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* (CORE|core) { token ITcore_prag }
237 "{-#" $whitechar* (UNPACK|unpack) { token ITunpack_prag }
239 "{-#" $whitechar* (DOCOPTIONS|docoptions)
240 / { ifExtension haddockEnabled } { lex_string_prag ITdocOptions }
242 "{-#" { nested_comment lexToken }
244 -- ToDo: should only be valid inside a pragma:
245 "#-}" { token ITclose_prag}
249 "{-#" $whitechar* (OPTIONS|options) { lex_string_prag IToptions_prag }
250 "{-#" $whitechar* (OPTIONS_GHC|options_ghc)
251 { lex_string_prag IToptions_prag }
252 "{-#" $whitechar* (LANGUAGE|language) { token ITlanguage_prag }
253 "{-#" $whitechar* (INCLUDE|include) { lex_string_prag ITinclude_prag }
256 <0,option_prags,glaexts> {
257 -- This is to catch things like {-# OPTIONS OPTIONS_HUGS ...
258 "{-#" $whitechar* $idchar+ { nested_comment lexToken }
261 -- '0' state: ordinary lexemes
262 -- 'glaexts' state: glasgow extensions (postfix '#', etc.)
267 "-- " / $docsym { multiline_doc_comment }
268 "{-" \ ? / $docsym { nested_doc_comment }
274 "[:" / { ifExtension parrEnabled } { token ITopabrack }
275 ":]" / { ifExtension parrEnabled } { token ITcpabrack }
279 "[|" / { ifExtension thEnabled } { token ITopenExpQuote }
280 "[e|" / { ifExtension thEnabled } { token ITopenExpQuote }
281 "[p|" / { ifExtension thEnabled } { token ITopenPatQuote }
282 "[d|" / { ifExtension thEnabled } { layout_token ITopenDecQuote }
283 "[t|" / { ifExtension thEnabled } { token ITopenTypQuote }
284 "|]" / { ifExtension thEnabled } { token ITcloseQuote }
285 \$ @varid / { ifExtension thEnabled } { skip_one_varid ITidEscape }
286 "$(" / { ifExtension thEnabled } { token ITparenEscape }
290 "(|" / { ifExtension arrowsEnabled `alexAndPred` notFollowedBySymbol }
291 { special IToparenbar }
292 "|)" / { ifExtension arrowsEnabled } { special ITcparenbar }
296 \? @varid / { ifExtension ipEnabled } { skip_one_varid ITdupipvarid }
300 "(#" / { notFollowedBySymbol } { token IToubxparen }
301 "#)" { token ITcubxparen }
302 "{|" { token ITocurlybar }
303 "|}" { token ITccurlybar }
306 <0,option_prags,glaexts> {
307 \( { special IToparen }
308 \) { special ITcparen }
309 \[ { special ITobrack }
310 \] { special ITcbrack }
311 \, { special ITcomma }
312 \; { special ITsemi }
313 \` { special ITbackquote }
319 <0,option_prags,glaexts> {
320 @qual @varid { check_qvarid }
321 @qual @conid { idtoken qconid }
323 @conid { idtoken conid }
326 -- after an illegal qvarid, such as 'M.let',
327 -- we back up and try again in the bad_qvarid state:
329 @conid { pop_and (idtoken conid) }
330 @qual @conid { pop_and (idtoken qconid) }
334 @qual @varid "#"+ { idtoken qvarid }
335 @qual @conid "#"+ { idtoken qconid }
336 @varid "#"+ { varid }
337 @conid "#"+ { idtoken conid }
343 @qual @varsym { idtoken qvarsym }
344 @qual @consym { idtoken qconsym }
350 @decimal { tok_decimal }
351 0[oO] @octal { tok_octal }
352 0[xX] @hexadecimal { tok_hexadecimal }
356 @decimal \# { prim_decimal }
357 0[oO] @octal \# { prim_octal }
358 0[xX] @hexadecimal \# { prim_hexadecimal }
361 <0,glaexts> @floating_point { strtoken tok_float }
362 <glaexts> @floating_point \# { init_strtoken 1 prim_float }
363 <glaexts> @floating_point \# \# { init_strtoken 2 prim_double }
365 -- Strings and chars are lexed by hand-written code. The reason is
366 -- that even if we recognise the string or char here in the regex
367 -- lexer, we would still have to parse the string afterward in order
368 -- to convert it to a String.
