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|
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedStrings #-}
{- |
Module : Text.Pandoc.Readers.HTML.Parsing
Copyright : Copyright (C) 2006-2021 John MacFarlane
License : GNU GPL, version 2 or above
Maintainer : John MacFarlane <jgm@berkeley.edu>
Stability : alpha
Portability : portable
Parsing functions and utilities.
-}
module Text.Pandoc.Readers.HTML.Parsing
( TagOmission (..)
, pInTags
, pInTags'
, pInTag
, pInTagWithAttribs
, pAny
, pCloses
, pSatisfy
, pBlank
, matchTagClose
, matchTagOpen
, isSpace
, maybeFromAttrib
, toAttr
, toStringAttr
)
where
import Control.Monad (void, mzero, mplus)
import Data.Maybe (fromMaybe)
import Data.Text (Text)
import Text.HTML.TagSoup
( Attribute, Tag (..), isTagPosition, isTagOpen, isTagClose, (~==) )
import Text.Pandoc.Class.PandocMonad (PandocMonad (..))
import Text.Pandoc.Definition (Attr)
import Text.Pandoc.Parsing
( (<|>), eof, getPosition, lookAhead, manyTill, newPos, option, optional
, skipMany, setPosition, token, try)
import Text.Pandoc.Readers.HTML.TagCategories
import Text.Pandoc.Readers.HTML.Types
import Text.Pandoc.Shared (tshow)
import Text.Pandoc.XML (html5Attributes, html4Attributes, rdfaAttributes)
import qualified Data.Set as Set
import qualified Data.Text as T
-- | Whether no tag, the closing tag, or both tags can be omitted.
data TagOmission
= TagsRequired -- ^ Opening and closing tags are both required
| ClosingTagOptional -- ^ The closing tag can be omitted
| TagsOmittable -- ^ Both tags, opening and closing, can be omitted.
deriving (Eq)
pInTags :: (PandocMonad m, Monoid a) => Text -> TagParser m a -> TagParser m a
pInTags tagtype parser = pInTags' tagtype (const True) parser
pInTags' :: (PandocMonad m, Monoid a)
=> Text
-> (Tag Text -> Bool)
-> TagParser m a
-> TagParser m a
pInTags' tagtype tagtest parser = try $ do
pSatisfy $ \t -> matchTagOpen tagtype [] t && tagtest t
mconcat <$> manyTill parser (pCloses tagtype <|> eof)
pInTag :: PandocMonad m
=> TagOmission -- ^ Whether some tags can be omitted
-> Text -- ^ @tagtype@ Tag name
-> TagParser m a -- ^ @p@ Content parser
-> TagParser m a
pInTag tagOmission tagtype = fmap snd . pInTagWithAttribs tagOmission tagtype
-- | Returns the contents of a tag together with its attributes; parses
-- @p@, preceded by an opening tag (optional if TagsOmittable) and
-- followed by a closing tag (optional unless TagsRequired).
pInTagWithAttribs :: PandocMonad m
=> TagOmission -- ^ Whether some tags can be omitted
-> Text -- ^ @tagtype@ Tag name
-> TagParser m a -- ^ @p@ Content parser
-> TagParser m ([Attribute Text], a)
pInTagWithAttribs tagOmission tagtype p = try $ do
let openingOptional = tagOmission == TagsOmittable
let closingOptional = tagOmission /= TagsRequired
skipMany pBlank
attribs <- (if openingOptional then option [] else id)
(getAttribs <$> pSatisfy (matchTagOpen tagtype []))
skipMany pBlank
x <- p
skipMany pBlank
(if closingOptional then optional else void) $
pSatisfy (matchTagClose tagtype)
skipMany pBlank
return (attribs, x)
where
getAttribs = \case
TagOpen _ attribs -> attribs
_ -> []
pCloses :: PandocMonad m => Text -> TagParser m ()
pCloses tagtype = try $ do
t <- lookAhead $ pSatisfy $ \tag -> isTagClose tag || isTagOpen tag
case t of
(TagClose t') | t' == tagtype -> void pAny
(TagOpen t' _) | t' `closes` tagtype -> return ()
(TagClose "ul") | tagtype == "li" -> return ()
(TagClose "ol") | tagtype == "li" -> return ()
(TagClose "dl") | tagtype == "dd" -> return ()
(TagClose "table") | tagtype == "td" -> return ()
(TagClose "table") | tagtype == "th" -> return ()
(TagClose "table") | tagtype == "tr" -> return ()
(TagClose "td") | tagtype `Set.member` blockHtmlTags -> return ()
(TagClose "th") | tagtype `Set.member` blockHtmlTags -> return ()
(TagClose t') | tagtype == "p" && t' `Set.member` blockHtmlTags
-> return () -- see #3794
_ -> mzero
