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erl_nbt

0.2.0
1.0.0 0.2.0 0.1.0

An Erlang/OTP library for manipulating NBT (Named Binary Tag) data

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erl_nbt src erl_nbt_encode.erl
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src/erl_nbt_encode.erl 

%%%-------------------------------------------------------------------

%%% @author Matthijs Bakker <matthijs at hypothermic .nl>

%%% @copyright (C) 2021 hypothermic.nl

%%% @doc

%%%		Provides encoding functions for NBT data

%%% @end

%%% Created : 23. Jun 2021 2:41 PM

%%%-------------------------------------------------------------------

-module(erl_nbt_encode).

-author("Matthijs Bakker <matthijs at hypothermic .nl>").

-copyright("Copyright (C) 2021 hypothermic.nl").



-include("erl_nbt.hrl").



%%%-------------------------------------------------------------------

%%% Private API

%%%-------------------------------------------------------------------



-export([

	encode/1

]).



-spec encode(Nbt :: erl_nbt:nbt()) ->

	{ok, Binary :: binary()} |

	{error, {invalid_nbt, Details :: string()}}.

encode(Nbt) ->

	{ok, encode_compound(Nbt)}.



%%%-------------------------------------------------------------------

%%% Internal Functions

%%%-------------------------------------------------------------------



encode_tag(Key, {?TAG_BYTE_TYPE, Value}) ->

	<<

		?TAG_BYTE_ID:8/unsigned-integer,

		(encode_string(Key))/binary,

		Value:8/big-signed-integer

	>>;



encode_tag(Key, {?TAG_SHORT_TYPE, Value}) ->

	<<

		?TAG_SHORT_ID:8/unsigned-integer,

		(encode_string(Key))/binary,

		Value:16/big-signed-integer

	>>;



encode_tag(Key, {?TAG_INT_TYPE, Value}) ->

	<<

		?TAG_INT_ID:8/unsigned-integer,

		(encode_string(Key))/binary,

		Value:32/big-signed-integer

	>>;



encode_tag(Key, {?TAG_LONG_TYPE, Value}) ->

	<<

		?TAG_LONG_ID:8/unsigned-integer,

		(encode_string(Key))/binary,

		Value:64/big-signed-integer

	>>;



encode_tag(Key, {?TAG_FLOAT_TYPE, Value}) ->

	<<

		?TAG_FLOAT_ID:8/unsigned-integer,

		(encode_string(Key))/binary,

		Value:32/big-signed-float

	>>;



encode_tag(Key, {?TAG_DOUBLE_TYPE, Value}) ->

	<<

		?TAG_DOUBLE_ID:8/unsigned-integer,

		(encode_string(Key))/binary,

		Value:64/big-signed-float

	>>;



encode_tag(Key, {?TAG_BYTE_ARRAY_TYPE, Value}) ->

	<<

		?TAG_BYTE_ARRAY_ID:8/unsigned-integer,

		(encode_string(Key))/binary,

		(length(Value)):32/big-signed-integer,

		(lists:foldl(fun (E, Acc) -> <<Acc/binary, E:8/signed-integer>> end, <<>>, Value))/binary

	>>;



encode_tag(Key, {?TAG_INT_ARRAY_TYPE, Value}) ->

	<<

		?TAG_INT_ARRAY_ID:8/unsigned-integer,

		(encode_string(Key))/binary,

		(length(Value)):32/big-signed-integer,

		(lists:foldl(fun (E, Acc) -> <<Acc/binary, E:32/signed-integer>> end, <<>>, Value))/binary

	>>;



encode_tag(Key, {?TAG_LONG_ARRAY_TYPE, Value}) ->

	<<

		?TAG_LONG_ARRAY_ID:8/unsigned-integer,

		(encode_string(Key))/binary,

		(length(Value)):32/big-signed-integer,

		(lists:foldl(fun (E, Acc) -> <<Acc/binary, E:64/signed-integer>> end, <<>>, Value))/binary

	>>;



encode_tag(Key, {?TAG_STRING_TYPE, Value}) ->

	<<

		?TAG_STRING_ID:8/unsigned-integer,

		(encode_string(Key))/binary,

		(encode_string(Value))/binary

	>>;



encode_tag(Key, Value) when is_map(Value) ->

	encode_tag(Key, {compound, Value});



encode_tag(Key, {?TAG_COMPOUND_TYPE, Value}) ->

	<<

		?TAG_COMPOUND_ID:8/unsigned-integer,

		(encode_string(Key))/binary,

		(encode_compound(Value))/binary,

		?TAG_END_ID:8/unsigned-integer

	>>.



encode_string(String) ->

	<<

		(length(String)):16/unsigned-integer,

		(list_to_binary(String))/binary

	>>.



encode_compound(Nbt) ->

	maps:fold(fun (Key, Value, Acc) ->

		<<

			Acc/binary,

			(encode_tag(Key, Value))/binary

		>>

		end, <<>>, Nbt).