371 \" { lex_string_tok }
375 -- work around bug in Alex 2.0
376 #if __GLASGOW_HASKELL__ < 503
377 unsafeAt arr i = arr ! i
380 -- -----------------------------------------------------------------------------
384 = ITas -- Haskell keywords
409 | ITscc -- ToDo: remove (we use {-# SCC "..." #-} now)
411 | ITforall -- GHC extension keywords
427 | ITinline_prag Bool -- True <=> INLINE, False <=> NOINLINE
428 | ITspec_prag -- SPECIALISE
429 | ITspec_inline_prag Bool -- SPECIALISE INLINE (or NOINLINE)
435 | ITcore_prag -- hdaume: core annotations
438 | IToptions_prag String
439 | ITinclude_prag String
442 | ITdotdot -- reserved symbols
458 | ITbiglam -- GHC-extension symbols
460 | ITocurly -- special symbols
462 | ITocurlybar -- {|, for type applications
463 | ITccurlybar -- |}, for type applications
467 | ITopabrack -- [:, for parallel arrays with -fparr
468 | ITcpabrack -- :], for parallel arrays with -fparr
479 | ITvarid FastString -- identifiers
481 | ITvarsym FastString
482 | ITconsym FastString
483 | ITqvarid (FastString,FastString)
484 | ITqconid (FastString,FastString)
485 | ITqvarsym (FastString,FastString)
486 | ITqconsym (FastString,FastString)
488 | ITdupipvarid FastString -- GHC extension: implicit param: ?x
490 | ITpragma StringBuffer
493 | ITstring FastString
495 | ITrational Rational
498 | ITprimstring FastString
500 | ITprimfloat Rational
501 | ITprimdouble Rational
503 -- MetaHaskell extension tokens
504 | ITopenExpQuote -- [| or [e|
505 | ITopenPatQuote -- [p|
506 | ITopenDecQuote -- [d|
507 | ITopenTypQuote -- [t|
509 | ITidEscape FastString -- $x
510 | ITparenEscape -- $(
514 -- Arrow notation extension
521 | ITLarrowtail -- -<<
522 | ITRarrowtail -- >>-
524 | ITunknown String -- Used when the lexer can't make sense of it
525 | ITeof -- end of file token
527 -- Documentation annotations
528 | ITdocCommentNext String -- something beginning '-- |'
529 | ITdocCommentPrev String -- something beginning '-- ^'
530 | ITdocCommentNamed String -- something beginning '-- $'
531 | ITdocSection Int String -- a section heading
532 | ITdocOptions String -- doc options (prune, ignore-exports, etc)
535 deriving Show -- debugging
538 isSpecial :: Token -> Bool
539 -- If we see M.x, where x is a keyword, but
540 -- is special, we treat is as just plain M.x,
542 isSpecial ITas = True
543 isSpecial IThiding = True
544 isSpecial ITfor = True
545 isSpecial ITqualified = True
546 isSpecial ITforall = True
547 isSpecial ITexport = True
548 isSpecial ITlabel = True
549 isSpecial ITdynamic = True
550 isSpecial ITsafe = True
551 isSpecial ITthreadsafe = True
552 isSpecial ITunsafe = True
553 isSpecial ITccallconv = True
554 isSpecial ITstdcallconv = True
555 isSpecial ITmdo = True
556 isSpecial ITiso = True
557 isSpecial ITfamily = True
560 -- the bitmap provided as the third component indicates whether the
561 -- corresponding extension keyword is valid under the extension options
562 -- provided to the compiler; if the extension corresponding to *any* of the
563 -- bits set in the bitmap is enabled, the keyword is valid (this setup
564 -- facilitates using a keyword in two different extensions that can be
565 -- activated independently)
567 reservedWordsFM = listToUFM $
568 map (\(x, y, z) -> (mkFastString x, (y, z)))
569 [( "_", ITunderscore, 0 ),
571 ( "case", ITcase, 0 ),
572 ( "class", ITclass, 0 ),
573 ( "data", ITdata, 0 ),
574 ( "default", ITdefault, 0 ),
575 ( "deriving", ITderiving, 0 ),
577 ( "else", ITelse, 0 ),
579 ( "hiding", IThiding, 0 ),
581 ( "import", ITimport, 0 ),
583 ( "infix", ITinfix, 0 ),
584 ( "infixl", ITinfixl, 0 ),
585 ( "infixr", ITinfixr, 0 ),
586 ( "instance", ITinstance, 0 ),
588 ( "module", ITmodule, 0 ),
