X-0.3.1.0: src/Text/XML/Lexer.hs
{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE Safe #-}
{-# LANGUAGE TypeSynonymInstances #-}
{-
Copyright (c) 2019 Herbert Valerio Riedel <hvr@gnu.org>
This file is free software: you may copy, redistribute and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 3 of the License, or (at your
option) any later version.
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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 (see `LICENSE.GPLv3`). If not, see
<https://www.gnu.org/licenses/gpl-3.0.html>.
This file incorporates work covered by the following copyright and
permission notice:
(c) 2007 Galois Inc.
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
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1. Redistributions of source code must retain the above copyright
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3. Neither the name of the author nor the names of his contributors
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without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND ANY EXPRESS
OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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POSSIBILITY OF SUCH DAMAGE.
-}
-- |
-- Module : Text.XML.Lexer
-- Copyright : (c) Galois, Inc. 2007
-- (c) Herbert Valerio Riedel 2019
-- SPDX-License-Identifier: BSD-3-Clause AND GPL-3.0-or-later
--
module Text.XML.Lexer where
import Common
import Text.XML.Types
import Utils
import Data.Char (isAsciiLower, isAsciiUpper, isDigit, toLower)
import qualified Data.Text as T
import qualified Data.Text.Lazy as TL
import qualified Data.Text.Short as TS
nullNs :: URI
nullNs = URI mempty
class XmlSource s where
uncons :: s -> Maybe (Char,s)
instance XmlSource String where
uncons (c:s) = Just (c,s)
uncons "" = Nothing
instance XmlSource T.Text where
uncons = T.uncons
instance XmlSource TL.Text where
uncons = TL.uncons
-- | This type may be used to provide a custom scanning function
-- for extracting characters.
data Scanner s = Scanner (Maybe (Char,s)) (s -> Maybe (Char,s))
-- | This type may be used to provide a custom scanning function
-- for extracting characters.
customScanner :: (s -> Maybe (Char,s)) -> s -> Scanner s
customScanner next s = Scanner (next s) next
instance XmlSource (Scanner s) where
uncons (Scanner this next) = do
(c,s1) <- this
return (c, Scanner (next s1) next)
-- Lexer -----------------------------------------------------------------------
type LChar = (Pos,Char)
type LString = [LChar]
type LexCont = LString -> [Token]
-- | XML Lexer token.
data Token = TokStart !Pos QName [Attr] Bool
-- ^ opening start-tag (the 'Bool' field denotes whether this is an empty tag)
| TokEnd !Pos QName -- ^ closing end-tag
| TokCRef ShortText -- ^ character entity reference
| TokText CData -- ^ character data
| TokError !Pos String -- ^ Lexer error
| TokXmlDecl XmlDeclaration
| TokComment Comment
| TokPI !Pos PI
| TokDTD Text
deriving (Show,Data,Typeable,Generic)
instance NFData Token
eofErr :: [Token]
eofErr = [TokError (-1) "Premature EOF"]
-- | Run XML lexer over 'XmlSource'
scanXML :: XmlSource source => source -> [Token]
scanXML = tokens2 . eolNorm . go 0
where
go !n src = case uncons src of
Just (c,src') -> (n,c) : go (n+1) src'
Nothing -> []
scanXML' :: XmlSource source => source -> [Token]
scanXML' = tokens1 . eolNorm . go 0
where
go !n src = case uncons src of
Just (c,src') -> (n,c) : go (n+1) src'
Nothing -> []
{-
> [XML 1.0] 2.11 End-of-Line Handling
>
> [...] the XML processor must behave as if it normalized all line breaks
> in external parsed entities (including the document entity) on input,
> before parsing, by translating both the two-character sequence #xD #xA
> and any #xD that is not followed by #xA to a single #xA character.
