pandoc/src/Text/Pandoc/Writers/LaTeX.hs

{-
Copyright (C) 2006-2010 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.Writers.LaTeX
   Copyright   : Copyright (C) 2006-2010 John MacFarlane
   License     : GNU GPL, version 2 or above 

   Maintainer  : John MacFarlane <jgm@berkeley.edu>
   Stability   : alpha 
   Portability : portable

Conversion of 'Pandoc' format into LaTeX.
-}
module Text.Pandoc.Writers.LaTeX ( writeLaTeX ) where
import Text.Pandoc.Definition
import Text.Pandoc.Shared
import Text.Pandoc.Templates
import Text.Printf ( printf )
import Data.List ( (\\), isSuffixOf, isPrefixOf, intersperse )
import Data.Char ( toLower )
import Control.Monad.State
import Text.PrettyPrint.HughesPJ hiding ( Str )

data WriterState = 
  WriterState { stInNote     :: Bool          -- @True@ if we're in a note
              , stOLLevel    :: Int           -- level of ordered list nesting
              , stOptions    :: WriterOptions -- writer options, so they don't have to be parameter 
              , stVerbInNote :: Bool          -- true if document has verbatim text in note
              , stEnumerate  :: Bool          -- true if document needs fancy enumerated lists
              , stTable      :: Bool          -- true if document has a table
              , stStrikeout  :: Bool          -- true if document has strikeout
              , stSubscript  :: Bool          -- true if document has subscript
              , stUrl        :: Bool          -- true if document has visible URL link
              , stGraphics   :: Bool          -- true if document contains images
              , stLHS        :: Bool          -- true if document has literate haskell code
              , stBook       :: Bool          -- true if document uses book or memoir class
              }

-- | Convert Pandoc to LaTeX.
writeLaTeX :: WriterOptions -> Pandoc -> String
writeLaTeX options document = 
  evalState (pandocToLaTeX options document) $ 
  WriterState { stInNote = False, stOLLevel = 1, stOptions = options,
                stVerbInNote = False, stEnumerate = False,
                stTable = False, stStrikeout = False, stSubscript = False,
                stUrl = False, stGraphics = False,
                stLHS = False, stBook = False } 

pandocToLaTeX :: WriterOptions -> Pandoc -> State WriterState String
pandocToLaTeX options (Pandoc (Meta title authors date) blocks) = do
  let template = writerTemplate options
  let usesBookClass x = "\\documentclass" `isPrefixOf` x &&
         ("{memoir}" `isSuffixOf` x || "{book}" `isSuffixOf` x ||
          "{report}" `isSuffixOf` x)
  when (any usesBookClass (lines template)) $
    modify $ \s -> s{stBook = True}
  titletext <- liftM render $ inlineListToLaTeX title
  authorsText <- mapM (liftM render . inlineListToLaTeX) authors
  dateText <- liftM render $ inlineListToLaTeX date
  body <- blockListToLaTeX blocks
  let main = render body
  st <- get
  let context  = writerVariables options ++
                 [ ("toc", if writerTableOfContents options then "yes" else "")
                 , ("body", main)
                 , ("title", titletext)
                 , ("date", dateText) ] ++
                 [ ("author", a) | a <- authorsText ] ++
                 [ ("xetex", "yes") | writerXeTeX options ] ++
                 [ ("verbatim-in-note", "yes") | stVerbInNote st ] ++
                 [ ("fancy-enums", "yes") | stEnumerate st ] ++
                 [ ("tables", "yes") | stTable st ] ++
                 [ ("strikeout", "yes") | stStrikeout st ] ++
                 [ ("subscript", "yes") | stSubscript st ] ++
                 [ ("url", "yes") | stUrl st ] ++
                 [ ("numbersections", "yes") | writerNumberSections options ] ++
                 [ ("lhs", "yes") | stLHS st ] ++
                 [ ("graphics", "yes") | stGraphics st ]
  return $ if writerStandalone options
              then renderTemplate context template
              else main

