Change reader types, allowing better tracking of source positions.

Previously, when multiple file arguments were provided, pandoc
simply concatenated them and passed the contents to the readers,
which took a Text argument.

As a result, the readers had no way of knowing which file
was the source of any particular bit of text.  This meant that
we couldn't report accurate source positions on errors or
include accurate source positions as attributes in the AST.
More seriously, it meant that we couldn't resolve resource
paths relative to the files containing them
(see e.g. #5501, #6632, #6384, #3752).

Add Text.Pandoc.Sources (exported module), with a `Sources` type
and a `ToSources` class.  A `Sources` wraps a list of `(SourcePos,
Text)` pairs. [API change] A parsec `Stream` instance is provided for
`Sources`.  The module also exports versions of parsec's `satisfy` and
other Char parsers that track source positions accurately from a
`Sources` stream (or any instance of the new `UpdateSourcePos` class).

Text.Pandoc.Parsing now exports these modified Char parsers instead of
the ones parsec provides.  Modified parsers to use a `Sources` as stream
[API change].

The readers that previously took a `Text` argument have been
modified to take any instance of `ToSources`. So, they may still
be used with a `Text`, but they can also be used with a `Sources`
object.

In Text.Pandoc.Error, modified the constructor PandocParsecError
to take a `Sources` rather than a `Text` as first argument,
so parse error locations can be accurately reported.

T.P.Error: showPos, do not print "-" as source name.

1 files changed, 9 insertions, 8 deletions

diff --git a/src/Text/Pandoc/Readers/Muse.hs b/src/Text/Pandoc/Readers/Muse.hs
index 698bfd3d7..a0d4534f1 100644
--- a/src/Text/Pandoc/Readers/Muse.hs
+++ b/src/Text/Pandoc/Readers/Muse.hs
@@ -37,18 +37,19 @@ import Text.Pandoc.Error (PandocError (PandocParsecError))
 import Text.Pandoc.Logging
 import Text.Pandoc.Options
 import Text.Pandoc.Parsing
-import Text.Pandoc.Shared (crFilter, trimr, tshow)
+import Text.Pandoc.Shared (trimr, tshow)
 
 -- | Read Muse from an input string and return a Pandoc document.
-readMuse :: PandocMonad m
+readMuse :: (PandocMonad m, ToSources a)
          => ReaderOptions
-         -> Text
+         -> a
          -> m Pandoc
 readMuse opts s = do
-  let input = crFilter s
-  res <- flip runReaderT def $ runParserT parseMuse def{ museOptions = opts } "source" input
+  let sources = toSources s
+  res <- flip runReaderT def $ runParserT parseMuse def{ museOptions = opts }
+              (initialSourceName sources) sources
   case res of
-       Left e  -> throwError $ PandocParsecError input e
+       Left e  -> throwError $ PandocParsecError sources e
        Right d -> return d
 
 type F = Future MuseState
@@ -82,7 +83,7 @@ instance Default MuseEnv where
                 , museInPara = False
                 }
 
-type MuseParser m = ParserT Text MuseState (ReaderT MuseEnv m)
+type MuseParser m = ParserT Sources MuseState (ReaderT MuseEnv m)
 
 instance HasReaderOptions MuseState where
   extractReaderOptions = museOptions
@@ -155,7 +156,7 @@ firstColumn = getPosition >>= \pos -> guard (sourceColumn pos == 1)
 -- * Parsers
 
 -- | Parse end-of-line, which can be either a newline or end-of-file.
-eol :: Stream s m Char => ParserT s st m ()
+eol :: (Stream s m Char, UpdateSourcePos s Char) => ParserT s st m ()
 eol = void newline <|> eof
 
 getIndent :: PandocMonad m