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{-
Copyright (C) 2006-7 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.Markdown
Copyright : Copyright (C) 2006-7 John MacFarlane
License : GNU GPL, version 2 or above
Maintainer : John MacFarlane <jgm@berkeley.edu>
Stability : alpha
Portability : portable
Conversion of 'Pandoc' documents to markdown-formatted plain text.
Markdown: <http://daringfireball.net/projects/markdown/>
-}
module Text.Pandoc.Writers.Markdown ( writeMarkdown) where
import Text.Pandoc.Definition
import Text.Pandoc.Shared
import Text.Pandoc.Blocks
import Text.ParserCombinators.Parsec ( parse, GenParser )
import Data.List ( group, isPrefixOf, drop, find, intersperse, intercalate )
import Text.PrettyPrint.HughesPJ hiding ( Str )
import Control.Monad.State
type Notes = [[Block]]
type Refs = KeyTable
type WriterState = (Notes, Refs)
-- | Convert Pandoc to Markdown.
writeMarkdown :: WriterOptions -> Pandoc -> String
writeMarkdown opts document =
render $ evalState (pandocToMarkdown opts document) ([],[])
-- | Return markdown representation of document.
pandocToMarkdown :: WriterOptions -> Pandoc -> State WriterState Doc
pandocToMarkdown opts (Pandoc meta blocks) = do
let before = writerIncludeBefore opts
let after = writerIncludeAfter opts
let header = writerHeader opts
let before' = if null before then empty else text before
let after' = if null after then empty else text after
let header' = if null header then empty else text header
metaBlock <- metaToMarkdown opts meta
let head' = if writerStandalone opts
then metaBlock $+$ header'
else empty
let headerBlocks = filter isHeaderBlock blocks
let toc = if writerTableOfContents opts
then tableOfContents opts headerBlocks
else empty
body <- blockListToMarkdown opts blocks
(notes, _) <- get
notes' <- notesToMarkdown opts (reverse notes)
(_, refs) <- get -- note that the notes may contain refs
refs' <- keyTableToMarkdown opts (reverse refs)
return $ head' $+$ before' $+$ toc $+$ body $+$ text "" $+$
notes' $+$ text "" $+$ refs' $+$ after'
-- | Return markdown representation of reference key table.
keyTableToMarkdown :: WriterOptions -> KeyTable -> State WriterState Doc
keyTableToMarkdown opts refs = mapM (keyToMarkdown opts) refs >>= return . vcat
-- | Return markdown representation of a reference key.
keyToMarkdown :: WriterOptions
-> ([Inline], (String, String))
-> State WriterState Doc
keyToMarkdown opts (label, (src, tit)) = do
label' <- inlineListToMarkdown opts label
let tit' = if null tit then empty else text $ " \"" ++ tit ++ "\""
return $ text " " <> char '[' <> label' <> char ']' <> text ": " <>
text src <> tit'
-- | Return markdown representation of notes.
notesToMarkdown :: WriterOptions -> [[Block]] -> State WriterState Doc
notesToMarkdown opts notes =
mapM (\(num, note) -> noteToMarkdown opts num note) (zip [1..] notes) >>=
return . vcat
-- | Return markdown representation of a note.
noteToMarkdown :: WriterOptions -> Int -> [Block] -> State WriterState Doc
noteToMarkdown opts num blocks = do
contents <- blockListToMarkdown opts blocks
let marker = text "[^" <> text (show num) <> text "]:"
return $ hang' marker (writerTabStop opts) contents
-- | Escape special characters for Markdown.
escapeString :: String -> String
escapeString = escapeStringUsing markdownEscapes
where markdownEscapes = backslashEscapes "`<\\*_^~"
-- | Convert bibliographic information into Markdown header.
metaToMarkdown :: WriterOptions -> Meta -> State WriterState Doc
metaToMarkdown _ (Meta [] [] []) = return empty
metaToMarkdown opts (Meta title authors date) = do
title' <- titleToMarkdown opts title
authors' <- authorsToMarkdown authors
date' <- dateToMarkdown date
return $ title' $+$ authors' $+$ date' $+$ text ""
titleToMarkdown :: WriterOptions -> [Inline] -> State WriterState Doc
titleToMarkdown _ [] = return empty
titleToMarkdown opts lst = do
contents <- inlineListToMarkdown opts lst
return $ text "% " <> contents
authorsToMarkdown :: [String] -> State WriterState Doc
authorsToMarkdown [] = return empty
authorsToMarkdown lst = return $
text "% " <> text (intercalate ", " (map escapeString lst))
dateToMarkdown :: String -> State WriterState Doc
dateToMarkdown [] = return empty
dateToMarkdown str = return $ text "% " <> text (escapeString str)
-- | Construct table of contents from list of header blocks.
