gistfile1.erl

-module(binaries).

-export([by_char/2, whole/2, by_list/2, count/0]).

by_char(Rest, <<>>) ->
    Rest;
by_char(<<C, String/binary>>, <<C, Pattern/binary>>) ->
    by_char(String, Pattern);
by_char(_, _) ->
    no_match.


whole(String, Pattern) ->
    PatternSize = byte_size(Pattern),
    case String of
        <<Pattern:PatternSize/binary, Rest/binary>> ->
            Rest;
        _ ->
            no_match
    end.


by_list(String, Boundary) ->
    by_list0(String, binary_to_list(Boundary)).

by_list0(<<C, String/binary>>, [C | Pattern]) ->
    by_list0(String, Pattern);
by_list0(Rest, []) ->
    Rest;
by_list0(_, _) ->
    no_match.


count() ->
    [count(Fun, 1000, 0) || Fun <- [by_char, by_list, whole]].

count(Fun, 0, Result) ->
    {Fun, Result};
count(Fun, N, Result) ->
    S = crypto:rand_bytes(2000),
    B = binary:part(S, {0, 20}),
    {Time, _} = timer:tc(?MODULE, Fun, [S, B]),
    count(Fun, N - 1, Result + Time).