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emqx/apps/emqx_plugin_libs/src/emqx_placeholder.erl

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%%--------------------------------------------------------------------
%% Copyright (c) 2021-2022 EMQ Technologies Co., Ltd. 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.
%%--------------------------------------------------------------------
-module(emqx_placeholder).
%% preprocess and process template string with place holders
-export([
preproc_tmpl/1,
preproc_tmpl/2,
proc_tmpl/2,
proc_tmpl/3,
preproc_cmd/1,
proc_cmd/2,
proc_cmd/3,
preproc_sql/1,
preproc_sql/2,
proc_sql/2,
proc_sql_param_str/2,
proc_cql_param_str/2,
preproc_tmpl_deep/1,
preproc_tmpl_deep/2,
proc_tmpl_deep/2,
proc_tmpl_deep/3,
bin/1,
sql_data/1
]).
-define(EX_PLACE_HOLDER, "(\\$\\{[a-zA-Z0-9\\._]+\\})").
-define(EX_PLACE_HOLDER_DOUBLE_QUOTE, "(\\$\\{[a-zA-Z0-9\\._]+\\}|\"\\$\\{[a-zA-Z0-9\\._]+\\}\")").
%% Space and CRLF
-define(EX_WITHE_CHARS, "\\s").
-type tmpl_token() :: list({var, binary()} | {str, binary()}).
-type tmpl_cmd() :: list(tmpl_token()).
-type prepare_statement_key() :: binary().
-type var_trans() ::
fun((FoundValue :: term()) -> binary())
| fun((Placeholder :: term(), FoundValue :: term()) -> binary()).
-type preproc_tmpl_opts() :: #{placeholders => list(binary())}.
-type preproc_sql_opts() :: #{
placeholders => list(binary()),
replace_with => '?' | '$n',
strip_double_quote => boolean()
}.
-type preproc_deep_opts() :: #{
placeholders => list(binary()),
process_keys => boolean()
}.
-type proc_tmpl_opts() :: #{
return => rawlist | full_binary,
var_trans => var_trans()
}.
-type deep_template() ::
#{deep_template() => deep_template()}
| {tuple, [deep_template()]}
| [deep_template()]
| {tmpl, tmpl_token()}
| {value, term()}.
%%------------------------------------------------------------------------------
%% APIs
%%------------------------------------------------------------------------------
-spec preproc_tmpl(binary()) -> tmpl_token().
preproc_tmpl(Str) ->
preproc_tmpl(Str, #{}).
-spec preproc_tmpl(binary(), preproc_tmpl_opts()) -> tmpl_token().
preproc_tmpl(Str, Opts) ->
RE = preproc_var_re(Opts),
Tokens = re:split(Str, RE, [{return, binary}, group, trim]),
do_preproc_tmpl(Opts, Tokens, []).
-spec proc_tmpl(tmpl_token(), map()) -> binary().
proc_tmpl(Tokens, Data) ->
proc_tmpl(Tokens, Data, #{return => full_binary}).
-spec proc_tmpl(tmpl_token(), map(), proc_tmpl_opts()) -> binary() | list().
proc_tmpl(Tokens, Data, Opts = #{return := full_binary}) ->
Trans = maps:get(var_trans, Opts, fun emqx_plugin_libs_rule:bin/1),
list_to_binary(
proc_tmpl(Tokens, Data, #{return => rawlist, var_trans => Trans})
);
proc_tmpl(Tokens, Data, Opts = #{return := rawlist}) ->
Trans = maps:get(var_trans, Opts, undefined),
lists:map(
fun
({str, Str}) ->
Str;
({var, Phld}) when is_function(Trans, 1) ->
Trans(get_phld_var(Phld, Data));
({var, Phld}) when is_function(Trans, 2) ->
Trans(Phld, get_phld_var(Phld, Data));
({var, Phld}) ->
get_phld_var(Phld, Data)
end,
Tokens
).
-spec preproc_cmd(binary()) -> tmpl_cmd().
preproc_cmd(Str) ->
SubStrList = re:split(Str, ?EX_WITHE_CHARS, [{return, binary}, trim]),
[preproc_tmpl(SubStr) || SubStr <- SubStrList].
-spec proc_cmd([tmpl_token()], map()) -> binary() | list().
proc_cmd(Tokens, Data) ->
proc_cmd(Tokens, Data, #{return => full_binary}).
