{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ViewPatterns #-}
-- |
-- Module : Documentation.Haddock.Parser
-- Copyright : (c) Mateusz Kowalczyk 2013-2014,
-- Simon Hengel 2013
-- License : BSD-like
--
-- Maintainer : haddock@projects.haskell.org
-- Stability : experimental
-- Portability : portable
--
-- Parser used for Haddock comments. For external users of this
-- library, the most commonly used combination of functions is going
-- to be
--
-- @'toRegular' . 'parseParas'@
module Documentation.Haddock.Parser ( parseString, parseParas
, overIdentifier, toRegular, Identifier
) where
import Control.Applicative
import Control.Arrow (first)
import Control.Monad
import qualified Data.ByteString.Char8 as BS
import Data.Char (chr, isAsciiUpper)
import Data.List (stripPrefix, intercalate, unfoldr)
import Data.Maybe (fromMaybe)
import Data.Monoid
import Documentation.Haddock.Doc
import Documentation.Haddock.Parser.Monad hiding (take, endOfLine)
import Documentation.Haddock.Parser.Util
import Documentation.Haddock.Types
import Documentation.Haddock.Utf8
import Prelude hiding (takeWhile)
-- $setup
-- >>> :set -XOverloadedStrings
-- | Identifier string surrounded with opening and closing quotes/backticks.
type Identifier = (Char, String, Char)
-- | Drops the quotes/backticks around all identifiers, as if they
-- were valid but still 'String's.
toRegular :: DocH mod Identifier -> DocH mod String
toRegular = fmap (\(_, x, _) -> x)
-- | Maps over 'DocIdentifier's over 'String' with potentially failing
-- conversion using user-supplied function. If the conversion fails,
-- the identifier is deemed to not be valid and is treated as a
-- regular string.
overIdentifier :: (String -> Maybe a)
-> DocH mod Identifier
-> DocH mod a
overIdentifier f d = g d
where
g (DocIdentifier (o, x, e)) = case f x of
Nothing -> DocString $ o : x ++ [e]
Just x' -> DocIdentifier x'
g DocEmpty = DocEmpty
g (DocAppend x x') = DocAppend (g x) (g x')
g (DocString x) = DocString x
g (DocParagraph x) = DocParagraph $ g x
g (DocIdentifierUnchecked x) = DocIdentifierUnchecked x
g (DocModule x) = DocModule x
g (DocWarning x) = DocWarning $ g x
g (DocEmphasis x) = DocEmphasis $ g x
g (DocMonospaced x) = DocMonospaced $ g x
g (DocBold x) = DocBold $ g x
g (DocUnorderedList x) = DocUnorderedList $ fmap g x
g (DocOrderedList x) = DocOrderedList $ fmap g x
g (DocDefList x) = DocDefList $ fmap (\(y, z) -> (g y, g z)) x
g (DocCodeBlock x) = DocCodeBlock $ g x
g (DocHyperlink x) = DocHyperlink x
g (DocPic x) = DocPic x
g (DocAName x) = DocAName x
g (DocProperty x) = DocProperty x
g (DocExamples x) = DocExamples x
g (DocHeader (Header l x)) = DocHeader . Header l $ g x
parse :: Parser a -> BS.ByteString -> (ParserState, a)
parse p = either err id . parseOnly (p <* endOfInput)
where
err = error . ("Haddock.Parser.parse: " ++)
-- | Main entry point to the parser. Appends the newline character
-- to the input string.
parseParas :: String -- ^ String to parse
-> MetaDoc mod Identifier
parseParas input = case parseParasState input of
(state, a) -> MetaDoc { _meta = Meta { _version = parserStateSince state }
, _doc = a
}
parseParasState :: String -> (ParserState, DocH mod Identifier)
parseParasState =
parse (p <* skipSpace) . encodeUtf8 . (++ "\n") . filter (/= '\r')
where
p :: Parser (DocH mod Identifier)
p = docConcat <$> paragraph `sepBy` many (skipHorizontalSpace *> "\n")
parseParagraphs :: String -> Parser (DocH mod Identifier)
parseParagraphs input = case parseParasState input of
(state, a) -> setParserState state >> return a
-- | Parse a text paragraph. Actually just a wrapper over 'parseStringBS' which
-- drops leading whitespace and encodes the string to UTF8 first.
