module Configuration.Dotenv.Parse (configParser) where
import Text.Megaparsec ((<?>), anyChar, char, eof, manyTill, try)
import Text.Megaparsec.String (Parser)
import Text.Megaparsec.Char
(digitChar, letterChar, eol, noneOf, oneOf)
import Control.Applicative
import Prelude
import Data.Maybe (catMaybes)
import Control.Monad (liftM2)
configParser :: Parser [(String, String)]
configParser = catMaybes <$> many envLine <* eof
envLine :: Parser (Maybe (String, String))
envLine = (comment <|> blankLine) *> return Nothing <|> Just <$> optionLine
blankLine :: Parser String
blankLine = many verticalSpace <* eol <?> "blank line"
optionLine :: Parser (String, String)
optionLine = liftM2 (,)
(many verticalSpace *> variableName <* variableValueSeparator)
value
variableName :: Parser String
variableName = liftM2 (:) (letterChar <|> char '_')
(many (letterChar <|> char '_' <|> digitChar <?>
unwords [ "valid non-leading shell variable character (alphanumeric,"
, "digit or underscore)" ]))
<?> unwords [ "shell variable name (letter or underscore followed"
, "by alphanumeric characters or underscores)" ]
value :: Parser String
value = quotedValue <|> unquotedValue <?> "variable value"
quotedValue :: Parser String
quotedValue = (quotedWith '\'' <|> quotedWith '\"')
<* (comment *> return () <|> many verticalSpace *> endOfLineOrInput)
<?> "variable value surrounded with single or double quotes"
unquotedValue :: Parser String
unquotedValue =
manyTill anyChar (comment <|> many verticalSpace <* endOfLineOrInput)
quotedWith :: Char -> Parser String
quotedWith c = char c *> many chr <* (char c <?> "closing quote character")
where chr = esc <|> noneOf [c]
esc = escape *> char c <?> "escape character"
comment :: Parser String
comment = try (many verticalSpace *> char '#')
*> manyTill anyChar endOfLineOrInput
<?> "comment"
endOfLineOrInput :: Parser ()
endOfLineOrInput = eol *> return () <|> eof
variableValueSeparator :: Parser ()
variableValueSeparator =
many verticalSpace *> (char '=' <?> "variable-value separator character (=)")
*> many verticalSpace *> return ()
escape :: Parser Char
escape = char '\\'
verticalSpace :: Parser Char
verticalSpace = oneOf " \t"