{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-} -- new
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE PackageImports #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE StandaloneDeriving #-} -- new

module Text.Megaparsec.Custom (
  -- * Custom parse error type
  CustomErr,

  -- * Failing with an arbitrary source position
  parseErrorAt,
  parseErrorAtRegion,

  -- * Re-parsing
  SourceExcerpt,
  getExcerptText,

  excerpt_,
  reparseExcerpt,

  -- * Pretty-printing custom parse errors
  customErrorBundlePretty,


  -- * "Final" parse errors
  FinalParseError,
  FinalParseError',
  FinalParseErrorBundle,
  FinalParseErrorBundle',

  -- * Constructing "final" parse errors
  finalError,
  finalFancyFailure,
  finalFail,
  finalCustomFailure,

  -- * Pretty-printing "final" parse errors
  finalErrorBundlePretty,
  attachSource,

  -- * Handling parse errors from include files with "final" parse errors
  parseIncludeFile,
)
where

import Control.Monad.Except
import Control.Monad.State.Strict (StateT, evalStateT)
import qualified Data.List.NonEmpty as NE
import Data.Monoid (Alt(..))
import qualified Data.Set as S
import Data.Text (Text)
import Text.Megaparsec


--- * Custom parse error type

-- | A custom error type for the parser. The type is specialized to
-- parsers of 'Text' streams.

data CustomErr
  -- | Fail with a message at a specific source position interval. The
  -- interval must be contained within a single line.
  = ErrorFailAt Int -- Starting offset
                Int -- Ending offset
                String -- Error message
  -- | Re-throw parse errors obtained from the "re-parsing" of an excerpt
  -- of the source text.
  | ErrorReparsing
      (NE.NonEmpty (ParseError Text CustomErr)) -- Source fragment parse errors
  deriving (Int -> CustomErr -> ShowS
[CustomErr] -> ShowS
CustomErr -> String
(Int -> CustomErr -> ShowS)
-> (CustomErr -> String)
-> ([CustomErr] -> ShowS)
-> Show CustomErr
forall a.
(Int -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
showList :: [CustomErr] -> ShowS
$cshowList :: [CustomErr] -> ShowS
show :: CustomErr -> String
$cshow :: CustomErr -> String
showsPrec :: Int -> CustomErr -> ShowS
$cshowsPrec :: Int -> CustomErr -> ShowS
Show, CustomErr -> CustomErr -> Bool
(CustomErr -> CustomErr -> Bool)
-> (CustomErr -> CustomErr -> Bool) -> Eq CustomErr
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: CustomErr -> CustomErr -> Bool
$c/= :: CustomErr -> CustomErr -> Bool
== :: CustomErr -> CustomErr -> Bool
$c== :: CustomErr -> CustomErr -> Bool
Eq, Eq CustomErr
Eq CustomErr
-> (CustomErr -> CustomErr -> Ordering)
-> (CustomErr -> CustomErr -> Bool)
-> (CustomErr -> CustomErr -> Bool)
-> (CustomErr -> CustomErr -> Bool)
-> (CustomErr -> CustomErr -> Bool)
-> (CustomErr -> CustomErr -> CustomErr)
-> (CustomErr -> CustomErr -> CustomErr)
-> Ord CustomErr
CustomErr -> CustomErr -> Bool
CustomErr -> CustomErr -> Ordering
CustomErr -> CustomErr -> CustomErr
forall a.
Eq a
-> (a -> a -> Ordering)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> a)
-> (a -> a -> a)
-> Ord a
min :: CustomErr -> CustomErr -> CustomErr
$cmin :: CustomErr -> CustomErr -> CustomErr
max :: CustomErr -> CustomErr -> CustomErr
$cmax :: CustomErr -> CustomErr -> CustomErr
>= :: CustomErr -> CustomErr -> Bool
$c>= :: CustomErr -> CustomErr -> Bool
> :: CustomErr -> CustomErr -> Bool
$c> :: CustomErr -> CustomErr -> Bool
<= :: CustomErr -> CustomErr -> Bool
$c<= :: CustomErr -> CustomErr -> Bool
< :: CustomErr -> CustomErr -> Bool
$c< :: CustomErr -> CustomErr -> Bool
compare :: CustomErr -> CustomErr -> Ordering
$ccompare :: CustomErr -> CustomErr -> Ordering
$cp1Ord :: Eq CustomErr
Ord)

-- We require an 'Ord' instance for 'CustomError' so that they may be
-- stored in a 'Set'. The actual instance is inconsequential, so we just
-- derive it, but the derived instance requires an (orphan) instance for
-- 'ParseError'. Hopefully this does not cause any trouble.

deriving instance Ord (ParseError Text CustomErr)

-- Note: the pretty-printing of our 'CustomErr' type is only partally
-- defined in its 'ShowErrorComponent' instance; we perform additional
-- adjustments in 'customErrorBundlePretty'.

instance ShowErrorComponent CustomErr where
  showErrorComponent :: CustomErr -> String
showErrorComponent (ErrorFailAt Int
_ Int
_ String
errMsg) = String
errMsg
  showErrorComponent (ErrorReparsing NonEmpty (ParseError Text CustomErr)
_) = String
"" -- dummy value

  errorComponentLen :: CustomErr -> Int
errorComponentLen (ErrorFailAt Int
startOffset Int
endOffset String
_) =
    Int
endOffset Int -> Int -> Int
forall a. Num a => a -> a -> a
- Int
startOffset
  errorComponentLen (ErrorReparsing NonEmpty (ParseError Text CustomErr)
_) = Int
1 -- dummy value


--- * Failing with an arbitrary source position

-- | Fail at a specific source position, given by the raw offset from the
-- start of the input stream (the number of tokens processed at that
-- point).

parseErrorAt :: Int -> String -> CustomErr
parseErrorAt :: Int -> String -> CustomErr
parseErrorAt Int
offset = Int -> Int -> String -> CustomErr
ErrorFailAt Int
offset (Int
offsetInt -> Int -> Int
forall a. Num a => a -> a -> a
+Int
1)

-- | Fail at a specific source interval, given by the raw offsets of its
-- endpoints from the start of the input stream (the numbers of tokens
-- processed at those points).
--
-- Note that care must be taken to ensure that the specified interval does
-- not span multiple lines of the input source. This will not be checked.

parseErrorAtRegion
  :: Int    -- ^ Start offset
  -> Int    -- ^ End end offset
  -> String -- ^ Error message
  -> CustomErr
parseErrorAtRegion :: Int -> Int -> String -> CustomErr
parseErrorAtRegion Int
startOffset Int
endOffset String
msg =
  if Int
startOffset Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
< Int
endOffset
    then Int -> Int -> String -> CustomErr
ErrorFailAt Int
startOffset Int
endOffset String
msg
    else Int -> Int -> String -> CustomErr
ErrorFailAt Int
startOffset (Int
startOffsetInt -> Int -> Int
forall a. Num a => a -> a -> a
+Int
1) String
msg


--- * Re-parsing

-- | A fragment of source suitable for "re-parsing". The purpose of this
-- data type is to preserve the content and source position of the excerpt
-- so that parse errors raised during "re-parsing" may properly reference
-- the original source.

data SourceExcerpt = SourceExcerpt Int  -- Offset of beginning of excerpt
                                   Text -- Fragment of source file

-- | Get the raw text of a source excerpt.

getExcerptText :: SourceExcerpt -> Text
getExcerptText :: SourceExcerpt -> Text
getExcerptText (SourceExcerpt Int
_ Text
txt) = Text
txt

-- | 'excerpt_ p' applies the given parser 'p' and extracts the portion of
-- the source consumed by 'p', along with the source position of this
-- portion. This is the only way to create a source excerpt suitable for
-- "re-parsing" by 'reparseExcerpt'.

-- This function could be extended to return the result of 'p', but we don't
-- currently need this.

excerpt_ :: MonadParsec CustomErr Text m => m a -> m SourceExcerpt
excerpt_ :: m a -> m SourceExcerpt
excerpt_ m a
p = do
  Int
offset <- m Int
forall e s (m :: * -> *). MonadParsec e s m => m Int
getOffset
  (!Text
txt, a
_) <- m a -> m (Tokens Text, a)
forall e s (m :: * -> *) a.
MonadParsec e s m =>
m a -> m (Tokens s, a)
match m a
p
  SourceExcerpt -> m SourceExcerpt
forall (f :: * -> *) a. Applicative f => a -> f a
pure (SourceExcerpt -> m SourceExcerpt)
-> SourceExcerpt -> m SourceExcerpt
forall a b. (a -> b) -> a -> b
$ Int -> Text -> SourceExcerpt
SourceExcerpt Int
offset Text
txt

-- | 'reparseExcerpt s p' "re-parses" the source excerpt 's' using the
-- parser 'p'. Parse errors raised by 'p' will be re-thrown at the source
-- position of the source excerpt.
--
-- In order for the correct source file to be displayed when re-throwing
-- parse errors, we must ensure that the source file during the use of
-- 'reparseExcerpt s p' is the same as that during the use of 'excerpt_'
-- that generated the source excerpt 's'. However, we can usually expect
-- this condition to be satisfied because, at the time of writing, the
-- only changes of source file in the codebase take place through include
-- files, and the parser for include files neither accepts nor returns
-- 'SourceExcerpt's.

reparseExcerpt
  :: Monad m
  => SourceExcerpt
  -> ParsecT CustomErr Text m a
  -> ParsecT CustomErr Text m a
reparseExcerpt :: SourceExcerpt
-> ParsecT CustomErr Text m a -> ParsecT CustomErr Text m a
reparseExcerpt (SourceExcerpt Int
offset Text
txt) ParsecT CustomErr Text m a
p = do
  (State Text CustomErr
_, Either (ParseErrorBundle Text CustomErr) a
res) <- m (State Text CustomErr,
   Either (ParseErrorBundle Text CustomErr) a)
-> ParsecT
     CustomErr
     Text
     m
     (State Text CustomErr, Either (ParseErrorBundle Text CustomErr) a)
forall (t :: (* -> *) -> * -> *) (m :: * -> *) a.
(MonadTrans t, Monad m) =>
m a -> t m a
lift (m (State Text CustomErr,
    Either (ParseErrorBundle Text CustomErr) a)
 -> ParsecT
      CustomErr
      Text
      m
      (State Text CustomErr, Either (ParseErrorBundle Text CustomErr) a))
-> m (State Text CustomErr,
      Either (ParseErrorBundle Text CustomErr) a)
-> ParsecT
     CustomErr
     Text
     m
     (State Text CustomErr, Either (ParseErrorBundle Text CustomErr) a)
forall a b. (a -> b) -> a -> b
$ ParsecT CustomErr Text m a
-> State Text CustomErr
-> m (State Text CustomErr,
      Either (ParseErrorBundle Text CustomErr) a)
forall (m :: * -> *) e s a.
Monad m =>
ParsecT e s m a
-> State s e -> m (State s e, Either (ParseErrorBundle s e) a)
runParserT' ParsecT CustomErr Text m a
p (Int -> Text -> State Text CustomErr
forall s e. Int -> s -> State s e
offsetInitialState Int
offset Text
txt)
  case Either (ParseErrorBundle Text CustomErr) a
res of
    Right a
result -> a -> ParsecT CustomErr Text m a
forall (f :: * -> *) a. Applicative f => a -> f a
pure a
result
    Left ParseErrorBundle Text CustomErr
errBundle -> CustomErr -> ParsecT CustomErr Text m a
forall e s (m :: * -> *) a. MonadParsec e s m => e -> m a
customFailure (CustomErr -> ParsecT CustomErr Text m a)
-> CustomErr -> ParsecT CustomErr Text m a
forall a b. (a -> b) -> a -> b
$ NonEmpty (ParseError Text CustomErr) -> CustomErr
ErrorReparsing (NonEmpty (ParseError Text CustomErr) -> CustomErr)
-> NonEmpty (ParseError Text CustomErr) -> CustomErr
forall a b. (a -> b) -> a -> b
$ ParseErrorBundle Text CustomErr
-> NonEmpty (ParseError Text CustomErr)
forall s e. ParseErrorBundle s e -> NonEmpty (ParseError s e)
bundleErrors ParseErrorBundle Text CustomErr
errBundle

  where
    offsetInitialState :: Int -> s ->
#if MIN_VERSION_megaparsec(8,0,0)
      State s e
#else
      State s
#endif
    offsetInitialState :: Int -> s -> State s e
offsetInitialState Int
initialOffset s
s = State :: forall s e. s -> Int -> PosState s -> [ParseError s e] -> State s e
State
      { stateInput :: s
stateInput  = s
s
      , stateOffset :: Int
stateOffset = Int
initialOffset
      , statePosState :: PosState s
statePosState = PosState :: forall s. s -> Int -> SourcePos -> Pos -> String -> PosState s
PosState
        { pstateInput :: s
pstateInput = s
s
        , pstateOffset :: Int
pstateOffset = Int
initialOffset
        , pstateSourcePos :: SourcePos
pstateSourcePos = String -> SourcePos
initialPos String
""
        , pstateTabWidth :: Pos
pstateTabWidth = Pos
defaultTabWidth
        , pstateLinePrefix :: String
pstateLinePrefix = String
""
        }
#if MIN_VERSION_megaparsec(8,0,0)
      , stateParseErrors :: [ParseError s e]
stateParseErrors = []
#endif
      }

--- * Pretty-printing custom parse errors

-- | Pretty-print our custom parse errors. It is necessary to use this
-- instead of 'errorBundlePretty' when custom parse errors are thrown.
--
-- This function intercepts our custom parse errors and applies final
-- adjustments ('finalizeCustomError') before passing them to
-- 'errorBundlePretty'. These adjustments are part of the implementation
-- of the behaviour of our custom parse errors.
--
-- Note: We must ensure that the offset of the 'PosState' of the provided
-- 'ParseErrorBundle' is no larger than the offset specified by a
-- 'ErrorFailAt' constructor. This is guaranteed if this offset is set to
-- 0 (that is, the beginning of the source file), which is the
-- case for 'ParseErrorBundle's returned from 'runParserT'.

