[Haskell-cafe] "Dynamic" CSV Parsing - Parsec

[Bernd Holzmüller]

Hi Günther,

A simple method is to parameterize a parse function by something you
parsed previously.
For the example you gave, I would try something like this:

import ParseToken

cellContent = do ... -- parses the contents of a cell

cvsParser = do
  headings <- sepBy identifier semi
  cs <- count (length headings - 1) (do c <- cellContent; semi; return c)
  c <- cellContent
  return (cs ++ [c])

Of course, you can put the last two lines into a separate function that
is parameterized with the list of headings found.
(Instead of these lines, I would also define an abstraction function
sepByCount p n sep that parses n occurrences of p, each separated by sep.)

Best regards,
Bernd

Am 07.05.2010 00:40, schrieb Günther Schmidt:
> Hello,
>
> I'm trying to build a CSV parser that can dynamically assemble a
> parser from the values of the first line.
>
> As the most simple example the parse of the first line would return a
> parser with which subsequent lines would then be parsed.
> This parser would, for instance, only parse lines with the exact
> number of columns as found in the first line.
>
> Where I eventually want to go is a bit more complicated than this, but
> for now I'd be grateful for suggestions on how to go about the simple
> case.
>
> Best regards
>
> Günther
>
>
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