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%% @private |
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%% @doc Functions for encoding a term as an SQL literal. This is not really |
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%% part of the protocol; thus the separate module. |
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-module(mysql_encode). |
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-export([encode/1, backslash_escape/1]). |
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%% @doc Encodes a term as an ANSI SQL literal so that it can be used to inside |
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%% a query. In strings only single quotes (') are escaped. If backslash escapes |
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%% are enabled for the connection, you should first use backslash_escape/1 to |
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%% escape backslashes in strings. |
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-spec encode(term()) -> iodata(). |
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encode(null) -> <<"NULL">>; |
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encode(Int) when is_integer(Int) -> |
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integer_to_binary(Int); |
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encode(Float) when is_float(Float) -> |
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%% "floats are printed accurately as the shortest, correctly rounded string" |
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io_lib:format("~w", [Float]); |
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encode(Bin) when is_binary(Bin) -> |
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Escaped = binary:replace(Bin, <<"'">>, <<"''">>, [global]), |
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[$', Escaped, $']; |
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encode(String) when is_list(String) -> |
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encode(unicode:characters_to_binary(String)); |
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encode(Bitstring) when is_bitstring(Bitstring) -> |
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["b'", [ case B of 0 -> $0; 1 -> $1 end || <<B:1>> <= Bitstring ], $']; |
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encode({Y, M, D}) -> |
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io_lib:format("'~4..0b-~2..0b-~2..0b'", [Y, M, D]); |
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encode({{Y, M, D}, {H, Mi, S}}) when is_integer(S) -> |
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io_lib:format("'~4..0b-~2..0b-~2..0b ~2..0b:~2..0b:~2..0b'", |
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[Y, M, D, H, Mi, S]); |
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encode({{Y, M, D}, {H, Mi, S}}) when is_float(S) -> |
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io_lib:format("'~4..0b-~2..0b-~2..0b ~2..0b:~2..0b:~9.6.0f'", |
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[Y, M, D, H, Mi, S]); |
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encode({D, {H, M, S}}) when D >= 0 -> |
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Args = [H1 = D * 24 + H, M, S], |
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if |
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H1 > 99, is_integer(S) -> io_lib:format("'~b:~2..0b:~2..0b'", Args); |
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H1 > 99, is_float(S) -> io_lib:format("'~b:~2..0b:~9.6.0f'", Args); |
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is_integer(S) -> io_lib:format("'~2..0b:~2..0b:~2..0b'", Args); |
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is_float(S) -> io_lib:format("'~2..0b:~2..0b:~9.6.0f'", Args) |
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end; |
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encode({D, {H, M, S}}) when D < 0, is_integer(S) -> |
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Sec = (D * 24 + H) * 3600 + M * 60 + S, |
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{D1, {H1, M1, S1}} = calendar:seconds_to_daystime(-Sec), |
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Args = [H2 = D1 * 24 + H1, M1, S1], |
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if |
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H2 > 99 -> io_lib:format("'-~b:~2..0b:~2..0b'", Args); |
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true -> io_lib:format("'-~2..0b:~2..0b:~2..0b'", Args) |
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end; |
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encode({D, {H, M, S}}) when D < 0, is_float(S) -> |
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SInt = trunc(S), % trunc(57.654321) = 57 |
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{SInt1, Frac} = case S - SInt of % 57.6543 - 57 = 0.654321 |
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0.0 -> {SInt, 0.0}; |
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Rest -> {SInt + 1, 1 - Rest} % {58, 0.345679} |
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end, |
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Sec = (D * 24 + H) * 3600 + M * 60 + SInt1, |
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{D1, {H1, M1, S1}} = calendar:seconds_to_daystime(-Sec), |
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Args = [H2 = D1 * 24 + H1, M1, S1 + Frac], |
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if |
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H2 > 99 -> io_lib:format("'-~b:~2..0b:~9.6.0f'", Args); |
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true -> io_lib:format("'-~2..0b:~2..0b:~9.6.0f'", Args) |
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end. |
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%% @doc Escapes backslashes with an extra backslash. This is necessary if |
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%% backslash escapes are enabled in the session. |
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backslash_escape(String) -> |
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Bin = iolist_to_binary(String), |
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binary:replace(Bin, <<"\\">>, <<"\\\\">>, [global]). |