Added Text.Pandoc.Logging (exported module).

This now contains the Verbosity definition previously
in Options, as well as a new LogMessage datatype that
will eventually be used instead of raw strings for
warnings.

This will enable us, among other things, to provide
machine-readable warnings if desired.

See #3392.

12 files changed, 94 insertions, 19 deletions

diff --git a/src/Text/Pandoc.hs b/src/Text/Pandoc.hs
index 1a0bbc4ab..47b891eb3 100644
--- a/src/Text/Pandoc.hs
+++ b/src/Text/Pandoc.hs
@@ -58,6 +58,8 @@ module Text.Pandoc
                , module Text.Pandoc.Generic
                -- * Options
                , module Text.Pandoc.Options
+               -- * Logging
+               , module Text.Pandoc.Logging
                -- * Typeclass
                , PandocMonad
                , runIO
@@ -189,6 +191,7 @@ import Text.Pandoc.Writers.Custom
 import Text.Pandoc.Writers.TEI
 import Text.Pandoc.Templates
 import Text.Pandoc.Options
+import Text.Pandoc.Logging
 import Text.Pandoc.Shared (safeRead, mapLeft, pandocVersion)
 import Text.Pandoc.Error
 import Text.Pandoc.Class
diff --git a/src/Text/Pandoc/Class.hs b/src/Text/Pandoc/Class.hs
index df831c8b2..b1958510c 100644
--- a/src/Text/Pandoc/Class.hs
+++ b/src/Text/Pandoc/Class.hs
@@ -72,8 +72,8 @@ import qualified Text.Pandoc.Shared as IO ( readDataFile
                                           , openURL )
 import qualified Text.Pandoc.UTF8 as UTF8
 import Text.Pandoc.Compat.Time (UTCTime)
-import Text.Pandoc.Options (Verbosity(..))
-import Text.Parsec (ParsecT, SourcePos, getPosition)
+import Text.Pandoc.Logging
+import Text.Parsec (ParsecT, SourcePos)
 import qualified Text.Pandoc.Compat.Time as IO (getCurrentTime)
 import Text.Pandoc.MIME (MimeType, getMimeType)
 import Data.Time.Clock.POSIX ( utcTimeToPOSIXSeconds
diff --git a/src/Text/Pandoc/Error.hs b/src/Text/Pandoc/Error.hs
index b624f4cb0..55b2d981a 100644
--- a/src/Text/Pandoc/Error.hs
+++ b/src/Text/Pandoc/Error.hs
@@ -29,7 +29,9 @@ This module provides a standard way to deal with possible errors encounted
 during parsing.
 
 -}
-module Text.Pandoc.Error (PandocError(..), handleError) where
+module Text.Pandoc.Error (
+  PandocError(..),
+  handleError) where
 
 import Text.Parsec.Error
 import Text.Parsec.Pos hiding (Line)
@@ -47,13 +49,6 @@ data PandocError = PandocFileReadError FilePath
                  | PandocParsecError Input ParseError
                  deriving (Show, Typeable, Generic)
 
-
--- data PandocError = -- | Generic parse failure
---                    ParseFailure String
---                  -- | Error thrown by a Parsec parser
---                  | ParsecError Input ParseError
---                  deriving (Show, Typeable, Generic)
-
 instance Exception PandocError
 
