginalArgs,
[],
[{match,LineNum,FilterResultArgs,
{call,LineNum ,{atom, LineNum, Filter},FilterArgs}},
{call,LineNum,
{atom,LineNum, RenamedFunc},
RenamedFuncArgs}]}]}).
-define(after_form, {function,LineNum,Original,Arity,
[{clause, LineNum,
OriginalArgs,
[],
[{match,LineNum,
RenamdFuncResultArg,
{call,LineNum,{atom,LineNum, RenamedFunc}, OriginalArgs}},
{call,LineNum,{atom,LineNum,Filter},FilterArgs}]}]}).
before_exec(Form, Funcs, Filter) ->
Fun = fun(A, B, C, D) -> before_exec_function(A, B, C, D) end,
apply_alteration(Form, Funcs, Filter, Fun).
after_exec(Form, Funcs, Filter) ->
Fun = fun(A, B, C, D) -> after_exec_function(A, B, C, D) end,
apply_alteration(Form, Funcs, Filter, Fun).
apply_alteration(Form, [], _filter, _alteration) -> Form;
apply_alteration(Form, [Original|T], Filter, FunctionAddition) ->
{function, LineNum, Original, Arity, Clauses} = util:find_function(Form, Original),
{function, _linenum, Filter, FilterArity, _clauses} = util:find_function(Form, Filter),
RenamedFunc = rename(before, Original, Filter),
Renamed = {function, LineNum, RenamedFunc, Arity, Clauses},
Replaced = lists:keyreplace(Original, 3, Form, Renamed),
Appended = append(Replaced, FunctionAddition({Original, Arity}, {Filter, FilterArity}, RenamedFunc, eof_line(Replaced))),
apply_alteration(Appended, T, Filter, FunctionAddition).
before_exec_function({Original, Arity}, {Filter, FArity}, RenamedFunc, LineNum) ->
OriginalArgs = util:args_list_form(Arity, LineNum, "Original"),
FilterResultArgs = var_list_form(Arity, LineNum, "Result"),
FilterArgs = case {Arity == FArity, FArity == 1} of
{true, _} ->
util:args_list_form(Arity, LineNum, "Original");
{_, true} ->
[var_list_form(Arity, LineNum, "Original")];
_ -> throw(invalide_filter_arity)
end,
RenamedFuncArgs = util:args_list_form(Arity, LineNum, "Result"),
?before_form.
after_exec_function({Original, Arity}, {Filter, FArity}, RenamedFunc, LineNum) ->
OriginalArgs = util:args_list_form(Arity, LineNum, "Original"),
RenamdFuncResultArg = var_form(LineNum, "Result1"),
FilterArgs = case FArity == 1 of
true ->
util:args_list_form(1, LineNum, "Result");
false -> throw(invalide_filter_arity)
end,
?after_form.
var_list_form(0, LineNum, _nameseed) ->
{nil, LineNum};
var_list_form(Count, LineNum, NameSeed) ->
VarName = list_to_atom(NameSeed ++ util:to_string(Count)),
{cons, LineNum, var_form(LineNum, VarName), var_list_form(Count-1, LineNum, NameSeed)}.
var_form(Num, Name) when is_list(Name) ->
var_form(Num, list_to_atom(Name));
var_form(Num, Name) when is_number(Num) ->
{var, Num, Name}.
rename(Type, Original, Filter) ->
Name = lists:flatten(io_lib:format("~s_~s_~s" , [util:to_string(Type), util:to_string(Original), util:to_string(Filter)])),
list_to_atom(Name).
append(Form, Addition) ->
End = {eof, _} = lists:last(Form),
lists:delete(End, Form) ++ [Addition, End].
eof_line(Form)->
{eof, LineNum} = lists:last(Form),
LineNum.