Added --list-* options.

Added `--list-input-formats`, `--list-output-formats`,
`--list-extensions`, `--list-highlight-languages`,
`--list-highlight-styles`.

Removed list of highlighting languages from `--version`
output.

Removed list of input and output formats from default
`--help` output.

Closes #3173.

2 files changed, 91 insertions, 29 deletions

diff --git a/MANUAL.txt b/MANUAL.txt
index 16d562ca0..23aed0d92 100644
--- a/MANUAL.txt
+++ b/MANUAL.txt
@@ -262,7 +262,8 @@ General options
     `markdown-pipe_tables+hard_line_breaks` is pandoc's Markdown
     without pipe tables and with hard line breaks. See [Pandoc's
     Markdown], below, for a list of extensions and
-    their names.
+    their names.  See `--list-input-formats` and `--list-extensions`,
+    below.
 
 `-t` *FORMAT*, `-w` *FORMAT*, `--to=`*FORMAT*, `--write=`*FORMAT*
 
@@ -297,6 +298,7 @@ General options
     below.  Markdown syntax extensions can be individually
     enabled or disabled by appending `+EXTENSION` or
     `-EXTENSION` to the format name, as described above under `-f`.
+    See `--list-output-formats` and `--list-extensions`, below.
 
 `-o` *FILE*, `--output=`*FILE*
 
@@ -338,6 +340,30 @@ General options
 :   Give verbose debugging output.  Currently this only has an effect
     with PDF output.
 
+`--list-input-formats`
+
+:   List supported input formats, one per line.
+
+`--list-output-formats`
+
+:   List supported output formats, one per line.
+
+`--list-extensions`
+
+:   List supported Markdown extensions, one per line, followed
+    by a `+` or `-` indicating whether it is enabled by default
+    in pandoc's Markdown.
+
+`--list-highlight-languages`
+
+:   List supported languages for syntax highlighting, one per
+    line.
+
+`--list-highlight-styles`
+
+:   List supported styles for syntax highlighting, one per line.
+    See `--highlight-style`.
+
 `-v`, `--version`
 
 :   Print version.
@@ -583,6 +609,7 @@ General writer options
     Options are `pygments` (the default), `kate`, `monochrome`,
     `espresso`, `zenburn`, `haddock`, and `tango`.  For more information
     on syntax highlighting in pandoc, see [Syntax highlighting], below.
+    See also `--list-highlight-styles`.
 
 `-H` *FILE*, `--include-in-header=`*FILE*
 
diff --git a/pandoc.hs b/pandoc.hs
index 86ca9502f..4f87947e7 100644
--- a/pandoc.hs
+++ b/pandoc.hs
@@ -48,8 +48,9 @@ import System.Environment ( getArgs, getProgName )
 import System.Exit ( ExitCode (..), exitSuccess )
 import System.FilePath
 import System.Console.GetOpt
+import qualified Data.Set as Set
 import Data.Char ( toLower, toUpper )
-import Data.List ( delete, intercalate, isPrefixOf, isSuffixOf, sort )
+import Data.List ( intercalate, isPrefixOf, isSuffixOf, sort )
 import System.Directory ( getAppUserDataDirectory, findExecutable,
                           doesFileExist, Permissions(..), getPermissions )
 import System.IO ( stdout, stderr )
@@ -88,10 +89,7 @@ copyrightMessage = intercalate "\n" [
 compileInfo :: String
 compileInfo =
   "\nCompiled with texmath " ++
-  VERSION_texmath ++ ", highlighting-kate " ++ VERSION_highlighting_kate ++
-   ".\nSyntax highlighting is supported for the following languages:\n    " ++
-       wrapWords 4 78
-       [map toLower l | l <- languages, l /= "Alert" && l /= "Alert_indent"]
+  VERSION_texmath ++ ", highlighting-kate " ++ VERSION_highlighting_kate
 
 -- | Converts a list of strings into a single string with the items printed as
 -- comma separated words in lines with a maximum line length.
@@ -158,6 +156,16 @@ externalFilter f args' d = do
        filterException e = err 83 $ "Error running filter " ++ f ++ "\n" ++
                                        show e
 