-spec proc_cmd([tmpl_token()], map(), map()) -> list().
proc_cmd(Tokens, Data, Opts) ->
[proc_tmpl(Tks, Data, Opts) || Tks <- Tokens].
%% preprocess SQL with place holders
-spec preproc_sql(Sql :: binary()) -> {prepare_statement_key(), tmpl_token()}.
preproc_sql(Sql) ->
preproc_sql(Sql, '?').
-spec preproc_sql(binary(), '?' | '$n' | preproc_sql_opts()) ->
{prepare_statement_key(), tmpl_token()}.
preproc_sql(Sql, ReplaceWith) when is_atom(ReplaceWith) ->
preproc_sql(Sql, #{replace_with => ReplaceWith});
preproc_sql(Sql, Opts) ->
RE = preproc_var_re(Opts),
Strip = maps:get(strip_double_quote, Opts, false),
ReplaceWith = maps:get(replace_with, Opts, '?'),
case re:run(Sql, RE, [{capture, all_but_first, binary}, global]) of
{match, PlaceHolders} ->
PhKs = [parse_nested(unwrap(Phld, Strip)) || [Phld | _] <- PlaceHolders],
{replace_with(Sql, RE, ReplaceWith), [{var, Phld} || Phld <- PhKs]};
nomatch ->
{Sql, []}
end.
-spec proc_sql(tmpl_token(), map()) -> list().
proc_sql(Tokens, Data) ->
proc_tmpl(Tokens, Data, #{return => rawlist, var_trans => fun sql_data/1}).
-spec proc_sql_param_str(tmpl_token(), map()) -> binary().
proc_sql_param_str(Tokens, Data) ->
proc_param_str(Tokens, Data, fun quote_sql/1).
-spec proc_cql_param_str(tmpl_token(), map()) -> binary().
proc_cql_param_str(Tokens, Data) ->
proc_param_str(Tokens, Data, fun quote_cql/1).
-spec preproc_tmpl_deep(term()) -> deep_template().
preproc_tmpl_deep(Data) ->
preproc_tmpl_deep(Data, #{process_keys => true}).
-spec preproc_tmpl_deep(term(), preproc_deep_opts()) -> deep_template().
preproc_tmpl_deep(List, Opts) when is_list(List) ->
[preproc_tmpl_deep(El, Opts) || El <- List];
preproc_tmpl_deep(Map, Opts) when is_map(Map) ->
maps:from_list(
lists:map(
fun({K, V}) ->
{preproc_tmpl_deep_map_key(K, Opts), preproc_tmpl_deep(V, Opts)}
end,
maps:to_list(Map)
)
);
preproc_tmpl_deep(Binary, Opts) when is_binary(Binary) ->
{tmpl, preproc_tmpl(Binary, Opts)};
preproc_tmpl_deep(Tuple, Opts) when is_tuple(Tuple) ->
{tuple, preproc_tmpl_deep(tuple_to_list(Tuple), Opts)};
preproc_tmpl_deep(Other, _Opts) ->
{value, Other}.
-spec proc_tmpl_deep(deep_template(), map()) -> term().
proc_tmpl_deep(DeepTmpl, Data) ->
proc_tmpl_deep(DeepTmpl, Data, #{return => full_binary}).
-spec proc_tmpl_deep(deep_template(), map(), proc_tmpl_opts()) -> term().
proc_tmpl_deep(List, Data, Opts) when is_list(List) ->
[proc_tmpl_deep(El, Data, Opts) || El <- List];
proc_tmpl_deep(Map, Data, Opts) when is_map(Map) ->
maps:from_list(
lists:map(
fun({K, V}) ->
{proc_tmpl_deep(K, Data, Opts), proc_tmpl_deep(V, Data, Opts)}
end,
maps:to_list(Map)
)
);
proc_tmpl_deep({value, Value}, _Data, _Opts) ->
Value;
proc_tmpl_deep({tmpl, Tokens}, Data, Opts) ->
proc_tmpl(Tokens, Data, Opts);
proc_tmpl_deep({tuple, Elements}, Data, Opts) ->
list_to_tuple([proc_tmpl_deep(El, Data, Opts) || El <- Elements]).