parseString :: String -> DocH mod Identifier
parseString = parseStringBS . encodeUtf8 . dropWhile isSpace . filter (/= '\r')
parseStringBS :: BS.ByteString -> DocH mod Identifier
parseStringBS = snd . parse p
where
p :: Parser (DocH mod Identifier)
p = docConcat <$> many (monospace <|> anchor <|> identifier <|> moduleName
<|> picture <|> markdownImage <|> hyperlink <|> bold
<|> emphasis <|> encodedChar <|> string'
<|> skipSpecialChar)
-- | Parses and processes
-- <https://en.wikipedia.org/wiki/Numeric_character_reference Numeric character references>
--
-- >>> parseString "A"
-- DocString "A"
encodedChar :: Parser (DocH mod a)
encodedChar = "&#" *> c <* ";"
where
c = DocString . return . chr <$> num
num = hex <|> decimal
hex = ("x" <|> "X") *> hexadecimal
-- | List of characters that we use to delimit any special markup.
-- Once we have checked for any of these and tried to parse the
-- relevant markup, we can assume they are used as regular text.
specialChar :: [Char]
specialChar = "_/<@\"&'`# "
-- | Plain, regular parser for text. Called as one of the last parsers
-- to ensure that we have already given a chance to more meaningful parsers
-- before capturing their characers.
string' :: Parser (DocH mod a)
string' = DocString . unescape . decodeUtf8 <$> takeWhile1_ (`notElem` specialChar)
where
unescape "" = ""
unescape ('\\':x:xs) = x : unescape xs
unescape (x:xs) = x : unescape xs
-- | Skips a single special character and treats it as a plain string.
-- This is done to skip over any special characters belonging to other
-- elements but which were not deemed meaningful at their positions.
skipSpecialChar :: Parser (DocH mod a)
skipSpecialChar = DocString . return <$> satisfy (`elem` specialChar)
-- | Emphasis parser.
--
-- >>> parseString "/Hello world/"
-- DocEmphasis (DocString "Hello world")
emphasis :: Parser (DocH mod Identifier)
emphasis = DocEmphasis . parseStringBS <$>
mfilter ('\n' `BS.notElem`) ("/" *> takeWhile1_ (/= '/') <* "/")
-- | Bold parser.
--
-- >>> parseString "__Hello world__"
-- DocBold (DocString "Hello world")
bold :: Parser (DocH mod Identifier)
bold = DocBold . parseStringBS <$> disallowNewline ("__" *> takeUntil "__")
disallowNewline :: Parser BS.ByteString -> Parser BS.ByteString
disallowNewline = mfilter ('\n' `BS.notElem`)
-- | Like `takeWhile`, but unconditionally take escaped characters.
takeWhile_ :: (Char -> Bool) -> Parser BS.ByteString
takeWhile_ p = scan False p_
where
p_ escaped c
| escaped = Just False
| not $ p c = Nothing
| otherwise = Just (c == '\\')
-- | Like `takeWhile1`, but unconditionally take escaped characters.
takeWhile1_ :: (Char -> Bool) -> Parser BS.ByteString
takeWhile1_ = mfilter (not . BS.null) . takeWhile_
-- | Text anchors to allow for jumping around the generated documentation.
--
-- >>> parseString "#Hello world#"
-- DocAName "Hello world"
anchor :: Parser (DocH mod a)
anchor = DocAName . decodeUtf8 <$>
disallowNewline ("#" *> takeWhile1_ (/= '#') <* "#")
-- | Monospaced strings.
