150 lines
4.7 KiB
Erlang
150 lines
4.7 KiB
Erlang
%%%-------------------------------------------------------------------
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%%% @author licheng5
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%%% @copyright (C) 2020, <COMPANY>
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%%% @doc
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%%%
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%%% @end
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%%% Created : 11. 12月 2020 上午10:57
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%%%-------------------------------------------------------------------
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-module(iot_util).
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-author("licheng5").
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%% API
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-export([timestamp/0, number_format/2, current_time/0, timestamp_of_seconds/0, float_to_binary/2, int_format/2, file_uri/1]).
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-export([step/3, chunks/2, rand_bytes/1, uuid/0, md5/1, parse_mapper/1]).
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-export([json_data/1, json_error/2]).
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-export([queue_limited_in/3, assert_call/2, assert/2]).
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%% 时间，精确到毫秒
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timestamp() ->
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{Mega, Seconds, Micro} = os:timestamp(),
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(Mega * 1000000 + Seconds) * 1000 + Micro div 1000.
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current_time() ->
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{Mega, Seconds, _Micro} = os:timestamp(),
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Mega * 1000000 + Seconds.
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timestamp_of_seconds() ->
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{Mega, Seconds, _Micro} = os:timestamp(),
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Mega * 1000000 + Seconds.
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number_format(Num, _Decimals) when is_integer(Num) ->
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Num;
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number_format(Float, Decimals) when is_float(Float) ->
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list_to_float(float_to_list(Float, [{decimals, Decimals}, compact])).
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int_format(Num, Len) when is_integer(Num), Len > 0 ->
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S = integer_to_list(Num),
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case length(S) > Len of
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true ->
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list_to_integer(lists:sublist(S, 1, Len));
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false ->
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Num
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end.
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step(Start, End, Step) when is_integer(Start), is_integer(End), is_integer(Step), Start < End, Step > 0 ->
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step(Start, End, Step, []).
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step(Start, End, Step, Acc) when Start < End ->
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step(Start + Step, End, Step, [{Start, min(Start + Step, End)} | Acc]);
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step(_, _, _, Acc) ->
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lists:reverse(Acc).
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%% 将数据分组
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-spec chunks(list(), integer()) -> [list()].
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chunks(List, Size) when is_list(List), is_integer(Size), Size > 0, length(List) =< Size ->
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[List];
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chunks(List, Size) when is_list(List), is_integer(Size), Size > 0 ->
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chunks0(List, Size, Size, [], []).
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chunks0([], _, _, [], AccTarget) ->
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lists:reverse(AccTarget);
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chunks0([], _, _, Target, AccTarget) ->
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lists:reverse([lists:reverse(Target) | AccTarget]);
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chunks0(List, Size, 0, Target, AccTarget) ->
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chunks0(List, Size, Size, [], [lists:reverse(Target) | AccTarget]);
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chunks0([Hd | Tail], Size, Num, Target, AccTarget) ->
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chunks0(Tail, Size, Num - 1, [Hd | Target], AccTarget).
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json_data(Data) ->
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jiffy:encode(#{
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<<"result">> => Data
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}, [force_utf8]).
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json_error(ErrCode, ErrMessage) when is_integer(ErrCode), is_binary(ErrMessage) ->
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jiffy:encode(#{
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<<"error">> => #{
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<<"code">> => ErrCode,
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<<"message">> => ErrMessage
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}
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}, [force_utf8]).
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uuid() ->
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rand_bytes(16).
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-spec rand_bytes(Size :: integer()) -> string().
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rand_bytes(Size) when is_integer(Size), Size > 0 ->
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Size1 = erlang:ceil(Size / 2),
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Bytes = crypto:strong_rand_bytes(Size1),
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S = lists:flatten([integer_to_list(E, 16) || <<E:4>> <= Bytes]),
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lists:sublist(string:to_lower(S), 1, Size).
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queue_limited_in(Item, Q, Num) when is_integer(Num) ->
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case queue:len(Q) >= Num of
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true ->
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Q1 = queue:drop(Q),
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queue:in(Item, Q1);
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false ->
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queue:in(Item, Q)
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end.
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assert_call(true, Fun) ->
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Fun();
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assert_call(false, _) ->
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ok.
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-spec md5(Str :: binary()) -> binary().
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md5(Str) when is_binary(Str) ->
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list_to_binary(lists:flatten([hex(X) || <<X:4>> <= erlang:md5(Str)])).
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hex(N) when N < 10 ->
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$0 + N;
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hex(N) ->
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$a + (N - 10).
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%% 转换映射器
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-spec parse_mapper(Mapper :: binary() | string()) -> error | {ok, F :: fun((binary(), any()) -> any())}.
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parse_mapper(Mapper) when is_binary(Mapper) ->
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parse_mapper(binary_to_list(Mapper));
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parse_mapper(Mapper) when is_list(Mapper) ->
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{ok, Tokens, _} = erl_scan:string(Mapper),
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{ok, ExprList} = erl_parse:parse_exprs(Tokens),
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{value, F, _} = erl_eval:exprs(ExprList, []),
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case is_function(F, 2) orelse is_function(F, 3) of
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true ->
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{ok, F};
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false ->
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error
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end.
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-spec float_to_binary(Num :: number(), integer()) -> binary().
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float_to_binary(V, _) when is_integer(V) ->
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integer_to_binary(V);
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float_to_binary(V, Decimals) when is_float(V), is_integer(Decimals) ->
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S = float_to_list(V, [{decimals, Decimals}, compact]),
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list_to_binary(S).
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assert(true, _) ->
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ok;
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assert(false, F) when is_function(F) ->
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F();
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assert(false, Msg) ->
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throw(Msg).
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-spec file_uri(Filename :: binary()) -> error | {ok, FileUri :: binary()}.
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file_uri(Filename) when is_binary(Filename) ->
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case binary:split(Filename, <<"-">>, [global]) of
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[Year, Month, Day | _] ->
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{ok, <<"https://lgsiot.njau.edu.cn/upload/", Year/binary, $/, Month/binary, $/, Day/binary, $/, Filename/binary>>};
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_ ->
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error
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end. |