Haskell 标识符识别
我使用 Haskell 进行文件解析，并且同时使用 Data.Attoparsec.Char8 和 Data.ByteString.Char8。我想解析一个可以包含以下符号的表达式：- / [ ] _ .（减号、斜杠、括号和下划线）。
我已经编写了以下解析器
import qualified Data.ByteString.Char8 as B
import qualified Data.Attoparsec.Char8 as A
identifier' :: Parser B.ByteString
identifier' = A.takeWhile $ A.inClass "A-Za-z0-9_//- /[/]"
...但它没有按预期工作。
ghc> A.parse identifier' (B.pack "EMBXSHM-PortClo")
Done "-PortClo" "EMBXSHM"
ghc> A.parse identifier' (B.pack "AU_D[1].PCMPTask")
Done ".PCMPTask" "AU_D[1]"
有人可以帮助我吗？
感谢您抽出时间。
my working in file parsing using Haskell, and I'm using both Data.Attoparsec.Char8 and Data.ByteString.Char8. I want to parse an expression which can contains symbols like : - / [ ] _ . (minus, slashes, braquets and underscore).
I've write the following parser
import qualified Data.ByteString.Char8 as B
import qualified Data.Attoparsec.Char8 as A
identifier' :: Parser B.ByteString
identifier' = A.takeWhile $ A.inClass "A-Za-z0-9_//- /[/]"
... but it's not works like expected.
ghc> A.parse identifier' (B.pack "EMBXSHM-PortClo")
Done "-PortClo" "EMBXSHM"
ghc> A.parse identifier' (B.pack "AU_D[1].PCMPTask")
Done ".PCMPTask" "AU_D[1]"
can someone help me.
Thanks for your time.
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查看文档： http://hackage.haskell.org/packages/archive/attoparsec/0.10.1.0/doc/html/Data-Attoparsec-ByteString-Char8.html#g:9
添加“-”到一个集合，将其放置在字符串的开头或结尾。
后者不会解析，因为您的类列表中没有点。
Take a look at the documentation: http://hackage.haskell.org/packages/archive/attoparsec/0.10.1.0/doc/html/Data-Attoparsec-ByteString-Char8.html#g:9
To add a "-" to a set, place it a the beginning or end of a string.
The latter doesn't parse because you don't have dots in your class listing.
您希望在标识符中允许使用
'-'字符，但A.inClass使用'-'作为范围。您必须将其放在范围字符串的开头或结尾：You want to allow
'-'characters in identifiers, butA.inClassuses'-'for ranges. You have to put it at the start or end of the range string: