[Haskell-cafe] please comment on my parser, can I do this cleaner?
All I want to do is split on commas, but not the commas inside () or tags.
I have been wanting to master parsec for a long time and this simple
exercise looked like a good place to start.
The code below does the right thing. Am I missing any tricks to make
this simpler/neater?
Thanks, thomas.
thart...@ubuntu:~/perlArenacat splitEm.
splitEm.hs splitEm.hs~ splitEm.pl splitEm.pl~
thart...@ubuntu:~/perlArenacat splitEm.hs
{-# LANGUAGE ScopedTypeVariables #-}
import Text.ParserCombinators.Parsec
import Text.ParserCombinators.Parsec.Char
import Text.PrettyPrint (vcat, render, text)
import Data.List.Split hiding (sepBy, chunk)
import Text.ParserCombinators.Parsec.Token
import Debug.Trace
import Debug.Trace.Helpers
-- this works, but is there a neater/cleaner way?
main = ripInputsXs (toEof splitter) splitter [ goodS, badS ]
-- I need a way to split on commas, but not the commas inside '' or
'()' characters
goodS = *2FOO2,1,*3(SigB8:0:2,BAR),*2Siga2:0,Sigb8,7,6,5,0
badS = *2)FOO2,1,*3(SigB8:0:2,BAR),*2Siga2:0,Sigb8,7,6,5,0
-- the first matches a ), so reject this
splitter = do
chunks :: [String] - toEof (many chunk)
let pieces = map concat $ splitOn [,] chunks
return pieces -- chunks
where
atom = string ,
| ( many1 $ noneOf () )
chunk = parenExpr | atom
parenExpr :: GenParser Char st [Char]
parenExpr = let paren p = betweenInc (char '(' ) (char ')' ) p
| betweenInc (char '' ) (char '' )
p
in paren $ option $ do ps - many1 $ parenExpr | atom
return . concat $ ps
betweenInc o' c' p' = do
o - o'
p - p'
c - c'
return $ [o] ++ p ++ [c]
toEof p' = do
r - p'
eof
return r
ripInputs prs prsName xs = mapM_ (putStrLn . show . parse prs prsName ) xs
ripInputsXs prs prsName xs = mapM_ (putStrLn . showXs . parse prs prsName ) xs
where showXs v = case v of
Left e - show e
Right xs - render . vcat . map text $ xs
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Re: [Haskell-cafe] please comment on my parser, can I do this cleaner?
Am Dienstag 09 Juni 2009 20:29:09 schrieb Thomas Hartman:
All I want to do is split on commas, but not the commas inside () or
tags.
I have been wanting to master parsec for a long time and this simple
exercise looked like a good place to start.
The code below does the right thing. Am I missing any tricks to make
this simpler/neater?
Thanks, thomas.
thart...@ubuntu:~/perlArenacat splitEm.
splitEm.hs splitEm.hs~ splitEm.pl splitEm.pl~
thart...@ubuntu:~/perlArenacat splitEm.hs
{-# LANGUAGE ScopedTypeVariables #-}
import Text.ParserCombinators.Parsec
import Text.ParserCombinators.Parsec.Char
import Text.PrettyPrint (vcat, render, text)
import Data.List.Split hiding (sepBy, chunk)
import Text.ParserCombinators.Parsec.Token
import Debug.Trace
import Debug.Trace.Helpers
-- this works, but is there a neater/cleaner way?
main = ripInputsXs (toEof splitter) splitter [ goodS, badS ]
-- I need a way to split on commas, but not the commas inside '' or
'()' characters
goodS = *2FOO2,1,*3(SigB8:0:2,BAR),*2Siga2:0,Sigb8,7,6,5,0
badS = *2)FOO2,1,*3(SigB8:0:2,BAR),*2Siga2:0,Sigb8,7,6,5,0
-- the first matches a ), so reject this
splitter = do
chunks :: [String] - toEof (many chunk)
let pieces = map concat $ splitOn [,] chunks
return pieces -- chunks
where
atom = string ,
| ( many1 $ noneOf () )
chunk = parenExpr | atom
I think that does not do what you want.
For input FOO,BAR,BAZ, chunks is [FOO,BAR,BAZ], that won't be split; as far
as I can
see, it splits only on commas directly following a parenExpr (or at the
beginning of the
input or directly following another splitting comma).
parenExpr :: GenParser Char st [Char]
parenExpr = let paren p = betweenInc (char '(' ) (char ')' ) p
| betweenInc (char '' ) (char '' )
p
in paren $ option $ do ps - many1 $ parenExpr | atom
return . concat $ ps
betweenInc o' c' p' = do
o - o'
p - p'
c - c'
return $ [o] ++ p ++ [c]
toEof p' = do
r - p'
eof
return r
ripInputs prs prsName xs = mapM_ (putStrLn . show . parse prs prsName ) xs
ripInputsXs prs prsName xs = mapM_ (putStrLn . showXs . parse prs prsName )
xs where showXs v = case v of
Left e - show e
Right xs - render . vcat . map text $ xs
I can offer (sorry for the names, and I don't know if what that does is really
what you
want):
keepSepBy :: Parser a - Parser a - Parser [a]
keepSepBy p sep = (do
r - p
(do s - sep
xs - keepSepBy p sep
return (r:s:xs)) | return [r])
| return []
twain :: Parser a - Parser a - Parser [a] - Parser [a]
twain open close list = do
o - open
l - list
c - close
return (o:l++[c])
comma :: Parser String
comma = string ,
simpleChar :: Parser Char
simpleChar = noneOf (),
suite :: Parser String
suite = many1 simpleChar
atom :: Parser String
atom = fmap concat $ many1 (parenExp | suite)
parenGroup :: Parser String
parenGroup = fmap concat $ keepSepBy atom comma
parenExp :: Parser String
parenExp = twain (char '') (char '') parenGroup
| twain (char '(') (char ')') parenGroup
chunks :: Parser [String]
chunks = sepBy atom comma
splitter = do
cs - chunks
eof
return cs
goodS = *2FOO2,1,*3(SigB8:0:2,BAR),*2Siga2:0,Sigb8,7,6,5,0
badS = *2)FOO2,1,*3(SigB8:0:2,BAR),*2Siga2:0,Sigb8,7,6,5,0
goodRes = parse splitter splitter goodS
badRes = parse splitter splitter badS
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Re: [Haskell-cafe] please comment on my parser, can I do this cleaner?
Thanks. It seems my original parser also works against FOO,BAR,BAZ if
you only modify
atom = string ,
| ( many1 $ noneOf (), ) -- add ,
Indeed, what to call the thingies in a parser is a source of some
personal consternation.
What is a token, what is an atom, what is an expr? It all seems to be
somewhat ad hoc.
2009/6/9 Daniel Fischer daniel.is.fisc...@web.de:
Am Dienstag 09 Juni 2009 20:29:09 schrieb Thomas Hartman:
All I want to do is split on commas, but not the commas inside () or
tags.
I have been wanting to master parsec for a long time and this simple
exercise looked like a good place to start.
The code below does the right thing. Am I missing any tricks to make
this simpler/neater?
Thanks, thomas.
thart...@ubuntu:~/perlArenacat splitEm.
splitEm.hs splitEm.hs~ splitEm.pl splitEm.pl~
thart...@ubuntu:~/perlArenacat splitEm.hs
{-# LANGUAGE ScopedTypeVariables #-}
import Text.ParserCombinators.Parsec
import Text.ParserCombinators.Parsec.Char
import Text.PrettyPrint (vcat, render, text)
import Data.List.Split hiding (sepBy, chunk)
import Text.ParserCombinators.Parsec.Token
import Debug.Trace
import Debug.Trace.Helpers
-- this works, but is there a neater/cleaner way?
main = ripInputsXs (toEof splitter) splitter [ goodS, badS ]
-- I need a way to split on commas, but not the commas inside '' or
'()' characters
goodS = *2FOO2,1,*3(SigB8:0:2,BAR),*2Siga2:0,Sigb8,7,6,5,0
badS = *2)FOO2,1,*3(SigB8:0:2,BAR),*2Siga2:0,Sigb8,7,6,5,0
-- the first matches a ), so reject this
splitter = do
chunks :: [String] - toEof (many chunk)
let pieces = map concat $ splitOn [,] chunks
return pieces -- chunks
where
atom = string ,
| ( many1 $ noneOf () )
chunk = parenExpr | atom
I think that does not do what you want.
For input FOO,BAR,BAZ, chunks is [FOO,BAR,BAZ], that won't be split; as
far as I can
see, it splits only on commas directly following a parenExpr (or at the
beginning of the
input or directly following another splitting comma).
parenExpr :: GenParser Char st [Char]
parenExpr = let paren p = betweenInc (char '(' ) (char ')' ) p
| betweenInc (char '' ) (char '' )
p
in paren $ option $ do ps - many1 $ parenExpr | atom
return . concat $ ps
betweenInc o' c' p' = do
o - o'
p - p'
c - c'
return $ [o] ++ p ++ [c]
toEof p' = do
r - p'
eof
return r
ripInputs prs prsName xs = mapM_ (putStrLn . show . parse prs prsName ) xs
ripInputsXs prs prsName xs = mapM_ (putStrLn . showXs . parse prs prsName )
xs where showXs v = case v of
Left e - show e
Right xs - render . vcat . map text $ xs
I can offer (sorry for the names, and I don't know if what that does is
really what you
want):
keepSepBy :: Parser a - Parser a - Parser [a]
keepSepBy p sep = (do
r - p
(do s - sep
xs - keepSepBy p sep
return (r:s:xs)) | return [r])
| return []
twain :: Parser a - Parser a - Parser [a] - Parser [a]
twain open close list = do
o - open
l - list
c - close
return (o:l++[c])
comma :: Parser String
comma = string ,
simpleChar :: Parser Char
simpleChar = noneOf (),
suite :: Parser String
suite = many1 simpleChar
atom :: Parser String
atom = fmap concat $ many1 (parenExp | suite)
parenGroup :: Parser String
parenGroup = fmap concat $ keepSepBy atom comma
parenExp :: Parser String
parenExp = twain (char '') (char '') parenGroup
| twain (char '(') (char ')') parenGroup
chunks :: Parser [String]
chunks = sepBy atom comma
splitter = do
cs - chunks
eof
return cs
goodS = *2FOO2,1,*3(SigB8:0:2,BAR),*2Siga2:0,Sigb8,7,6,5,0
badS = *2)FOO2,1,*3(SigB8:0:2,BAR),*2Siga2:0,Sigb8,7,6,5,0
goodRes = parse splitter splitter goodS
badRes = parse splitter splitter badS
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