589 ( "newtype", ITnewtype, 0 ),
591 ( "qualified", ITqualified, 0 ),
592 ( "then", ITthen, 0 ),
593 ( "type", ITtype, 0 ),
594 ( "where", ITwhere, 0 ),
595 ( "_scc_", ITscc, 0 ), -- ToDo: remove
597 ( "forall", ITforall, bit tvBit),
598 ( "mdo", ITmdo, bit glaExtsBit),
599 ( "family", ITfamily, bit idxTysBit),
601 ( "foreign", ITforeign, bit ffiBit),
602 ( "export", ITexport, bit ffiBit),
603 ( "label", ITlabel, bit ffiBit),
604 ( "dynamic", ITdynamic, bit ffiBit),
605 ( "safe", ITsafe, bit ffiBit),
606 ( "threadsafe", ITthreadsafe, bit ffiBit),
607 ( "unsafe", ITunsafe, bit ffiBit),
608 ( "stdcall", ITstdcallconv, bit ffiBit),
609 ( "ccall", ITccallconv, bit ffiBit),
610 ( "dotnet", ITdotnet, bit ffiBit),
612 ( "rec", ITrec, bit arrowsBit),
613 ( "proc", ITproc, bit arrowsBit)
616 reservedSymsFM = listToUFM $
617 map (\ (x,y,z) -> (mkFastString x,(y,z)))
618 [ ("..", ITdotdot, 0)
619 ,(":", ITcolon, 0) -- (:) is a reserved op,
620 -- meaning only list cons
633 ,("*", ITstar, bit glaExtsBit .|.
634 bit idxTysBit) -- For data T (a::*) = MkT
635 ,(".", ITdot, bit tvBit) -- For 'forall a . t'
637 ,("-<", ITlarrowtail, bit arrowsBit)
638 ,(">-", ITrarrowtail, bit arrowsBit)
639 ,("-<<", ITLarrowtail, bit arrowsBit)
640 ,(">>-", ITRarrowtail, bit arrowsBit)
642 #if __GLASGOW_HASKELL__ >= 605
643 ,("λ", ITlam, bit glaExtsBit)
644 ,("∷", ITdcolon, bit glaExtsBit)
645 ,("⇒", ITdarrow, bit glaExtsBit)
646 ,("∀", ITforall, bit glaExtsBit)
647 ,("→", ITrarrow, bit glaExtsBit)
648 ,("←", ITlarrow, bit glaExtsBit)
649 ,("⋯", ITdotdot, bit glaExtsBit)
650 -- ToDo: ideally, → and ∷ should be "specials", so that they cannot
651 -- form part of a large operator. This would let us have a better
652 -- syntax for kinds: ɑ∷*→* would be a legal kind signature. (maybe).
656 -- -----------------------------------------------------------------------------
659 type Action = SrcSpan -> StringBuffer -> Int -> P (Located Token)
661 special :: Token -> Action
662 special tok span _buf len = return (L span tok)
664 token, layout_token :: Token -> Action
665 token t span buf len = return (L span t)
666 layout_token t span buf len = pushLexState layout >> return (L span t)
668 idtoken :: (StringBuffer -> Int -> Token) -> Action
669 idtoken f span buf len = return (L span $! (f buf len))
671 skip_one_varid :: (FastString -> Token) -> Action
672 skip_one_varid f span buf len
673 = return (L span $! f (lexemeToFastString (stepOn buf) (len-1)))
675 strtoken :: (String -> Token) -> Action
676 strtoken f span buf len =
677 return (L span $! (f $! lexemeToString buf len))
679 init_strtoken :: Int -> (String -> Token) -> Action
680 -- like strtoken, but drops the last N character(s)
681 init_strtoken drop f span buf len =
682 return (L span $! (f $! lexemeToString buf (len-drop)))
684 begin :: Int -> Action
685 begin code _span _str _len = do pushLexState code; lexToken
688 pop _span _buf _len = do popLexState; lexToken
690 pop_and :: Action -> Action
691 pop_and act span buf len = do popLexState; act span buf len
693 {-# INLINE nextCharIs #-}
694 nextCharIs buf p = not (atEnd buf) && p (currentChar buf)
696 notFollowedBy char _ _ _ (AI _ _ buf)
697 = nextCharIs buf (/=char)
699 notFollowedBySymbol _ _ _ (AI _ _ buf)
700 = nextCharIs buf (`notElem` "!#$%&*+./<=>?@\\^|-~")
702 isNormalComment bits _ _ (AI _ _ buf)
703 | haddockEnabled bits = notFollowedByDocOrPragma
704 | otherwise = nextCharIs buf (/='#')
706 notFollowedByDocOrPragma
707 = not $ spaceAndP buf (`nextCharIs` (`elem` "|^*$#"))
709 spaceAndP buf p = p buf || nextCharIs buf (==' ') && p (snd (nextChar buf))
711 haddockDisabledAnd p bits _ _ (AI _ _ buf)
712 = if haddockEnabled bits then False else (p buf)
