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所以我写了两个版本的gen_fsm来解析一个字节流。我正在寻找一个以字符串snp
开头的数据包,然后我想在p
之后保存下一个20个字节。这段代码只关心查找标题。我需要一些建议,指出哪一种是更加惯用的Erlang或更好的写法。哪一种比较习惯?
选项1
parse_header({parse, Byte}, {Header, [Next | Rest]}) ->
case Byte of
Next when length(Rest) > 0 -> {next_state, parse_header, {Header, Rest}};
Next when length(Rest) == 0 -> {next_state, parse_data, []};
$s -> parse_header({parse, Byte}, {Header, Header});
_ -> {next_state, parse_header, {Header, Header}}
end.
选项2
parse_start({parse, Byte}, State) when Byte == $s ->
{next_state, parse_new, State};
parse_start({parse, Byte}, State) when Byte /= $s ->
{next_state, parse_start, State}.
parse_new({parse, Byte}, State) when Byte == $n ->
{next_state, parse_packet, State};
parse_new({parse, Byte}, State) when Byte == $s ->
parse_start({parse, Byte}, State);
parse_new({parse, _Byte}, State) ->
{next_state, parse_start, State}.
parse_packet({parse, Byte}, State) when Byte == $p ->
{next_state, parse_data, State};
parse_packet({parse, Byte}, State) when Byte == $s ->
parse_start({parse, Byte}, State);
parse_packet({parse, _Byte}, State) ->
{next_state, parse_start, State}.