customErrorBundlePretty :: ParseErrorBundle Text CustomErr -> String
customErrorBundlePretty :: ParseErrorBundle Text CustomErr -> String
customErrorBundlePretty ParseErrorBundle Text CustomErr
errBundle =
  let errBundle' :: ParseErrorBundle Text CustomErr
errBundle' = ParseErrorBundle Text CustomErr
errBundle { bundleErrors :: NonEmpty (ParseError Text CustomErr)
bundleErrors =
        (ParseError Text CustomErr -> Int)
-> NonEmpty (ParseError Text CustomErr)
-> NonEmpty (ParseError Text CustomErr)
forall o a. Ord o => (a -> o) -> NonEmpty a -> NonEmpty a
NE.sortWith ParseError Text CustomErr -> Int
forall s e. ParseError s e -> Int
errorOffset (NonEmpty (ParseError Text CustomErr)
 -> NonEmpty (ParseError Text CustomErr))
-> NonEmpty (ParseError Text CustomErr)
-> NonEmpty (ParseError Text CustomErr)
forall a b. (a -> b) -> a -> b
$ -- megaparsec requires that the list of errors be sorted by their offsets
        ParseErrorBundle Text CustomErr
-> NonEmpty (ParseError Text CustomErr)
forall s e. ParseErrorBundle s e -> NonEmpty (ParseError s e)
bundleErrors ParseErrorBundle Text CustomErr
errBundle NonEmpty (ParseError Text CustomErr)
-> (ParseError Text CustomErr
    -> NonEmpty (ParseError Text CustomErr))
-> NonEmpty (ParseError Text CustomErr)
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= ParseError Text CustomErr -> NonEmpty (ParseError Text CustomErr)
finalizeCustomError }
  in  ParseErrorBundle Text CustomErr -> String
forall s e.
(VisualStream s, TraversableStream s, ShowErrorComponent e) =>
ParseErrorBundle s e -> String
errorBundlePretty ParseErrorBundle Text CustomErr
errBundle'

  where
    finalizeCustomError
      :: ParseError Text CustomErr -> NE.NonEmpty (ParseError Text CustomErr)
    finalizeCustomError :: ParseError Text CustomErr -> NonEmpty (ParseError Text CustomErr)
finalizeCustomError ParseError Text CustomErr
err = case ParseError Text CustomErr -> Maybe CustomErr
findCustomError ParseError Text CustomErr
err of
      Maybe CustomErr
Nothing -> ParseError Text CustomErr -> NonEmpty (ParseError Text CustomErr)
forall (f :: * -> *) a. Applicative f => a -> f a
pure ParseError Text CustomErr
err

      Just errFailAt :: CustomErr
errFailAt@(ErrorFailAt Int
startOffset Int
_ String
_) ->
        -- Adjust the offset
        ParseError Text CustomErr -> NonEmpty (ParseError Text CustomErr)
forall (f :: * -> *) a. Applicative f => a -> f a
pure (ParseError Text CustomErr -> NonEmpty (ParseError Text CustomErr))
-> ParseError Text CustomErr
-> NonEmpty (ParseError Text CustomErr)
forall a b. (a -> b) -> a -> b
$ Int -> Set (ErrorFancy CustomErr) -> ParseError Text CustomErr
forall s e. Int -> Set (ErrorFancy e) -> ParseError s e
FancyError Int
startOffset (Set (ErrorFancy CustomErr) -> ParseError Text CustomErr)
-> Set (ErrorFancy CustomErr) -> ParseError Text CustomErr
forall a b. (a -> b) -> a -> b
$ ErrorFancy CustomErr -> Set (ErrorFancy CustomErr)
forall a. a -> Set a
S.singleton (ErrorFancy CustomErr -> Set (ErrorFancy CustomErr))
-> ErrorFancy CustomErr -> Set (ErrorFancy CustomErr)
forall a b. (a -> b) -> a -> b
$ CustomErr -> ErrorFancy CustomErr
forall e. e -> ErrorFancy e
ErrorCustom CustomErr
errFailAt

      Just (ErrorReparsing NonEmpty (ParseError Text CustomErr)
errs) ->
        -- Extract and finalize the inner errors
        NonEmpty (ParseError Text CustomErr)
errs NonEmpty (ParseError Text CustomErr)
-> (ParseError Text CustomErr
    -> NonEmpty (ParseError Text CustomErr))
-> NonEmpty (ParseError Text CustomErr)
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= ParseError Text CustomErr -> NonEmpty (ParseError Text CustomErr)
finalizeCustomError

    -- If any custom errors are present, arbitrarily take the first one
    -- (since only one custom error should be used at a time).
    findCustomError :: ParseError Text CustomErr -> Maybe CustomErr
    findCustomError :: ParseError Text CustomErr -> Maybe CustomErr
findCustomError ParseError Text CustomErr
err = case ParseError Text CustomErr
err of
      FancyError Int
_ Set (ErrorFancy CustomErr)
errSet ->
        (ErrorFancy CustomErr -> Maybe CustomErr)
-> Set (ErrorFancy CustomErr) -> Maybe CustomErr
forall (t :: * -> *) a b.
Foldable t =>
(a -> Maybe b) -> t a -> Maybe b
finds (\case {ErrorCustom CustomErr
e -> CustomErr -> Maybe CustomErr
forall a. a -> Maybe a
Just CustomErr
e; ErrorFancy CustomErr
_ -> Maybe CustomErr
forall a. Maybe a
Nothing}) Set (ErrorFancy CustomErr)
errSet
      ParseError Text CustomErr
_ -> Maybe CustomErr
forall a. Maybe a
Nothing

    finds :: (Foldable t) => (a -> Maybe b) -> t a -> Maybe b
    finds :: (a -> Maybe b) -> t a -> Maybe b
finds a -> Maybe b
f = Alt Maybe b -> Maybe b
forall k (f :: k -> *) (a :: k). Alt f a -> f a
getAlt (Alt Maybe b -> Maybe b) -> (t a -> Alt Maybe b) -> t a -> Maybe b
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (a -> Alt Maybe b) -> t a -> Alt Maybe b
forall (t :: * -> *) m a.
(Foldable t, Monoid m) =>
(a -> m) -> t a -> m
foldMap (Maybe b -> Alt Maybe b
forall k (f :: k -> *) (a :: k). f a -> Alt f a
Alt (Maybe b -> Alt Maybe b) -> (a -> Maybe b) -> a -> Alt Maybe b
forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> Maybe b
f)


--- * "Final" parse errors
--
-- | A type representing "final" parse errors that cannot be backtracked
-- from and are guaranteed to halt parsing. The anti-backtracking
-- behaviour is implemented by an 'ExceptT' layer in the parser's monad
-- stack, using this type as the 'ExceptT' error type.
--
-- We have three goals for this type:
-- (1) it should be possible to convert any parse error into a "final"
-- parse error,
-- (2) it should be possible to take a parse error thrown from an include
-- file and re-throw it in the parent file, and
-- (3) the pretty-printing of "final" parse errors should be consistent
-- with that of ordinary parse errors, but should also report a stack of
-- files for errors thrown from include files.
--
-- In order to pretty-print a "final" parse error (goal 3), it must be
-- bundled with include filepaths and its full source text. When a "final"
-- parse error is thrown from within a parser, we do not have access to
-- the full source, so we must hold the parse error until it can be joined
-- with its source (and include filepaths, if it was thrown from an
-- include file) by the parser's caller.
--
-- A parse error with include filepaths and its full source text is
-- represented by the 'FinalParseErrorBundle' type, while a parse error in
-- need of either include filepaths, full source text, or both is
-- represented by the 'FinalParseError' type.

data FinalParseError' e
  -- a parse error thrown as a "final" parse error
  = FinalError           (ParseError Text e)
  -- a parse error obtained from running a parser, e.g. using 'runParserT'
  | FinalBundle          (ParseErrorBundle Text e)
  -- a parse error thrown from an include file
  | FinalBundleWithStack (FinalParseErrorBundle' e)
  deriving (Int -> FinalParseError' e -> ShowS
[FinalParseError' e] -> ShowS
FinalParseError' e -> String
(Int -> FinalParseError' e -> ShowS)
-> (FinalParseError' e -> String)
-> ([FinalParseError' e] -> ShowS)
-> Show (FinalParseError' e)
forall e. Show e => Int -> FinalParseError' e -> ShowS
forall e. Show e => [FinalParseError' e] -> ShowS
forall e. Show e => FinalParseError' e -> String
forall a.
(Int -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
showList :: [FinalParseError' e] -> ShowS
$cshowList :: forall e. Show e => [FinalParseError' e] -> ShowS
show :: FinalParseError' e -> String
$cshow :: forall e. Show e => FinalParseError' e -> String
showsPrec :: Int -> FinalParseError' e -> ShowS
$cshowsPrec :: forall e. Show e => Int -> FinalParseError' e -> ShowS
Show)

type FinalParseError = FinalParseError' CustomErr

-- We need a 'Monoid' instance for 'FinalParseError' so that 'ExceptT
-- FinalParseError m' is an instance of Alternative and MonadPlus, which
-- is needed to use some parser combinators, e.g. 'many'.
--
-- This monoid instance simply takes the first (left-most) error.

instance Semigroup (FinalParseError' e) where
  FinalParseError' e
e <> :: FinalParseError' e -> FinalParseError' e -> FinalParseError' e
<> FinalParseError' e
_ = FinalParseError' e
e

instance Monoid (FinalParseError' e) where
  mempty :: FinalParseError' e
mempty = ParseError Text e -> FinalParseError' e
forall e. ParseError Text e -> FinalParseError' e
FinalError (ParseError Text e -> FinalParseError' e)
-> ParseError Text e -> FinalParseError' e
forall a b. (a -> b) -> a -> b
$ Int -> Set (ErrorFancy e) -> ParseError Text e
forall s e. Int -> Set (ErrorFancy e) -> ParseError s e
FancyError Int
0 (Set (ErrorFancy e) -> ParseError Text e)
-> Set (ErrorFancy e) -> ParseError Text e
forall a b. (a -> b) -> a -> b
$
            ErrorFancy e -> Set (ErrorFancy e)
forall a. a -> Set a
S.singleton (String -> ErrorFancy e
forall e. String -> ErrorFancy e
ErrorFail String
"default parse error")
  mappend :: FinalParseError' e -> FinalParseError' e -> FinalParseError' e
mappend = FinalParseError' e -> FinalParseError' e -> FinalParseError' e
forall a. Semigroup a => a -> a -> a
(<>)

-- | A type bundling a 'ParseError' with its full source text, filepath,
-- and stack of include files. Suitable for pretty-printing.
--
-- Megaparsec's 'ParseErrorBundle' type already bundles a parse error with
-- its full source text and filepath, so we just add a stack of include
-- files.

