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Make XLSError a sub-type of XlsException #1

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Make XLSError a sub-type of XlsException #1

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10 changes: 7 additions & 3 deletions lib/Data/Xls.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -129,13 +129,15 @@ CCALL(xls_cell_hidden, XLSCell -> IO Int8 -- Int8)
data XlsException =
XlsFileNotFound String
| XlsParseError String
| Libxls XLSError
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The two cases of XLSError are already represented in XlsException. We can add the other cases as well, something like this:

data XlsException =
      XlsFileNotFound String
    | XlsParseError String
    | XlsSeekError String
    | XlsReadError String 
    | XlsMallocError String

And just translate XLSError to XlsException, and then do not export XLSError.

deriving (Show, Typeable)

instance Exception XlsException

exceptionLeft :: XlsException -> Either XLSError a
exceptionLeft (XlsFileNotFound _) = Left LIBXLS_ERROR_OPEN
exceptionLeft (XlsParseError _) = Left LIBXLS_ERROR_PARSE
exceptionLeft (Libxls e) = Left e

catchXls :: IO a -> IO (Either XLSError a)
catchXls = flip catch (return.exceptionLeft) . fmap Right
Expand Down Expand Up @@ -179,15 +181,17 @@ decodeXlsByteString content = withSystemTempFile "decodeXlsByteString"
hPut h content
decodeXlsIO filePath

-- | Experimental: This function uses the @xls_open_buffer@ function of libxls.
decodeXlsByteString' :: ByteString -> IO (Either XLSError [[[Cell]]])
-- | Alternative to 'decodeXlsByteString':
-- This function uses the @xls_open_buffer@ function of libxls.
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This is hard to understand for users of the library. We can instead say something like:

"This function does not use a temporary file unlike decodeXlsByteString".

BTW, why don't we just use solely this API and remove the other one? Is this not reliable?

-- Can throw 'XlsException' when decoding fails.
decodeXlsByteString' :: ByteString -> IO [[[Cell]]]
decodeXlsByteString' bs = do
(buf,buflen) <- toCBuffer bs
enc <- newCString "UTF-8"
outError <- malloc
wb <- c_xls_open_buffer buf buflen enc outError
e <- peek outError
case e of
either (throwIO. Libxls) return =<< case e of
LIBXLS_OK -> decodeXLSWorkbook Nothing wb
_ -> return (Left e)

Expand Down