pBlank :: PandocMonad m => TagParser m ()
pBlank = void $ pSatisfy isBlank
where
isBlank (TagText t) = T.all isSpace t
isBlank (TagComment _) = True
isBlank _ = False
pLocation :: PandocMonad m => TagParser m ()
pLocation = do
(TagPosition r c) <- pSat isTagPosition
setPosition $ newPos "input" r c
pSat :: PandocMonad m => (Tag Text -> Bool) -> TagParser m (Tag Text)
pSat f = do
pos <- getPosition
token tshow (const pos) (\x -> if f x then Just x else Nothing)
pSatisfy :: PandocMonad m => (Tag Text -> Bool) -> TagParser m (Tag Text)
pSatisfy f = try $ optional pLocation >> pSat f
matchTagClose :: Text -> (Tag Text -> Bool)
matchTagClose t = (~== TagClose t)
matchTagOpen :: Text -> [(Text, Text)] -> (Tag Text -> Bool)
matchTagOpen t as = (~== TagOpen t as)
pAny :: PandocMonad m => TagParser m (Tag Text)
pAny = pSatisfy (const True)
isSpace :: Char -> Bool
isSpace ' ' = True
isSpace '\t' = True
isSpace '\n' = True
isSpace '\r' = True
isSpace _ = False
-- taken from HXT and extended
-- See http://www.w3.org/TR/html5/syntax.html sec 8.1.2.4 optional tags
closes :: Text -> Text -> Bool
_ `closes` "body" = False
_ `closes` "html" = False
"body" `closes` "head" = True
"a" `closes` "a" = True
"li" `closes` "li" = True
"th" `closes` t | t `elem` ["th","td"] = True
"td" `closes` t | t `elem` ["th","td"] = True
"tr" `closes` t | t `elem` ["th","td","tr","colgroup"] = True
"dd" `closes` t | t `elem` ["dt", "dd"] = True
"dt" `closes` t | t `elem` ["dt","dd"] = True
"rt" `closes` t | t `elem` ["rb", "rt", "rtc"] = True
"col" `closes` "col" = True
"colgroup" `closes` "col" = True
"optgroup" `closes` "optgroup" = True
"optgroup" `closes` "option" = True
"option" `closes` "option" = True
-- https://html.spec.whatwg.org/multipage/syntax.html#optional-tags
x `closes` "p" | x `elem` ["address", "article", "aside", "blockquote",
"dir", "div", "dl", "fieldset", "footer", "form", "h1", "h2", "h3", "h4",
"h5", "h6", "header", "hr", "main", "menu", "nav", "ol", "p", "pre", "section",
"table", "ul"] = True
_ `closes` "meta" = True
"form" `closes` "form" = True
"label" `closes` "label" = True
"map" `closes` "map" = True
"object" `closes` "object" = True
_ `closes` t | t `elem` ["option","style","script","textarea","title"] = True
t `closes` "select" | t /= "option" = True
"thead" `closes` "colgroup" = True
"tfoot" `closes` t | t `elem` ["thead","colgroup"] = True
"tbody" `closes` t | t `elem` ["tbody","tfoot","thead","colgroup"] = True
t `closes` t2 |
t `elem` ["h1","h2","h3","h4","h5","h6","dl","ol","ul","table","div","main","p"] &&
t2 `elem` ["h1","h2","h3","h4","h5","h6","p" ] = True -- not "div" or "main"
t1 `closes` t2 |
t1 `Set.member` blockTags &&
t2 `Set.notMember` blockTags &&
t2 `Set.notMember` eitherBlockOrInline = True
_ `closes` _ = False
toStringAttr :: [(Text, Text)] -> [(Text, Text)]
toStringAttr = foldr go []
where
go :: (Text, Text) -> [(Text, Text)] -> [(Text, Text)]
-- treat xml:lang as lang
go ("xml:lang",y) ats = go ("lang",y) ats
-- prevent duplicate attributes
go (x,y) ats
| any (\(x',_) -> x == x') ats = ats
| otherwise =
case T.stripPrefix "data-" x of
Just x' | x' `Set.notMember` (html5Attributes <>
html4Attributes <> rdfaAttributes)
-> go (x',y) ats
_ -> (x,y):ats
-- Unlike fromAttrib from tagsoup, this distinguishes
-- between a missing attribute and an attribute with empty content.
maybeFromAttrib :: Text -> Tag Text -> Maybe Text
maybeFromAttrib name (TagOpen _ attrs) = lookup name attrs
maybeFromAttrib _ _ = Nothing
mkAttr :: [(Text, Text)] -> Attr
mkAttr attr = (attribsId, attribsClasses, attribsKV)
where attribsId = fromMaybe "" $ lookup "id" attr `mplus` lookup "name" attr
attribsClasses = T.words (fromMaybe "" $ lookup "class" attr) <> epubTypes
attribsKV = filter (\(k,_) -> k /= "class" && k /= "id" && k /= "name")
attr
epubTypes = T.words $ fromMaybe "" $ lookup "epub:type" attr
toAttr :: [(Text, Text)] -> Attr
toAttr = mkAttr . toStringAttr
|
