In your use case, do different commads have a clear delimiter character,
like a newline? That would simplify things.
On Saturday, October 24, 2015 at 7:30:57 AM UTC+2, Michael Whitehead wrote:
>
> Not sure if I should try to solve my problem with attoparsec itself or
> with pipes. Either way I don't really know where to start so I would
> appreciate it if someone could help me a little.
>
> {-# LANGUAGE OverloadedStrings #-}
>
> module Main where
>
> import qualified Data.ByteString as B
> import Pipes
> import qualified Pipes.Prelude as P
> import qualified Pipes.Attoparsec as P
> import Data.Attoparsec.ByteString.Char8 as A
>
>
> data Foo = Foo deriving Show
> data Bar = Bar deriving Show
> data Baz = Baz deriving Show
> data Command = Command Foo Bar Baz deriving Show
> data Escape = Escape deriving Show
>
> fooParser :: Parser Foo
> fooParser = string "foo" >> return Foo
>
> barParser :: Parser Bar
> barParser = string "bar" >> return Bar
>
> bazParser :: Parser Baz
> bazParser = string "baz" >> return Baz
>
> exitParser :: Parser Escape
> exitParser = string "escape" >> return Escape
>
> commandParser :: Parser Command
> commandParser =
> Command <$> fooParser
> <*> barParser
> <*> bazParser
>
>
> example :: Producer B.ByteString IO ()
> example = do
> yield "foobarbaz"
> yield "foo"
> yield "bar"
> yield "invalid" -- skip over invalid input
> yield "baz"
> yield "foo"
> yield "escape" -- exit early from parse based on specific value
> yield "foobarbaz"
>
> main :: IO ()
> main = do
> runEffect $ P.parsed commandParser example >-> P.print
> return ()
>
>
> Basically I want to make it so that when there is an invalid input it will
> just skip it and continue where it left off. Also I would like to be able
> to handle special values that will allow an exit from the parsing so I can
> start fresh.
>
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