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August 29, 2015 14:04
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Erlang stdlib provides string:join/2 function but not binary:join/2. Below are few options how to do binary:join/2. Guess which one is the fastest.
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-module(binary2). | |
-export([joinl/2]). | |
-export([joinfl/2]). | |
-export([joinfr/2]). | |
% use list comprehension | |
joinl([], Sep) when is_binary(Sep) -> | |
<<>>; | |
joinl([H|T], Sep) -> | |
erlang:iolist_to_binary([H, [[Sep, X] || X <- T]]). | |
% use lists:foldl/3 followed by lists:reverse/1 | |
joinfl([], Sep) when is_binary(Sep) -> | |
<<>>; | |
joinfl([H|T], Sep) -> | |
erlang:iolist_to_binary([H, lists:reverse( | |
lists:foldl(fun(X, Acc) -> [X|[Sep|Acc]] end, [], T))]). | |
% use lists:foldr/3 | |
joinfr([], Sep) when is_binary(Sep) -> | |
<<>>; | |
joinfr([H|T], Sep) -> | |
erlang:iolist_to_binary([H| | |
lists:foldr(fun(X, Acc) -> [Sep|[X|Acc]] end, [], T)]). |
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