714 atEOL _ _ _ (AI _ _ buf) = atEnd buf || currentChar buf == '\n'
716 ifExtension pred bits _ _ _ = pred bits
718 multiline_doc_comment :: Action
719 multiline_doc_comment span buf _len = withLexedDocType (worker "")
721 worker commentAcc input docType oneLine = case alexGetChar input of
723 | oneLine -> docCommentEnd input commentAcc docType buf span
724 | otherwise -> case checkIfCommentLine input' of
725 Just input -> worker ('\n':commentAcc) input docType False
726 Nothing -> docCommentEnd input commentAcc docType buf span
727 Just (c, input) -> worker (c:commentAcc) input docType oneLine
728 Nothing -> docCommentEnd input commentAcc docType buf span
730 checkIfCommentLine input = check (dropNonNewlineSpace input)
732 check input = case alexGetChar input of
733 Just ('-', input) -> case alexGetChar input of
734 Just ('-', input) -> case alexGetChar input of
735 Just (c, _) | c /= '-' -> Just input
740 dropNonNewlineSpace input = case alexGetChar input of
742 | isSpace c && c /= '\n' -> dropNonNewlineSpace input'
747 nested comments require traversing by hand, they can't be parsed
748 using regular expressions.
750 nested_comment :: P (Located Token) -> Action
751 nested_comment cont span _str _len = do
755 go 0 input = do setInput input; cont
756 go n input = case alexGetChar input of
757 Nothing -> errBrace input span
758 Just ('-',input) -> case alexGetChar input of
759 Nothing -> errBrace input span
760 Just ('\125',input) -> go (n-1) input
761 Just (c,_) -> go n input
762 Just ('\123',input) -> case alexGetChar input of
763 Nothing -> errBrace input span
764 Just ('-',input) -> go (n+1) input
765 Just (c,_) -> go n input
766 Just (c,input) -> go n input
768 nested_doc_comment :: Action
769 nested_doc_comment span buf _len = withLexedDocType (go "")
771 go commentAcc input docType _ = case alexGetChar input of
772 Nothing -> errBrace input span
773 Just ('-',input) -> case alexGetChar input of
774 Nothing -> errBrace input span
775 Just ('\125',input@(AI end _ buf2)) ->
776 docCommentEnd input commentAcc docType buf span
777 Just (c,_) -> go ('-':commentAcc) input docType False
778 Just ('\123', input) -> case alexGetChar input of
779 Nothing -> errBrace input span
780 Just ('-',input) -> do
782 let cont = do input <- getInput; go commentAcc input docType False
783 nested_comment cont span buf _len
784 Just (c,_) -> go ('\123':commentAcc) input docType False
785 Just (c,input) -> go (c:commentAcc) input docType False
787 withLexedDocType lexDocComment = do
789 case alexGetChar input of
790 Nothing -> error "Can't happen"
791 Just ('|', input) -> lexDocComment input ITdocCommentNext False
792 Just ('^', input) -> lexDocComment input ITdocCommentPrev False
793 Just ('$', input) -> lexDocComment input ITdocCommentNamed False
794 Just ('*', input) -> lexDocSection 1 input
796 lexDocSection n input = case alexGetChar input of
797 Just ('*', input) -> lexDocSection (n+1) input
798 Just (c, _) -> lexDocComment input (ITdocSection n) True
799 Nothing -> do setInput input; lexToken -- eof reached, lex it normally
802 -------------------------------------------------------------------------------
803 -- This function is quite tricky. We can't just return a new token, we also
804 -- need to update the state of the parser. Why? Because the token is longer
805 -- than what was lexed by Alex, and the lexToken function doesn't know this, so
806 -- it writes the wrong token length to the parser state. This function is
807 -- called afterwards, so it can just update the state.
809 -- This is complicated by the fact that Haddock tokens can span multiple lines,
810 -- which is something that the original lexer didn't account for.