-- escape things as needed for LaTeX

stringToLaTeX :: String -> String
stringToLaTeX = escapeStringUsing latexEscapes
  where latexEscapes = backslashEscapes "{}$%&_#" ++ 
                       [ ('^', "\\^{}")
                       , ('\\', "\\textbackslash{}")
                       , ('~', "\\ensuremath{\\sim}")
                       , ('|', "\\textbar{}")
                       , ('<', "\\textless{}")
                       , ('>', "\\textgreater{}")
                       , ('[', "{[}")  -- to avoid interpretation as
                       , (']', "{]}")  -- optional arguments
                       , ('\160', "~")
                       , ('\x2018', "`")
                       , ('\x2019', "'")
                       , ('\x201C', "``")
                       , ('\x201D', "''")
                       ]

-- | Puts contents into LaTeX command.
inCmd :: String -> Doc -> Doc
inCmd cmd contents = char '\\' <> text cmd <> braces contents

-- | Remove all code elements from list of inline elements
-- (because it's illegal to have verbatim inside some command arguments)
deVerb :: [Inline] -> [Inline]
deVerb [] = []
deVerb ((Code str):rest) = 
  (TeX $ "\\texttt{" ++ stringToLaTeX str ++ "}"):(deVerb rest)
deVerb (other:rest) = other:(deVerb rest)

-- | Convert Pandoc block element to LaTeX.
blockToLaTeX :: Block     -- ^ Block to convert
             -> State WriterState Doc
blockToLaTeX Null = return empty
blockToLaTeX (Plain lst) = do
  st <- get
  let opts = stOptions st
  wrapTeXIfNeeded opts True inlineListToLaTeX lst
blockToLaTeX (Para [Image txt (src,tit)]) = do
  capt <- inlineListToLaTeX txt
  img <- inlineToLaTeX (Image txt (src,tit))
  return $ text "\\begin{figure}[htb]" $$ text "\\centering" $$ img $$
           (text "\\caption{" <> capt <> char '}') $$ text "\\end{figure}\n"
blockToLaTeX (Para lst) = do
  st <- get
  let opts = stOptions st
  result <- wrapTeXIfNeeded opts True inlineListToLaTeX lst
  return $ result <> char '\n'
blockToLaTeX (BlockQuote lst) = do
  contents <- blockListToLaTeX lst
  return $ text "\\begin{quote}" $$ contents $$ text "\\end{quote}"
blockToLaTeX (CodeBlock (_,classes,_) str) = do
  st <- get
  env <- if writerLiterateHaskell (stOptions st) && "haskell" `elem` classes &&
                    "literate" `elem` classes
            then do
              modify $ \s -> s{ stLHS = True }
              return "code"
            else if stInNote st
                    then do
                      modify $ \s -> s{ stVerbInNote = True }
                      return "Verbatim"
                    else return "verbatim"
  return $ text ("\\begin{" ++ env ++ "}\n") <> text str <> 
           text ("\n\\end{" ++ env ++ "}")
blockToLaTeX (RawHtml _) = return empty
blockToLaTeX (BulletList lst) = do
  items <- mapM listItemToLaTeX lst
  return $ text "\\begin{itemize}" $$ vcat items $$ text "\\end{itemize}"
blockToLaTeX (OrderedList (start, numstyle, numdelim) lst) = do
  st <- get
  let oldlevel = stOLLevel st
  put $ st {stOLLevel = oldlevel + 1}
  items <- mapM listItemToLaTeX lst
  modify (\s -> s {stOLLevel = oldlevel})
  exemplar <- if numstyle /= DefaultStyle || numdelim /= DefaultDelim
                 then do
                   modify $ \s -> s{ stEnumerate = True }
                   return $ char '[' <> 
                       text (head (orderedListMarkers (1, numstyle,
                            numdelim))) <> char ']'
                 else return empty
  let resetcounter = if start /= 1 && oldlevel <= 4
                        then text $ "\\setcounter{enum" ++ 
                             map toLower (toRomanNumeral oldlevel) ++
                             "}{" ++ show (start - 1) ++ "}"
                        else empty 
  return $ text "\\begin{enumerate}" <> exemplar $$ resetcounter $$
           vcat items $$ text "\\end{enumerate}"
blockToLaTeX (DefinitionList lst) = do
  items <- mapM defListItemToLaTeX lst
  return $ text "\\begin{description}" $$ vcat items $$
           text "\\end{description}"
blockToLaTeX HorizontalRule = return $ text $
    "\\begin{center}\\rule{3in}{0.4pt}\\end{center}\n"
blockToLaTeX (Header level lst) = do
  let lst' = deVerb lst
  txt <- inlineListToLaTeX lst'
  let noNote (Note _) = Str ""
      noNote x        = x
  let lstNoNotes = processWith noNote lst'
  -- footnotes in sections don't work unless you specify an optional
  -- argument:  \section[mysec]{mysec\footnote{blah}}
  optional <- if lstNoNotes == lst'
                 then return empty
                 else do
                   res <- inlineListToLaTeX lstNoNotes
                   return $ char '[' <> res <> char ']'
  let stuffing = optional <> char '{' <> txt <> char '}'
  book <- liftM stBook get
  return $ case (book, level) of
                (True, 1)    -> text "\\chapter" <> stuffing <> char '\n'
                (True, 2)    -> text "\\section" <> stuffing <> char '\n'
                (True, 3)    -> text "\\subsection" <> stuffing <> char '\n'
                (True, 4)    -> text "\\subsubsection" <> stuffing <> char '\n'
                (False, 1)   -> text "\\section" <> stuffing <> char '\n'
                (False, 2)   -> text "\\subsection" <> stuffing <> char '\n'
                (False, 3)   -> text "\\subsubsection" <> stuffing <> char '\n'
                _            -> txt <> char '\n' 
blockToLaTeX (Table caption aligns widths heads rows) = do
  headers <- if all null heads
                then return empty
                else liftM ($$ text "\\hline") $ tableRowToLaTeX heads
  captionText <- inlineListToLaTeX caption
  rows' <- mapM tableRowToLaTeX rows
  let colDescriptors = concat $ zipWith toColDescriptor widths aligns
  let tableBody = text ("\\begin{tabular}{" ++ colDescriptors ++ "}") $$
                  headers $$ vcat rows' $$ text "\\end{tabular}" 
  let centered txt = text "\\begin{center}" $$ txt $$ text "\\end{center}"
  modify $ \s -> s{ stTable = True }
  return $ if isEmpty captionText
              then centered tableBody <> char '\n'
              else text "\\begin{table}[h]" $$ centered tableBody $$ 
                   inCmd "caption" captionText $$ text "\\end{table}\n" 

