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|
{-# LANGUAGE OverloadedStrings #-}
-- |
-- Module: Data.Configurator.Parser
-- Copyright: (c) 2011 MailRank, Inc.
-- License: BSD3
-- Maintainer: Bryan O'Sullivan <bos@serpentine.com>
-- Stability: experimental
-- Portability: portable
--
-- A parser for configuration files.
module Data.Configurator.Parser
(
topLevel
, interp
) where
import Control.Applicative
import Control.Exception (throw)
import Control.Monad (when)
import Data.Attoparsec.Text as A
import Data.Bits (shiftL)
import Data.Char (chr, isAlpha, isAlphaNum, isSpace)
import Data.Configurator.Types.Internal
import Data.Monoid (Monoid(..))
import Data.Text (Text)
import Data.Text.Lazy.Builder (fromText, singleton, toLazyText)
import qualified Data.Text as T
import qualified Data.Text.Lazy as L
topLevel :: Parser [Directive]
topLevel = directives <* skipLWS <* endOfInput
directive :: Parser Directive
directive =
mconcat [
string "import" *> skipLWS *> (Import <$> string_)
, Bind <$> try (ident <* skipLWS <* char '=' <* skipLWS) <*> value
, Group <$> try (ident <* skipLWS <* char '{' <* skipLWS)
<*> directives <* skipLWS <* char '}'
]
directives :: Parser [Directive]
directives = (skipLWS *> directive <* skipHWS) `sepBy`
(satisfy $ \c -> c == '\r' || c == '\n')
data Skip = Space | Comment
-- | Skip lines, comments, or horizontal white space.
skipLWS :: Parser ()
skipLWS = scan Space go *> pure ()
where go Space c | isSpace c = Just Space
go Space '#' = Just Comment
go Space _ = Nothing
go Comment '\r' = Just Space
go Comment '\n' = Just Space
go Comment _ = Just Comment
-- | Skip comments or horizontal white space.
skipHWS :: Parser ()
skipHWS = scan Space go *> pure ()
where go Space ' ' = Just Space
go Space '\t' = Just Space
go Space '#' = Just Comment
go Space _ = Nothing
go Comment '\r' = Nothing
go Comment '\n' = Nothing
go Comment _ = Just Comment
ident :: Parser Name
ident = do
n <- T.cons <$> satisfy isAlpha <*> A.takeWhile isCont
when (n == "import") $
throw (ParseError "" $ "reserved word (" ++ show n ++ ") used as identifier")
return n
where
isCont c = isAlphaNum c || c == '_' || c == '-'
value :: Parser Value
value = mconcat [
string "on" *> pure (Bool True)
, string "off" *> pure (Bool False)
, string "true" *> pure (Bool True)
, string "false" *> pure (Bool False)
, String <$> string_
, Number <$> rational
, List <$> brackets '[' ']'
((value <* skipLWS) `sepBy` (char ',' <* skipLWS))
]
string_ :: Parser Text
string_ = do
s <- char '"' *> scan False isChar <* char '"'
if "\\" `T.isInfixOf` s
then unescape s
else return s
where
isChar True _ = Just False
isChar _ '"' = Nothing
isChar _ c = Just (c == '\\')
brackets :: Char -> Char -> Parser a -> Parser a
brackets open close p = char open *> skipLWS *> p <* char close
embed :: Parser a -> Text -> Parser a
embed p s = case parseOnly p s of
Left err -> fail err
Right v -> return v
unescape :: Text -> Parser Text
unescape = fmap (L.toStrict . toLazyText) . embed (p mempty)
where
p acc = do
h <- A.takeWhile (/='\\')
let rest = do
let cont c = p (acc `mappend` fromText h `mappend` singleton c)
c <- char '\\' *> satisfy (inClass "ntru\"\\")
case c of
'n' -> cont '\n'
't' -> cont '\t'
'r' -> cont '\r'
'"' -> cont '"'
'\\' -> cont '\\'
_ -> cont =<< hexQuad
done <- atEnd
if done
then return (acc `mappend` fromText h)
else rest
hexQuad :: Parser Char
hexQuad = do
a <- embed hexadecimal =<< A.take 4
if a < 0xd800 || a > 0xdfff
then return (chr a)
else do
b <- embed hexadecimal =<< string "\\u" *> A.take 4
if a <= 0xdbff && b >= 0xdc00 && b <= 0xdfff
then return $! chr (((a - 0xd800) `shiftL` 10) + (b - 0xdc00) + 0x10000)
else fail "invalid UTF-16 surrogates"
-- | Parse a string interpolation spec.
--
-- The sequence @$$@ is treated as a single @$@ character. The
-- sequence @$(@ begins a section to be interpolated, and @)@ ends it.
interp :: Parser [Interpolate]
interp = reverse <$> p []
where
p acc = do
h <- Literal <$> A.takeWhile (/='$')
let rest = do
let cont x = p (x : h : acc)
c <- char '$' *> satisfy (\c -> c == '$' || c == '(')
case c of
'$' -> cont (Literal (T.singleton '$'))
_ -> (cont . Interpolate) =<< A.takeWhile1 (/=')') <* char ')'
done <- atEnd
if done
then return (h : acc)
else rest
|
