    {-# LANGUAGE DerivingStrategies         #-}
    {-# LANGUAGE FlexibleInstances          #-}
    {-# LANGUAGE GeneralizedNewtypeDeriving #-}
    {-# LANGUAGE InstanceSigs               #-}
    {-# LANGUAGE ScopedTypeVariables        #-}
    {-# LANGUAGE TypeApplications           #-}
    {-# LANGUAGE TypeFamilies               #-}
    --------------------------------------------------------------------
    -- |
    -- Module      : XMonad.Util.Parser
    -- Description : A parser combinator library for xmonad
    -- Copyright   : (c) 2021  Tony Zorman
    -- License     : BSD3
    -- Maintainer  : Tony Zorman <soliditsallgood@mailbox.org>
    -- Stability   : experimental
    -- Portability : non-portable
    --
    -- A small wrapper around the 'ReadP' parser combinator in @base@,
    -- providing a more intuitive behaviour.  While it's theoretically nice
    -- that 'ReadP' is actually commutative, this makes a lot of parsing
    -- operations rather awkward—more often than not, one only wants the
    -- argument that's parsed "first".
    --
    -- Due to the left-biased nature of the chosen semigroup implementation,
    -- using functions like 'many' or 'optional' from "Control.Applicative"
    -- now yields more consistent behaviour with other parser combinator
    -- libraries.
    --
    --------------------------------------------------------------------
    module XMonad.Util.Parser (
      -- * Usage
      -- $usage

      -- * Running
      Parser,
      runParser,

      -- * Primitive Parsers
      eof,
      num,
      char,
      string,
      skipSpaces,
      get,
      look,

      -- * Combining Parsers
      satisfy,
      choice,
      many1,
      sepBy,
      sepBy1,
      endBy,
      endBy1,
      munch,
      munch1,
      pfail
    ) where

    import XMonad.Prelude

    import qualified Text.ParserCombinators.ReadP as ReadP

    import Data.Coerce (coerce)
    import Data.String (IsString (fromString))
    import Text.ParserCombinators.ReadP (ReadP, (<++))

    {- $usage

    NOTE: This module is mostly intended for developing of other modules.
    If you are a users, you probably won't find much use here—you have been
    warned.

    The high-level API tries to stay as close to 'ReadP' as possible.  If
    you are familiar with that then no functions here should surprise you.

    One notable usability difference when forcing left-biasedness is /when/
    one wants to disambiguate a parse.  For normal 'ReadP' usage this
    happens after the actual parsing stage by going through the list of
    successful parses.  For 'Parser' it does when constructing the relevant
    combinators, leading to only one successful parse.  As an example,
    consider the 'ReadP'-based parser

    > pLangle = ReadP.string "<"
    > pLongerSequence = ReadP.char '<' *> ReadP.string "f" <* ReadP.char '>'
    > pCombination = pLangle ReadP.+++ pLongerSequence

    Parsing the string @"<f>"@ will return

    >>> ReadP.readP_to_S pCombination "<f>"
    [("<","f>"),("f","")]

    One would now need to, for example, filter for the second (leftover)
    string being empty and take the head of the resulting list (which may
    still have more than one element).

    With 'Parser', the same situation would look like the following

    > pLangle' = string "<"
    > pLongerSequence' = char '<' *> string "f" <* char '>'
    > pCombination' = pLongerSequence' <> pLangle'

    Notice how @pLangle'@ and @pLongerSequence'@ have traded places—since we
    are not forcing @pLangle'@ to consume the entire string and @(<>)@ is
    left-biased, @pLongerSequence'@ parses a superset of @pLangle'@!
    Running @runParser pCombination'@ now yields the expected result:

    >>> runParser pCombination' "<f>"
    Just "f"

    One might also define @pLangle'@ as @string "<" <* eof@, which would
    enable a definition of @pCombination' = pLangle' <> pLongerSequence'@.