tableOfContents :: WriterOptions -> [Block] -> Doc
tableOfContents opts headers =
let opts' = opts { writerIgnoreNotes = True }
contents = BulletList $ map elementToListItem $ hierarchicalize headers
in evalState (blockToMarkdown opts' contents) ([],[])
-- | Converts an Element to a list item for a table of contents,
elementToListItem :: Element -> [Block]
elementToListItem (Blk _) = []
elementToListItem (Sec headerText subsecs) = [Plain headerText] ++
if null subsecs
then []
else [BulletList $ map elementToListItem subsecs]
-- | Ordered list start parser for use in Para below.
olMarker :: GenParser Char st Char
olMarker = do (start, style', delim) <- anyOrderedListMarker
if delim == Period &&
(style' == UpperAlpha || (style' == UpperRoman &&
start `elem` [1, 5, 10, 50, 100, 500, 1000]))
then spaceChar >> spaceChar
else spaceChar
-- | True if string begins with an ordered list marker
beginsWithOrderedListMarker :: String -> Bool
beginsWithOrderedListMarker str =
case parse olMarker "para start" str of
Left _ -> False
Right _ -> True
wrappedMarkdown :: WriterOptions -> [Inline] -> State WriterState Doc
wrappedMarkdown opts inlines = do
let chunks = splitBy LineBreak inlines
let chunks' = if null chunks
then []
else (map (++ [Str " "]) $ init chunks) ++ [last chunks]
lns <- mapM (wrapIfNeeded opts (inlineListToMarkdown opts)) chunks'
return $ vcat lns
-- | Convert Pandoc block element to markdown.
blockToMarkdown :: WriterOptions -- ^ Options
-> Block -- ^ Block element
-> State WriterState Doc
blockToMarkdown _ Null = return empty
blockToMarkdown opts (Plain inlines) =
wrappedMarkdown opts inlines
blockToMarkdown opts (Para inlines) = do
contents <- wrappedMarkdown opts inlines
-- escape if para starts with ordered list marker
let esc = if (not (writerStrictMarkdown opts)) &&
beginsWithOrderedListMarker (render contents)
then char '\\'
else empty
return $ esc <> contents <> text "\n"
blockToMarkdown _ (RawHtml str) = return $ text str
blockToMarkdown _ HorizontalRule = return $ text "\n* * * * *\n"
blockToMarkdown opts (Header level inlines) = do
contents <- inlineListToMarkdown opts inlines
-- use setext style headers if in literate haskell mode.
-- ghc interprets '#' characters in column 1 as line number specifiers.
if writerLiterateHaskell opts
then let len = length $ render contents
in return $ contents <> text "\n" <>
case level of
1 -> text $ replicate len '=' ++ "\n"
2 -> text $ replicate len '-' ++ "\n"
_ -> empty
else return $ text ((replicate level '#') ++ " ") <> contents <> text "\n"
blockToMarkdown opts (CodeBlock (_,classes,_) str) | "haskell" `elem` classes &&
writerLiterateHaskell opts =
return $ (vcat $ map (text "> " <>) $ map text (lines str)) <> text "\n"
blockToMarkdown opts (CodeBlock _ str) = return $
(nest (writerTabStop opts) $ vcat $ map text (lines str)) <> text "\n"
blockToMarkdown opts (BlockQuote blocks) = do
-- if we're writing literate haskell, put a space before the bird tracks
-- so they won't be interpreted as lhs...
let leader = if writerLiterateHaskell opts
then text . (" > " ++)
else text . ("> " ++)
contents <- blockListToMarkdown opts blocks
return $ (vcat $ map leader $ lines $ render contents) <>
text "\n"
blockToMarkdown opts (Table caption aligns widths headers rows) = do
caption' <- inlineListToMarkdown opts caption
let caption'' = if null caption
then empty
else text "" $+$ (text "Table: " <> caption')
headers' <- mapM (blockListToMarkdown opts) headers
let widthsInChars = map (floor . (78 *)) widths
let alignHeader alignment = case alignment of
AlignLeft -> leftAlignBlock
AlignCenter -> centerAlignBlock
AlignRight -> rightAlignBlock
AlignDefault -> leftAlignBlock
let makeRow = hsepBlocks . (zipWith alignHeader aligns) .
