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}]copy

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

• atom/0
• list/0
• reference/0
• pid/0
• function/0
• map/0

Examples

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

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

Encodes the prefix and tuple into a binary.

Examples

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

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

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

With versionstamps, encodes the tuple into a binary.

Special types

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

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

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

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

Decodes the binary into a tuple.

Examples

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

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

Decodes the binary into a prefix and tuple.

Examples

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

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