    For example uses, see "XMonad.Util.EZConfig" or "XMonad.Prompt.OrgMode".
    -}

    -- Parser :: Type -> Type
    newtype Parser a = Parser (ReadP a)
      deriving newtype ((forall a b. (a -> b) -> Parser a -> Parser b)
    -> (forall a b. a -> Parser b -> Parser a) -> Functor Parser
    forall a b. a -> Parser b -> Parser a
    forall a b. (a -> b) -> Parser a -> Parser b
    forall (f :: * -> *).
    (forall a b. (a -> b) -> f a -> f b)
    -> (forall a b. a -> f b -> f a) -> Functor f
    $cfmap :: forall a b. (a -> b) -> Parser a -> Parser b
    fmap :: forall a b. (a -> b) -> Parser a -> Parser b
    $c<$ :: forall a b. a -> Parser b -> Parser a
    <$ :: forall a b. a -> Parser b -> Parser a
    Functor, Functor Parser
    Functor Parser
    -> (forall a. a -> Parser a)
    -> (forall a b. Parser (a -> b) -> Parser a -> Parser b)
    -> (forall a b c.
        (a -> b -> c) -> Parser a -> Parser b -> Parser c)
    -> (forall a b. Parser a -> Parser b -> Parser b)
    -> (forall a b. Parser a -> Parser b -> Parser a)
    -> Applicative Parser
    forall a. a -> Parser a
    forall a b. Parser a -> Parser b -> Parser a
    forall a b. Parser a -> Parser b -> Parser b
    forall a b. Parser (a -> b) -> Parser a -> Parser b
    forall a b c. (a -> b -> c) -> Parser a -> Parser b -> Parser c
    forall (f :: * -> *).
    Functor f
    -> (forall a. a -> f a)
    -> (forall a b. f (a -> b) -> f a -> f b)
    -> (forall a b c. (a -> b -> c) -> f a -> f b -> f c)
    -> (forall a b. f a -> f b -> f b)
    -> (forall a b. f a -> f b -> f a)
    -> Applicative f
    $cpure :: forall a. a -> Parser a
    pure :: forall a. a -> Parser a
    $c<*> :: forall a b. Parser (a -> b) -> Parser a -> Parser b
    <*> :: forall a b. Parser (a -> b) -> Parser a -> Parser b
    $cliftA2 :: forall a b c. (a -> b -> c) -> Parser a -> Parser b -> Parser c
    liftA2 :: forall a b c. (a -> b -> c) -> Parser a -> Parser b -> Parser c
    $c*> :: forall a b. Parser a -> Parser b -> Parser b
    *> :: forall a b. Parser a -> Parser b -> Parser b
    $c<* :: forall a b. Parser a -> Parser b -> Parser a
    <* :: forall a b. Parser a -> Parser b -> Parser a
    Applicative, Applicative Parser
    Applicative Parser
    -> (forall a b. Parser a -> (a -> Parser b) -> Parser b)
    -> (forall a b. Parser a -> Parser b -> Parser b)
    -> (forall a. a -> Parser a)
    -> Monad Parser
    forall a. a -> Parser a
    forall a b. Parser a -> Parser b -> Parser b
    forall a b. Parser a -> (a -> Parser b) -> Parser b
    forall (m :: * -> *).
    Applicative m
    -> (forall a b. m a -> (a -> m b) -> m b)
    -> (forall a b. m a -> m b -> m b)
    -> (forall a. a -> m a)
    -> Monad m
    $c>>= :: forall a b. Parser a -> (a -> Parser b) -> Parser b
    >>= :: forall a b. Parser a -> (a -> Parser b) -> Parser b
    $c>> :: forall a b. Parser a -> Parser b -> Parser b
    >> :: forall a b. Parser a -> Parser b -> Parser b
    $creturn :: forall a. a -> Parser a
    return :: forall a. a -> Parser a
    Monad)

    instance Semigroup (Parser a) where
      -- | Local, exclusive, left-biased choice: If left parser locally
      -- produces any result at all, then right parser is not used.
      (<>) :: Parser a -> Parser a -> Parser a
      <> :: Parser a -> Parser a -> Parser a
    (<>) = (ReadP a -> ReadP a -> ReadP a) -> Parser a -> Parser a -> Parser a
    forall a b. Coercible a b => a -> b
    coerce (forall a. ReadP a -> ReadP a -> ReadP a
    (<++) @a)

    instance Monoid (Parser a) where
      -- | A parser that always fails.
      mempty :: Parser a
      mempty :: Parser a
    mempty = ReadP a -> Parser a
    forall a. ReadP a -> Parser a
    Parser ReadP a
    forall a. ReadP a
    forall (f :: * -> *) a. Alternative f => f a
    empty

    instance Alternative Parser where
      empty :: Parser a
      empty :: forall a. Parser a
    empty = Parser a
    forall a. Monoid a => a
    mempty

      (<|>) :: Parser a -> Parser a -> Parser a
      <|> :: forall a. Parser a -> Parser a -> Parser a
    (<|>) = Parser a -> Parser a -> Parser a
    forall a. Semigroup a => a -> a -> a
    (<>)

    -- | When @-XOverloadedStrings@ is on, treat a string @s@ as the parser
    -- @'string' s@, when appropriate.  This allows one to write things like
    -- @"a" *> otherParser@ instead of @'string' "a" *> otherParser@.
    instance a ~ String => IsString (Parser a) where
      fromString :: String -> Parser a
      fromString :: String -> Parser a
    fromString = String -> Parser a
    String -> Parser String
    string

