1 -----------------------------------------------------------------------------
2 -- (c) The University of Glasgow, 2006
6 -- This is a combination of an Alex-generated lexer from a regex
7 -- definition, with some hand-coded bits.
9 -- Completely accurate information about token-spans within the source
10 -- file is maintained. Every token has a start and end SrcLoc attached to it.
12 -----------------------------------------------------------------------------
16 -- - parsing integers is a bit slow
17 -- - readRational is a bit slow
19 -- Known bugs, that were also in the previous version:
20 -- - M... should be 3 tokens, not 1.
21 -- - pragma-end should be only valid in a pragma
25 Token(..), lexer, pragState, mkPState, PState(..),
26 P(..), ParseResult(..), getSrcLoc,
27 failLocMsgP, failSpanMsgP, srcParseFail,
28 popContext, pushCurrentContext, setLastToken, setSrcLoc,
29 getLexState, popLexState, pushLexState,
30 extension, glaExtsEnabled, bangPatEnabled
33 #include "HsVersions.h"
35 import ErrUtils ( Message )
44 import Util ( maybePrefixMatch, readRational )
47 import Data.Char ( chr, isSpace )
51 #if __GLASGOW_HASKELL__ >= 605
52 import Data.Char ( GeneralCategory(..), generalCategory, isPrint, isUpper )
54 import Compat.Unicode ( GeneralCategory(..), generalCategory, isPrint, isUpper )
59 $whitechar = [\ \t\n\r\f\v\xa0 $unispace]
60 $white_no_nl = $whitechar # \n
64 $decdigit = $ascdigit -- for now, should really be $digit (ToDo)
65 $digit = [$ascdigit $unidigit]
67 $special = [\(\)\,\;\[\]\`\{\}]
68 $ascsymbol = [\!\#\$\%\&\*\+\.\/\<\=\>\?\@\\\^\|\-\~ \xa1-\xbf \xd7 \xf7]
70 $symbol = [$ascsymbol $unisymbol] # [$special \_\:\"\']
73 $asclarge = [A-Z \xc0-\xd6 \xd8-\xde]
74 $large = [$asclarge $unilarge]
77 $ascsmall = [a-z \xdf-\xf6 \xf8-\xff]
78 $small = [$ascsmall $unismall \_]
81 $graphic = [$small $large $symbol $digit $special $unigraphic \:\"\']
84 $hexit = [$decdigit A-F a-f]
85 $symchar = [$symbol \:]
87 $idchar = [$small $large $digit \']
89 $docsym = [\| \^ \* \$]
91 @varid = $small $idchar*
92 @conid = $large $idchar*
94 @varsym = $symbol $symchar*
95 @consym = \: $symchar*
99 @hexadecimal = $hexit+
100 @exponent = [eE] [\-\+]? @decimal
102 -- we support the hierarchical module name extension:
105 @floating_point = @decimal \. @decimal @exponent? | @decimal @exponent
109 -- everywhere: skip whitespace and comments
112 -- Everywhere: deal with nested comments. We explicitly rule out
113 -- pragmas, "{-#", so that we don't accidentally treat them as comments.
114 -- (this can happen even though pragmas will normally take precedence due to
115 -- longest-match, because pragmas aren't valid in every state, but comments
116 -- are). We also rule out nested Haddock comments, if the -haddock flag is
119 "{-" / { isNormalComment } { nested_comment lexToken }
121 -- Single-line comments are a bit tricky. Haskell 98 says that two or
122 -- more dashes followed by a symbol should be parsed as a varsym, so we
123 -- have to exclude those.
125 -- Since Haddock comments aren't valid in every state, we need to rule them
128 -- The following two rules match comments that begin with two dashes, but
129 -- continue with a different character. The rules test that this character
130 -- is not a symbol (in which case we'd have a varsym), and that it's not a
131 -- space followed by a Haddock comment symbol (docsym) (in which case we'd
132 -- have a Haddock comment). The rules then munch the rest of the line.
135 "--" [^$symbol : \ ] .* ;
137 -- Next, match Haddock comments if no -haddock flag
139 "-- " $docsym .* / { ifExtension (not . haddockEnabled) } ;
141 -- Now, when we've matched comments that begin with 2 dashes and continue
142 -- with a different character, we need to match comments that begin with three
143 -- or more dashes (which clearly can't be Haddock comments). We only need to
144 -- make sure that the first non-dash character isn't a symbol, and munch the
147 "---"\-* [^$symbol :] .* ;
149 -- Since the previous rules all match dashes followed by at least one
150 -- character, we also need to match a whole line filled with just dashes.
152 "--"\-* / { atEOL } ;
154 -- We need this rule since none of the other single line comment rules
155 -- actually match this case.
159 -- 'bol' state: beginning of a line. Slurp up all the whitespace (including
160 -- blank lines) until we find a non-whitespace character, then do layout
163 -- One slight wibble here: what if the line begins with {-#? In
164 -- theory, we have to lex the pragma to see if it's one we recognise,
165 -- and if it is, then we backtrack and do_bol, otherwise we treat it
166 -- as a nested comment. We don't bother with this: if the line begins
167 -- with {-#, then we'll assume it's a pragma we know about and go for do_bol.
170 ^\# (line)? { begin line_prag1 }
171 ^\# pragma .* \n ; -- GCC 3.3 CPP generated, apparently
172 ^\# \! .* \n ; -- #!, for scripts
176 -- after a layout keyword (let, where, do, of), we begin a new layout
177 -- context if the curly brace is missing.
178 -- Careful! This stuff is quite delicate.
179 <layout, layout_do> {
180 \{ / { notFollowedBy '-' } { pop_and open_brace }
181 -- we might encounter {-# here, but {- has been handled already
183 ^\# (line)? { begin line_prag1 }
186 -- do is treated in a subtly different way, see new_layout_context
187 <layout> () { new_layout_context True }
188 <layout_do> () { new_layout_context False }
190 -- after a new layout context which was found to be to the left of the
191 -- previous context, we have generated a '{' token, and we now need to
192 -- generate a matching '}' token.
193 <layout_left> () { do_layout_left }
195 <0,option_prags,glaexts> \n { begin bol }
197 "{-#" $whitechar* (line|LINE) { begin line_prag2 }
199 -- single-line line pragmas, of the form
200 -- # <line> "<file>" <extra-stuff> \n
201 <line_prag1> $decdigit+ { setLine line_prag1a }
202 <line_prag1a> \" [$graphic \ ]* \" { setFile line_prag1b }
203 <line_prag1b> .* { pop }
205 -- Haskell-style line pragmas, of the form
206 -- {-# LINE <line> "<file>" #-}
207 <line_prag2> $decdigit+ { setLine line_prag2a }
208 <line_prag2a> \" [$graphic \ ]* \" { setFile line_prag2b }
209 <line_prag2b> "#-}"|"-}" { pop }
210 -- NOTE: accept -} at the end of a LINE pragma, for compatibility
211 -- with older versions of GHC which generated these.