toColDescriptor :: Double -> Alignment -> String
toColDescriptor 0 align =
  case align of
         AlignLeft    -> "l"
         AlignRight   -> "r"
         AlignCenter  -> "c"
         AlignDefault -> "l"
toColDescriptor width align = ">{\\PBS" ++
  (case align of
         AlignLeft -> "\\raggedright"
         AlignRight -> "\\raggedleft"
         AlignCenter -> "\\centering"
         AlignDefault -> "\\raggedright") ++
  "\\hspace{0pt}}p{" ++ printf "%.2f" width ++
  "\\columnwidth}"

blockListToLaTeX :: [Block] -> State WriterState Doc
blockListToLaTeX lst = mapM blockToLaTeX lst >>= return . vcat

tableRowToLaTeX :: [[Block]] -> State WriterState Doc
tableRowToLaTeX cols = mapM blockListToLaTeX cols >>= 
  return . ($$ text "\\\\") . foldl (\row item -> row $$
  (if isEmpty row then text "" else text " & ") <> item) empty

listItemToLaTeX :: [Block] -> State WriterState Doc
listItemToLaTeX lst = blockListToLaTeX lst >>= return .  (text "\\item" $$) .
                      (nest 2)

defListItemToLaTeX :: ([Inline], [[Block]]) -> State WriterState Doc
defListItemToLaTeX (term, defs) = do
    term' <- inlineListToLaTeX $ deVerb term
    def'  <- liftM (vcat . intersperse (text "")) $ mapM blockListToLaTeX defs
    return $ text "\\item[" <> term' <> text "]" $$ def'

-- | Convert list of inline elements to LaTeX.
inlineListToLaTeX :: [Inline]  -- ^ Inlines to convert
                  -> State WriterState Doc
inlineListToLaTeX lst = mapM inlineToLaTeX lst >>= return . hcat

isQuoted :: Inline -> Bool
isQuoted (Quoted _ _) = True
isQuoted Apostrophe = True
isQuoted _ = False