    -- | Run a parser on a given string.
    runParser :: Parser a -> String -> Maybe a
    runParser :: forall a. Parser a -> String -> Maybe a
    runParser (Parser ReadP a
    p) = ((a, String) -> a) -> Maybe (a, String) -> Maybe a
    forall a b. (a -> b) -> Maybe a -> Maybe b
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap (a, String) -> a
    forall a b. (a, b) -> a
    fst (Maybe (a, String) -> Maybe a)
    -> (String -> Maybe (a, String)) -> String -> Maybe a
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [(a, String)] -> Maybe (a, String)
    forall a. [a] -> Maybe a
    listToMaybe ([(a, String)] -> Maybe (a, String))
    -> (String -> [(a, String)]) -> String -> Maybe (a, String)
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . ReadP a -> String -> [(a, String)]
    forall a. ReadP a -> ReadS a
    ReadP.readP_to_S ReadP a
    p

    -- | Always fails
    pfail :: Parser a
    pfail :: forall a. Parser a
    pfail = Parser a
    forall a. Parser a
    forall (f :: * -> *) a. Alternative f => f a
    empty

    -- | Consume and return the next character.  Fails if there is no input
    -- left.
    get :: Parser Char
    get :: Parser Char
    get = ReadP Char -> Parser Char
    forall a b. Coercible a b => a -> b
    coerce ReadP Char
    ReadP.get

    -- | Look-ahead: return the part of the input that is left, without
    -- consuming it.
    look :: Parser String
    look :: Parser String
    look = ReadP String -> Parser String
    forall a b. Coercible a b => a -> b
    coerce ReadP String
    ReadP.look

    -- | Succeeds if and only if we are at the end of input.
    eof :: Parser ()
    eof :: Parser ()
    eof = ReadP () -> Parser ()
    forall a b. Coercible a b => a -> b
    coerce ReadP ()
    ReadP.eof

    -- | Parse an integral number number.
    num :: (Read a, Integral a) => Parser a
    num :: forall a. (Read a, Integral a) => Parser a
    num = String -> a
    forall a. Read a => String -> a
    read (String -> a) -> Parser String -> Parser a
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    <$> (Char -> Bool) -> Parser String
    munch1 Char -> Bool
    isDigit
    {-# SPECIALISE num :: Parser Word    #-}
    {-# SPECIALISE num :: Parser Int     #-}
    {-# SPECIALISE num :: Parser Integer #-}

    -- | Parse and return the specified character.
    char :: Char -> Parser Char
    char :: Char -> Parser Char
    char = (Char -> ReadP Char) -> Char -> Parser Char
    forall a b. Coercible a b => a -> b
    coerce Char -> ReadP Char
    ReadP.char

    -- | Parse and return the specified string.
    string :: String -> Parser String
    string :: String -> Parser String
    string = (String -> ReadP String) -> String -> Parser String
    forall a b. Coercible a b => a -> b
    coerce String -> ReadP String
    ReadP.string

    -- | Skip all whitespace.
    skipSpaces :: Parser ()
    skipSpaces :: Parser ()
    skipSpaces = ReadP () -> Parser ()
    forall a b. Coercible a b => a -> b
    coerce ReadP ()
    ReadP.skipSpaces

    -- | Consume and return the next character if it satisfies the specified
    -- predicate.
    satisfy :: (Char -> Bool) -> Parser Char
    satisfy :: (Char -> Bool) -> Parser Char
    satisfy = ((Char -> Bool) -> ReadP Char) -> (Char -> Bool) -> Parser Char
    forall a b. Coercible a b => a -> b
    coerce (Char -> Bool) -> ReadP Char
    ReadP.satisfy

    -- | Combine all parsers in the given list in a left-biased way.
    choice :: [Parser a] -> Parser a
    choice :: forall a. [Parser a] -> Parser a
    choice = (Parser a -> Parser a -> Parser a)
    -> Parser a -> [Parser a] -> Parser a
    forall b a. (b -> a -> b) -> b -> [a] -> b
    forall (t :: * -> *) b a.
    Foldable t =>
    (b -> a -> b) -> b -> t a -> b
    foldl' Parser a -> Parser a -> Parser a
    forall a. Semigroup a => a -> a -> a
    (<>) Parser a
    forall a. Monoid a => a
    mempty

    -- | Parse the first zero or more characters satisfying the predicate.
    -- Always succeeds; returns an empty string if the predicate returns
    -- @False@ on the first character of input.
    munch :: (Char -> Bool) -> Parser String
    munch :: (Char -> Bool) -> Parser String
    munch = ((Char -> Bool) -> ReadP String) -> (Char -> Bool) -> Parser String
    forall a b. Coercible a b => a -> b
    coerce (Char -> Bool) -> ReadP String
    ReadP.munch