-}
eolNorm :: LString -> LString
eolNorm [] = []
eolNorm ((_,'\xD'):c@(_,'\xA'):cs) = c : eolNorm cs
eolNorm ((n,'\xD'):cs) = (n,'\xA') : eolNorm cs
eolNorm (c:cs) = c : eolNorm cs
-- prolog
tokens1 :: LexCont
tokens1 [] = []
tokens1 ((_,'<') : (_,'!') : cs) = special tokens1 cs
tokens1 ((n,'<') : (_,'?') : cs) = procins tokens1 n cs
tokens1 ((_,'<') : cs) = tag tokens2 cs
tokens1 cs@(_:_) = sData tokens1 cs
sData :: LexCont -> LString -> [Token]
sData lcont [] = lcont []
sData lcont cs@((n,_):_)
= case breakn (not . isS) cs of
("",_:_) -> [TokError n "unexpected (non-misc) content nodes before root element"]
(as,bs) -> TokText CData { cdVerbatim = CDataText, cdData = T.pack as } : lcont bs
-- after prolog
tokens2 :: LexCont
tokens2 [] = []
tokens2 ((_,'<') : (_,'!') : cs) = special tokens2 cs
tokens2 ((n,'<') : (_,'?') : cs) = procins tokens2 n cs
tokens2 ((_,'<') : cs) = tag tokens2 cs
tokens2 cs@(_:_) = charData tokens2 cs
charData :: LexCont -> LString -> [Token]
charData lcont [] = lcont []
charData lcont cs@((n,_):_)
= let (as,bs) = breakn ('<' ==) cs
in foldr cvt (lcont bs) (decode_text as)
where
cvt :: Txt -> ([Token] -> [Token])
-- XXX: Note, some of the lines might be a bit inacuarate
cvt (TxtBit x) cont
| T.isInfixOf "]]>" dat = [TokError n "invalid literal ']]>' sequence in text content"]
| T.all isChar dat = TokText CData { cdVerbatim = CDataText, cdData = dat } : cont
| otherwise = [TokError n "invalid code-point in text content"]
where
dat = T.pack x
cvt (CRefBit _ False) _ = [TokError n "invalid character reference"]
cvt (CRefBit x True) cont = case cref_to_char x of
Just c
| isChar c -> TokText CData { cdVerbatim = CDataText, cdData = T.singleton c } : cont
| otherwise -> [TokError n "invalid character reference"]
Nothing -> TokCRef (fromString x) : cont
--
-- PI ::= '<?' PITarget (S (Char* - (Char* '?>' Char*)))? '?>'
-- PITarget ::= Name - (('X' | 'x') ('M' | 'm') ('L' | 'l'))
procins :: LexCont -> Pos -> LString -> [Token]
procins lcont n0 = go ""
where
go acc ((_,'?') : (_,'>') : ds) = mkPI (reverse acc) (lcont ds)
go acc ((_,c) : ds) = go (c:acc) ds
go _ [] = eofErr
mkPI :: String -> [Token] -> [Token]
mkPI s0 ts
| tgt == "xml" = mkXMLDecl s' ts
| map toLower tgt0 == "xml" || not (isNCName tgt0) = [TokError (n0+2) "Invalid PI name"]
| not (T.all isChar payload) = [TokError (n0+2) "invalid code-point in PI data"]
| otherwise = TokPI n0 (PI tgt payload) : ts
where
(tgt0,s') = break isS s0
tgt = TS.fromString tgt0
payload = T.pack (dropWhile isS s')
{-
XMLDecl ::= '<?xml' VersionInfo EncodingDecl? SDDecl? S? '?>'
VersionInfo ::= S 'version' Eq ("'" VersionNum "'" | '"' VersionNum '"')
EncodingDecl ::= S 'encoding' Eq ('"' EncName '"' | "'" EncName "'" )
SDDecl ::= S 'standalone' Eq (("'" ('yes' | 'no') "'") | ('"' ('yes' | 'no') '"'))
Eq ::= S? '=' S?
VersionNum ::= '1.0'
EncName ::= [A-Za-z] ([A-Za-z0-9._] | '-')*
-}
-- needs serious rewrite...
