content: {-# LANGUAGE OverloadedStrings #-}
  
  module Haddock.Backends.Hyperlinker.ParserSpec (main, spec) where
  
  import Test.Hspec
  import Test.QuickCheck
  
  import Control.Monad.IO.Class
  import GHC (getSessionDynFlags, runGhc)
  import GHC.Driver.Session (DynFlags)
  
  import Data.ByteString (ByteString)
  import qualified Data.ByteString as BS
  import Data.String (fromString)
  
  import Haddock (getGhcDirs)
  import Haddock.Backends.Hyperlinker.Parser
  import Haddock.Backends.Hyperlinker.Types
  
  withDynFlags :: (DynFlags -> IO ()) -> IO ()
  withDynFlags cont = do
    libDir <- fmap snd (getGhcDirs [])
    runGhc libDir $ do
      dflags <- getSessionDynFlags
      liftIO $ cont dflags
  
  main :: IO ()
  main = hspec spec
  
  spec :: Spec
  spec = describe "parse" parseSpec
  
  -- | Defined for its instance of 'Arbitrary'. Represents strings that, when
  -- considered as GHC source, won't be rewritten.
  newtype NoGhcRewrite = NoGhcRewrite String deriving (Show, Eq)
  
  -- | Filter out strings where GHC would replace/remove some characters during
  -- lexing.
  noGhcRewrite :: String -> Bool
  noGhcRewrite ('\t' : _) = False -- GHC replaces tabs with 8 spaces
  noGhcRewrite ('\r' : _) = False
  noGhcRewrite ('\f' : _) = False
  noGhcRewrite ('\v' : _) = False
  noGhcRewrite (' ' : '\n' : _) = False -- GHC strips whitespace on empty lines
  noGhcRewrite (_ : s) = noGhcRewrite s
  noGhcRewrite "" = True
  
  instance Arbitrary NoGhcRewrite where
    arbitrary = fmap NoGhcRewrite (arbitrary `suchThat` noGhcRewrite)
    shrink (NoGhcRewrite src) =
      [ NoGhcRewrite shrunk
      | shrunk <- shrink src
      , noGhcRewrite shrunk
      ]
  
  parseSpec :: Spec
  parseSpec = around withDynFlags $ do
    it "is total" $ \dflags ->
      property $ \src -> length (parse dflags "" (fromString src)) `shouldSatisfy` (>= 0)
  
    it "retains file layout" $ \dflags ->
      property $ \(NoGhcRewrite src) ->
        let orig = fromString src
            lexed = BS.concat (map tkValue (parse dflags "" orig))
         in lexed == orig
  
    context "when parsing single-line comments" $ do
      it "should ignore content until the end of line" $ \dflags ->
        shouldParseTo
          "-- some very simple comment\nidentifier"
          [TkComment, TkSpace, TkIdentifier]
          dflags
  
      it "should allow endline escaping" $ \dflags ->
        shouldParseTo
          "#define first line\\\nsecond line\\\nand another one"
          [TkCpp]
          dflags
  
    context "when parsing multi-line comments" $ do
      it "should support nested comments" $ \dflags ->
        shouldParseTo
          "{- comment {- nested -} still comment -} {- next comment -}"
          [TkComment, TkSpace, TkComment]
          dflags
  
      it "should distinguish compiler pragma" $ \dflags ->
        shouldParseTo
          "{- comment -}{-# LANGUAGE GADTs #-}{- comment -}"
          [TkComment, TkPragma, TkComment]
          dflags
  
    it "should recognize preprocessor directives" $ \dflags -> do
      shouldParseTo
        "\n#define foo bar"
        [TkCpp]
        dflags
      shouldParseTo
        "x # y"
        [TkIdentifier, TkSpace, TkOperator, TkSpace, TkIdentifier]
        dflags
  
    it "should distinguish basic language constructs" $ \dflags -> do
      shouldParseTo
        "(* 2) <$> (\"abc\", foo)"
        [ TkSpecial
        , TkOperator
        , TkSpace
        , TkNumber
        , TkSpecial
        , TkSpace
        , TkOperator
        , TkSpace
        , TkSpecial
        , TkString
        , TkSpecial
        , TkSpace
        , TkIdentifier
        , TkSpecial
        ]
        dflags
  
      shouldParseTo
        "let foo' = foo in foo' + foo'"
        [ TkKeyword
        , TkSpace
        , TkIdentifier
        , TkSpace
        , TkGlyph
        , TkSpace
        , TkIdentifier
        , TkSpace
        , TkKeyword
        , TkSpace
        , TkIdentifier
        , TkSpace
        , TkOperator
        , TkSpace
        , TkIdentifier
        ]
        dflags
  
      shouldParseTo
        "square x = y^2 where y = x"
        [ TkIdentifier
        , TkSpace
        , TkIdentifier
        , TkSpace
        , TkGlyph
        , TkSpace
        , TkIdentifier
        , TkOperator
        , TkNumber
        , TkSpace
        , TkKeyword
        , TkSpace
        , TkIdentifier
        , TkSpace
        , TkGlyph
        , TkSpace
        , TkIdentifier
        ]
        dflags
  
    it "should parse do-notation syntax" $ \dflags -> do
      shouldParseTo
        "do { foo <- getLine; putStrLn foo }"
        [ TkKeyword
        , TkSpace
        , TkSpecial
        , TkSpace
        , TkIdentifier
        , TkSpace
        , TkGlyph
        , TkSpace
        , TkIdentifier
        , TkSpecial
        , TkSpace
        , TkIdentifier
        , TkSpace
        , TkIdentifier
        , TkSpace
        , TkSpecial
        ]
        dflags
  
      shouldParseTo
        ( fromString $
            unlines
              [ "do"
              , "    foo <- getLine"
              , "    putStrLn foo"
              ]
        )
        [ TkKeyword
        , TkSpace
        , TkIdentifier
        , TkSpace
        , TkGlyph
        , TkSpace
        , TkIdentifier
        , TkSpace
        , TkIdentifier
        , TkSpace
        , TkIdentifier
        , TkSpace
        ]
        dflags
    where
      shouldParseTo :: ByteString -> [TokenType] -> DynFlags -> Expectation
      shouldParseTo str tokens dflags =
        [ tkType tok
        | tok <- parse dflags "" str
        , not (BS.null (tkValue tok))
        ]
          `shouldBe` tokens
  