--
-- >>> parseString "@cruel@"
-- DocMonospaced (DocString "cruel")
monospace :: Parser (DocH mod Identifier)
monospace = DocMonospaced . parseStringBS
<$> ("@" *> takeWhile1_ (/= '@') <* "@")
-- | Module names: we try our reasonable best to only allow valid
-- Haskell module names, with caveat about not matching on technically
-- valid unicode symbols.
moduleName :: Parser (DocH mod a)
moduleName = DocModule <$> (char '"' *> modid <* char '"')
where
modid = intercalate "." <$> conid `sepBy1` "."
conid = (:)
<$> satisfy isAsciiUpper
-- NOTE: According to Haskell 2010 we should actually only
-- accept {small | large | digit | ' } here. But as we can't
-- match on unicode characters, this is currently not possible.
-- Note that we allow ‘#’ to suport anchors.
<*> (decodeUtf8 <$> takeWhile (`notElem` (" .&[{}(=*)+]!|@/;,^?\"\n"::String)))
-- | Picture parser, surrounded by \<\< and \>\>. It's possible to specify
-- a title for the picture.
--
-- >>> parseString "<<hello.png>>"
-- DocPic (Picture {pictureUri = "hello.png", pictureTitle = Nothing})
-- >>> parseString "<<hello.png world>>"
-- DocPic (Picture {pictureUri = "hello.png", pictureTitle = Just "world"})
picture :: Parser (DocH mod a)
picture = DocPic . makeLabeled Picture . decodeUtf8
<$> disallowNewline ("<<" *> takeUntil ">>")
markdownImage :: Parser (DocH mod a)
markdownImage = fromHyperlink <$> ("!" *> linkParser)
where
fromHyperlink (Hyperlink url label) = DocPic (Picture url label)
-- | Paragraph parser, called by 'parseParas'.
paragraph :: Parser (DocH mod Identifier)
paragraph = examples <|> do
indent <- takeIndent
choice
[ since
, unorderedList indent
, orderedList indent
, birdtracks
, codeblock
, property
, header
, textParagraphThatStartsWithMarkdownLink
, definitionList indent
, docParagraph <$> textParagraph
]
since :: Parser (DocH mod a)
since = ("@since " *> version <* skipHorizontalSpace <* endOfLine) >>= setSince >> return DocEmpty
where
version = decimal `sepBy1'` "."
-- | Headers inside the comment denoted with @=@ signs, up to 6 levels
-- deep.
--
-- >>> snd <$> parseOnly header "= Hello"
-- Right (DocHeader (Header {headerLevel = 1, headerTitle = DocString "Hello"}))
-- >>> snd <$> parseOnly header "== World"
-- Right (DocHeader (Header {headerLevel = 2, headerTitle = DocString "World"}))
header :: Parser (DocH mod Identifier)
header = do
let psers = map (string . encodeUtf8 . concat . flip replicate "=") [6, 5 .. 1]
pser = foldl1 (<|>) psers
delim <- decodeUtf8 <$> pser
line <- skipHorizontalSpace *> nonEmptyLine >>= return . parseString
rest <- paragraph <|> return DocEmpty
return $ DocHeader (Header (length delim) line) `docAppend` rest
textParagraph :: Parser (DocH mod Identifier)
textParagraph = parseString . intercalate "\n" <$> many1 nonEmptyLine
textParagraphThatStartsWithMarkdownLink :: Parser (DocH mod Identifier)
textParagraphThatStartsWithMarkdownLink = docParagraph <$> (docAppend <$> markdownLink <*> optionalTextParagraph)
where
optionalTextParagraph :: Parser (DocH mod Identifier)
optionalTextParagraph = (docAppend <$> whitespace <*> textParagraph) <|> pure DocEmpty
whitespace :: Parser (DocH mod a)
whitespace = DocString <$> (f <$> takeHorizontalSpace <*> optional "\n")
where
f :: BS.ByteString -> Maybe BS.ByteString -> String
f xs (fromMaybe "" -> x)
| BS.null (xs <> x) = ""
| otherwise = " "
-- | Parses unordered (bullet) lists.
unorderedList :: BS.ByteString -> Parser (DocH mod Identifier)
unorderedList indent = DocUnorderedList <$> p
where
p = ("*" <|> "-") *> innerList indent p
-- | Parses ordered lists (numbered or dashed).
orderedList :: BS.ByteString -> Parser (DocH mod Identifier)
orderedList indent = DocOrderedList <$> p
where
p = (paren <|> dot) *> innerList indent p
dot = (decimal :: Parser Int) <* "."
paren = "(" *> decimal <* ")"
-- | Generic function collecting any further lines belonging to the
-- list entry and recursively collecting any further lists in the
-- same paragraph. Usually used as
--
-- > someListFunction = listBeginning *> innerList someListFunction
innerList :: BS.ByteString -> Parser [DocH mod Identifier]
-> Parser [DocH mod Identifier]
innerList indent item = do
c <- takeLine
(cs, items) <- more indent item
let contents = docParagraph . parseString . dropNLs . unlines $ c : cs
return $ case items of
Left p -> [contents `docAppend` p]
Right i -> contents : i
-- | Parses definition lists.
definitionList :: BS.ByteString -> Parser (DocH mod Identifier)
definitionList indent = DocDefList <$> p
where
p = do
label <- "[" *> (parseStringBS <$> takeWhile1 (`notElem` ("]\n" :: String))) <* ("]" <* optional ":")
c <- takeLine
(cs, items) <- more indent p
let contents = parseString . dropNLs . unlines $ c : cs
return $ case items of
Left x -> [(label, contents `docAppend` x)]
Right i -> (label, contents) : i
-- | Drops all trailing newlines.
dropNLs :: String -> String
dropNLs = reverse . dropWhile (== '\n') . reverse
-- | Main worker for 'innerList' and 'definitionList'.
-- We need the 'Either' here to be able to tell in the respective functions
-- whether we're dealing with the next list or a nested paragraph.
more :: Monoid a => BS.ByteString -> Parser a
-> Parser ([String], Either (DocH mod Identifier) a)
more indent item = innerParagraphs indent
<|> moreListItems indent item
<|> moreContent indent item
<|> pure ([], Right mempty)
-- | Used by 'innerList' and 'definitionList' to parse any nested paragraphs.
innerParagraphs :: BS.ByteString
-> Parser ([String], Either (DocH mod Identifier) a)
innerParagraphs indent = (,) [] . Left <$> ("\n" *> indentedParagraphs indent)
-- | Attempts to fetch the next list if possibly. Used by 'innerList' and
-- 'definitionList' to recursively grab lists that aren't separated by a whole
-- paragraph.
moreListItems :: BS.ByteString -> Parser a
-> Parser ([String], Either (DocH mod Identifier) a)
moreListItems indent item = (,) [] . Right <$> indentedItem
where
indentedItem = string indent *> skipSpace *> item
-- | Helper for 'innerList' and 'definitionList' which simply takes
-- a line of text and attempts to parse more list content with 'more'.
moreContent :: Monoid a => BS.ByteString -> Parser a
-> Parser ([String], Either (DocH mod Identifier) a)
moreContent indent item = first . (:) <$> nonEmptyLine <*> more indent item
-- | Parses an indented paragraph.
-- The indentation is 4 spaces.
indentedParagraphs :: BS.ByteString -> Parser (DocH mod Identifier)
indentedParagraphs indent =
(concat <$> dropFrontOfPara indent') >>= parseParagraphs
where
indent' = string $ BS.append indent " "
-- | Grab as many fully indented paragraphs as we can.
dropFrontOfPara :: Parser BS.ByteString -> Parser [String]
dropFrontOfPara sp = do
currentParagraph <- some (sp *> takeNonEmptyLine)
followingParagraphs <-
skipHorizontalSpace *> nextPar -- we have more paragraphs to take
<|> skipHorizontalSpace *> nlList -- end of the ride, remember the newline
<|> endOfInput *> return [] -- nothing more to take at all
return (currentParagraph ++ followingParagraphs)
where
nextPar = (++) <$> nlList <*> dropFrontOfPara sp
nlList = "\n" *> return ["\n"]
nonSpace :: BS.ByteString -> Parser BS.ByteString
nonSpace xs
| not $ any (not . isSpace) $ decodeUtf8 xs = fail "empty line"
| otherwise = return xs
-- | Takes a non-empty, not fully whitespace line.
--
-- Doesn't discard the trailing newline.
takeNonEmptyLine :: Parser String
takeNonEmptyLine = do
(++ "\n") . decodeUtf8 <$> (takeWhile1 (/= '\n') >>= nonSpace) <* "\n"
-- | Takes indentation of first non-empty line.
--
-- More precisely: skips all whitespace-only lines and returns indentation
-- (horizontal space, might be empty) of that non-empty line.
takeIndent :: Parser BS.ByteString
takeIndent = do
indent <- takeHorizontalSpace
"\n" *> takeIndent <|> return indent
-- | Blocks of text of the form:
--
-- >> foo
-- >> bar
-- >> baz
--
birdtracks :: Parser (DocH mod a)
birdtracks = DocCodeBlock . DocString . intercalate "\n" . stripSpace <$> many1 line
where
line = skipHorizontalSpace *> ">" *> takeLine
stripSpace :: [String] -> [String]
stripSpace = fromMaybe <*> mapM strip'
where
strip' (' ':xs') = Just xs'
strip' "" = Just ""
strip' _ = Nothing
-- | Parses examples. Examples are a paragraph level entitity (separated by an empty line).
-- Consecutive examples are accepted.
examples :: Parser (DocH mod a)
examples = DocExamples <$> (many (skipHorizontalSpace *> "\n") *> go)
where
go :: Parser [Example]
go = do
prefix <- decodeUtf8 <$> takeHorizontalSpace <* ">>>"
expr <- takeLine
(rs, es) <- resultAndMoreExamples
return (makeExample prefix expr rs : es)
where
resultAndMoreExamples :: Parser ([String], [Example])
resultAndMoreExamples = moreExamples <|> result <|> pure ([], [])
where
moreExamples :: Parser ([String], [Example])
moreExamples = (,) [] <$> go
result :: Parser ([String], [Example])
result = first . (:) <$> nonEmptyLine <*> resultAndMoreExamples
makeExample :: String -> String -> [String] -> Example
makeExample prefix expression res =
Example (strip expression) result
where
result = map (substituteBlankLine . tryStripPrefix) res
tryStripPrefix xs = fromMaybe xs (stripPrefix prefix xs)
substituteBlankLine "<BLANKLINE>" = ""
substituteBlankLine xs = xs
nonEmptyLine :: Parser String
nonEmptyLine = mfilter (any (not . isSpace)) takeLine
takeLine :: Parser String
takeLine = decodeUtf8 <$> takeWhile (/= '\n') <* endOfLine
endOfLine :: Parser ()
endOfLine = void "\n" <|> endOfInput
-- | Property parser.