(zipWith docToBlock widthsInChars)
let head' = makeRow headers'
rows' <- mapM (\row -> do cols <- mapM (blockListToMarkdown opts) row
return $ makeRow cols) rows
let maxRowHeight = maximum $ map heightOfBlock (head':rows')
let isMultilineTable = maxRowHeight > 1
let underline = hsep $
map (\width -> text $ replicate width '-') widthsInChars
let border = if isMultilineTable
then text $ replicate (sum widthsInChars + (length widthsInChars - 1)) '-'
else empty
let spacer = if isMultilineTable
then text ""
else empty
let body = vcat $ intersperse spacer $ map blockToDoc rows'
return $ (nest 2 $ border $+$ (blockToDoc head') $+$ underline $+$ body $+$
border $+$ caption'') <> text "\n"
blockToMarkdown opts (BulletList items) = do
contents <- mapM (bulletListItemToMarkdown opts) items
return $ (vcat contents) <> text "\n"
blockToMarkdown opts (OrderedList attribs items) = do
let markers = orderedListMarkers attribs
let markers' = map (\m -> if length m < 3
then m ++ replicate (3 - length m) ' '
else m) markers
contents <- mapM (\(item, num) -> orderedListItemToMarkdown opts item num) $
zip markers' items
return $ (vcat contents) <> text "\n"
blockToMarkdown opts (DefinitionList items) = do
contents <- mapM (definitionListItemToMarkdown opts) items
return $ (vcat contents) <> text "\n"
-- | Convert bullet list item (list of blocks) to markdown.
bulletListItemToMarkdown :: WriterOptions -> [Block] -> State WriterState Doc
bulletListItemToMarkdown opts items = do
contents <- blockListToMarkdown opts items
return $ hang' (text "- ") (writerTabStop opts) contents
-- | Convert ordered list item (a list of blocks) to markdown.
orderedListItemToMarkdown :: WriterOptions -- ^ options
-> String -- ^ list item marker
-> [Block] -- ^ list item (list of blocks)
-> State WriterState Doc
orderedListItemToMarkdown opts marker items = do
contents <- blockListToMarkdown opts items
return $ hsep [nest (min (3 - length marker) 0) (text marker),
nest (writerTabStop opts) contents]
-- | Convert definition list item (label, list of blocks) to markdown.
definitionListItemToMarkdown :: WriterOptions
-> ([Inline],[Block])
-> State WriterState Doc
definitionListItemToMarkdown opts (label, items) = do
labelText <- inlineListToMarkdown opts label
let tabStop = writerTabStop opts
let leader = char ':'
contents <- mapM (\item -> blockToMarkdown opts item >>=
(\txt -> return (leader $$ nest tabStop txt)))
items >>= return . vcat
return $ labelText $+$ contents
-- | Convert list of Pandoc block elements to markdown.
blockListToMarkdown :: WriterOptions -- ^ Options
-> [Block] -- ^ List of block elements
-> State WriterState Doc
blockListToMarkdown opts blocks =
mapM (blockToMarkdown opts) blocks >>= return . vcat
-- | Get reference for target; if none exists, create unique one and return.
-- Prefer label if possible; otherwise, generate a unique key.
getReference :: [Inline] -> Target -> State WriterState [Inline]
getReference label (src, tit) = do
(_,refs) <- get
case find ((== (src, tit)) . snd) refs of
Just (ref, _) -> return ref
Nothing -> do
let label' = case find ((== label) . fst) refs of
Just _ -> -- label is used; generate numerical label
case find (\n -> not (any (== [Str (show n)])
(map fst refs))) [1..(10000 :: Integer)] of
Just x -> [Str (show x)]
Nothing -> error "no unique label"
Nothing -> label
modify (\(notes, refs') -> (notes, (label', (src,tit)):refs'))
return label'
-- | Convert list of Pandoc inline elements to markdown.
inlineListToMarkdown :: WriterOptions -> [Inline] -> State WriterState Doc
inlineListToMarkdown opts lst =
mapM (inlineToMarkdown opts) lst >>= return . hcat
-- | Convert Pandoc inline element to markdown.