811 -- I have added last_line_len in the parser state which represents the length
812 -- of the part of the token that is on the last line. It is now used for layout
813 -- calculation in pushCurrentContext instead of last_len. last_len is, like it
814 -- was before, the full length of the token, and it is now only used for error
817 docCommentEnd :: AlexInput -> String -> (String -> Token) -> StringBuffer ->
818 SrcSpan -> P (Located Token)
819 docCommentEnd input commentAcc docType buf span = do
821 let (AI loc last_offs nextBuf) = input
822 comment = reverse commentAcc
823 span' = mkSrcSpan (srcSpanStart span) loc
824 last_len = byteDiff buf nextBuf
826 last_line_len = if (last_offs - last_len < 0)
830 span `seq` setLastToken span' last_len last_line_len
831 return (L span' (docType comment))
833 errBrace (AI end _ _) span = failLocMsgP (srcSpanStart span) end "unterminated `{-'"
835 open_brace, close_brace :: Action
836 open_brace span _str _len = do
838 setContext (NoLayout:ctx)
839 return (L span ITocurly)
840 close_brace span _str _len = do
842 return (L span ITccurly)
844 -- We have to be careful not to count M.<varid> as a qualified name
845 -- when <varid> is a keyword. We hack around this by catching
846 -- the offending tokens afterward, and re-lexing in a different state.
847 check_qvarid span buf len = do
848 case lookupUFM reservedWordsFM var of
850 | not (isSpecial keyword) ->
854 b <- extension (\i -> exts .&. i /= 0)
857 _other -> return token
859 (mod,var) = splitQualName buf len
860 token = L span (ITqvarid (mod,var))
863 (AI _ offs _) <- getInput
864 setInput (AI (srcSpanStart span) (offs-len) buf)
865 pushLexState bad_qvarid
868 qvarid buf len = ITqvarid $! splitQualName buf len
869 qconid buf len = ITqconid $! splitQualName buf len
871 splitQualName :: StringBuffer -> Int -> (FastString,FastString)
872 -- takes a StringBuffer and a length, and returns the module name
873 -- and identifier parts of a qualified name. Splits at the *last* dot,
874 -- because of hierarchical module names.
875 splitQualName orig_buf len = split orig_buf orig_buf
878 | orig_buf `byteDiff` buf >= len = done dot_buf
879 | c == '.' = found_dot buf'
880 | otherwise = split buf' dot_buf
882 (c,buf') = nextChar buf
884 -- careful, we might get names like M....
885 -- so, if the character after the dot is not upper-case, this is
886 -- the end of the qualifier part.
887 found_dot buf -- buf points after the '.'
888 | isUpper c = split buf' buf
889 | otherwise = done buf
891 (c,buf') = nextChar buf
894 (lexemeToFastString orig_buf (qual_size - 1),
895 lexemeToFastString dot_buf (len - qual_size))
897 qual_size = orig_buf `byteDiff` dot_buf
900 case lookupUFM reservedWordsFM fs of
901 Just (keyword,0) -> do
903 return (L span keyword)
904 Just (keyword,exts) -> do
905 b <- extension (\i -> exts .&. i /= 0)
906 if b then do maybe_layout keyword
907 return (L span keyword)
908 else return (L span (ITvarid fs))
909 _other -> return (L span (ITvarid fs))
911 fs = lexemeToFastString buf len
913 conid buf len = ITconid fs
914 where fs = lexemeToFastString buf len
916 qvarsym buf len = ITqvarsym $! splitQualName buf len
917 qconsym buf len = ITqconsym $! splitQualName buf len
919 varsym = sym ITvarsym
920 consym = sym ITconsym
922 sym con span buf len =
923 case lookupUFM reservedSymsFM fs of
924 Just (keyword,0) -> return (L span keyword)
925 Just (keyword,exts) -> do
926 b <- extension (\i -> exts .&. i /= 0)
927 if b then return (L span keyword)
928 else return (L span $! con fs)
929 _other -> return (L span $! con fs)
931 fs = lexemeToFastString buf len
933 tok_decimal span buf len
934 = return (L span (ITinteger $! parseInteger buf len 10 octDecDigit))
936 tok_octal span buf len
937 = return (L span (ITinteger $! parseInteger (offsetBytes 2 buf) (len-2) 8 octDecDigit))
939 tok_hexadecimal span buf len
940 = return (L span (ITinteger $! parseInteger (offsetBytes 2 buf) (len-2) 16 hexDigit))
942 prim_decimal span buf len
943 = return (L span (ITprimint $! parseInteger buf (len-1) 10 octDecDigit))
945 prim_octal span buf len
946 = return (L span (ITprimint $! parseInteger (offsetBytes 2 buf) (len-3) 8 octDecDigit))
948 prim_hexadecimal span buf len
949 = return (L span (ITprimint $! parseInteger (offsetBytes 2 buf) (len-3) 16 hexDigit))
951 tok_float str = ITrational $! readRational str
952 prim_float str = ITprimfloat $! readRational str
953 prim_double str = ITprimdouble $! readRational str
955 -- -----------------------------------------------------------------------------
958 -- we're at the first token on a line, insert layout tokens if necessary
960 do_bol span _str _len = do
964 --trace "layout: inserting '}'" $ do
966 -- do NOT pop the lex state, we might have a ';' to insert
967 return (L span ITvccurly)
969 --trace "layout: inserting ';'" $ do
971 return (L span ITsemi)
976 -- certain keywords put us in the "layout" state, where we might
977 -- add an opening curly brace.