data FinalParseErrorBundle' e = FinalParseErrorBundle'
  { FinalParseErrorBundle' e -> ParseErrorBundle Text e
finalErrorBundle :: ParseErrorBundle Text e
  , FinalParseErrorBundle' e -> [String]
includeFileStack :: [FilePath]
  } deriving (Int -> FinalParseErrorBundle' e -> ShowS
[FinalParseErrorBundle' e] -> ShowS
FinalParseErrorBundle' e -> String
(Int -> FinalParseErrorBundle' e -> ShowS)
-> (FinalParseErrorBundle' e -> String)
-> ([FinalParseErrorBundle' e] -> ShowS)
-> Show (FinalParseErrorBundle' e)
forall e. Show e => Int -> FinalParseErrorBundle' e -> ShowS
forall e. Show e => [FinalParseErrorBundle' e] -> ShowS
forall e. Show e => FinalParseErrorBundle' e -> String
forall a.
(Int -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
showList :: [FinalParseErrorBundle' e] -> ShowS
$cshowList :: forall e. Show e => [FinalParseErrorBundle' e] -> ShowS
show :: FinalParseErrorBundle' e -> String
$cshow :: forall e. Show e => FinalParseErrorBundle' e -> String
showsPrec :: Int -> FinalParseErrorBundle' e -> ShowS
$cshowsPrec :: forall e. Show e => Int -> FinalParseErrorBundle' e -> ShowS
Show)

type FinalParseErrorBundle = FinalParseErrorBundle' CustomErr


--- * Constructing and throwing final parse errors

-- | Convert a "regular" parse error into a "final" parse error.

finalError :: ParseError Text e -> FinalParseError' e
finalError :: ParseError Text e -> FinalParseError' e
finalError = ParseError Text e -> FinalParseError' e
forall e. ParseError Text e -> FinalParseError' e
FinalError

-- | Like megaparsec's 'fancyFailure', but as a "final" parse error.

finalFancyFailure
  :: (MonadParsec e s m, MonadError (FinalParseError' e) m)
  => S.Set (ErrorFancy e) -> m a
finalFancyFailure :: Set (ErrorFancy e) -> m a
finalFancyFailure Set (ErrorFancy e)
errSet = do
  Int
offset <- m Int
forall e s (m :: * -> *). MonadParsec e s m => m Int
getOffset
  FinalParseError' e -> m a
forall e (m :: * -> *) a. MonadError e m => e -> m a
throwError (FinalParseError' e -> m a) -> FinalParseError' e -> m a
forall a b. (a -> b) -> a -> b
$ ParseError Text e -> FinalParseError' e
forall e. ParseError Text e -> FinalParseError' e
FinalError (ParseError Text e -> FinalParseError' e)
-> ParseError Text e -> FinalParseError' e
forall a b. (a -> b) -> a -> b
$ Int -> Set (ErrorFancy e) -> ParseError Text e
forall s e. Int -> Set (ErrorFancy e) -> ParseError s e
FancyError Int
offset Set (ErrorFancy e)
errSet

-- | Like 'fail', but as a "final" parse error.

finalFail
  :: (MonadParsec e s m, MonadError (FinalParseError' e) m) => String -> m a
finalFail :: String -> m a
finalFail = Set (ErrorFancy e) -> m a
forall e s (m :: * -> *) a.
(MonadParsec e s m, MonadError (FinalParseError' e) m) =>
Set (ErrorFancy e) -> m a
finalFancyFailure (Set (ErrorFancy e) -> m a)
-> (String -> Set (ErrorFancy e)) -> String -> m a
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ErrorFancy e -> Set (ErrorFancy e)
forall a. a -> Set a
S.singleton (ErrorFancy e -> Set (ErrorFancy e))
-> (String -> ErrorFancy e) -> String -> Set (ErrorFancy e)
forall b c a. (b -> c) -> (a -> b) -> a -> c
. String -> ErrorFancy e
forall e. String -> ErrorFancy e
ErrorFail

-- | Like megaparsec's 'customFailure', but as a "final" parse error.

finalCustomFailure
  :: (MonadParsec e s m, MonadError (FinalParseError' e) m) => e -> m a
finalCustomFailure :: e -> m a
finalCustomFailure = Set (ErrorFancy e) -> m a
forall e s (m :: * -> *) a.
(MonadParsec e s m, MonadError (FinalParseError' e) m) =>
Set (ErrorFancy e) -> m a
finalFancyFailure (Set (ErrorFancy e) -> m a)
-> (e -> Set (ErrorFancy e)) -> e -> m a
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ErrorFancy e -> Set (ErrorFancy e)
forall a. a -> Set a
S.singleton (ErrorFancy e -> Set (ErrorFancy e))
-> (e -> ErrorFancy e) -> e -> Set (ErrorFancy e)
forall b c a. (b -> c) -> (a -> b) -> a -> c
. e -> ErrorFancy e
forall e. e -> ErrorFancy e
ErrorCustom


--- * Pretty-printing "final" parse errors

-- | Pretty-print a "final" parse error: print the stack of include files,
-- then apply the pretty-printer for parse error bundles. Note that
-- 'attachSource' must be used on a "final" parse error before it can be
-- pretty-printed.

