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module Fun.Parser where
data Trace = StringTrace String | OrTrace [Trace] [Trace]
deriving (Eq, Show)
data State = State
{ trace :: [Trace]
, line :: Maybe String
}
deriving (Eq, Show)
type Parser a = String -> Either State (a, String)
----
lowerAlpha :: [Char]
lowerAlpha = "abcdefghijklmnopqrstuvwxyzαβγδεζηθικλμνξοπρστυφχψω"
upperAlpha :: [Char]
upperAlpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZΑΒΓΔΕΖΗΘΙΚΛΜΝΞΟΠΡΣΤΥΦΧΨΩ"
isDigit :: Char -> Bool
isDigit = (`elem` "0123456789")
isAlpha :: Char -> Bool
isAlpha = (`elem` lowerAlpha ++ upperAlpha)
isLower :: Char -> Bool
isLower = (`elem` lowerAlpha)
isUpper :: Char -> Bool
isUpper = (`elem` upperAlpha)
----
char :: Parser Char
char [] = Left $ State [StringTrace "char"] Nothing
char (x : xs) = Right (x, xs)
endOfFile :: Parser Char
endOfFile [] = Right ('\00', [])
endOfFile _ = Left $ State [StringTrace "end of file"] Nothing
digit :: Parser Char
digit = char <=> isDigit <?> "digit"
digits :: Parser String
digits = oneOrMore digit <?> "digits"
number :: Parser Integer
number =
literal '-'
<-+> digits
>>> (\n -> -1 * (read n :: Integer))
<|> digits
>>> (\n -> read n :: Integer)
<?> "number"
space :: Parser Char
space = char <=> (== ' ') <?> "space"
notSpace :: Parser Char
notSpace = char <=> (/= ' ') <?> "non-space"
newline :: Parser Char
newline = char <=> (== '\n') <?> "newline"
letter :: Parser Char
letter = char <=> isAlpha <?> "letter"
letters :: Parser String
letters = oneOrMore letter <?> "letters"
alphanum :: Parser Char
alphanum = digit <|> letter <?> "letter or digit"
special :: Parser Char
special = oneOf "+-*/<^>$@#&!?" <?> "special character"
specialWord :: Parser String
specialWord = oneOrMore (alphanum <|> special) <?> "special word"
internalWord :: Parser String
internalWord = literal '_' <+> specialWord >>> build <?> "special word"
where build (x, xs) = x : xs
oneOf :: [Char] -> Parser Char
oneOf s = char <=> (`elem` s) <?> "one of"
string :: Parser String
string =
literal '"' <-+> iter (char <=> (/= '"')) <+-> literal '"' <?> "string"
literal :: Char -> Parser Char
literal c = char <=> (== c) <?> "char (" ++ [c] ++ ")"
result :: a -> Parser a
result a cs = Right (a, cs)
oneOrMore :: Parser Char -> Parser String
oneOrMore m = (iter m) <=> (/= "") <?> "one or more chars"
iter :: Parser a -> Parser [a]
iter m = m <+> iter m >>> (\(x, y) -> x : y) <|> result [] <?> "multiple"
iterFull :: Parser a -> Parser [a]
iterFull m = m <+> iterFull m >>> (\(x, y) -> x : y) <|> iterFull'
iterFull' "" = Right ([], "")
iterFull' _ = Left $ State [] $ Nothing
acceptSpecial :: String -> Parser String
acceptSpecial w = specialWord <=> (== w)
-- Given a parser and a predicate return the parser only if it satisfies the predicate
infix 7 <=>
(<=>) :: Parser a -> (a -> Bool) -> Parser a
(parser <=> predicate) input = case parser input of
Left a -> Left a
Right (a, rest) -> if (predicate a)
then Right (a, rest)
else Left $ State [] $ Just $ head . lines $ input
-- Combine two parser together pairing their results up in a tuple
infixl 6 <+>
(<+>) :: Parser a -> Parser b -> Parser (a, b)
(parserA <+> parserB) input = case parserA input of
Left a -> Left a
Right (resultA, remainder) -> case parserB remainder of
Left a -> Left a
Right (resultB, cs) -> Right ((resultA, resultB), cs)
-- Sequence operator that discards the second result
infixl 6 <+->
(<+->) :: Parser a -> Parser b -> Parser a
(parserA <+-> parserB) input = case parserA input of
Left a -> Left a
Right (resultA, remainder) -> case parserB remainder of
Left a -> Left a
Right (_, cs) -> Right (resultA, cs)
-- Sequence operator that discards the first result
infixl 6 <-+>
(<-+>) :: Parser a -> Parser b -> Parser b
(parserA <-+> parserB) input = case parserA input of
Left a -> Left a
Right (resultA, remainder) -> case parserB remainder of
Left a -> Left a
Right (resultB, cs) -> Right (resultB, cs)
-- Transform a parsers result
infixl 5 >>>
(>>>) :: Parser a -> (a -> b) -> Parser b
(parser >>> transformer) input = case parser input of
Left a -> Left a
Right (resultA, remainder) -> Right ((transformer resultA), remainder)
-- Extract a parsers result
infix 4 +>
(+>) :: Parser a -> (a -> Parser b) -> Parser b
(parser +> function) input = case parser input of
Left a -> Left a
Right (a, cs) -> function a cs
-- Combine two parsers using a 'or' type operation
infixl 3 <|>
(<|>) :: Parser a -> Parser a -> Parser a
(parserA <|> parserB) input = case parserA input of
Left (State t _) -> case parserB input of
Left (State t' l) -> case (t, t') of
(t , []) -> Left (State t l)
([], t') -> Left (State t' l)
(t , t') -> Left (State [OrTrace t t'] l)
Right (result, cs) -> Right (result, cs)
result -> result
-- Describe a parser with a string for error reporting
infix 0 <?>
(<?>) :: Parser a -> String -> Parser a
(parser <?> string) input = case parser input of
Left (State t l) -> Left $ State ([StringTrace string] ++ t) l
Right a -> Right a
|