 -- | Handle PandocError by exiting with an error message.
diff --git a/src/Text/Pandoc/Logging.hs b/src/Text/Pandoc/Logging.hs
new file mode 100644
index 000000000..1272ff095
--- /dev/null
+++ b/src/Text/Pandoc/Logging.hs
@@ -0,0 +1,76 @@
+{-# LANGUAGE DeriveDataTypeable, DeriveGeneric #-}
+{-
+Copyright (C) 2016-17 John MacFarlane <jgm@berkeley.edu>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+-}
+{- |
+   Module      : Text.Pandoc.Logging
+   Copyright   : Copyright (C) 2006-2016 John MacFarlane
+   License     : GNU GPL, version 2 or above
+
+   Maintainer  : John MacFarlane <jgm@berkeley.edu>
+   Stability   : alpha
+   Portability : portable
+
+This module provides data types and functions for warnings
+and info messages.
+
+-}
+module Text.Pandoc.Logging (
+    Verbosity(..)
+  , LogMessage(..)
+  , messageVerbosity
+  ) where
+
+import Text.Parsec.Pos
+import Data.Data (Data)
+import Data.Generics (Typeable)
+import GHC.Generics (Generic)
+
+-- | Verbosity level.
+data Verbosity = ERROR | WARNING | INFO | DEBUG
+     deriving (Show, Read, Eq, Data, Enum, Ord, Bounded, Typeable, Generic)
+
+data LogMessage =
+    SkippedInput String SourcePos
+  | NotRendered String
+  | YamlSectionNotAnObject SourcePos
+  | DuplicateLinkReference String SourcePos
+  | DuplicateNoteReference String SourcePos
+  | ParsingUnescaped String SourcePos
+  | DocxCommentWillNotRetainFormatting String
+  | CouldNotFetchResource String String
+  | CouldNotDetermineImageSize String
+  | CouldNotDetermineMimeType String
+  | CouldNotConvertTeXMath String
+  deriving (Show, Eq, Data, Ord, Typeable, Generic)
+
+messageVerbosity:: LogMessage -> Verbosity
+messageVerbosity msg =
+  case msg of
+       SkippedInput{} -> INFO
+       NotRendered{} -> INFO
+       YamlSectionNotAnObject{} -> WARNING
+       DuplicateLinkReference{} -> WARNING
+       DuplicateNoteReference{} -> WARNING
+       ParsingUnescaped{} -> INFO
+       DocxCommentWillNotRetainFormatting{} -> INFO
+       CouldNotFetchResource{} -> WARNING
+       CouldNotDetermineImageSize{} -> WARNING
+       CouldNotDetermineMimeType{} -> WARNING
+       CouldNotConvertTeXMath{} -> WARNING
+
+
diff --git a/src/Text/Pandoc/Options.hs b/src/Text/Pandoc/Options.hs
index 2e11a64d0..bc62f87d0 100644
--- a/src/Text/Pandoc/Options.hs
+++ b/src/Text/Pandoc/Options.hs
@@ -37,7 +37,6 @@ module Text.Pandoc.Options ( module Text.Pandoc.Extensions
                            , HTMLSlideVariant (..)
                            , EPUBVersion (..)
                            , WrapOption (..)
-                           , Verbosity (..)
                            , TopLevelDivision (..)
                            , WriterOptions (..)
                            , TrackChanges (..)
@@ -138,10 +137,6 @@ data ReferenceLocation = EndOfBlock    -- ^ End of block
                        | EndOfDocument -- ^ at end of document
                        deriving (Show, Read, Eq, Data, Typeable, Generic)
 
