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|
{- |
Description : Command-line options parsing and printing
Maintainer : defanor <defanor@uberspace.net>
Stability : unstable
Portability : non-portable (uses GHC extensions)
Coalpit is a library for building "command-line program interfaces":
the goal is to get interfaces between programs quickly and easily,
while keeping them language-agnostic and more user- and shell
scripting-friendly than JSON and similar formats.
-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE DefaultSignatures #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE ScopedTypeVariables #-}
module Coalpit (
-- * Core classes
ArgParser(..)
, ToArgs(..)
-- * Utility functions
, fromArgs
-- * Modifiers
, Modifiers(..)
, defMod
-- * Parsing helpers
, Parser
, Args(..)
, pS
, readArg
) where
import Data.List
import GHC.Generics
import Text.Megaparsec
import Text.Megaparsec.Char
import Data.Char
import Data.Proxy
import Data.Semigroup
-- | Command-line arguments wrapper, used to avoid an orphan 'Stream'
-- instance.
newtype Args = Args [String]
-- | Advances by one token.
advance :: Pos -> SourcePos -> t -> SourcePos
advance _ (SourcePos n l c) _ = SourcePos n l (c <> pos1)
-- | A list of strings (command-line arguments) stream.
instance Stream Args where
type Token Args = String
type Tokens Args = [String]
tokenToChunk Proxy = pure
tokensToChunk Proxy = id
chunkToTokens Proxy = id
chunkLength Proxy = length
chunkEmpty Proxy = null
advance1 Proxy = advance
advanceN Proxy w = foldl' (advance w)
take1_ (Args []) = Nothing
take1_ (Args (t:ts)) = Just (t, Args ts)
takeN_ n (Args s)
| n <= 0 = Just ([], Args s)
| null s = Nothing
| otherwise = Just (take n s, Args (drop n s))
takeWhile_ f (Args s) = (takeWhile f s, Args (dropWhile f s))
-- | Command-line arguments parser.
type Parser = Parsec String Args
-- | Applies a String parser to a single argument.
pS :: Parsec String String a -> Parsec String Args a
pS p = try $ do
x <- token Right Nothing
case parse p "argument" x of
Left e -> fail $ show e
Right x' -> pure x'
-- | Name modifiers.
data Modifiers = Modifiers { conNameMod :: String -> String
-- ^ Constructor name modifier.
, selNameMod :: String -> String
-- ^ Record selector name modifier.
, alwaysUseSelName :: Bool
-- ^ Add record selector name always, not
-- just for optional arguments.
}
-- | Default modifiers.
defMod :: Modifiers
defMod = Modifiers (map toLower) (("--" ++) . map toLower) False
-- Core classes
-- | Arguments parser class.
class ArgParser a where
argParser :: Modifiers -> Parser a
default argParser :: (Generic a, GArgParser (Rep a)) => Modifiers -> Parser a
argParser m = to <$> gArgParser m
class GArgParser f where
gArgParser :: Modifiers -> Parser (f a)
-- | Parses arguments.
fromArgs :: ArgParser a => Modifiers -> [String] -> Either String a
fromArgs m args = case parse (argParser m) "arguments" (Args args) of
Left err -> Left $ show err
Right x -> Right x
-- | Arguments serializer class.
class ToArgs a where
toArgs :: Modifiers -> a -> [String]
default toArgs :: (Generic a, GToArgs (Rep a)) => Modifiers -> a -> [String]
toArgs m a = gToArgs m (from a)
class GToArgs f where
gToArgs :: Modifiers -> f a -> [String]
-- Units
instance GArgParser U1 where
gArgParser _ = pure U1
instance GToArgs U1 where
gToArgs _ U1 = []
-- Products
instance (GArgParser a, GArgParser b) => GArgParser (a :*: b) where
gArgParser m = (:*:) <$> gArgParser m <*> gArgParser m
instance (GToArgs a, GToArgs b) => GToArgs (a :*: b) where
gToArgs m (a :*: b) = gToArgs m a ++ gToArgs m b
-- Sums
instance (Constructor c1, GArgParser f1, GArgParser (f :+: g)) =>
GArgParser ((f :+: g) :+: C1 c1 f1) where
gArgParser m =
L1 <$> gArgParser m
<|>
R1 <$> (pS (string (conNameMod m $ conName (undefined :: C1 c1 f a)))
*> gArgParser m)
instance (Constructor c1, GArgParser f1, GArgParser (f :+: g)) =>
GArgParser (C1 c1 f1 :+: (f :+: g)) where
gArgParser m =
L1 <$> (pS (string (conNameMod m $ conName (undefined :: C1 c1 f a)))
*> gArgParser m)
<|>
R1 <$> gArgParser m
instance (Constructor c1, Constructor c2, GArgParser f1, GArgParser f2) =>
GArgParser (C1 c1 f1 :+: C1 c2 f2) where
gArgParser m =
