[英]Can Ragel perform individual command parsing and throw errors accordingly
我正在嘗試解析命令:LoadSdf 12 abc.ldf
我正在嘗試在命令的每個階段獲取錯誤( :LoadSdf
, 12
, abc.ldf
)。 但是我得到了不同的行為,如問題的后面部分所示。
以下是我的拉格爾偽代碼
%%
machine ldf;
LOAD_CMD = ":LoadSdf" $!(cmd_error);
CHANNEL_NR = [digit]+ $!(channel_error);
FILENAME = [a-zA-Z0-9\.\-\_]+ $!(filename_error);
SPACE = ' ';
main:= (LOAD_CMD.SPACE+.CHANNEL_NR.SPACE.FILENAME) %/job_done;
%%
預期產量:
./a.out ":Load"
incorrect command //corresponding actions contain these error messages
./a.out ":LoadSdf"
whitespace missing //corresponding actions contain these error messages
./a.out ":LoadSdf "
channel number missing //corresponding actions contain these error messages
./a.out ":LoadSdf 12 "
file name missing //corresponding actions contain these error messages
./a.out ":LoadSdf 12 abc.ldf"
parsing success //corresponding actions contain these messages
觀察輸出:
./a.out ":Load"
incorrect command
./a.out ":LoadSdf"
whitespace missing
./a.out ":LoadSdf "
whitespace missing
channel number missing
./a.out ":LoadSdf 12 "
whitespace missing
file name missing
./a.out ":LoadSdf 12"
channel number missing
./a.out ":LoadSdf 12 abc.ldf"
parsing success
用於錯誤處理的Ragel語法非常困難,並且解釋非常有限。 如果對當前案例提供任何建議,那將有很大的幫助。
在狀態機的幫助下進行更多的調試,我可以得出答案。 基本上是>!
僅在啟動條件下可用於錯誤處理。
LOAD_CMD = ":LoadSdf" @!(cmd_error);
CHANNEL_NR = [digit]+ >!(channel_error);
FILENAME = [a-zA-Z0-9\.\-\_]+ $!(filename_error);
SPACE = ' ' >!(whitespace_error);
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