--
-- >>> snd <$> parseOnly property "prop> hello world"
-- Right (DocProperty "hello world")
property :: Parser (DocH mod a)
property = DocProperty . strip . decodeUtf8 <$> ("prop>" *> takeWhile1 (/= '\n'))
-- |
-- Paragraph level codeblock. Anything between the two delimiting \@ is parsed
-- for markup.
codeblock :: Parser (DocH mod Identifier)
codeblock =
DocCodeBlock . parseStringBS . dropSpaces
<$> ("@" *> skipHorizontalSpace *> "\n" *> block' <* "@")
where
dropSpaces xs =
let rs = decodeUtf8 xs
in case splitByNl rs of
[] -> xs
ys -> case last ys of
' ':_ -> case mapM dropSpace ys of
Nothing -> xs
Just zs -> encodeUtf8 $ intercalate "\n" zs
_ -> xs
-- This is necessary because ‘lines’ swallows up a trailing newline
-- and we lose information about whether the last line belongs to @ or to
-- text which we need to decide whether we actually want to be dropping
-- anything at all.
splitByNl = unfoldr (\x -> case x of
'\n':s -> Just (span (/= '\n') s)
_ -> Nothing)
. ('\n' :)
dropSpace "" = Just ""
dropSpace (' ':xs) = Just xs
dropSpace _ = Nothing
block' = scan False p
where
p isNewline c
| isNewline && c == '@' = Nothing
| isNewline && isSpace c = Just isNewline
| otherwise = Just $ c == '\n'
hyperlink :: Parser (DocH mod a)
hyperlink = DocHyperlink . makeLabeled Hyperlink . decodeUtf8
<$> disallowNewline ("<" *> takeUntil ">")
<|> autoUrl
<|> markdownLink
markdownLink :: Parser (DocH mod a)
markdownLink = DocHyperlink <$> linkParser
linkParser :: Parser Hyperlink
linkParser = flip Hyperlink <$> label <*> (whitespace *> url)
where
label :: Parser (Maybe String)
label = Just . strip . decode <$> ("[" *> takeUntil "]")
whitespace :: Parser ()
whitespace = skipHorizontalSpace <* optional ("\n" *> skipHorizontalSpace)
url :: Parser String
url = rejectWhitespace (decode <$> ("(" *> takeUntil ")"))
rejectWhitespace :: MonadPlus m => m String -> m String
rejectWhitespace = mfilter (all (not . isSpace))
decode :: BS.ByteString -> String
decode = removeEscapes . decodeUtf8
-- | Looks for URL-like things to automatically hyperlink even if they
-- weren't marked as links.
autoUrl :: Parser (DocH mod a)
autoUrl = mkLink <$> url
where
url = mappend <$> ("http://" <|> "https://" <|> "ftp://") <*> takeWhile1 (not . isSpace)
mkLink :: BS.ByteString -> DocH mod a
mkLink s = case unsnoc s of
Just (xs, x) | x `elem` (",.!?" :: String) -> DocHyperlink (Hyperlink (decodeUtf8 xs) Nothing) `docAppend` DocString [x]
_ -> DocHyperlink (Hyperlink (decodeUtf8 s) Nothing)
-- | Parses strings between identifier delimiters. Consumes all input that it
-- deems to be valid in an identifier. Note that it simply blindly consumes
-- characters and does no actual validation itself.
parseValid :: Parser String
parseValid = p some
where
idChar = satisfy (`elem` ("_.!#$%&*+/<=>?@\\|-~:^"::String))
<|> digit <|> letter_ascii
p p' = do
vs' <- p' $ utf8String "⋆" <|> return <$> idChar
let vs = concat vs'
c <- peekChar'
case c of
'`' -> return vs
'\'' -> (\x -> vs ++ "'" ++ x) <$> ("'" *> p many') <|> return vs
_ -> fail "outofvalid"
-- | Parses UTF8 strings from ByteString streams.
utf8String :: String -> Parser String
utf8String x = decodeUtf8 <$> string (encodeUtf8 x)
-- | Parses identifiers with help of 'parseValid'. Asks GHC for
-- 'String' from the string it deems valid.
identifier :: Parser (DocH mod Identifier)
identifier = do
o <- idDelim
vid <- parseValid
e <- idDelim
return $ DocIdentifier (o, vid, e)
where
idDelim = char '\'' <|> char '`'