mkXMLDecl s0 ts
| n0 > 0 = [TokError n0 "XML declaration allowed only at the start of the document"]
| otherwise = go1 (simpleTokenize s0)
where
go1 ("":"version":"=":ver:rest)
| Just "1.0" <- unbrack ver = go2 rest
go1 _ = [TokError n0 "Unsupported or missing 'version' in XML declaration"]
go2 ("":"encoding":"=":enc:rest)
| Just enc' <- unbrack enc, isEnc enc' = go3 (Just $ TS.pack enc') rest
| otherwise = [TokError n0 "Bad 'encoding' value in XML declaration"]
go2 rest = go3 Nothing rest
go3 enc ("":"standalone":"=":sd:rest)
| Just sd' <- unbrack sd, Just sd'' <- isBoo sd' = go4 enc (Just sd'') rest
| otherwise = [TokError n0 "Bad 'standalone' value in XML declaration"]
go3 enc rest = go4 enc Nothing rest
go4 enc sd [] = TokXmlDecl (XmlDeclaration enc sd) : ts
go4 enc sd [""] = TokXmlDecl (XmlDeclaration enc sd) : ts
go4 _ _ _ = [TokError n0 "unexpected or malformed attribute in XML declaration"]
isEnc [] = False
isEnc (c:cs) = (isAsciiLower c || isAsciiUpper c) &&
all (\c' -> isAsciiLower c' || isAsciiUpper c' || isDigit c' || c' `elem` ['.','_','-']) cs
isBoo "yes" = Just True
isBoo "no" = Just False
isBoo _ = Nothing
unbrack ('\'':xs) | Just (s,'\'') <- unsnoc xs = Just s
unbrack ('"':xs) | Just (s,'"') <- unsnoc xs = Just s
unbrack _ = Nothing
special :: LexCont -> LString -> [Token]
-- <!--
--
-- Comment ::= '<!--' ((Char - '-') | ('-' (Char - '-')))* '-->'
special lcont ((n0,'-') : (_,'-') : cs) = go "" cs
where
go acc ((n,'-') : (_,'-') : (_,x) : ds)
| x == '>' = let dat = T.pack (reverse acc)
in if T.all isChar dat
then TokComment (Comment dat) : lcont ds
else [TokError (n0-2) "invalid code-point in comment"]
| otherwise = [TokError n "double hyphen within comment"]
go acc ((_,c) : ds) = go (c:acc) ds
go _ [] = eofErr
-- <![CDATA[
special lcont ((n,'[') : (_,'C') : (_,'D') : (_,'A') : (_,'T') : (_,'A') : (_,'[') : cs) =
let (xs,ts) = cdata cs
dat = T.pack xs
in if T.all isChar dat then TokText CData { cdVerbatim = CDataVerbatim, cdData = dat } : lcont ts
else [TokError (n-2) "invalid code-point in CDATA block"]
where
cdata ((_,']') : (_,']') : (_,'>') : ds) = ([],ds)
cdata ((_,d) : ds) = let (xs,ys) = cdata ds in (d:xs,ys)
cdata [] = ([],[])
-- <!DOCTYPE
special lcont ((_,'D') : (_,'O') : (_,'C') : (_,'T') : (_,'Y') : (_,'P') : (_,'E') : cs) =
let (xs,ts) = munch "" 0 cs in TokDTD (T.pack (reverse xs)) : lcont ts
where
munch acc nesting ((_,'>') : ds)
| nesting == (0::Int) = (acc,ds)
| otherwise = munch ('>':acc) (nesting-1) ds
munch acc nesting ((_,'<') : ds) = munch ('<':acc) (nesting+1) ds
munch acc n ((_,x) : ds) = munch (x:acc) n ds
munch acc _ [] = (acc,[]) -- unterminated DTD markup
special _ ((n,_):_) = [TokError (n-1) "invalid element name"]
special _ [] = eofErr
qualName :: LString -> (QName,LString)
qualName xs = (QName { qURI = nullNs
, qPrefix = fmap fromString q
, qLName = LName (fromString n)
}, bs)
where
(as,bs) = breakn endName xs
(q,n) = case break (':'==) as of
(q1,_:n1) -> (Just q1, n1)
_ -> (Nothing, as)
endName x = isS x || x == '=' || x == '>' || x == '/'
{-
EmptyElemTag ::= '<' Name (S Attribute)* S? '/>'
STag ::= '<' Name (S Attribute)* S? '>'
ETag ::= '</' Name S? '>'
Attribute ::= Name Eq AttValue
-}
tag :: LexCont -> LString -> [Token]
tag lcont ((p,'/') : cs)
| isValidQName n
= TokEnd p n : case dropSpace ds of
(_,'>') : es -> lcont es
-- tag was not properly closed...
(p',_) : _ -> [TokError p' "expected '>'"]
[] -> eofErr
| otherwise = [TokError p "invalid element name"]
where
(n,ds) = qualName cs
tag _ [] = eofErr
tag lcont cs@((pos,_):_)
| not (isValidQName n) = [TokError pos "invalid element name"]
| not (all (isValidQName . attrKey) as) = [TokError pos "invalid attribute name"]
| not (all (T.all isChar . attrVal) as) = [TokError pos "invalid attribute value"]
| otherwise = TokStart pos n as b : ts
where
(n,ds) = qualName cs
(as,b,ts) = attribs lcont ds
attribs :: LexCont -> LString -> ([Attr], Bool, [Token])
attribs lcont = go
where
go cs = case (isS' cs, dropSpace cs) of
(_,(_,'>') : ds) -> ([], False, lcont ds)
(_,(_,'/') : ds) -> ([], True, case ds of
(_,'>') : es -> lcont es
(pos,_) : _ -> [TokError pos "expected '>'"]
[] -> eofErr)
(_,(_,'?') : (_,'>') : ds) -> ([], True, lcont ds)
-- doc ended within a tag..
