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Diffstat (limited to 'Text/Pandoc/Writers/Markdown.hs')
-rw-r--r-- | Text/Pandoc/Writers/Markdown.hs | 373 |
1 files changed, 373 insertions, 0 deletions
diff --git a/Text/Pandoc/Writers/Markdown.hs b/Text/Pandoc/Writers/Markdown.hs new file mode 100644 index 000000000..4cecaae5d --- /dev/null +++ b/Text/Pandoc/Writers/Markdown.hs @@ -0,0 +1,373 @@ +{- +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 ) +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 before' = if null before then empty else text before + let after' = if null after then empty else text after + metaBlock <- metaToMarkdown opts meta + let head = if writerStandalone opts + then metaBlock $+$ text (writerHeader opts) + 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 = ('\160', " "):(backslashEscapes "`<\\*_^~") + +-- | Convert bibliographic information into Markdown header. +metaToMarkdown :: WriterOptions -> Meta -> State WriterState Doc +metaToMarkdown opts (Meta title authors date) = do + title' <- titleToMarkdown opts title + authors' <- authorsToMarkdown authors + date' <- dateToMarkdown date + return $ title' $+$ authors' $+$ date' + +titleToMarkdown :: WriterOptions -> [Inline] -> State WriterState Doc +titleToMarkdown opts [] = 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 (joinWithSep ", " (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 opts 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 opts (RawHtml str) = return $ text str +blockToMarkdown opts HorizontalRule = return $ text "\n* * * * *\n" +blockToMarkdown opts (Header level inlines) = do + contents <- inlineListToMarkdown opts inlines + return $ text ((replicate level '#') ++ " ") <> contents <> text "\n" +blockToMarkdown opts (CodeBlock str) = return $ + (nest (writerTabStop opts) $ vcat $ map text (lines str)) <> text "\n" +blockToMarkdown opts (BlockQuote blocks) = do + contents <- blockListToMarkdown opts blocks + return $ (vcat $ map (text . ("> " ++)) $ 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 tableWidth = sum widthsInChars + 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 + -- The complexities here are needed to ensure that if the list + -- marker is 4 characters or longer, the second and following + -- lines are indented 4 spaces but the list item begins after the marker. + return $ sep [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] 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 (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 opts EmDash = return $ text "--" +inlineToMarkdown opts EnDash = return $ char '-' +inlineToMarkdown opts Apostrophe = return $ char '\'' +inlineToMarkdown opts Ellipses = return $ text "..." +inlineToMarkdown opts (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 opts (Str str) = return $ text $ escapeString str +inlineToMarkdown opts (TeX str) = return $ text str +inlineToMarkdown opts (HtmlInline str) = return $ text str +inlineToMarkdown opts (LineBreak) = return $ text " \n" +inlineToMarkdown opts Space = return $ 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 opts (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 ']' |