213 -- We only want RULES pragmas to be picked up when -fglasgow-exts
214 -- is on, because the contents of the pragma is always written using
215 -- glasgow-exts syntax (using forall etc.), so if glasgow exts are not
216 -- enabled, we're sure to get a parse error.
217 -- (ToDo: we should really emit a warning when ignoring pragmas)
219 "{-#" $whitechar* (RULES|rules) { token ITrules_prag }
221 <0,option_prags,glaexts> {
222 "{-#" $whitechar* (INLINE|inline) { token (ITinline_prag True) }
223 "{-#" $whitechar* (NO(T?)INLINE|no(t?)inline)
224 { token (ITinline_prag False) }
225 "{-#" $whitechar* (SPECIALI[SZ]E|speciali[sz]e)
226 { token ITspec_prag }
227 "{-#" $whitechar* (SPECIALI[SZ]E|speciali[sz]e)
228 $whitechar* (INLINE|inline) { token (ITspec_inline_prag True) }
229 "{-#" $whitechar* (SPECIALI[SZ]E|speciali[sz]e)
230 $whitechar* (NO(T?)INLINE|no(t?)inline)
231 { token (ITspec_inline_prag False) }
232 "{-#" $whitechar* (SOURCE|source) { token ITsource_prag }
233 "{-#" $whitechar* (DEPRECATED|deprecated)
234 { token ITdeprecated_prag }
235 "{-#" $whitechar* (SCC|scc) { token ITscc_prag }
236 "{-#" $whitechar* (GENERATED|generated)
237 { token ITgenerated_prag }
238 "{-#" $whitechar* (CORE|core) { token ITcore_prag }
239 "{-#" $whitechar* (UNPACK|unpack) { token ITunpack_prag }
241 "{-#" $whitechar* (DOCOPTIONS|docoptions)
242 / { ifExtension haddockEnabled } { lex_string_prag ITdocOptions }
244 "{-#" { nested_comment lexToken }
246 -- ToDo: should only be valid inside a pragma:
247 "#-}" { token ITclose_prag}
251 "{-#" $whitechar* (OPTIONS|options) { lex_string_prag IToptions_prag }
252 "{-#" $whitechar* (OPTIONS_GHC|options_ghc)
253 { lex_string_prag IToptions_prag }
254 "{-#" $whitechar* (LANGUAGE|language) { token ITlanguage_prag }
255 "{-#" $whitechar* (INCLUDE|include) { lex_string_prag ITinclude_prag }
258 <0,option_prags,glaexts> {
259 -- This is to catch things like {-# OPTIONS OPTIONS_HUGS ...
260 "{-#" $whitechar* $idchar+ { nested_comment lexToken }
263 -- '0' state: ordinary lexemes
264 -- 'glaexts' state: glasgow extensions (postfix '#', etc.)
269 "-- " / $docsym { multiline_doc_comment }
270 "{-" \ ? / $docsym { nested_doc_comment }
276 "[:" / { ifExtension parrEnabled } { token ITopabrack }
277 ":]" / { ifExtension parrEnabled } { token ITcpabrack }
281 "[|" / { ifExtension thEnabled } { token ITopenExpQuote }
282 "[e|" / { ifExtension thEnabled } { token ITopenExpQuote }
283 "[p|" / { ifExtension thEnabled } { token ITopenPatQuote }
284 "[d|" / { ifExtension thEnabled } { layout_token ITopenDecQuote }
285 "[t|" / { ifExtension thEnabled } { token ITopenTypQuote }
286 "|]" / { ifExtension thEnabled } { token ITcloseQuote }
287 \$ @varid / { ifExtension thEnabled } { skip_one_varid ITidEscape }
288 "$(" / { ifExtension thEnabled } { token ITparenEscape }
292 "(|" / { ifExtension arrowsEnabled `alexAndPred` notFollowedBySymbol }
293 { special IToparenbar }
294 "|)" / { ifExtension arrowsEnabled } { special ITcparenbar }
298 \? @varid / { ifExtension ipEnabled } { skip_one_varid ITdupipvarid }
302 "(#" / { notFollowedBySymbol } { token IToubxparen }
303 "#)" { token ITcubxparen }
304 "{|" { token ITocurlybar }
305 "|}" { token ITccurlybar }
308 <0,option_prags,glaexts> {
309 \( { special IToparen }
310 \) { special ITcparen }
311 \[ { special ITobrack }
312 \] { special ITcbrack }
313 \, { special ITcomma }
314 \; { special ITsemi }
315 \` { special ITbackquote }
321 <0,option_prags,glaexts> {
322 @qual @varid { check_qvarid }
323 @qual @conid { idtoken qconid }
325 @conid { idtoken conid }
328 -- after an illegal qvarid, such as 'M.let',
329 -- we back up and try again in the bad_qvarid state:
331 @conid { pop_and (idtoken conid) }
332 @qual @conid { pop_and (idtoken qconid) }
336 @qual @varid "#"+ { idtoken qvarid }
337 @qual @conid "#"+ { idtoken qconid }
338 @varid "#"+ { varid }
339 @conid "#"+ { idtoken conid }
345 @qual @varsym { idtoken qvarsym }
346 @qual @consym { idtoken qconsym }
352 @decimal { tok_decimal }
353 0[oO] @octal { tok_octal }
354 0[xX] @hexadecimal { tok_hexadecimal }
358 @decimal \# { prim_decimal }
359 0[oO] @octal \# { prim_octal }
360 0[xX] @hexadecimal \# { prim_hexadecimal }
363 <0,glaexts> @floating_point { strtoken tok_float }
364 <glaexts> @floating_point \# { init_strtoken 1 prim_float }
365 <glaexts> @floating_point \# \# { init_strtoken 2 prim_double }
367 -- Strings and chars are lexed by hand-written code. The reason is
368 -- that even if we recognise the string or char here in the regex
369 -- lexer, we would still have to parse the string afterward in order
370 -- to convert it to a String.