finalErrorBundlePretty :: FinalParseErrorBundle' CustomErr -> String
finalErrorBundlePretty :: FinalParseErrorBundle' CustomErr -> String
finalErrorBundlePretty FinalParseErrorBundle' CustomErr
bundle =
     ShowS -> [String] -> String
forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap ShowS
showIncludeFilepath (FinalParseErrorBundle' CustomErr -> [String]
forall e. FinalParseErrorBundle' e -> [String]
includeFileStack FinalParseErrorBundle' CustomErr
bundle)
  String -> ShowS
forall a. Semigroup a => a -> a -> a
<> ParseErrorBundle Text CustomErr -> String
customErrorBundlePretty (FinalParseErrorBundle' CustomErr -> ParseErrorBundle Text CustomErr
forall e. FinalParseErrorBundle' e -> ParseErrorBundle Text e
finalErrorBundle FinalParseErrorBundle' CustomErr
bundle)
  where
    showIncludeFilepath :: ShowS
showIncludeFilepath String
path = String
"in file included from " String -> ShowS
forall a. Semigroup a => a -> a -> a
<> String
path String -> ShowS
forall a. Semigroup a => a -> a -> a
<> String
",\n"

-- | Supply a filepath and source text to a "final" parse error so that it
-- can be pretty-printed. You must ensure that you provide the appropriate
-- source text and filepath.

attachSource
  :: FilePath -> Text -> FinalParseError' e -> FinalParseErrorBundle' e
attachSource :: String -> Text -> FinalParseError' e -> FinalParseErrorBundle' e
attachSource String
filePath Text
sourceText FinalParseError' e
finalParseError = case FinalParseError' e
finalParseError of

  -- A parse error thrown directly with the 'FinalError' constructor
  -- requires both source and filepath.
  FinalError ParseError Text e
parseError ->
    let bundle :: ParseErrorBundle Text e
bundle = ParseErrorBundle :: forall s e.
NonEmpty (ParseError s e) -> PosState s -> ParseErrorBundle s e
ParseErrorBundle
          { bundleErrors :: NonEmpty (ParseError Text e)
bundleErrors = ParseError Text e
parseError ParseError Text e
-> [ParseError Text e] -> NonEmpty (ParseError Text e)
forall a. a -> [a] -> NonEmpty a
NE.:| []
          , bundlePosState :: PosState Text
bundlePosState = String -> Text -> PosState Text
initialPosState String
filePath Text
sourceText }
    in  FinalParseErrorBundle' :: forall e.
ParseErrorBundle Text e -> [String] -> FinalParseErrorBundle' e
FinalParseErrorBundle'
          { finalErrorBundle :: ParseErrorBundle Text e
finalErrorBundle = ParseErrorBundle Text e
bundle
          , includeFileStack :: [String]
includeFileStack  = [] }

  -- A 'ParseErrorBundle' already has the appropriate source and filepath
  -- and so needs neither.
  FinalBundle ParseErrorBundle Text e
peBundle -> FinalParseErrorBundle' :: forall e.
ParseErrorBundle Text e -> [String] -> FinalParseErrorBundle' e
FinalParseErrorBundle'
    { finalErrorBundle :: ParseErrorBundle Text e
finalErrorBundle = ParseErrorBundle Text e
peBundle
    , includeFileStack :: [String]
includeFileStack = [] }

  -- A parse error from a 'FinalParseErrorBundle' was thrown from an
  -- include file, so we add the filepath to the stack.
  FinalBundleWithStack FinalParseErrorBundle' e
fpeBundle -> FinalParseErrorBundle' e
fpeBundle
    { includeFileStack :: [String]
includeFileStack = String
filePath String -> [String] -> [String]
forall a. a -> [a] -> [a]
: FinalParseErrorBundle' e -> [String]
forall e. FinalParseErrorBundle' e -> [String]
includeFileStack FinalParseErrorBundle' e
fpeBundle }


--- * Handling parse errors from include files with "final" parse errors

-- | Parse a file with the given parser and initial state, discarding the
-- final state and re-throwing any parse errors as "final" parse errors.

