47 lines
1.5 KiB
Haskell
47 lines
1.5 KiB
Haskell
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{-# OPTIONS_HADDOCK ignore-exports #-}
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module Parser.PathParser where
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import Control.Applicative
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import Parser.Core
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import Algorithms.RangeSearch.Core (Quad(NW, NE, SW, SE), Orient(North, South, West, East))
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-- |Can either be an Orientation or a Quad, corresponding to the
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-- Algorithms.RangeSearch module.
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data QuadOrOrient = Orient Orient
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| Quad Quad
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deriving (Show)
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-- |Parse a string such as "ne, n, sw, e" into
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-- [Quad NE, Orient North, Quad SW, Orient East].
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stringToQuads :: String -> [QuadOrOrient]
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stringToQuads str = case runParser parsePath str of
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Nothing -> []
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Just xs -> fst xs
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where
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parsePath = zeroOrMore ((parseQuad <|> parseOrient)
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<* zeroOrMore (char ',')
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<* spaces)
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-- |Parses a string that represents a single squad into the
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-- QuadOrOrient ADT.
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parseQuad :: Parser QuadOrOrient
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parseQuad =
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const (Quad NW) <$> (string "nw" <|> string "NW")
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<|> const (Quad NE) <$> (string "ne" <|> string "NE")
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<|> const (Quad SW) <$> (string "sw" <|> string "SW")
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<|> const (Quad SE) <$> (string "se" <|> string "SE")
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-- |Parses a string that represents a single Orientation into the
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-- QuadOrOrient ADT.
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parseOrient :: Parser QuadOrOrient
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parseOrient =
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const (Orient North) <$> (string "n" <|> string "N")
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<|> const (Orient South) <$> (string "s" <|> string "S")
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<|> const (Orient West) <$> (string "w" <|> string "W")
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<|> const (Orient East) <$> (string "e" <|> string "E")
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