373 \" { lex_string_tok }
377 -- work around bug in Alex 2.0
378 #if __GLASGOW_HASKELL__ < 503
379 unsafeAt arr i = arr ! i
382 -- -----------------------------------------------------------------------------
386 = ITas -- Haskell keywords
411 | ITscc -- ToDo: remove (we use {-# SCC "..." #-} now)
413 | ITforall -- GHC extension keywords
429 | ITinline_prag Bool -- True <=> INLINE, False <=> NOINLINE
430 | ITspec_prag -- SPECIALISE
431 | ITspec_inline_prag Bool -- SPECIALISE INLINE (or NOINLINE)
438 | ITcore_prag -- hdaume: core annotations
441 | IToptions_prag String
442 | ITinclude_prag String
445 | ITdotdot -- reserved symbols
461 | ITbiglam -- GHC-extension symbols
463 | ITocurly -- special symbols
465 | ITocurlybar -- {|, for type applications
466 | ITccurlybar -- |}, for type applications
470 | ITopabrack -- [:, for parallel arrays with -fparr
471 | ITcpabrack -- :], for parallel arrays with -fparr
482 | ITvarid FastString -- identifiers
484 | ITvarsym FastString
485 | ITconsym FastString
486 | ITqvarid (FastString,FastString)
487 | ITqconid (FastString,FastString)
488 | ITqvarsym (FastString,FastString)
489 | ITqconsym (FastString,FastString)
491 | ITdupipvarid FastString -- GHC extension: implicit param: ?x
493 | ITpragma StringBuffer
496 | ITstring FastString
498 | ITrational Rational
501 | ITprimstring FastString
503 | ITprimfloat Rational
504 | ITprimdouble Rational
506 -- MetaHaskell extension tokens
507 | ITopenExpQuote -- [| or [e|
508 | ITopenPatQuote -- [p|
509 | ITopenDecQuote -- [d|
510 | ITopenTypQuote -- [t|
512 | ITidEscape FastString -- $x
513 | ITparenEscape -- $(
517 -- Arrow notation extension
524 | ITLarrowtail -- -<<
525 | ITRarrowtail -- >>-
527 | ITunknown String -- Used when the lexer can't make sense of it
528 | ITeof -- end of file token
530 -- Documentation annotations
531 | ITdocCommentNext String -- something beginning '-- |'
532 | ITdocCommentPrev String -- something beginning '-- ^'
533 | ITdocCommentNamed String -- something beginning '-- $'
534 | ITdocSection Int String -- a section heading
535 | ITdocOptions String -- doc options (prune, ignore-exports, etc)
538 deriving Show -- debugging
541 isSpecial :: Token -> Bool
542 -- If we see M.x, where x is a keyword, but
543 -- is special, we treat is as just plain M.x,
545 isSpecial ITas = True
546 isSpecial IThiding = True
547 isSpecial ITderived = True
548 isSpecial ITqualified = True
549 isSpecial ITforall = True
550 isSpecial ITexport = True
551 isSpecial ITlabel = True
552 isSpecial ITdynamic = True
553 isSpecial ITsafe = True
554 isSpecial ITthreadsafe = True
555 isSpecial ITunsafe = True
556 isSpecial ITccallconv = True
557 isSpecial ITstdcallconv = True
558 isSpecial ITmdo = True
559 isSpecial ITiso = True
560 isSpecial ITfamily = True
563 -- the bitmap provided as the third component indicates whether the
564 -- corresponding extension keyword is valid under the extension options
565 -- provided to the compiler; if the extension corresponding to *any* of the
566 -- bits set in the bitmap is enabled, the keyword is valid (this setup
567 -- facilitates using a keyword in two different extensions that can be
568 -- activated independently)
570 reservedWordsFM = listToUFM $
571 map (\(x, y, z) -> (mkFastString x, (y, z)))
572 [( "_", ITunderscore, 0 ),
574 ( "case", ITcase, 0 ),
575 ( "class", ITclass, 0 ),
576 ( "data", ITdata, 0 ),
577 ( "default", ITdefault, 0 ),
578 ( "deriving", ITderiving, 0 ),
579 ( "derived", ITderived, 0 ),
581 ( "else", ITelse, 0 ),
582 ( "hiding", IThiding, 0 ),
584 ( "import", ITimport, 0 ),
586 ( "infix", ITinfix, 0 ),
587 ( "infixl", ITinfixl, 0 ),
588 ( "infixr", ITinfixr, 0 ),
589 ( "instance", ITinstance, 0 ),
591 ( "module", ITmodule, 0 ),
592 ( "newtype", ITnewtype, 0 ),
594 ( "qualified", ITqualified, 0 ),
595 ( "then", ITthen, 0 ),
596 ( "type", ITtype, 0 ),
597 ( "where", ITwhere, 0 ),
598 ( "_scc_", ITscc, 0 ), -- ToDo: remove
600 ( "forall", ITforall, bit tvBit),
601 ( "mdo", ITmdo, bit glaExtsBit),
602 ( "family", ITfamily, bit idxTysBit),
604 ( "foreign", ITforeign, bit ffiBit),
605 ( "export", ITexport, bit ffiBit),
606 ( "label", ITlabel, bit ffiBit),
607 ( "dynamic", ITdynamic, bit ffiBit),
608 ( "safe", ITsafe, bit ffiBit),
609 ( "threadsafe", ITthreadsafe, bit ffiBit),
610 ( "unsafe", ITunsafe, bit ffiBit),
611 ( "stdcall", ITstdcallconv, bit ffiBit),
612 ( "ccall", ITccallconv, bit ffiBit),
613 ( "dotnet", ITdotnet, bit ffiBit),
615 ( "rec", ITrec, bit arrowsBit),
616 ( "proc", ITproc, bit arrowsBit)
619 reservedSymsFM = listToUFM $
620 map (\ (x,y,z) -> (mkFastString x,(y,z)))
621 [ ("..", ITdotdot, 0)
622 ,(":", ITcolon, 0) -- (:) is a reserved op,
623 -- meaning only list cons
636 ,("*", ITstar, bit glaExtsBit .|.
637 bit idxTysBit) -- For data T (a::*) = MkT
638 ,(".", ITdot, bit tvBit) -- For 'forall a . t'
640 ,("-<", ITlarrowtail, bit arrowsBit)
641 ,(">-", ITrarrowtail, bit arrowsBit)
642 ,("-<<", ITLarrowtail, bit arrowsBit)
643 ,(">>-", ITRarrowtail, bit arrowsBit)
645 #if __GLASGOW_HASKELL__ >= 605
646 ,("λ", ITlam, bit glaExtsBit)
647 ,("∷", ITdcolon, bit glaExtsBit)
648 ,("⇒", ITdarrow, bit glaExtsBit)
649 ,("∀", ITforall, bit glaExtsBit)
650 ,("→", ITrarrow, bit glaExtsBit)
651 ,("←", ITlarrow, bit glaExtsBit)
652 ,("⋯", ITdotdot, bit glaExtsBit)
653 -- ToDo: ideally, → and ∷ should be "specials", so that they cannot
654 -- form part of a large operator. This would let us have a better
655 -- syntax for kinds: ɑ∷*→* would be a legal kind signature. (maybe).