parseIncludeFile
  :: Monad m
  => StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
  -> st
  -> FilePath
  -> Text
  -> StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
parseIncludeFile :: StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
-> st
-> String
-> Text
-> StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
parseIncludeFile StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
parser st
initialState String
filepath Text
text =
  StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
-> (FinalParseError
    -> StateT
         st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a)
-> StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
forall e (m :: * -> *) a.
MonadError e m =>
m a -> (e -> m a) -> m a
catchError StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
parser' FinalParseError
-> StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
forall e (m :: * -> *) a.
MonadError (FinalParseError' e) m =>
FinalParseError' e -> m a
handler
  where
    parser' :: StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
parser' = do
      Either (ParseErrorBundle Text CustomErr) a
eResult <- ParsecT
  CustomErr
  Text
  (ExceptT FinalParseError m)
  (Either (ParseErrorBundle Text CustomErr) a)
-> StateT
     st
     (ParsecT CustomErr Text (ExceptT FinalParseError m))
     (Either (ParseErrorBundle Text CustomErr) a)
forall (t :: (* -> *) -> * -> *) (m :: * -> *) a.
(MonadTrans t, Monad m) =>
m a -> t m a
lift (ParsecT
   CustomErr
   Text
   (ExceptT FinalParseError m)
   (Either (ParseErrorBundle Text CustomErr) a)
 -> StateT
      st
      (ParsecT CustomErr Text (ExceptT FinalParseError m))
      (Either (ParseErrorBundle Text CustomErr) a))
-> ParsecT
     CustomErr
     Text
     (ExceptT FinalParseError m)
     (Either (ParseErrorBundle Text CustomErr) a)
-> StateT
     st
     (ParsecT CustomErr Text (ExceptT FinalParseError m))
     (Either (ParseErrorBundle Text CustomErr) a)
forall a b. (a -> b) -> a -> b
$ ExceptT
  FinalParseError m (Either (ParseErrorBundle Text CustomErr) a)
-> ParsecT
     CustomErr
     Text
     (ExceptT FinalParseError m)
     (Either (ParseErrorBundle Text CustomErr) a)
forall (t :: (* -> *) -> * -> *) (m :: * -> *) a.
(MonadTrans t, Monad m) =>
m a -> t m a
lift (ExceptT
   FinalParseError m (Either (ParseErrorBundle Text CustomErr) a)
 -> ParsecT
      CustomErr
      Text
      (ExceptT FinalParseError m)
      (Either (ParseErrorBundle Text CustomErr) a))
-> ExceptT
     FinalParseError m (Either (ParseErrorBundle Text CustomErr) a)
-> ParsecT
     CustomErr
     Text
     (ExceptT FinalParseError m)
     (Either (ParseErrorBundle Text CustomErr) a)
forall a b. (a -> b) -> a -> b
$
                  ParsecT CustomErr Text (ExceptT FinalParseError m) a
-> String
-> Text
-> ExceptT
     FinalParseError m (Either (ParseErrorBundle Text CustomErr) a)
forall (m :: * -> *) e s a.
Monad m =>
ParsecT e s m a
-> String -> s -> m (Either (ParseErrorBundle s e) a)
runParserT (StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
-> st -> ParsecT CustomErr Text (ExceptT FinalParseError m) a
forall (m :: * -> *) s a. Monad m => StateT s m a -> s -> m a
evalStateT StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
parser st
initialState) String
filepath Text
text
      case Either (ParseErrorBundle Text CustomErr) a
eResult of
        Left ParseErrorBundle Text CustomErr
parseErrorBundle -> FinalParseError
-> StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
forall e (m :: * -> *) a. MonadError e m => e -> m a
throwError (FinalParseError
 -> StateT
      st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a)
-> FinalParseError
-> StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
forall a b. (a -> b) -> a -> b
$ ParseErrorBundle Text CustomErr -> FinalParseError
forall e. ParseErrorBundle Text e -> FinalParseError' e
FinalBundle ParseErrorBundle Text CustomErr
parseErrorBundle
        Right a
result -> a
-> StateT st (ParsecT CustomErr Text (ExceptT FinalParseError m)) a
forall (f :: * -> *) a. Applicative f => a -> f a
pure a
result

    -- Attach source and filepath of the include file to its parse errors
    handler :: FinalParseError' e -> m a
handler FinalParseError' e
e = FinalParseError' e -> m a
forall e (m :: * -> *) a. MonadError e m => e -> m a
throwError (FinalParseError' e -> m a) -> FinalParseError' e -> m a
forall a b. (a -> b) -> a -> b
$ FinalParseErrorBundle' e -> FinalParseError' e
forall e. FinalParseErrorBundle' e -> FinalParseError' e
FinalBundleWithStack (FinalParseErrorBundle' e -> FinalParseError' e)
-> FinalParseErrorBundle' e -> FinalParseError' e
forall a b. (a -> b) -> a -> b
$ String -> Text -> FinalParseError' e -> FinalParseErrorBundle' e
forall e.
String -> Text -> FinalParseError' e -> FinalParseErrorBundle' e
attachSource String
filepath Text
text FinalParseError' e
e


--- * Helpers

-- Like megaparsec's 'initialState', but instead for 'PosState'. Used when
-- constructing 'ParseErrorBundle's. The values for "tab width" and "line
-- prefix" are taken from 'initialState'.

initialPosState :: FilePath -> Text -> PosState Text
initialPosState :: String -> Text -> PosState Text
initialPosState String
filePath Text
sourceText = PosState :: forall s. s -> Int -> SourcePos -> Pos -> String -> PosState s
PosState
  { pstateInput :: Text
pstateInput      = Text
sourceText
  , pstateOffset :: Int
pstateOffset     = Int
0
  , pstateSourcePos :: SourcePos
pstateSourcePos  = String -> SourcePos
initialPos String
filePath
  , pstateTabWidth :: Pos
pstateTabWidth   = Pos
defaultTabWidth
  , pstateLinePrefix :: String
pstateLinePrefix = String
"" }