978 maybe_layout ITdo = pushLexState layout_do
979 maybe_layout ITmdo = pushLexState layout_do
980 maybe_layout ITof = pushLexState layout
981 maybe_layout ITlet = pushLexState layout
982 maybe_layout ITwhere = pushLexState layout
983 maybe_layout ITrec = pushLexState layout
984 maybe_layout _ = return ()
986 -- Pushing a new implicit layout context. If the indentation of the
987 -- next token is not greater than the previous layout context, then
988 -- Haskell 98 says that the new layout context should be empty; that is
989 -- the lexer must generate {}.
991 -- We are slightly more lenient than this: when the new context is started
992 -- by a 'do', then we allow the new context to be at the same indentation as
993 -- the previous context. This is what the 'strict' argument is for.
995 new_layout_context strict span _buf _len = do
997 (AI _ offset _) <- getInput
1000 Layout prev_off : _ |
1001 (strict && prev_off >= offset ||
1002 not strict && prev_off > offset) -> do
1003 -- token is indented to the left of the previous context.
1004 -- we must generate a {} sequence now.
1005 pushLexState layout_left
1006 return (L span ITvocurly)
1008 setContext (Layout offset : ctx)
1009 return (L span ITvocurly)
1011 do_layout_left span _buf _len = do
1013 pushLexState bol -- we must be at the start of a line
1014 return (L span ITvccurly)
1016 -- -----------------------------------------------------------------------------
1019 setLine :: Int -> Action
1020 setLine code span buf len = do
1021 let line = parseInteger buf len 10 octDecDigit
1022 setSrcLoc (mkSrcLoc (srcSpanFile span) (fromIntegral line - 1) 0)
1023 -- subtract one: the line number refers to the *following* line
1028 setFile :: Int -> Action
1029 setFile code span buf len = do
1030 let file = lexemeToFastString (stepOn buf) (len-2)
1031 setSrcLoc (mkSrcLoc file (srcSpanEndLine span) (srcSpanEndCol span))
1037 -- -----------------------------------------------------------------------------
1038 -- Options, includes and language pragmas.
1040 lex_string_prag :: (String -> Token) -> Action
1041 lex_string_prag mkTok span buf len
1042 = do input <- getInput
1046 return (L (mkSrcSpan start end) tok)
1048 = if isString input "#-}"
1049 then do setInput input
1050 return (mkTok (reverse acc))
1051 else case alexGetChar input of
1052 Just (c,i) -> go (c:acc) i
1053 Nothing -> err input
1054 isString i [] = True
1056 = case alexGetChar i of
1057 Just (c,i') | c == x -> isString i' xs
1059 err (AI end _ _) = failLocMsgP (srcSpanStart span) end "unterminated options pragma"
1062 -- -----------------------------------------------------------------------------
1065 -- This stuff is horrible. I hates it.
1067 lex_string_tok :: Action
1068 lex_string_tok span buf len = do
1069 tok <- lex_string ""
1071 return (L (mkSrcSpan (srcSpanStart span) end) tok)
1073 lex_string :: String -> P Token
1076 case alexGetChar' i of
1077 Nothing -> lit_error
1081 glaexts <- extension glaExtsEnabled
1085 case alexGetChar' i of
1089 then failMsgP "primitive string literal must contain only characters <= \'\\xFF\'"
1090 else let s' = mkZFastString (reverse s) in
1091 return (ITprimstring s')
1092 -- mkZFastString is a hack to avoid encoding the
1093 -- string in UTF-8. We just want the exact bytes.
