module Configuration.Dotenv.Parse (configParser) where
import Text.Parsec ((<|>), anyChar, char, many, manyTill, try)
import Text.Parsec.Combinator (eof)
import Text.Parsec.String (Parser)
import Text.ParserCombinators.Parsec.Char
(digit, letter, newline, noneOf, oneOf)
import Control.Applicative ((<*), (*>), (<$>))
import Data.Maybe (catMaybes)
import Control.Monad (liftM2)
configParser :: Parser [(String, String)]
configParser = catMaybes <$> many envLine <* eof
envLine :: Parser (Maybe (String, String))
envLine = (comment <|> blankLine) *> return Nothing <|> Just <$> optionLine
blankLine :: Parser String
blankLine = many verticalSpace <* newline
optionLine :: Parser (String, String)
optionLine = liftM2 (,)
(many verticalSpace *> variableName <* keywordArgSeparator)
argumentParser
variableName :: Parser String
variableName =
liftM2 (:) (letter <|> char '_') (many (letter <|> char '_' <|> digit))
argumentParser :: Parser String
argumentParser = quotedArgument <|> unquotedArgument
quotedArgument :: Parser String
quotedArgument = quotedWith '\'' <|> quotedWith '\"'
unquotedArgument :: Parser String
unquotedArgument =
manyTill anyChar (comment <|> many verticalSpace <* endOfLineOrInput)
quotedWith :: Char -> Parser String
quotedWith c = char c *> many chr <* char c
where chr = esc <|> noneOf [c]
esc = escape *> char c
comment :: Parser String
comment = try (many verticalSpace *> char '#')
*> manyTill anyChar endOfLineOrInput
endOfLineOrInput :: Parser ()
endOfLineOrInput = newline *> return () <|> eof
keywordArgSeparator :: Parser ()
keywordArgSeparator =
many verticalSpace *> char '=' *> many verticalSpace *> return ()
escape :: Parser Char
escape = char '\\'
verticalSpace :: Parser Char
verticalSpace = oneOf " \t"