659 -- -----------------------------------------------------------------------------
662 type Action = SrcSpan -> StringBuffer -> Int -> P (Located Token)
664 special :: Token -> Action
665 special tok span _buf len = return (L span tok)
667 token, layout_token :: Token -> Action
668 token t span buf len = return (L span t)
669 layout_token t span buf len = pushLexState layout >> return (L span t)
671 idtoken :: (StringBuffer -> Int -> Token) -> Action
672 idtoken f span buf len = return (L span $! (f buf len))
674 skip_one_varid :: (FastString -> Token) -> Action
675 skip_one_varid f span buf len
676 = return (L span $! f (lexemeToFastString (stepOn buf) (len-1)))
678 strtoken :: (String -> Token) -> Action
679 strtoken f span buf len =
680 return (L span $! (f $! lexemeToString buf len))
682 init_strtoken :: Int -> (String -> Token) -> Action
683 -- like strtoken, but drops the last N character(s)
684 init_strtoken drop f span buf len =
685 return (L span $! (f $! lexemeToString buf (len-drop)))
687 begin :: Int -> Action
688 begin code _span _str _len = do pushLexState code; lexToken
691 pop _span _buf _len = do popLexState; lexToken
693 pop_and :: Action -> Action
694 pop_and act span buf len = do popLexState; act span buf len
696 {-# INLINE nextCharIs #-}
697 nextCharIs buf p = not (atEnd buf) && p (currentChar buf)
699 notFollowedBy char _ _ _ (AI _ _ buf)
700 = nextCharIs buf (/=char)
702 notFollowedBySymbol _ _ _ (AI _ _ buf)
703 = nextCharIs buf (`notElem` "!#$%&*+./<=>?@\\^|-~")
705 isNormalComment bits _ _ (AI _ _ buf)
706 | haddockEnabled bits = notFollowedByDocOrPragma
707 | otherwise = nextCharIs buf (/='#')
709 notFollowedByDocOrPragma
710 = not $ spaceAndP buf (`nextCharIs` (`elem` "|^*$#"))
712 spaceAndP buf p = p buf || nextCharIs buf (==' ') && p (snd (nextChar buf))
714 haddockDisabledAnd p bits _ _ (AI _ _ buf)
715 = if haddockEnabled bits then False else (p buf)
717 atEOL _ _ _ (AI _ _ buf) = atEnd buf || currentChar buf == '\n'
719 ifExtension pred bits _ _ _ = pred bits
721 multiline_doc_comment :: Action
722 multiline_doc_comment span buf _len = withLexedDocType (worker "")
724 worker commentAcc input docType oneLine = case alexGetChar input of
726 | oneLine -> docCommentEnd input commentAcc docType buf span
727 | otherwise -> case checkIfCommentLine input' of
728 Just input -> worker ('\n':commentAcc) input docType False
729 Nothing -> docCommentEnd input commentAcc docType buf span
730 Just (c, input) -> worker (c:commentAcc) input docType oneLine
731 Nothing -> docCommentEnd input commentAcc docType buf span
733 checkIfCommentLine input = check (dropNonNewlineSpace input)
735 check input = case alexGetChar input of
736 Just ('-', input) -> case alexGetChar input of
737 Just ('-', input) -> case alexGetChar input of
738 Just (c, _) | c /= '-' -> Just input
743 dropNonNewlineSpace input = case alexGetChar input of
745 | isSpace c && c /= '\n' -> dropNonNewlineSpace input'
750 nested comments require traversing by hand, they can't be parsed
751 using regular expressions.
753 nested_comment :: P (Located Token) -> Action
754 nested_comment cont span _str _len = do
758 go 0 input = do setInput input; cont
759 go n input = case alexGetChar input of
760 Nothing -> errBrace input span
761 Just ('-',input) -> case alexGetChar input of
762 Nothing -> errBrace input span
763 Just ('\125',input) -> go (n-1) input
764 Just (c,_) -> go n input
765 Just ('\123',input) -> case alexGetChar input of
766 Nothing -> errBrace input span
767 Just ('-',input) -> go (n+1) input
768 Just (c,_) -> go n input
769 Just (c,input) -> go n input
771 nested_doc_comment :: Action
772 nested_doc_comment span buf _len = withLexedDocType (go "")
774 go commentAcc input docType _ = case alexGetChar input of
775 Nothing -> errBrace input span
776 Just ('-',input) -> case alexGetChar input of
777 Nothing -> errBrace input span
778 Just ('\125',input@(AI end _ buf2)) ->
779 docCommentEnd input commentAcc docType buf span
780 Just (c,_) -> go ('-':commentAcc) input docType False
781 Just ('\123', input) -> case alexGetChar input of
782 Nothing -> errBrace input span
783 Just ('-',input) -> do
785 let cont = do input <- getInput; go commentAcc input docType False
786 nested_comment cont span buf _len
787 Just (c,_) -> go ('\123':commentAcc) input docType False
788 Just (c,input) -> go (c:commentAcc) input docType False
790 withLexedDocType lexDocComment = do
792 case alexGetChar input of
793 Nothing -> error "Can't happen"
794 Just ('|', input) -> lexDocComment input ITdocCommentNext False
795 Just ('^', input) -> lexDocComment input ITdocCommentPrev False
796 Just ('$', input) -> lexDocComment input ITdocCommentNamed False
797 Just ('*', input) -> lexDocSection 1 input
799 lexDocSection n input = case alexGetChar input of
800 Just ('*', input) -> lexDocSection (n+1) input
801 Just (c, _) -> lexDocComment input (ITdocSection n) True
802 Nothing -> do setInput input; lexToken -- eof reached, lex it normally
805 -------------------------------------------------------------------------------
806 -- This function is quite tricky. We can't just return a new token, we also
807 -- need to update the state of the parser. Why? Because the token is longer
808 -- than what was lexed by Alex, and the lexToken function doesn't know this, so
809 -- it writes the wrong token length to the parser state. This function is
810 -- called afterwards, so it can just update the state.
812 -- This is complicated by the fact that Haddock tokens can span multiple lines,
813 -- which is something that the original lexer didn't account for.
