{- Copyright (C) 2006-7 John MacFarlane 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.Readers.HTML Copyright : Copyright (C) 2006-7 John MacFarlane License : GNU GPL, version 2 or above Maintainer : John MacFarlane Stability : alpha Portability : portable Conversion of HTML to 'Pandoc' document. -} module Text.Pandoc.Readers.HTML ( readHtml, rawHtmlInline, rawHtmlBlock, anyHtmlBlockTag, anyHtmlInlineTag, anyHtmlTag, anyHtmlEndTag, htmlEndTag, extractTagType, htmlBlockElement ) where import Text.ParserCombinators.Parsec import Text.Pandoc.Definition import Text.Pandoc.Shared import Text.Pandoc.CharacterReferences ( characterReference, decodeCharacterReferences ) import Data.Maybe ( fromMaybe ) import Data.List ( takeWhile, dropWhile, isPrefixOf, isSuffixOf ) import Data.Char ( toUpper, toLower, isAlphaNum ) -- | Convert HTML-formatted string to 'Pandoc' document. readHtml :: ParserState -- ^ Parser state -> String -- ^ String to parse -> Pandoc readHtml = readWith parseHtml -- -- Constants -- eitherBlockOrInline = ["applet", "button", "del", "iframe", "ins", "map", "area", "object", "script"] inlineHtmlTags = ["a", "abbr", "acronym", "b", "basefont", "bdo", "big", "br", "cite", "code", "dfn", "em", "font", "i", "img", "input", "kbd", "label", "q", "s", "samp", "select", "small", "span", "strike", "strong", "sub", "sup", "textarea", "tt", "u", "var"] ++ eitherBlockOrInline blockHtmlTags = ["address", "blockquote", "center", "dir", "div", "dl", "fieldset", "form", "h1", "h2", "h3", "h4", "h5", "h6", "hr", "isindex", "menu", "noframes", "noscript", "ol", "p", "pre", "table", "ul", "dd", "dt", "frameset", "li", "tbody", "td", "tfoot", "th", "thead", "tr"] ++ eitherBlockOrInline -- -- HTML utility functions -- -- | Read blocks until end tag. blocksTilEnd tag = do blocks <- manyTill (block >>~ spaces) (htmlEndTag tag) return $ filter (/= Null) blocks -- | Read inlines until end tag. inlinesTilEnd tag = manyTill inline (htmlEndTag tag) -- | Parse blocks between open and close tag. blocksIn tag = try $ htmlTag tag >> spaces >> blocksTilEnd tag -- | Parse inlines between open and close tag. inlinesIn tag = try $ htmlTag tag >> spaces >> inlinesTilEnd tag -- | Extract type from a tag: e.g. @br@ from @\@ extractTagType :: String -> String extractTagType ('<':rest) = let isSpaceOrSlash c = c `elem` "/ \n\t" in map toLower $ takeWhile isAlphaNum $ dropWhile isSpaceOrSlash rest extractTagType _ = "" -- | Parse any HTML tag (opening or self-closing) and return text of tag anyHtmlTag = try $ do char '<' spaces tag <- many1 alphaNum attribs <- many htmlAttribute spaces ender <- option "" (string "/") let ender' = if null ender then "" else " /" spaces char '>' return $ "<" ++ tag ++ concatMap (\(_, _, raw) -> (' ':raw)) attribs ++ ender' ++ ">" anyHtmlEndTag = try $ do char '<' spaces char '/' spaces tagType <- many1 alphaNum spaces char '>' return $ "" htmlTag :: String -> GenParser Char st (String, [(String, String)]) htmlTag tag = try $ do char '<' spaces stringAnyCase tag attribs <- many htmlAttribute spaces optional (string "/") spaces char '>' return (tag, (map (\(name, content, raw) -> (name, content)) attribs)) -- parses a quoted html attribute value quoted quoteChar = do result <- between (char quoteChar) (char quoteChar) (many (noneOf [quoteChar])) return (result, [quoteChar]) htmlAttribute = htmlRegularAttribute <|> htmlMinimizedAttribute -- minimized boolean attribute htmlMinimizedAttribute = try $ do many1 space name <- many1 (choice [letter, oneOf ".-_:"]) return (name, name, name) htmlRegularAttribute = try $ do many1 space name <- many1 (choice [letter, oneOf ".