1095 return (ITstring (mkFastString (reverse s)))
1097 return (ITstring (mkFastString (reverse s)))
1100 | Just ('&',i) <- next -> do
1101 setInput i; lex_string s
1102 | Just (c,i) <- next, is_space c -> do
1103 setInput i; lex_stringgap s
1104 where next = alexGetChar' i
1110 lex_stringgap s = do
1113 '\\' -> lex_string s
1114 c | is_space c -> lex_stringgap s
1118 lex_char_tok :: Action
1119 -- Here we are basically parsing character literals, such as 'x' or '\n'
1120 -- but, when Template Haskell is on, we additionally spot
1121 -- 'x and ''T, returning ITvarQuote and ITtyQuote respectively,
1122 -- but WIHTOUT CONSUMING the x or T part (the parser does that).
1123 -- So we have to do two characters of lookahead: when we see 'x we need to
1124 -- see if there's a trailing quote
1125 lex_char_tok span buf len = do -- We've seen '
1126 i1 <- getInput -- Look ahead to first character
1127 let loc = srcSpanStart span
1128 case alexGetChar' i1 of
1129 Nothing -> lit_error
1131 Just ('\'', i2@(AI end2 _ _)) -> do -- We've seen ''
1132 th_exts <- extension thEnabled
1135 return (L (mkSrcSpan loc end2) ITtyQuote)
1138 Just ('\\', i2@(AI end2 _ _)) -> do -- We've seen 'backslash
1140 lit_ch <- lex_escape
1141 mc <- getCharOrFail -- Trailing quote
1142 if mc == '\'' then finish_char_tok loc lit_ch
1143 else do setInput i2; lit_error
1145 Just (c, i2@(AI end2 _ _))
1146 | not (isAny c) -> lit_error
1149 -- We've seen 'x, where x is a valid character
1150 -- (i.e. not newline etc) but not a quote or backslash
1151 case alexGetChar' i2 of -- Look ahead one more character
1152 Nothing -> lit_error
1153 Just ('\'', i3) -> do -- We've seen 'x'
1155 finish_char_tok loc c
1156 _other -> do -- We've seen 'x not followed by quote
1157 -- If TH is on, just parse the quote only
1158 th_exts <- extension thEnabled
1159 let (AI end _ _) = i1
1160 if th_exts then return (L (mkSrcSpan loc end) ITvarQuote)
1161 else do setInput i2; lit_error
1163 finish_char_tok :: SrcLoc -> Char -> P (Located Token)
1164 finish_char_tok loc ch -- We've already seen the closing quote
1165 -- Just need to check for trailing #
1166 = do glaexts <- extension glaExtsEnabled
1167 i@(AI end _ _) <- getInput
1169 case alexGetChar' i of
1170 Just ('#',i@(AI end _ _)) -> do
1172 return (L (mkSrcSpan loc end) (ITprimchar ch))
1174 return (L (mkSrcSpan loc end) (ITchar ch))
1176 return (L (mkSrcSpan loc end) (ITchar ch))
1178 lex_char :: Char -> AlexInput -> P Char
1181 '\\' -> do setInput inp; lex_escape
1182 c | isAny c -> do setInput inp; return c
1185 isAny c | c > '\xff' = isPrint c
1186 | otherwise = is_any c
1188 lex_escape :: P Char
1202 '^' -> do c <- getCharOrFail
1203 if c >= '@' && c <= '_'
1204 then return (chr (ord c - ord '@'))
1207 'x' -> readNum is_hexdigit 16 hexDigit
1208 'o' -> readNum is_octdigit 8 octDecDigit
1209 x | is_digit x -> readNum2 is_digit 10 octDecDigit (octDecDigit x)
1213 case alexGetChar' i of
1214 Nothing -> lit_error
1216 case alexGetChar' i2 of
1217 Nothing -> do setInput i2; lit_error
1219 let str = [c1,c2,c3] in
1220 case [ (c,rest) | (p,c) <- silly_escape_chars,
1221 Just rest <- [maybePrefixMatch p str] ] of
1222 (escape_char,[]):_ -> do
1225 (escape_char,_:_):_ -> do
1230 readNum :: (Char -> Bool) -> Int -> (Char -> Int) -> P Char
1231 readNum is_digit base conv = do
1235 then readNum2 is_digit base conv (conv c)
1236 else do setInput i; lit_error
1238 readNum2 is_digit base conv i = do
1241 where read i input = do
1242 case alexGetChar' input of
1243 Just (c,input') | is_digit c -> do
1244 read (i*base + conv c) input'
1246 if i >= 0 && i <= 0x10FFFF
1247 then do setInput input; return (chr i)
1250 silly_escape_chars = [
1287 -- before calling lit_error, ensure that the current input is pointing to
1288 -- the position of the error in the buffer. This is so that we can report
1289 -- a correct location to the user, but also so we can detect UTF-8 decoding
1290 -- errors if they occur.
