binary_array

binary_array is a simple Erlang library to provide memory-compact arrays of fixed-length binaries. For the use case of a large (>1000 elements) list of short (<20 bytes) binaries all the same length, binary_array provides an alternative that greatly reduces the memory footprint of the array while providing some key operations (insert, retrieve by position, find a position, sort). This limited set of operations fits the intended use case for this library but more could be added in the future. Note, a binary_array is 0-based (like an Erlang array), while Erlang lists and tuples are 1-based.

Compilation

Compile:

$ rebar compile

Run unit tests:

$ EUNIT=verbose rebar eunit

Using with Your Rebar App

If your Erlang app is built using Rebar, you can easily include binary_array as a dependency by adding this to your rebar.config file:

{deps, [
	{binary_array, ".*", {git, "git@github.com:tedb/binary_array.git"}}
]}.

If you already have a deps section, just add the middle line to the list. See the rebar documentation for details.

Example

This example shows how to download, compile, and exercise the binary_array library. This assumes you already have rebar (an Erlang build tool) installed on your path.

The $ represents your Bash prompt, and the N> represents your Erlang prompt.

$ git clone git@github.com:tedb/binary_array.git
Cloning into 'binary_array'...

$ cd binary_array

$ rebar compile
==> binary_array (compile)
Compiled src/binary_array.erl

$ rebar eunit
==> binary_array (eunit)
Compiled src/binary_array.erl
  All 5 tests passed.

$ erl -pa ebin
Erlang R15B02 [...etc...]
Eshell V5.9.2  (abort with ^G)

1> B = binary_array:new(5).
{binary_array,5,<<>>}

2> B2 = binary_array:insert(<<"Abcde">>, B).
{binary_array,5,<<"Abcde">>}

3> B3 = binary_array:insert(<<"_zzzz">>, B2).
{binary_array,5,<<"Abcde_zzzz">>}

4> B4 = binary_array:insert(<<"01234">>, B3).
{binary_array,5,<<"Abcde_zzzz01234">>}

5> PositionUnsorted = binary_array:position(<<"Abcde">>, B4).
0

6> BSorted = binary_array:sort(B4).
{binary_array,5,<<"01234Abcde_zzzz">>}

7> PositionSorted = binary_array:position(<<"Abcde">>, BSorted).
1

8> ListOfBinaries = binary_array:to_list(BSorted).
[<<"01234">>,<<"Abcde">>,<<"_zzzz">>]

9> init:stop().
ok

$

License

GPLv2

Contributing

Please fork the Github repo and send me a pull request with any changes you would like me to consider including.

tedb / binary_array