814 -- I have added last_line_len in the parser state which represents the length
815 -- of the part of the token that is on the last line. It is now used for layout
816 -- calculation in pushCurrentContext instead of last_len. last_len is, like it
817 -- was before, the full length of the token, and it is now only used for error
820 docCommentEnd :: AlexInput -> String -> (String -> Token) -> StringBuffer ->
821 SrcSpan -> P (Located Token)
822 docCommentEnd input commentAcc docType buf span = do
824 let (AI loc last_offs nextBuf) = input
825 comment = reverse commentAcc
826 span' = mkSrcSpan (srcSpanStart span) loc
827 last_len = byteDiff buf nextBuf
829 last_line_len = if (last_offs - last_len < 0)
833 span `seq` setLastToken span' last_len last_line_len
834 return (L span' (docType comment))
836 errBrace (AI end _ _) span = failLocMsgP (srcSpanStart span) end "unterminated `{-'"
838 open_brace, close_brace :: Action
839 open_brace span _str _len = do
841 setContext (NoLayout:ctx)
842 return (L span ITocurly)
843 close_brace span _str _len = do
845 return (L span ITccurly)
847 -- We have to be careful not to count M.<varid> as a qualified name
848 -- when <varid> is a keyword. We hack around this by catching
849 -- the offending tokens afterward, and re-lexing in a different state.
850 check_qvarid span buf len = do
851 case lookupUFM reservedWordsFM var of
853 | not (isSpecial keyword) ->
857 b <- extension (\i -> exts .&. i /= 0)
860 _other -> return token
862 (mod,var) = splitQualName buf len
863 token = L span (ITqvarid (mod,var))
866 (AI _ offs _) <- getInput
867 setInput (AI (srcSpanStart span) (offs-len) buf)
868 pushLexState bad_qvarid
871 qvarid buf len = ITqvarid $! splitQualName buf len
872 qconid buf len = ITqconid $! splitQualName buf len
874 splitQualName :: StringBuffer -> Int -> (FastString,FastString)
875 -- takes a StringBuffer and a length, and returns the module name
876 -- and identifier parts of a qualified name. Splits at the *last* dot,
877 -- because of hierarchical module names.
878 splitQualName orig_buf len = split orig_buf orig_buf
881 | orig_buf `byteDiff` buf >= len = done dot_buf
882 | c == '.' = found_dot buf'
883 | otherwise = split buf' dot_buf
885 (c,buf') = nextChar buf
887 -- careful, we might get names like M....
888 -- so, if the character after the dot is not upper-case, this is
889 -- the end of the qualifier part.
890 found_dot buf -- buf points after the '.'
891 | isUpper c = split buf' buf
892 | otherwise = done buf
894 (c,buf') = nextChar buf
897 (lexemeToFastString orig_buf (qual_size - 1),
898 lexemeToFastString dot_buf (len - qual_size))
900 qual_size = orig_buf `byteDiff` dot_buf
903 case lookupUFM reservedWordsFM fs of
904 Just (keyword,0) -> do
906 return (L span keyword)
907 Just (keyword,exts) -> do
908 b <- extension (\i -> exts .&. i /= 0)
909 if b then do maybe_layout keyword
910 return (L span keyword)
911 else return (L span (ITvarid fs))
912 _other -> return (L span (ITvarid fs))
914 fs = lexemeToFastString buf len
916 conid buf len = ITconid fs
917 where fs = lexemeToFastString buf len
919 qvarsym buf len = ITqvarsym $! splitQualName buf len
920 qconsym buf len = ITqconsym $! splitQualName buf len
922 varsym = sym ITvarsym
923 consym = sym ITconsym
925 sym con span buf len =
926 case lookupUFM reservedSymsFM fs of
927 Just (keyword,0) -> return (L span keyword)
928 Just (keyword,exts) -> do
929 b <- extension (\i -> exts .&. i /= 0)
930 if b then return (L span keyword)
931 else return (L span $! con fs)
932 _other -> return (L span $! con fs)
934 fs = lexemeToFastString buf len
936 tok_decimal span buf len
937 = return (L span (ITinteger $! parseInteger buf len 10 octDecDigit))
939 tok_octal span buf len
940 = return (L span (ITinteger $! parseInteger (offsetBytes 2 buf) (len-2) 8 octDecDigit))
942 tok_hexadecimal span buf len
943 = return (L span (ITinteger $! parseInteger (offsetBytes 2 buf) (len-2) 16 hexDigit))
945 prim_decimal span buf len
946 = return (L span (ITprimint $! parseInteger buf (len-1) 10 octDecDigit))
948 prim_octal span buf len
949 = return (L span (ITprimint $! parseInteger (offsetBytes 2 buf) (len-3) 8 octDecDigit))
951 prim_hexadecimal span buf len
952 = return (L span (ITprimint $! parseInteger (offsetBytes 2 buf) (len-3) 16 hexDigit))
954 tok_float str = ITrational $! readRational str
955 prim_float str = ITprimfloat $! readRational str
956 prim_double str = ITprimdouble $! readRational str
958 -- -----------------------------------------------------------------------------
961 -- we're at the first token on a line, insert layout tokens if necessary
963 do_bol span _str _len = do
967 --trace "layout: inserting '}'" $ do
969 -- do NOT pop the lex state, we might have a ';' to insert
970 return (L span ITvccurly)
972 --trace "layout: inserting ';'" $ do
974 return (L span ITsemi)
979 -- certain keywords put us in the "layout" state, where we might
980 -- add an opening curly brace.
981 maybe_layout ITdo = pushLexState layout_do
982 maybe_layout ITmdo = pushLexState layout_do
983 maybe_layout ITof = pushLexState layout
984 maybe_layout ITlet = pushLexState layout
985 maybe_layout ITwhere = pushLexState layout
986 maybe_layout ITrec = pushLexState layout
987 maybe_layout _ = return ()
989 -- Pushing a new implicit layout context. If the indentation of the
990 -- next token is not greater than the previous layout context, then
991 -- Haskell 98 says that the new layout context should be empty; that is
992 -- the lexer must generate {}.
994 -- We are slightly more lenient than this: when the new context is started
995 -- by a 'do', then we allow the new context to be at the same indentation as
996 -- the previous context. This is what the 'strict' argument is for.
998 new_layout_context strict span _buf _len = do
1000 (AI _ offset _) <- getInput
1003 Layout prev_off : _ |
1004 (strict && prev_off >= offset ||
1005 not strict && prev_off > offset) -> do
1006 -- token is indented to the left of the previous context.
1007 -- we must generate a {} sequence now.