-- | Convert inline element to LaTeX
inlineToLaTeX :: Inline    -- ^ Inline to convert
              -> State WriterState Doc
inlineToLaTeX (Emph lst) =
  inlineListToLaTeX (deVerb lst) >>= return . inCmd "emph"
inlineToLaTeX (Strong lst) = 
  inlineListToLaTeX (deVerb lst) >>= return . inCmd "textbf" 
inlineToLaTeX (Strikeout lst) = do
  contents <- inlineListToLaTeX $ deVerb lst
  modify $ \s -> s{ stStrikeout = True }
  return $ inCmd "sout" contents
inlineToLaTeX (Superscript lst) =
  inlineListToLaTeX (deVerb lst) >>= return . inCmd "textsuperscript"
inlineToLaTeX (Subscript lst) = do
  modify $ \s -> s{ stSubscript = True }
  contents <- inlineListToLaTeX $ deVerb lst
  -- oddly, latex includes \textsuperscript but not \textsubscript
  -- so we have to define it (using a different name so as not to conflict with memoir class):
  return $ inCmd "textsubscr" contents
inlineToLaTeX (SmallCaps lst) =
  inlineListToLaTeX (deVerb lst) >>= return . inCmd "textsc"
inlineToLaTeX (Cite _ lst) =
  inlineListToLaTeX lst
inlineToLaTeX (Code str) = do
  st <- get
  when (stInNote st) $ modify $ \s -> s{ stVerbInNote = True }
  let chr = ((enumFromTo '!' '~') \\ str) !! 0
  return $ text $ "\\verb" ++ [chr] ++ str ++ [chr]
inlineToLaTeX (Quoted SingleQuote lst) = do
  contents <- inlineListToLaTeX lst
  let s1 = if (not (null lst)) && (isQuoted (head lst))
              then text "\\,"
              else empty 
  let s2 = if (not (null lst)) && (isQuoted (last lst))
              then text "\\,"
              else empty
  return $ char '`' <> s1 <> contents <> s2 <> char '\''
inlineToLaTeX (Quoted DoubleQuote lst) = do
  contents <- inlineListToLaTeX lst
  let s1 = if (not (null lst)) && (isQuoted (head lst))
              then text "\\,"
              else empty 
  let s2 = if (not (null lst)) && (isQuoted (last lst))
              then text "\\,"
              else empty
  return $ text "``" <> s1 <> contents <> s2 <> text "''"
inlineToLaTeX Apostrophe = return $ char '\''
inlineToLaTeX EmDash = return $ text "---"
inlineToLaTeX EnDash = return $ text "--"
inlineToLaTeX Ellipses = return $ text "\\ldots{}"
inlineToLaTeX (Str str) = return $ text $ stringToLaTeX str
inlineToLaTeX (Math InlineMath str) = return $ char '$' <> text str <> char '$'
inlineToLaTeX (Math DisplayMath str) = return $ text "\\[" <> text str <> text "\\]"
inlineToLaTeX (TeX str) = return $ text str
inlineToLaTeX (HtmlInline _) = return empty
inlineToLaTeX (LineBreak) = return $ text "\\\\" 
inlineToLaTeX Space = return $ char ' '
inlineToLaTeX (Link txt (src, _)) =
  case txt of
        [Code x] | x == src ->  -- autolink
             do modify $ \s -> s{ stUrl = True }
                return $ text $ "\\url{" ++ x ++ "}"
        _ -> do contents <- inlineListToLaTeX $ deVerb txt
                return $ text ("\\href{" ++ src ++ "}{") <> contents <> 
                         char '}'
inlineToLaTeX (Image _ (source, _)) = do
  modify $ \s -> s{ stGraphics = True }
  return $ text $ "\\includegraphics{" ++ source ++ "}"
inlineToLaTeX (Note contents) = do
  st <- get
  put (st {stInNote = True})
  contents' <- blockListToLaTeX contents
  modify (\s -> s {stInNote = False})
  let rawnote = stripTrailingNewlines $ render contents'
  -- note: a \n before } is needed when note ends with a Verbatim environment
  let optNewline = "\\end{Verbatim}" `isSuffixOf` rawnote
  return $ text "\\footnote{" <> 
           text rawnote <> (if optNewline then char '\n' else empty) <> char '}'