(_,[]) -> ([],False,eofErr)
(True,cs') -> let (a,cs1) = attrib cs'
(as,b,ts) = go cs1
in (a:as,b,ts)
(False,(pos,_):_) -> ([], False, [TokError pos "expected whitespace"])
isS' ((_,c):_) = isS c
isS' [] = False
attrib :: LString -> (Attr,LString)
attrib cs = ((Attr ks (fromString $ decode_attr vs)),cs2)
where
(vs,cs2) = attr_val (dropSpace cs1)
(ks,cs1) = qualName cs
{-
AttValue ::= '"' ([^<&"] | Reference)* '"'
| "'" ([^<&'] | Reference)* "'"
-}
attr_val :: LString -> (String,LString)
attr_val ((_,'=') : cs0) = string (dropSpace cs0)
where
-- | Match the value for an attribute.
string :: LString -> (String,LString)
string ((_,'"') : cs) = break' ('"' ==) cs
string ((_,'\'') : cs) = break' ('\'' ==) cs
-- hack: inject invalid \0 character to trigger failure in caller
string cs = ("\0",cs)
attr_val cs = ("\0",cs)
dropSpace :: LString -> LString
dropSpace = dropWhile (isS . snd)
break' :: (a -> Bool) -> [(b,a)] -> ([a],[(b,a)])
break' p xs = let (as,bs) = breakn p xs
in (as, case bs of
[] -> []
_ : cs -> cs)
breakn :: (a -> Bool) -> [(b,a)] -> ([a],[(b,a)])
breakn p l = (map snd as,bs) where (as,bs) = break (p . snd) l
decode_attr :: String -> String
decode_attr cs = concatMap cvt (decode_text cs)
where
cvt (TxtBit x) = norm x
cvt (CRefBit _ False) = "\0"
cvt (CRefBit x True)
| Just c <- cref_to_char x = [c]
| otherwise = "\0" -- triggers error lateron (we can't represent refs in att-values)
norm [] = []
norm ('\x9':xs) = '\x20' : norm xs
norm ('\xA':xs) = '\x20' : norm xs
norm ('<':xs) = '<' : '\0' : norm xs -- hack: trigger error; literal '<'s are not allowed here
norm (x:xs) = x : norm xs
data Txt = TxtBit String
| CRefBit String Bool
decode_text :: [Char] -> [Txt]
decode_text ('&' : cs) = case break (';' ==) cs of
(as,_:bs) -> CRefBit as True : decode_text bs
(as,"") -> [CRefBit as False]
decode_text [] = []
decode_text cs = let (as,bs) = break ('&' ==) cs
in TxtBit as : decode_text bs
cref_to_char :: [Char] -> Maybe Char
cref_to_char cs = case cs of
'#' : ds -> maybe (Just '\0') Just $ -- trigger error lateron
num_esc ds
"lt" -> Just '<'
"gt" -> Just '>'
"amp" -> Just '&'
"apos" -> Just '\''
"quot" -> Just '"'
"" -> Just '\0' -- trigger error
(x:xs) | isNameStartChar x, all isNameChar xs -> Nothing
| otherwise -> Just '\0' -- invalid name
num_esc :: String -> Maybe Char
num_esc cs = case cs of
'x' : ds -> decodeCharRefHex ds
_ -> decodeCharRefDec cs
cvt_char :: Int -> Maybe Char
cvt_char x
| fromEnum (minBound :: Char) <= x && x <= fromEnum (maxBound::Char)
= Just (toEnum x)
| otherwise = Nothing
simpleTokenize :: String -> [String]
simpleTokenize [] = []
simpleTokenize (c:cs)
| isSorEQ c = case span isS (c:cs) of
(_,'=':rest) -> "=" : simpleTokenize (dropWhile isS rest)
(_:_,rest) -> "" : simpleTokenize rest
([],_) -> error "impossible"
| c == '\'' = case break (== '\'') cs of
(_,"") -> [c:cs]
(str,_:rest) -> (c:str++"'") : simpleTokenize rest
| c == '"' = case break (== '"') cs of
(_,"") -> [c:cs]
(str,_:rest) -> (c:str++"\"") : simpleTokenize rest
| otherwise = let (t,rest) = break isSorEQ (c:cs)
in t : simpleTokenize rest
where
isSorEQ x = isS x || x == '='
isValidQName :: QName -> Bool
isValidQName (QName { qPrefix = Just pfx, qLName = LName ln }) = isNCName (TS.unpack pfx) && isNCName (TS.unpack ln)
isValidQName (QName { qPrefix = Nothing, qLName = LName ln }) = isNCName (TS.unpack ln)