View Source erlfdb_tuple (erlfdb v1.2.0)

-type elem() ::
          null |
          boolean() |
          binary() |
          {utf8, binary()} |
          integer() |
          float() |
          {float, float()} |
          {float, float_tag(), <<_:32>>} |
          {double, float_tag(), <<_:64>>} |
          {uuid, <<_:128>>} |
          {id64, integer()} |
          versionstamp() |
          tuple().

float_tag()

-type float_tag() :: denormalized | infinite | nan.

versionstamp()

-type versionstamp() ::
          {versionstamp, Id :: non_neg_integer(), Batch :: non_neg_integer()} |
          {versionstamp, Id :: non_neg_integer(), Batch :: non_neg_integer(), Tx :: non_neg_integer()}.

Functions

compare(A, B)

-spec compare(tuple(), tuple()) -> -1 | 0 | 1.

Compares 2 Erlang tuples with the ordering defined by the tuple layer.

Return

0 if both tuples compare as equal.
-1 if the left tuple is less than the right tuple.
1 if the left tuple is greater than the right tuple.

Examples

The ordering isn't equivalent to the Erlang term ordering:

1> lists:sort(fun(A, B) -> erlfdb_tuple:compare(A, B) =< 0 end, [{1}, {null}]).
[{null},{1}]
2> lists:sort([{1}, {null}]).
[{1},{null}]

pack(Tuple)

-spec pack(tuple()) -> binary().

Encodes the tuple into a binary.

Supported Erlang types

binary/0: Encodes as binary blob.
integer/0: Encodes as variable-length integer.
float/0: Encodes as 64-bit floating point (double).
tuple/0: Encodes as nested tuple.

Special types

null: Encodes as NULL char (16#0) instead of as an atom.
boolean/0: Encodes as a boolean instead of as an atom.
{utf8, Bin :: binary()}: Encodes Bin as UTF-8 string.
{float, float()}: Advanced floating point encoding. See erlfdb_float.
{float, _, float()}: Advanced floating point encoding. See erlfdb_float.
{double, _, float()}: Advanced floating point encoding. See erlfdb_float.
{uuid, binary()}: Encodes a binary of size == 16 as a UUID type.
{id64, integer()}: Encodes a fixed-length 64-bit integer.
{versionstamp, Id :: integer(), Batch :: integer()}: Versionstamp encoding. For unset versionstamps use pack_vs/1.
{versionstamp, Id :: integer(), Batch :: integer(), Tx}: Versionstamp encoding. For unset versionstamps use pack_vs/1.

Unsupported Erlang types

Examples

1> erlfdb_tuple:pack({}).
<<>>

1> erlfdb_tuple:pack({<<"hello">>, 42}).
<<1,104,101,108,108,111,0,21,42>>

pack(Tuple, Prefix)

-spec pack(tuple(), binary()) -> binary().

Encodes the prefix and tuple into a binary.

Examples

1> erlfdb_tuple:pack({}, <<"foo">>).
<<"foo">>

1> erlfdb_tuple:pack({<<"foo">>}, <<>>).
<<1,102,111,111,0>>

1> erlfdb_tuple:pack({<<"hello">>, 42}, <<"foo">>).
<<102,111,111,1,104,101,108,108,111,0,21,42>>

pack_vs(Tuple)

-spec pack_vs(tuple()) -> binary().

With versionstamps, encodes the tuple into a binary.

Special types

{versionstamp, Id, Batch}: Versionstamp encoding
{versionstamp, Id, Batch, Tx}: Versionstamp encoding

pack_vs(Tuple, Prefix)

-spec pack_vs(tuple(), binary()) -> binary().

With versionstamps, encodes the prefix and tuple into a binary.

range(Tuple)

-spec range(tuple()) -> {binary(), binary()}.

Returns a {StartKey, EndKey} pair of binaries that includes all possible sub-tuples.

range(Tuple, Prefix)

-spec range(tuple(), binary()) -> {binary(), binary()}.

With prefix, returns a {StartKey, EndKey} pair of binaries that includes all possible sub-tuples.

unpack(Binary)

-spec unpack(binary()) -> tuple().

Decodes the binary into a tuple.

Examples

1> erlfdb_tuple:unpack(erlfdb_tuple:pack({})).
{}

1> erlfdb_tuple:unpack(erlfdb_tuple:pack({<<"hello">>, 42})).
{<<"hello">>,42}

unpack(Binary, Prefix)

-spec unpack(binary(), binary()) -> tuple().

Decodes the binary into a prefix and tuple.

Examples

1> erlfdb_tuple:unpack(erlfdb_tuple:pack({}, <<"foo">>), <<"foo">>).
{}

1> erlfdb_tuple:unpack(erlfdb_tuple:pack({<<"hello">>, 42}, <<"foo">>), <<"foo">>).
{<<"hello">>,42}