1008 pushLexState layout_left
1009 return (L span ITvocurly)
1011 setContext (Layout offset : ctx)
1012 return (L span ITvocurly)
1014 do_layout_left span _buf _len = do
1016 pushLexState bol -- we must be at the start of a line
1017 return (L span ITvccurly)
1019 -- -----------------------------------------------------------------------------
1022 setLine :: Int -> Action
1023 setLine code span buf len = do
1024 let line = parseInteger buf len 10 octDecDigit
1025 setSrcLoc (mkSrcLoc (srcSpanFile span) (fromIntegral line - 1) 0)
1026 -- subtract one: the line number refers to the *following* line
1031 setFile :: Int -> Action
1032 setFile code span buf len = do
1033 let file = lexemeToFastString (stepOn buf) (len-2)
1034 setSrcLoc (mkSrcLoc file (srcSpanEndLine span) (srcSpanEndCol span))
1040 -- -----------------------------------------------------------------------------
1041 -- Options, includes and language pragmas.
1043 lex_string_prag :: (String -> Token) -> Action
1044 lex_string_prag mkTok span buf len
1045 = do input <- getInput
1049 return (L (mkSrcSpan start end) tok)
1051 = if isString input "#-}"
1052 then do setInput input
1053 return (mkTok (reverse acc))
1054 else case alexGetChar input of
1055 Just (c,i) -> go (c:acc) i
1056 Nothing -> err input
1057 isString i [] = True
1059 = case alexGetChar i of
1060 Just (c,i') | c == x -> isString i' xs
1062 err (AI end _ _) = failLocMsgP (srcSpanStart span) end "unterminated options pragma"
1065 -- -----------------------------------------------------------------------------
1068 -- This stuff is horrible. I hates it.
1070 lex_string_tok :: Action
1071 lex_string_tok span buf len = do
1072 tok <- lex_string ""
1074 return (L (mkSrcSpan (srcSpanStart span) end) tok)
1076 lex_string :: String -> P Token
1079 case alexGetChar' i of
1080 Nothing -> lit_error
1084 glaexts <- extension glaExtsEnabled
1088 case alexGetChar' i of
1092 then failMsgP "primitive string literal must contain only characters <= \'\\xFF\'"
1093 else let s' = mkZFastString (reverse s) in
1094 return (ITprimstring s')
1095 -- mkZFastString is a hack to avoid encoding the
1096 -- string in UTF-8. We just want the exact bytes.
1098 return (ITstring (mkFastString (reverse s)))
1100 return (ITstring (mkFastString (reverse s)))
1103 | Just ('&',i) <- next -> do
1104 setInput i; lex_string s
1105 | Just (c,i) <- next, is_space c -> do
1106 setInput i; lex_stringgap s
1107 where next = alexGetChar' i
1113 lex_stringgap s = do
1116 '\\' -> lex_string s
1117 c | is_space c -> lex_stringgap s
1121 lex_char_tok :: Action
1122 -- Here we are basically parsing character literals, such as 'x' or '\n'
1123 -- but, when Template Haskell is on, we additionally spot
1124 -- 'x and ''T, returning ITvarQuote and ITtyQuote respectively,
1125 -- but WIHTOUT CONSUMING the x or T part (the parser does that).
1126 -- So we have to do two characters of lookahead: when we see 'x we need to
1127 -- see if there's a trailing quote
1128 lex_char_tok span buf len = do -- We've seen '
1129 i1 <- getInput -- Look ahead to first character
1130 let loc = srcSpanStart span
1131 case alexGetChar' i1 of
1132 Nothing -> lit_error
1134 Just ('\'', i2@(AI end2 _ _)) -> do -- We've seen ''
1135 th_exts <- extension thEnabled
1138 return (L (mkSrcSpan loc end2) ITtyQuote)
1141 Just ('\\', i2@(AI end2 _ _)) -> do -- We've seen 'backslash
1143 lit_ch <- lex_escape
1144 mc <- getCharOrFail -- Trailing quote
1145 if mc == '\'' then finish_char_tok loc lit_ch
1146 else do setInput i2; lit_error
1148 Just (c, i2@(AI end2 _ _))
1149 | not (isAny c) -> lit_error
1152 -- We've seen 'x, where x is a valid character
1153 -- (i.e. not newline etc) but not a quote or backslash
1154 case alexGetChar' i2 of -- Look ahead one more character
1155 Nothing -> lit_error
1156 Just ('\'', i3) -> do -- We've seen 'x'
1158 finish_char_tok loc c
1159 _other -> do -- We've seen 'x not followed by quote
1160 -- If TH is on, just parse the quote only
1161 th_exts <- extension thEnabled
1162 let (AI end _ _) = i1
1163 if th_exts then return (L (mkSrcSpan loc end) ITvarQuote)
1164 else do setInput i2; lit_error
1166 finish_char_tok :: SrcLoc -> Char -> P (Located Token)
1167 finish_char_tok loc ch -- We've already seen the closing quote
1168 -- Just need to check for trailing #
1169 = do glaexts <- extension glaExtsEnabled
1170 i@(AI end _ _) <- getInput
1172 case alexGetChar' i of
1173 Just ('#',i@(AI end _ _)) -> do
1175 return (L (mkSrcSpan loc end) (ITprimchar ch))
1177 return (L (mkSrcSpan loc end) (ITchar ch))
1179 return (L (mkSrcSpan loc end) (ITchar ch))
1181 lex_char :: Char -> AlexInput -> P Char
1184 '\\' -> do setInput inp; lex_escape
1185 c | isAny c -> do setInput inp; return c
1188 isAny c | c > '\xff' = isPrint c
1189 | otherwise = is_any c
1191 lex_escape :: P Char
1205 '^' -> do c <- getCharOrFail
1206 if c >= '@' && c <= '_'
1207 then return (chr (ord c - ord '@'))
1210 'x' -> readNum is_hexdigit 16 hexDigit
1211 'o' -> readNum is_octdigit 8 octDecDigit
1212 x | is_digit x -> readNum2 is_digit 10 octDecDigit (octDecDigit x)
1216 case alexGetChar' i of
1217 Nothing -> lit_error
1219 case alexGetChar' i2 of
1220 Nothing -> do setInput i2; lit_error
1222 let str = [c1,c2,c3] in
1223 case [ (c,rest) | (p,c) <- silly_escape_chars,
1224 Just rest <- [maybePrefixMatch p str] ] of
1225 (escape_char,[]):_ -> do
1228 (escape_char,_:_):_ -> do
1233 readNum :: (Char -> Bool) -> Int -> (Char -> Int) -> P Char
1234 readNum is_digit base conv = do
1238 then readNum2 is_digit base conv (conv c)
1239 else do setInput i; lit_error
1241 readNum2 is_digit base conv i = do
1244 where read i input = do
1245 case alexGetChar' input of
1246 Just (c,input') | is_digit c -> do
1247 read (i*base + conv c) input'
1249 if i >= 0 && i <= 0x10FFFF
1250 then do setInput input; return (chr i)
1253 silly_escape_chars = [
1290 -- before calling lit_error, ensure that the current input is pointing to
1291 -- the position of the error in the buffer. This is so that we can report
1292 -- a correct location to the user, but also so we can detect UTF-8 decoding
1293 -- errors if they occur.