inlineToMarkdown :: WriterOptions -> Inline -> State WriterState Doc
inlineToMarkdown opts (Emph lst) = do
contents <- inlineListToMarkdown opts lst
return $ char '*' <> contents <> char '*'
inlineToMarkdown opts (Strong lst) = do
contents <- inlineListToMarkdown opts lst
return $ text "**" <> contents <> text "**"
inlineToMarkdown opts (Strikeout lst) = do
contents <- inlineListToMarkdown opts lst
return $ text "~~" <> contents <> text "~~"
inlineToMarkdown opts (Superscript lst) = do
contents <- inlineListToMarkdown opts lst
let contents' = text $ substitute " " "\\ " $ render contents
return $ char '^' <> contents' <> char '^'
inlineToMarkdown opts (Subscript lst) = do
contents <- inlineListToMarkdown opts lst
let contents' = text $ substitute " " "\\ " $ render contents
return $ char '~' <> contents' <> char '~'
inlineToMarkdown opts (SmallCaps lst) = inlineListToMarkdown opts lst
inlineToMarkdown opts (Quoted SingleQuote lst) = do
contents <- inlineListToMarkdown opts lst
return $ char '\'' <> contents <> char '\''
inlineToMarkdown opts (Quoted DoubleQuote lst) = do
contents <- inlineListToMarkdown opts lst
return $ char '"' <> contents <> char '"'
inlineToMarkdown _ EmDash = return $ text "--"
inlineToMarkdown _ EnDash = return $ char '-'
inlineToMarkdown _ Apostrophe = return $ char '\''
inlineToMarkdown _ Ellipses = return $ text "..."
inlineToMarkdown _ (Code str) =
let tickGroups = filter (\s -> '`' `elem` s) $ group str
longest = if null tickGroups
then 0
else maximum $ map length tickGroups
marker = replicate (longest + 1) '`'
spacer = if (longest == 0) then "" else " " in
return $ text (marker ++ spacer ++ str ++ spacer ++ marker)
inlineToMarkdown _ (Str str) = return $ text $ escapeString str
inlineToMarkdown _ (Math InlineMath str) = return $ char '$' <> text str <> char '$'
inlineToMarkdown _ (Math DisplayMath str) = return $ text "$$" <> text str <> text "$$"
inlineToMarkdown _ (TeX str) = return $ text str
inlineToMarkdown _ (HtmlInline str) = return $ text str
inlineToMarkdown _ (LineBreak) = return $ text " \n"
inlineToMarkdown _ Space = return $ char ' '
inlineToMarkdown _ (Cite cits _ ) = do
let format (a,b) xs = text a <>
(if b /= [] then char '@' else empty) <>
text b <>
(if isEmpty xs then empty else text "; ") <>
xs
return $ char '[' <> foldr format empty cits <> char ']'
inlineToMarkdown opts (Link txt (src, tit)) = do
linktext <- inlineListToMarkdown opts txt
let linktitle = if null tit then empty else text $ " \"" ++ tit ++ "\""
let srcSuffix = if isPrefixOf "mailto:" src then drop 7 src else src
let useRefLinks = writerReferenceLinks opts
let useAuto = null tit && txt == [Code srcSuffix]
ref <- if useRefLinks then getReference txt (src, tit) else return []
reftext <- inlineListToMarkdown opts ref
return $ if useAuto
then char '<' <> text srcSuffix <> char '>'
else if useRefLinks
then let first = char '[' <> linktext <> char ']'
second = if txt == ref
then text "[]"
else char '[' <> reftext <> char ']'
in first <> second
else char '[' <> linktext <> char ']' <>
char '(' <> text src <> linktitle <> char ')'
inlineToMarkdown opts (Image alternate (source, tit)) = do
let txt = if (null alternate) || (alternate == [Str ""]) ||
(alternate == [Str source]) -- to prevent autolinks
then [Str "image"]
else alternate
linkPart <- inlineToMarkdown opts (Link txt (source, tit))
return $ char '!' <> linkPart
inlineToMarkdown _ (Note contents) = do
modify (\(notes, refs) -> (contents:notes, refs)) -- add to notes in state
(notes, _) <- get
let ref = show $ (length notes)
return $ text "[^" <> text ref <> char ']'
|