+highlightingStyles :: [(String, Style)]
+highlightingStyles =
+  [("pygments", pygments),
+   ("tango", tango),
+   ("espresso", espresso),
+   ("zenburn", zenburn),
+   ("kate", kate),
+   ("monochrome", monochrome),
+   ("haddock", haddock)]
+
 -- | Data structure for command line options.
 data Opt = Opt
     { optTabStop           :: Int     -- ^ Number of spaces per tab
@@ -517,17 +525,9 @@ options =
     , Option "" ["highlight-style"]
                 (ReqArg
                  (\arg opt -> do
-                   newStyle <- case map toLower arg of
-                                     "pygments"   -> return pygments
-                                     "tango"      -> return tango
-                                     "espresso"   -> return espresso
-                                     "zenburn"    -> return zenburn
-                                     "kate"       -> return kate
-                                     "monochrome" -> return monochrome
-                                     "haddock"    -> return haddock
-                                     _            -> err 39 $
-                                         "Unknown style :" ++ arg
-                   return opt{ optHighlightStyle = newStyle })
+                   case lookup (map toLower arg) highlightingStyles of
+                         Just s -> return opt{ optHighlightStyle = s }
+                         Nothing -> err 39 $ "Unknown style: " ++ arg)
                  "STYLE")
                  "" -- "Style for highlighted code"
 
@@ -918,11 +918,56 @@ options =
                      let allopts = unwords (concatMap optnames options)
                      UTF8.hPutStrLn stdout $ printf tpl allopts
                          (unwords (map fst readers))
-                         (unwords ("pdf": map fst writers))
+                         (unwords (map fst writers))
                          ddir
                      exitSuccess ))
                  "" -- "Print bash completion script"
 
+    , Option "" ["list-input-formats"]
+                 (NoArg
+                  (\_ -> do
+                     let readers'names = sort (map fst readers)
+                     mapM_ (UTF8.hPutStrLn stdout) readers'names
+                     exitSuccess ))
+                 ""
+
+    , Option "" ["list-output-formats"]
+                 (NoArg
+                  (\_ -> do
+                     let writers'names = sort (map fst writers)
+                     mapM_ (UTF8.hPutStrLn stdout) writers'names
+                     exitSuccess ))
+                 ""
+
+    , Option "" ["list-extensions"]
+                 (NoArg
+                  (\_ -> do
+                     let showExt x = drop 4 (show x) ++
+                                       if x `Set.member` pandocExtensions
+                                          then " +"
+                                          else " -"
+                     mapM_ (UTF8.hPutStrLn stdout . showExt)
+                               ([minBound..maxBound] :: [Extension])
+                     exitSuccess ))
+                 ""
+
+    , Option "" ["list-highlight-languages"]
+                 (NoArg
+                  (\_ -> do
+                     let langs = [map toLower l | l <- languages,
+                                   l /= "Alert" && l /= "Alert_indent"]
+                     mapM_ (UTF8.hPutStrLn stdout) langs
+                     exitSuccess ))
+                 ""
+
+    , Option "" ["list-highlight-styles"]
+                 (NoArg
+                  (\_ -> do
+                     mapM_ (UTF8.hPutStrLn stdout) $
+                           map fst highlightingStyles
+                     exitSuccess ))
+                 ""
+
     , Option "v" ["version"]
                  (NoArg
                   (\_ -> do
@@ -961,17 +1006,7 @@ readMetaValue s = case decode (UTF8.fromString s) of
 
 -- Returns usage message
 usageMessage :: String -> [OptDescr (Opt -> IO Opt)] -> String
-usageMessage programName = usageInfo
-  (programName ++ " [OPTIONS] [FILES]" ++ "\nInput formats:  " ++
-  wrapWords 16 78 readers'names ++
-     '\n' : replicate 16 ' ' ++
-     "[* only Pandoc's JSON version of native AST]" ++ "\nOutput formats: " ++
-  wrapWords 16 78 writers'names ++
-     '\n' : replicate 16 ' ' ++
-     "[** for pdf output, use latex or beamer and -o FILENAME.pdf]\nOptions:")
-  where
-    writers'names = sort $ "json*" : "pdf**" : delete "json" (map fst writers)
-    readers'names = sort $ "json*" : delete "json" (map fst readers)
+usageMessage programName = usageInfo (programName ++ " [OPTIONS] [FILES]")
 
 -- Determine default reader based on source file extensions
 defaultReaderName :: String -> [FilePath] -> String