--- | Verbosity level.
-data Verbosity = ERROR | WARNING | INFO | DEBUG
-     deriving (Show, Read, Eq, Data, Enum, Ord, Bounded, Typeable, Generic)
-
 -- | Options for writers
 data WriterOptions = WriterOptions
   { writerTemplate         :: Maybe String -- ^ Template to use
diff --git a/src/Text/Pandoc/PDF.hs b/src/Text/Pandoc/PDF.hs
index b3bbcb4f5..1b3b4eb88 100644
--- a/src/Text/Pandoc/PDF.hs
+++ b/src/Text/Pandoc/PDF.hs
@@ -52,8 +52,8 @@ import Text.Pandoc.MediaBag
 import Text.Pandoc.Walk (walkM)
 import Text.Pandoc.Shared (warn, withTempDir, inDirectory, stringify)
 import Text.Pandoc.Writers.Shared (getField, metaToJSON)
-import Text.Pandoc.Options (WriterOptions(..), HTMLMathMethod(..),
-          Verbosity(..))
+import Text.Pandoc.Options (WriterOptions(..), HTMLMathMethod(..))
+import Text.Pandoc.Logging (Verbosity(..))
 import Text.Pandoc.MIME (extensionFromMimeType, getMimeType)
 import Text.Pandoc.Process (pipeProcess)
 import Control.Monad.Trans (MonadIO(..))
diff --git a/src/Text/Pandoc/Readers/EPUB.hs b/src/Text/Pandoc/Readers/EPUB.hs
index 851d4771f..49a035c37 100644
--- a/src/Text/Pandoc/Readers/EPUB.hs
+++ b/src/Text/Pandoc/Readers/EPUB.hs
@@ -12,7 +12,8 @@ import Text.XML.Light
 import Text.Pandoc.Definition hiding (Attr)
 import Text.Pandoc.Readers.HTML (readHtml)
 import Text.Pandoc.Walk (walk, query)
-import Text.Pandoc.Options ( ReaderOptions(..), Verbosity(..))
+import Text.Pandoc.Options ( ReaderOptions(..))
+import Text.Pandoc.Logging (Verbosity(..))
 import Text.Pandoc.Extensions (enableExtension, Extension(Ext_raw_html))
 import Text.Pandoc.Shared (escapeURI, collapseFilePath, addMetaField)
 import Network.URI (unEscapeString)
diff --git a/src/Text/Pandoc/Readers/HTML.hs b/src/Text/Pandoc/Readers/HTML.hs
index a464847fb..c452d2acf 100644
--- a/src/Text/Pandoc/Readers/HTML.hs
+++ b/src/Text/Pandoc/Readers/HTML.hs
@@ -46,8 +46,9 @@ import Text.Pandoc.Builder (Blocks, Inlines, trimInlines, HasMeta(..))
 import Text.Pandoc.Shared ( extractSpaces, renderTags', addMetaField
                           , escapeURI, safeRead )
 import Text.Pandoc.Options (ReaderOptions(readerExtensions), extensionEnabled,
-                               Verbosity(..), Extension (Ext_epub_html_exts,
+                               Extension (Ext_epub_html_exts,
                                Ext_raw_html, Ext_native_divs, Ext_native_spans))
+import Text.Pandoc.Logging (Verbosity(..))
 import Text.Pandoc.Parsing hiding ((<|>))
 import Text.Pandoc.Walk
 import qualified Data.Map as M
diff --git a/src/Text/Pandoc/Readers/Markdown.hs b/src/Text/Pandoc/Readers/Markdown.hs
index 0c10889d4..e35b70240 100644
--- a/src/Text/Pandoc/Readers/Markdown.hs
+++ b/src/Text/Pandoc/Readers/Markdown.hs
@@ -51,6 +51,7 @@ import qualified Text.Pandoc.UTF8 as UTF8
 import qualified Data.Vector as V
 import Text.Pandoc.Builder (Inlines, Blocks, trimInlines)
 import Text.Pandoc.Options
+import Text.Pandoc.Logging (Verbosity(..))
 import Text.Pandoc.Shared
 import Text.Pandoc.Pretty (charWidth)
 import Text.Pandoc.XML (fromEntities)
diff --git a/src/Text/Pandoc/Readers/MediaWiki.hs b/src/Text/Pandoc/Readers/MediaWiki.hs
index b81d0f3e4..e70509bd1 100644
--- a/src/Text/Pandoc/Readers/MediaWiki.hs
+++ b/src/Text/Pandoc/Readers/MediaWiki.hs
@@ -41,6 +41,7 @@ import qualified Text.Pandoc.Builder as B
 import Text.Pandoc.Builder (Inlines, Blocks, trimInlines)
 import Data.Monoid ((<>))
 import Text.Pandoc.Options
+import Text.Pandoc.Logging (Verbosity(..))
 import Text.Pandoc.Readers.HTML ( htmlTag, isBlockTag, isCommentTag )
 import Text.Pandoc.XML ( fromEntities )
 import Text.Pandoc.Parsing hiding ( nested )
diff --git a/src/Text/Pandoc/Readers/TWiki.hs b/src/Text/Pandoc/Readers/TWiki.hs
index 1a827bcd9..af9b38895 100644
--- a/src/Text/Pandoc/Readers/TWiki.hs
+++ b/src/Text/Pandoc/Readers/TWiki.hs
@@ -35,6 +35,7 @@ module Text.Pandoc.Readers.TWiki ( readTWiki
 import Text.Pandoc.Definition
 import qualified Text.Pandoc.Builder as B
 import Text.Pandoc.Options
+import Text.Pandoc.Logging (Verbosity(..))
 import Text.Pandoc.Parsing hiding (enclosed, macro, nested)
 import Text.Pandoc.Readers.HTML (htmlTag, isCommentTag)
 import Control.Monad
diff --git a/src/Text/Pandoc/Readers/Textile.hs b/src/Text/Pandoc/Readers/Textile.hs
index 07fb65b20..f404079ec 100644
--- a/src/Text/Pandoc/Readers/Textile.hs
+++ b/src/Text/Pandoc/Readers/Textile.hs
@@ -56,6 +56,7 @@ import Text.Pandoc.Definition
 import Text.Pandoc.Builder (Inlines, Blocks, trimInlines)
 import qualified Text.Pandoc.Builder as B
 import Text.Pandoc.Options
+import Text.Pandoc.Logging (Verbosity(..))
 import Text.Pandoc.Parsing
 import Text.Pandoc.Readers.HTML ( htmlTag, isBlockTag, isInlineTag )
 import Text.Pandoc.Shared (trim)