-_:"]) spaces char '=' spaces (content, quoteStr) <- choice [ (quoted '\''), (quoted '"'), (do a <- many (alphaNum <|> (oneOf "-._:")) return (a,"")) ] return (name, content, (name ++ "=" ++ quoteStr ++ content ++ quoteStr)) -- | Parse an end tag of type 'tag' htmlEndTag tag = try $ do char '<' spaces char '/' spaces stringAnyCase tag spaces char '>' return $ "" -- | Returns @True@ if the tag is (or can be) an inline tag. isInline tag = (extractTagType tag) `elem` inlineHtmlTags -- | Returns @True@ if the tag is (or can be) a block tag. isBlock tag = (extractTagType tag) `elem` blockHtmlTags anyHtmlBlockTag = try $ do tag <- anyHtmlTag <|> anyHtmlEndTag if isBlock tag then return tag else fail "not a block tag" anyHtmlInlineTag = try $ do tag <- anyHtmlTag <|> anyHtmlEndTag if isInline tag then return tag else fail "not an inline tag" -- | Parses material between script tags. -- Scripts must be treated differently, because they can contain '<>' etc. htmlScript = try $ do open <- string "" -- | Parses material between style tags. -- Style tags must be treated differently, because they can contain CSS htmlStyle = try $ do open <- string "" htmlBlockElement = choice [ htmlScript, htmlStyle, htmlComment, xmlDec, definition ] rawHtmlBlock = try $ do body <- htmlBlockElement <|> anyHtmlTag <|> anyHtmlEndTag sp <- many space state <- getState if stateParseRaw state then return (RawHtml (body ++ sp)) else return Null -- We don't want to parse or as raw HTML, since these -- are handled in parseHtml. rawHtmlBlock' = do notFollowedBy' (htmlTag "/body" <|> htmlTag "/html") rawHtmlBlock -- | Parses an HTML comment. htmlComment = try $ do string "")) return $ "" -- -- parsing documents -- xmlDec = try $ do string "') return $ "" definition = try $ do string "') return $ "" nonTitleNonHead = try $ notFollowedBy' (htmlTag "title" <|> htmlTag "/head") >> ((rawHtmlBlock >> return ' ') <|> anyChar) parseTitle = try $ do (tag, _) <- htmlTag "title" contents <- inlinesTilEnd tag spaces return contents -- parse header and return meta-information (for now, just title) parseHead = try $ do htmlTag "head" spaces skipMany nonTitleNonHead contents <- option [] parseTitle skipMany nonTitleNonHead htmlTag "/head" return (contents, [], "") skipHtmlTag tag = optional (htmlTag tag) -- h1 class="title" representation of title in body bodyTitle = try $ do (tag, attribs) <- htmlTag "h1" cl <- case (extractAttribute "class" attribs) of Just "title" -> return "" otherwise -> fail "not title" inlinesTilEnd "h1" parseHtml = do sepEndBy (choice [xmlDec, definition, htmlComment]) spaces skipHtmlTag "html" spaces (title, authors, date) <- option ([], [], "") parseHead spaces skipHtmlTag "body" spaces optional bodyTitle -- skip title in body, because it's represented in meta blocks <- parseBlocks spaces optional (htmlEndTag "body") spaces optional (htmlEndTag "html" >> many anyChar) -- ignore anything after eof return $ Pandoc (Meta title authors date) blocks -- -- parsing blocks -- parseBlocks = spaces >> sepEndBy block spaces >>= (return . filter (/= Null)) block = choice [ codeBlock , header , hrule , list , blockQuote , para , plain , rawHtmlBlock' ] "block" -- -- header blocks -- header = choice (map headerLevel (enumFromTo 1 5)) "header" headerLevel n = try $ do let level = "h" ++ show n (tag, attribs) <- htmlTag level contents <- inlinesTilEnd level return $ Header n (normalizeSpaces contents) -- -- hrule block -- hrule = try $ do (tag, attribs) <- htmlTag "hr" state <- getState if not (null attribs) && stateParseRaw state then unexpected "attributes in hr" -- parse as raw in this case else return HorizontalRule -- -- code blocks -- -- Note: HTML tags in code blocks (e.g. for syntax highlighting) are -- skipped, because they are not portable to output formats other than HTML. codeBlock = try $ do htmlTag "pre" result <- manyTill (many1 (satisfy (/= '<')) <|> ((anyHtmlTag <|> anyHtmlEndTag) >> return "")) (htmlEndTag "pre") let result' = concat result -- drop leading newline if any let result'' = if "\n" `isPrefixOf` result' then drop 1 result' else result' -- drop trailing newline if any let result''' = if "\n" `isSuffixOf` result'' then init result'' else result'' return $ CodeBlock $ decodeCharacterReferences result''' -- -- block quotes -- blockQuote = try $ htmlTag "blockquote" >> spaces >> blocksTilEnd "blockquote" >>= (return . BlockQuote) -- -- list blocks -- list = choice [ bulletList, orderedList, definitionList ] "list" orderedList = try $ do (_, attribs) <- htmlTag "ol" (start, style) <- option (1, DefaultStyle) $ do failIfStrict let sta = fromMaybe "1" $ lookup "start" attribs let sty = fromMaybe (fromMaybe "" $ lookup "style" attribs) $ lookup "class" attribs let sty' = case sty of "lower-roman" -> LowerRoman "upper-roman" -> UpperRoman "lower-alpha" -> LowerAlpha "upper-alpha" -> UpperAlpha "decimal" -> Decimal _ -> DefaultStyle return (read sta, sty') spaces items <- sepEndBy1 (blocksIn "li") spaces htmlEndTag "ol" return $ OrderedList (start, style, DefaultDelim) items bulletList = try $ do htmlTag "ul" spaces items <- sepEndBy1 (blocksIn "li") spaces htmlEndTag "ul" return $ BulletList items definitionList = try $ do failIfStrict -- def lists not part of standard markdown tag <- htmlTag "dl" spaces items <- sepEndBy1 definitionListItem spaces htmlEndTag "dl" return $ DefinitionList items definitionListItem = try $ do terms <- sepEndBy1 (inlinesIn "dt") spaces defs <- sepEndBy1 (blocksIn "dd") spaces let term = joinWithSep [LineBreak] terms return (term, concat defs) -- -- paragraph block -- para = try $ htmlTag "p" >> inlinesTilEnd "p" >>= return . Para . normalizeSpaces -- -- plain block -- plain = many1 inline >>= return . Plain . normalizeSpaces -- -- inline -- inline = choice [ charRef , strong , emph , superscript , subscript , strikeout , spanStrikeout , code , str , linebreak , whitespace , link , image , rawHtmlInline ] "inline" code = try $ do htmlTag "code" result <- manyTill anyChar (htmlEndTag "code") -- remove internal line breaks, leading and trailing space, -- and decode character references return $ Code $ decodeCharacterReferences $ removeLeadingTrailingSpace $ joinWithSep " " $ lines result rawHtmlInline = do result <- htmlScript <|> htmlStyle <|> htmlComment <|> anyHtmlInlineTag state <- getState if stateParseRaw state then return (HtmlInline result) else return (Str "") betweenTags tag = try $ htmlTag tag >> inlinesTilEnd tag >>= return . normalizeSpaces emph = (betweenTags "em" <|> betweenTags "i") >>= return . Emph strong = (betweenTags "b" <|> betweenTags "strong") >>= return . Strong superscript = failIfStrict >> betweenTags "sup" >>= return . Superscript subscript = failIfStrict >> betweenTags "sub" >>= return . Subscript strikeout = failIfStrict >> (betweenTags "s" <|> betweenTags "strike") >>= return . Strikeout spanStrikeout = try $ do failIfStrict -- strict markdown has no strikeout, so treat as raw HTML (tag, attributes) <- htmlTag "span" result <- case (extractAttribute "class" attributes) of Just "strikeout" -> inlinesTilEnd "span" _ -> fail "not a strikeout" return $ Strikeout result whitespace = many1 space >> return Space -- hard line break linebreak = htmlTag "br" >> optional newline >> return LineBreak str = many1 (noneOf "<& \t\n") >>= return . Str -- -- links and images -- -- extract contents of attribute (attribute names are case-insensitive) extractAttribute name [] = Nothing extractAttribute name ((attrName, contents):rest) = let name' = map toLower name attrName' = map toLower attrName in if attrName' == name' then Just (decodeCharacterReferences contents) else extractAttribute name rest link = try $ do (tag, attributes) <- htmlTag "a" url <- case (extractAttribute "href" attributes) of Just url -> return url Nothing -> fail "no href" let title = fromMaybe "" $ extractAttribute "title" attributes label <- inlinesTilEnd "a" return $ Link (normalizeSpaces label) (url, title) image = try $ do (tag, attributes) <- htmlTag "img" url <- case (extractAttribute "src" attributes) of Just url -> return url Nothing -> fail "no src" let title = fromMaybe "" $ extractAttribute "title" attributes let alt = fromMaybe "" (extractAttribute "alt" attributes) return $ Image [Str alt] (url, title)