L1 <$> (pS (string (conNameMod m $ conName (undefined :: C1 c1 f a)))
*> gArgParser m)
<|>
R1 <$> (pS (string (conNameMod m $ conName (undefined :: C1 c2 f a)))
*> gArgParser m)
instance (Constructor c1, GToArgs f1, GToArgs (f :+: g)) =>
GToArgs ((f :+: g) :+: C1 c1 f1) where
gToArgs m (L1 x) = gToArgs m x
gToArgs m (R1 x) = conNameMod m (conName x) : gToArgs m x
instance (Constructor c1, GToArgs f1, GToArgs (f :+: g)) =>
GToArgs (C1 c1 f1 :+: (f :+: g)) where
gToArgs m (L1 x) = conNameMod m (conName x) : gToArgs m x
gToArgs m (R1 x) = gToArgs m x
instance (Constructor c1, Constructor c2, GToArgs f1, GToArgs f2) =>
GToArgs (C1 c1 f1 :+: C1 c2 f2) where
gToArgs m (L1 x) = conNameMod m (conName x) : gToArgs m x
gToArgs m (R1 x) = conNameMod m (conName x) : gToArgs m x
-- Record Selectors
instance (GArgParser a, Selector c) => GArgParser (S1 c a) where
gArgParser m = M1 <$> do
let sname = case (selName (undefined :: S1 c a f), alwaysUseSelName m) of
("", _) -> pure ()
(_, False) -> pure ()
(name, True) -> pS (string (selNameMod m name)) >> pure ()
sname *> gArgParser m
instance (GToArgs a, Selector c) => GToArgs (S1 c a) where
gToArgs m s@(M1 x) = case (selName s, alwaysUseSelName m) of
("", _) -> gToArgs m x
(_, False) -> gToArgs m x
(name, True) -> selNameMod m name : gToArgs m x
-- Optional arguments
instance {-#OVERLAPPING#-}
(ArgParser a, Selector c) => GArgParser (S1 c (Rec0 (Maybe a))) where
gArgParser m =
case selName (undefined :: S1 c (Rec0 (Maybe a)) f) of
"" -> M1 <$> gArgParser m
name -> do
x <- optional $ pS (string (selNameMod m name)) *> argParser m
pure $ M1 $ K1 x
instance {-#OVERLAPPING#-}
(ToArgs a, Selector c) => GToArgs (S1 c (Rec0 (Maybe a))) where
gToArgs m s@(M1 (K1 x)) = case (selName s, x) of
("", _) -> toArgs m x
(_, Nothing) -> []
(name, Just x') -> selNameMod m name : toArgs m x'
-- Constructors
instance (GArgParser a) => GArgParser (C1 c a) where
gArgParser m = M1 <$> gArgParser m
instance (GToArgs a) => GToArgs (C1 c a) where
gToArgs m (M1 x) = gToArgs m x
-- Data types
instance (GArgParser a) => GArgParser (D1 c a) where
gArgParser m = M1 <$> gArgParser m
instance (GToArgs a) => GToArgs (D1 c a) where
gToArgs m (M1 x) = gToArgs m x
-- Constraints and such
instance (ArgParser a) => GArgParser (K1 i a) where
gArgParser m = K1 <$> argParser m
instance (ToArgs a) => GToArgs (K1 i a) where
gToArgs m (K1 x) = toArgs m x
-- Common types
-- | Reads an argument using its 'Read' instance.
readArg :: Read a => Parser a
readArg = do
x <- token Right Nothing
case reads x of
[(n, "")] -> pure n
_ -> fail $ "Failed to read: " ++ x
instance ArgParser Int where
argParser _ = readArg
instance ToArgs Int where
toArgs _ i = [show i]
instance ArgParser Integer where
argParser _ = readArg
instance ToArgs Integer where
toArgs _ i = [show i]
instance ArgParser Rational where
argParser _ = readArg
instance ToArgs Rational where
toArgs _ i = [show i]
instance ArgParser Double where
argParser _ = readArg
instance ToArgs Double where
toArgs _ i = [show i]
instance {-#OVERLAPPING#-} ArgParser String where
argParser _ = token Right Nothing
instance {-#OVERLAPPING#-} ToArgs String where
toArgs _ i = [i]
instance ArgParser Bool
instance ToArgs Bool
instance ArgParser a => ArgParser (Maybe a)
instance ToArgs a => ToArgs (Maybe a)
instance ArgParser a => ArgParser [a]
instance ToArgs a => ToArgs [a]
instance (ArgParser a, ArgParser b) => ArgParser (Either a b)
instance (ToArgs a, ToArgs b) => ToArgs (Either a b)
-- | Expects a dot.
instance ArgParser () where
argParser _ = pS (char '.') *> pure ()
-- | Shows a dot.
instance ToArgs () where
toArgs _ () = ["."]
instance (ArgParser a, ArgParser b) => ArgParser (a, b)
instance (ToArgs a, ToArgs b) => ToArgs (a, b)
instance (ArgParser a, ArgParser b, ArgParser c) => ArgParser (a, b, c)
instance (ToArgs a, ToArgs b, ToArgs c) => ToArgs (a, b, c)
instance (ArgParser a, ArgParser b, ArgParser c, ArgParser d) =>
ArgParser (a, b, c, d)
instance (ToArgs a, ToArgs b, ToArgs c, ToArgs d) => ToArgs (a, b, c, d)
instance (ArgParser a, ArgParser b, ArgParser c, ArgParser d, ArgParser e) =>
ArgParser (a, b, c, d, e)
instance (ToArgs a, ToArgs b, ToArgs c, ToArgs d, ToArgs e) =>
ToArgs (a, b, c, d, e)
|