Initial commit
We can parse an obj file.
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commit
9ede6aecc0
4
.gitignore
vendored
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4
.gitignore
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*.pdf
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*.o
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*.hi
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*.obj
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20
Meshparser.hs
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Meshparser.hs
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module Meshparser where
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import Control.Applicative
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import Parser
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-- | Convert a text String with multiple vertices into
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-- an array of float tuples.
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meshToArr :: String -- ^ the string to convert
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-> [(Float, Float)] -- ^ the resulting float tuple
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meshToArr xs = fmap (\(Just (x, _)) -> x) .
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filter (/= Nothing) .
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fmap (runParser parseVertice) .
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lines $
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xs
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-- | Creates a Parser that accepts a single vertice, such as 'v 1.0 2.0'.
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parseVertice :: Parser (Float, Float)
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parseVertice = liftA2 (,)
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(char 'v' *> spaces *> posFloat)
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(spaces *> posFloat)
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91
Parser.hs
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Parser.hs
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module Parser (Parser,
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runParser,
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satisfy,
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char,
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posInt,
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posFloat,
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oneOrMore,
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zeroOrMore,
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spaces) where
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import Control.Applicative
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import Data.Char
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-- |The parser type. It allows us to create specific parsers,
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-- combine them and run them via 'runParser' to get a result.
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newtype Parser a = MkParser { runParser :: String -> Maybe (a, String) }
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-- |Functor instance.
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instance Functor Parser where
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fmap f p = (inParser . fmap . fmap . first $ f) p
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-- |Applicative functor instance.
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instance Applicative Parser where
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pure a = MkParser (\s -> Just (a, s))
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(MkParser fp) <*> xp = MkParser $ \s ->
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case fp s of
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Nothing -> Nothing
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Just (f,x) -> runParser (f <$> xp) x
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-- |Alternative functor instance.
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instance Alternative Parser where
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empty = MkParser (const Nothing)
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MkParser p1 <|> MkParser p2 = MkParser $ liftA2 (<|>) p1 p2
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inParser :: ((String -> Maybe (a1, String))
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-> String
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-> Maybe (a, String))
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-> Parser a1
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-> Parser a
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inParser f p = MkParser . f . runParser $ p
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first :: (a -> b) -> (a,c) -> (b,c)
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first f (x,y) = (f x, y)
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-- |Creates a Parser that parses a Char depending on a given condition.
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satisfy :: (Char -> Bool) -- ^ condition
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-> Parser Char -- ^ created Parser
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satisfy p = MkParser f
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where
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f [] = Nothing
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f (x:xs)
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| p x = Just (x, xs)
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| otherwise = Nothing
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-- |Creates a Parser that accepts a given Char.
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char :: Char -> Parser Char
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char c = satisfy (== c)
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-- |Creates a Parser that accepts positive integers.
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posInt :: Parser Integer
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posInt = MkParser f
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where
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f xs
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| null ns = Nothing
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| otherwise = Just (read ns, rest)
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where (ns, rest) = span isDigit xs
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-- |Creates a Parser that accepts positive integers.
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posFloat :: Parser Float
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posFloat = read <$>
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liftA3 (\x y z -> x ++ [y] ++ z)
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(MkParser f)
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(char '.')
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(MkParser f)
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where
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f xs
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| null ns = Nothing
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| otherwise = Just (ns, rest)
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where (ns, rest) = span isDigit xs
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-- |Convert a given Parser to a Parser that accepts zero or more occurences.
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zeroOrMore :: Parser a -> Parser [a]
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zeroOrMore p = oneOrMore p <|> pure []
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-- |Convert a given Parser to a Parser that accepts one or more occurences.
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oneOrMore :: Parser a -> Parser [a]
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oneOrMore p = (:) <$> p <*> zeroOrMore p
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-- |Creates a Parser that accepts spaces.
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spaces :: Parser String
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spaces = zeroOrMore (satisfy isSpace)
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