-spec sql_data(term()) -> term().
sql_data(undefined) -> null;
sql_data(List) when is_list(List) -> List;
sql_data(Bin) when is_binary(Bin) -> Bin;
sql_data(Num) when is_number(Num) -> Num;
sql_data(Bool) when is_boolean(Bool) -> Bool;
sql_data(Atom) when is_atom(Atom) -> atom_to_binary(Atom, utf8);
sql_data(Map) when is_map(Map) -> emqx_json:encode(Map).
-spec bin(term()) -> binary().
bin(Val) -> emqx_plugin_libs_rule:bin(Val).
%%------------------------------------------------------------------------------
%% Internal functions
%%------------------------------------------------------------------------------
proc_param_str(Tokens, Data, Quote) ->
iolist_to_binary(
proc_tmpl(Tokens, Data, #{return => rawlist, var_trans => Quote})
).
%% backward compatibility for hot upgrading from =< e4.2.1
get_phld_var(Fun, Data) when is_function(Fun) ->
Fun(Data);
get_phld_var(Phld, Data) ->
emqx_rule_maps:nested_get(Phld, Data).
preproc_var_re(#{placeholders := PHs, strip_double_quote := true}) ->
Res = [ph_to_re(PH) || PH <- PHs],
QuoteRes = ["\"" ++ Re ++ "\"" || Re <- Res],
"(" ++ string:join(Res ++ QuoteRes, "|") ++ ")";
preproc_var_re(#{placeholders := PHs}) ->
"(" ++ string:join([ph_to_re(PH) || PH <- PHs], "|") ++ ")";
preproc_var_re(#{strip_double_quote := true}) ->
?EX_PLACE_HOLDER_DOUBLE_QUOTE;
preproc_var_re(#{}) ->
?EX_PLACE_HOLDER.
ph_to_re(VarPH) ->
re:replace(VarPH, "[\\$\\{\\}]", "\\\\&", [global, {return, list}]).
do_preproc_tmpl(_Opts, [], Acc) ->
lists:reverse(Acc);
do_preproc_tmpl(Opts, [[Str, Phld] | Tokens], Acc) ->
Strip = maps:get(strip_double_quote, Opts, false),
do_preproc_tmpl(
Opts,
Tokens,
put_head(
var,
parse_nested(unwrap(Phld, Strip)),
put_head(str, Str, Acc)
)
);
do_preproc_tmpl(Opts, [[Str] | Tokens], Acc) ->
do_preproc_tmpl(
Opts,
Tokens,
put_head(str, Str, Acc)
).
put_head(_Type, <<>>, List) -> List;
put_head(Type, Term, List) -> [{Type, Term} | List].
preproc_tmpl_deep_map_key(Key, #{process_keys := true} = Opts) ->
preproc_tmpl_deep(Key, Opts);
preproc_tmpl_deep_map_key(Key, _) ->
{value, Key}.
replace_with(Tmpl, RE, '?') ->
re:replace(Tmpl, RE, "?", [{return, binary}, global]);
replace_with(Tmpl, RE, '$n') ->
Parts = re:split(Tmpl, RE, [{return, binary}, trim, group]),
{Res, _} =
lists:foldl(
fun
([Tkn, _Phld], {Acc, Seq}) ->
Seq1 = erlang:integer_to_binary(Seq),
{<<Acc/binary, Tkn/binary, "$", Seq1/binary>>, Seq + 1};
([Tkn], {Acc, Seq}) ->
{<<Acc/binary, Tkn/binary>>, Seq}
end,
{<<>>, 1},
Parts
),
Res.
parse_nested(Attr) ->
case string:split(Attr, <<".">>, all) of
[Attr] -> {var, Attr};
Nested -> {path, [{key, P} || P <- Nested]}
end.
unwrap(<<"\"${", Val/binary>>, _StripDoubleQuote = true) ->
binary:part(Val, {0, byte_size(Val) - 2});
unwrap(<<"${", Val/binary>>, _StripDoubleQuote) ->
binary:part(Val, {0, byte_size(Val) - 1}).
quote_sql(Str) ->
quote(Str, <<"\\\\'">>).
quote_cql(Str) ->
quote(Str, <<"''">>).
quote(Str, ReplaceWith) when
is_list(Str);
is_binary(Str);
is_atom(Str);
is_map(Str)
->
[$', escape_apo(bin(Str), ReplaceWith), $'];
quote(Val, _) ->
bin(Val).
escape_apo(Str, ReplaceWith) ->
re:replace(Str, <<"'">>, ReplaceWith, [{return, binary}, global]).
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