1294 lit_error = lexError "lexical error in string/character literal"
1296 getCharOrFail :: P Char
1299 case alexGetChar' i of
1300 Nothing -> lexError "unexpected end-of-file in string/character literal"
1301 Just (c,i) -> do setInput i; return c
1303 -- -----------------------------------------------------------------------------
1314 SrcSpan -- The start and end of the text span related to
1315 -- the error. Might be used in environments which can
1316 -- show this span, e.g. by highlighting it.
1317 Message -- The error message
1319 data PState = PState {
1320 buffer :: StringBuffer,
1321 last_loc :: SrcSpan, -- pos of previous token
1322 last_offs :: !Int, -- offset of the previous token from the
1323 -- beginning of the current line.
1324 -- \t is equal to 8 spaces.
1325 last_len :: !Int, -- len of previous token
1326 last_line_len :: !Int,
1327 loc :: SrcLoc, -- current loc (end of prev token + 1)
1328 extsBitmap :: !Int, -- bitmap that determines permitted extensions
1329 context :: [LayoutContext],
1332 -- last_loc and last_len are used when generating error messages,
1333 -- and in pushCurrentContext only. Sigh, if only Happy passed the
1334 -- current token to happyError, we could at least get rid of last_len.
1335 -- Getting rid of last_loc would require finding another way to
1336 -- implement pushCurrentContext (which is only called from one place).
1338 newtype P a = P { unP :: PState -> ParseResult a }
1340 instance Monad P where
1346 returnP a = P $ \s -> POk s a
1348 thenP :: P a -> (a -> P b) -> P b
1349 (P m) `thenP` k = P $ \ s ->
1351 POk s1 a -> (unP (k a)) s1
1352 PFailed span err -> PFailed span err
1354 failP :: String -> P a
1355 failP msg = P $ \s -> PFailed (last_loc s) (text msg)
1357 failMsgP :: String -> P a
1358 failMsgP msg = P $ \s -> PFailed (last_loc s) (text msg)
1360 failLocMsgP :: SrcLoc -> SrcLoc -> String -> P a
1361 failLocMsgP loc1 loc2 str = P $ \s -> PFailed (mkSrcSpan loc1 loc2) (text str)
1363 failSpanMsgP :: SrcSpan -> String -> P a
1364 failSpanMsgP span msg = P $ \s -> PFailed span (text msg)
1366 extension :: (Int -> Bool) -> P Bool
1367 extension p = P $ \s -> POk s (p $! extsBitmap s)
1370 getExts = P $ \s -> POk s (extsBitmap s)
1372 setSrcLoc :: SrcLoc -> P ()
1373 setSrcLoc new_loc = P $ \s -> POk s{loc=new_loc} ()
1375 getSrcLoc :: P SrcLoc
1376 getSrcLoc = P $ \s@(PState{ loc=loc }) -> POk s loc
1378 setLastToken :: SrcSpan -> Int -> Int -> P ()
1379 setLastToken loc len line_len = P $ \s -> POk s {
1382 last_line_len=line_len
1385 data AlexInput = AI SrcLoc {-#UNPACK#-}!Int StringBuffer
1387 alexInputPrevChar :: AlexInput -> Char
1388 alexInputPrevChar (AI _ _ buf) = prevChar buf '\n'
1390 alexGetChar :: AlexInput -> Maybe (Char,AlexInput)
1391 alexGetChar (AI loc ofs s)
1393 | otherwise = adj_c `seq` loc' `seq` ofs' `seq` s' `seq`
1394 --trace (show (ord c)) $
1395 Just (adj_c, (AI loc' ofs' s'))
1396 where (c,s') = nextChar s
1397 loc' = advanceSrcLoc loc c
1398 ofs' = advanceOffs c ofs
1406 other_graphic = '\x6'
1409 | c <= '\x06' = non_graphic
1412 case generalCategory c of
1413 UppercaseLetter -> upper
1414 LowercaseLetter -> lower
1415 TitlecaseLetter -> upper
1416 ModifierLetter -> other_graphic
1417 OtherLetter -> other_graphic
1418 NonSpacingMark -> other_graphic
1419 SpacingCombiningMark -> other_graphic
1420 EnclosingMark -> other_graphic
1421 DecimalNumber -> digit
1422 LetterNumber -> other_graphic
1423 OtherNumber -> other_graphic
1424 ConnectorPunctuation -> other_graphic
1425 DashPunctuation -> other_graphic
1426 OpenPunctuation -> other_graphic
1427 ClosePunctuation -> other_graphic
1428 InitialQuote -> other_graphic
1429 FinalQuote -> other_graphic
1430 OtherPunctuation -> other_graphic
1431 MathSymbol -> symbol
1432 CurrencySymbol -> symbol
1433 ModifierSymbol -> symbol
1434 OtherSymbol -> symbol
1436 _other -> non_graphic
1438 -- This version does not squash unicode characters, it is used when
1440 alexGetChar' :: AlexInput -> Maybe (Char,AlexInput)
1441 alexGetChar' (AI loc ofs s)
1443 | otherwise = c `seq` loc' `seq` ofs' `seq` s' `seq`
1444 --trace (show (ord c)) $
1445 Just (c, (AI loc' ofs' s'))
1446 where (c,s') = nextChar s
1447 loc' = advanceSrcLoc loc c
1448 ofs' = advanceOffs c ofs
1450 advanceOffs :: Char -> Int -> Int
1451 advanceOffs '\n' offs = 0
1452 advanceOffs '\t' offs = (offs `quot` 8 + 1) * 8
1453 advanceOffs _ offs = offs + 1
1455 getInput :: P AlexInput
1456 getInput = P $ \s@PState{ loc=l, last_offs=o, buffer=b } -> POk s (AI l o b)
1458 setInput :: AlexInput -> P ()
1459 setInput (AI l o b) = P $ \s -> POk s{ loc=l, last_offs=o, buffer=b } ()
1461 pushLexState :: Int -> P ()
1462 pushLexState ls = P $ \s@PState{ lex_state=l } -> POk s{lex_state=ls:l} ()
1464 popLexState :: P Int
1465 popLexState = P $ \s@PState{ lex_state=ls:l } -> POk s{ lex_state=l } ls
1467 getLexState :: P Int
1468 getLexState = P $ \s@PState{ lex_state=ls:l } -> POk s ls
1470 -- for reasons of efficiency, flags indicating language extensions (eg,
1471 -- -fglasgow-exts or -fparr) are represented by a bitmap stored in an unboxed
1474 glaExtsBit, ffiBit, parrBit :: Int
