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-module(binary_prop).
-export([prop_hex_encode_2/0]).
-compile([export_all, nowarn_export_all]).
-include_lib("common_test/include/ct_property_test.hrl").
prop_hex_encode_2() ->
?FORALL(Data, data(),
begin
UpperHex = binary:encode_hex(Data, uppercase),
LowerHex = binary:encode_hex(Data, lowercase),
binary:decode_hex(LowerHex) =:= Data andalso
binary:decode_hex(UpperHex) =:= Data andalso
check_hex_encoded(Data, UpperHex, LowerHex)
end).
data() ->
?SIZED(Size, resize(Size * 2, binary())).
%% @doc Credit to the <a href="https://github.com/erlang/otp/pull/6297#discussion_r1034771450">comment</a> of @Maria-12648430
-spec check_hex_encoded(Data :: binary(), UpperHex :: binary(), LoweHex :: binary()) -> boolean().
check_hex_encoded(<<I1:4, I2:4, Ins/binary>>, <<U1:8, U2:8, UCs/binary>>, <<L1:8, L2:8, LCs/binary>>) ->
check_hex_chars_match(I1, U1, L1) andalso
check_hex_chars_match(I2, U2, L2) andalso
check_hex_encoded(Ins, UCs, LCs);
check_hex_encoded(<<>>, <<>>, <<>>) ->
true;
check_hex_encoded(_, _, _) ->
false.
check_hex_chars_match(X, U, L) when X < 10 ->
(U =:= $0 + X) andalso (L =:= $0 + X);
check_hex_chars_match(X, U, L) ->
(U =:= $A + X -10) andalso (L =:= $a + X -10).
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