    -- | Parse the first one or more characters satisfying the predicate.
    -- Fails if none, else succeeds exactly once having consumed all the
    -- characters.
    munch1 :: (Char -> Bool) -> Parser String
    munch1 :: (Char -> Bool) -> Parser String
    munch1 = ((Char -> Bool) -> ReadP String) -> (Char -> Bool) -> Parser String
    forall a b. Coercible a b => a -> b
    coerce (Char -> Bool) -> ReadP String
    ReadP.munch1

    -- | @endBy p sep@ parses zero or more occurrences of @p@, separated and
    -- ended by @sep@.
    endBy :: Parser a -> Parser sep -> Parser [a]
    endBy :: forall a sep. Parser a -> Parser sep -> Parser [a]
    endBy Parser a
    p Parser sep
    sep = Parser a -> Parser [a]
    forall a. Parser a -> Parser [a]
    forall (f :: * -> *) a. Alternative f => f a -> f [a]
    many (Parser a
    p Parser a -> Parser sep -> Parser a
    forall a b. Parser a -> Parser b -> Parser a
    forall (f :: * -> *) a b. Applicative f => f a -> f b -> f a
    <* Parser sep
    sep)

    -- | @endBy p sep@ parses one or more occurrences of @p@, separated and
    -- ended by @sep@.
    endBy1 :: Parser a -> Parser sep -> Parser [a]
    endBy1 :: forall a sep. Parser a -> Parser sep -> Parser [a]
    endBy1 Parser a
    p Parser sep
    sep = Parser a -> Parser [a]
    forall a. Parser a -> Parser [a]
    many1 (Parser a
    p Parser a -> Parser sep -> Parser a
    forall a b. Parser a -> Parser b -> Parser a
    forall (f :: * -> *) a b. Applicative f => f a -> f b -> f a
    <* Parser sep
    sep)

    -- | Parse one or more occurrences of the given parser.
    many1 :: Parser a -> Parser [a]
    many1 :: forall a. Parser a -> Parser [a]
    many1 Parser a
    p = (a -> [a] -> [a]) -> Parser a -> Parser [a] -> Parser [a]
    forall a b c. (a -> b -> c) -> Parser a -> Parser b -> Parser c
    forall (f :: * -> *) a b c.
    Applicative f =>
    (a -> b -> c) -> f a -> f b -> f c
    liftA2 (:) Parser a
    p (Parser a -> Parser [a]
    forall a. Parser a -> Parser [a]
    forall (f :: * -> *) a. Alternative f => f a -> f [a]
    many Parser a
    p)

    -- | @sepBy p sep@ parses zero or more occurrences of @p@, separated by
    -- @sep@.  Returns a list of values returned by @p@.
    sepBy :: Parser a -> Parser sep -> Parser [a]
    sepBy :: forall a sep. Parser a -> Parser sep -> Parser [a]
    sepBy Parser a
    p Parser sep
    sep = Parser a -> Parser sep -> Parser [a]
    forall a sep. Parser a -> Parser sep -> Parser [a]
    sepBy1 Parser a
    p Parser sep
    sep Parser [a] -> Parser [a] -> Parser [a]
    forall a. Semigroup a => a -> a -> a
    <> [a] -> Parser [a]
    forall a. a -> Parser a
    forall (f :: * -> *) a. Applicative f => a -> f a
    pure []

    -- | @sepBy1 p sep@ parses one or more occurrences of @p@, separated by
    -- @sep@.  Returns a list of values returned by @p@.
    sepBy1 :: Parser a -> Parser sep -> Parser [a]
    sepBy1 :: forall a sep. Parser a -> Parser sep -> Parser [a]
    sepBy1 Parser a
    p Parser sep
    sep = (a -> [a] -> [a]) -> Parser a -> Parser [a] -> Parser [a]
    forall a b c. (a -> b -> c) -> Parser a -> Parser b -> Parser c
    forall (f :: * -> *) a b c.
    Applicative f =>
    (a -> b -> c) -> f a -> f b -> f c
    liftA2 (:) Parser a
    p (Parser a -> Parser [a]
    forall a. Parser a -> Parser [a]
    forall (f :: * -> *) a. Alternative f => f a -> f [a]
    many (Parser sep
    sep Parser sep -> Parser a -> Parser a
    forall a b. Parser a -> Parser b -> Parser b
    forall (f :: * -> *) a b. Applicative f => f a -> f b -> f b
    *> Parser a
    p))