1481 tvBit = 7 -- Scoped type variables enables 'forall' keyword
1482 bangPatBit = 8 -- Tells the parser to understand bang-patterns
1483 -- (doesn't affect the lexer)
1484 idxTysBit = 9 -- indexed type families: 'family' keyword and kind sigs
1485 haddockBit = 10 -- Lex and parse Haddock comments
1487 glaExtsEnabled, ffiEnabled, parrEnabled :: Int -> Bool
1488 glaExtsEnabled flags = testBit flags glaExtsBit
1489 ffiEnabled flags = testBit flags ffiBit
1490 parrEnabled flags = testBit flags parrBit
1491 arrowsEnabled flags = testBit flags arrowsBit
1492 thEnabled flags = testBit flags thBit
1493 ipEnabled flags = testBit flags ipBit
1494 tvEnabled flags = testBit flags tvBit
1495 bangPatEnabled flags = testBit flags bangPatBit
1496 idxTysEnabled flags = testBit flags idxTysBit
1497 haddockEnabled flags = testBit flags haddockBit
1499 -- PState for parsing options pragmas
1501 pragState :: StringBuffer -> SrcLoc -> PState
1505 last_loc = mkSrcSpan loc loc,
1512 lex_state = [bol, option_prags, 0]
1516 -- create a parse state
1518 mkPState :: StringBuffer -> SrcLoc -> DynFlags -> PState
1519 mkPState buf loc flags =
1522 last_loc = mkSrcSpan loc loc,
1527 extsBitmap = fromIntegral bitmap,
1529 lex_state = [bol, if glaExtsEnabled bitmap then glaexts else 0]
1530 -- we begin in the layout state if toplev_layout is set
1533 bitmap = glaExtsBit `setBitIf` dopt Opt_GlasgowExts flags
1534 .|. ffiBit `setBitIf` dopt Opt_FFI flags
1535 .|. parrBit `setBitIf` dopt Opt_PArr flags
1536 .|. arrowsBit `setBitIf` dopt Opt_Arrows flags
1537 .|. thBit `setBitIf` dopt Opt_TH flags
1538 .|. ipBit `setBitIf` dopt Opt_ImplicitParams flags
1539 .|. tvBit `setBitIf` dopt Opt_ScopedTypeVariables flags
1540 .|. bangPatBit `setBitIf` dopt Opt_BangPatterns flags
1541 .|. idxTysBit `setBitIf` dopt Opt_IndexedTypes flags
1542 .|. haddockBit `setBitIf` dopt Opt_Haddock flags
1544 setBitIf :: Int -> Bool -> Int
1545 b `setBitIf` cond | cond = bit b
1548 getContext :: P [LayoutContext]
1549 getContext = P $ \s@PState{context=ctx} -> POk s ctx
1551 setContext :: [LayoutContext] -> P ()
1552 setContext ctx = P $ \s -> POk s{context=ctx} ()
1555 popContext = P $ \ s@(PState{ buffer = buf, context = ctx,
1556 loc = loc, last_len = len, last_loc = last_loc }) ->
1558 (_:tl) -> POk s{ context = tl } ()
1559 [] -> PFailed last_loc (srcParseErr buf len)
1561 -- Push a new layout context at the indentation of the last token read.
1562 -- This is only used at the outer level of a module when the 'module'
1563 -- keyword is missing.
1564 pushCurrentContext :: P ()
1565 pushCurrentContext = P $ \ s@PState{ last_offs=offs, last_line_len=len, context=ctx } ->
1566 POk s{context = Layout (offs-len) : ctx} ()
1567 --trace ("off: " ++ show offs ++ ", len: " ++ show len) $ POk s{context = Layout (offs-len) : ctx} ()
1569 getOffside :: P Ordering
1570 getOffside = P $ \s@PState{last_offs=offs, context=stk} ->
1571 let ord = case stk of
1572 (Layout n:_) -> compare offs n
1576 -- ---------------------------------------------------------------------------
1577 -- Construct a parse error
1580 :: StringBuffer -- current buffer (placed just after the last token)
1581 -> Int -- length of the previous token
1584 = hcat [ if null token
1585 then ptext SLIT("parse error (possibly incorrect indentation)")
1586 else hcat [ptext SLIT("parse error on input "),
1587 char '`', text token, char '\'']
1589 where token = lexemeToString (offsetBytes (-len) buf) len
1591 -- Report a parse failure, giving the span of the previous token as
1592 -- the location of the error. This is the entry point for errors
1593 -- detected during parsing.
1595 srcParseFail = P $ \PState{ buffer = buf, last_len = len,
1596 last_loc = last_loc } ->
1597 PFailed last_loc (srcParseErr buf len)
1599 -- A lexical error is reported at a particular position in the source file,
1600 -- not over a token range.
1601 lexError :: String -> P a
1604 i@(AI end _ buf) <- getInput
1605 reportLexError loc end buf str
1607 -- -----------------------------------------------------------------------------
1608 -- This is the top-level function: called from the parser each time a
1609 -- new token is to be read from the input.
1611 lexer :: (Located Token -> P a) -> P a
1613 tok@(L span tok__) <- lexToken
1614 -- trace ("token: " ++ show tok__) $ do
1617 lexToken :: P (Located Token)
1619 inp@(AI loc1 _ buf) <- getInput
1622 case alexScanUser exts inp sc of
1623 AlexEOF -> do let span = mkSrcSpan loc1 loc1
1624 setLastToken span 0 0
1625 return (L span ITeof)
1626 AlexError (AI loc2 _ buf) -> do
1627 reportLexError loc1 loc2 buf "lexical error"
1628 AlexSkip inp2 _ -> do
1631 AlexToken inp2@(AI end _ buf2) len t -> do
1633 let span = mkSrcSpan loc1 end
1634 let bytes = byteDiff buf buf2
1635 span `seq` setLastToken span bytes bytes
1638 reportLexError loc1 loc2 buf str
1639 | atEnd buf = failLocMsgP loc1 loc2 (str ++ " at end of input")
1642 c = fst (nextChar buf)
1644 if c == '\0' -- decoding errors are mapped to '\0', see utf8DecodeChar#
1645 then failLocMsgP loc2 loc2 (str ++ " (UTF-8 decoding error)")
1646 else failLocMsgP loc1 loc2 (str ++ " at character " ++ show c)