1291 lit_error = lexError "lexical error in string/character literal"
1293 getCharOrFail :: P Char
1296 case alexGetChar' i of
1297 Nothing -> lexError "unexpected end-of-file in string/character literal"
1298 Just (c,i) -> do setInput i; return c
1300 -- -----------------------------------------------------------------------------
1311 SrcSpan -- The start and end of the text span related to
1312 -- the error. Might be used in environments which can
1313 -- show this span, e.g. by highlighting it.
1314 Message -- The error message
1316 data PState = PState {
1317 buffer :: StringBuffer,
1318 last_loc :: SrcSpan, -- pos of previous token
1319 last_offs :: !Int, -- offset of the previous token from the
1320 -- beginning of the current line.
1321 -- \t is equal to 8 spaces.
1322 last_len :: !Int, -- len of previous token
1323 last_line_len :: !Int,
1324 loc :: SrcLoc, -- current loc (end of prev token + 1)
1325 extsBitmap :: !Int, -- bitmap that determines permitted extensions
1326 context :: [LayoutContext],
1329 -- last_loc and last_len are used when generating error messages,
1330 -- and in pushCurrentContext only. Sigh, if only Happy passed the
1331 -- current token to happyError, we could at least get rid of last_len.
1332 -- Getting rid of last_loc would require finding another way to
1333 -- implement pushCurrentContext (which is only called from one place).
1335 newtype P a = P { unP :: PState -> ParseResult a }
1337 instance Monad P where
1343 returnP a = P $ \s -> POk s a
1345 thenP :: P a -> (a -> P b) -> P b
1346 (P m) `thenP` k = P $ \ s ->
1348 POk s1 a -> (unP (k a)) s1
1349 PFailed span err -> PFailed span err
1351 failP :: String -> P a
1352 failP msg = P $ \s -> PFailed (last_loc s) (text msg)
1354 failMsgP :: String -> P a
1355 failMsgP msg = P $ \s -> PFailed (last_loc s) (text msg)
1357 failLocMsgP :: SrcLoc -> SrcLoc -> String -> P a
1358 failLocMsgP loc1 loc2 str = P $ \s -> PFailed (mkSrcSpan loc1 loc2) (text str)
1360 failSpanMsgP :: SrcSpan -> String -> P a
1361 failSpanMsgP span msg = P $ \s -> PFailed span (text msg)
1363 extension :: (Int -> Bool) -> P Bool
1364 extension p = P $ \s -> POk s (p $! extsBitmap s)
1367 getExts = P $ \s -> POk s (extsBitmap s)
1369 setSrcLoc :: SrcLoc -> P ()
1370 setSrcLoc new_loc = P $ \s -> POk s{loc=new_loc} ()
1372 getSrcLoc :: P SrcLoc
1373 getSrcLoc = P $ \s@(PState{ loc=loc }) -> POk s loc
1375 setLastToken :: SrcSpan -> Int -> Int -> P ()
1376 setLastToken loc len line_len = P $ \s -> POk s {
1379 last_line_len=line_len
1382 data AlexInput = AI SrcLoc {-#UNPACK#-}!Int StringBuffer
1384 alexInputPrevChar :: AlexInput -> Char
1385 alexInputPrevChar (AI _ _ buf) = prevChar buf '\n'
1387 alexGetChar :: AlexInput -> Maybe (Char,AlexInput)
1388 alexGetChar (AI loc ofs s)
1390 | otherwise = adj_c `seq` loc' `seq` ofs' `seq` s' `seq`
1391 --trace (show (ord c)) $
1392 Just (adj_c, (AI loc' ofs' s'))
1393 where (c,s') = nextChar s
1394 loc' = advanceSrcLoc loc c
1395 ofs' = advanceOffs c ofs
1403 other_graphic = '\x6'
1406 | c <= '\x06' = non_graphic
1409 case generalCategory c of
1410 UppercaseLetter -> upper
1411 LowercaseLetter -> lower
1412 TitlecaseLetter -> upper
1413 ModifierLetter -> other_graphic
1414 OtherLetter -> other_graphic
1415 NonSpacingMark -> other_graphic
1416 SpacingCombiningMark -> other_graphic
1417 EnclosingMark -> other_graphic
1418 DecimalNumber -> digit
1419 LetterNumber -> other_graphic
1420 OtherNumber -> other_graphic
1421 ConnectorPunctuation -> other_graphic
1422 DashPunctuation -> other_graphic
1423 OpenPunctuation -> other_graphic
1424 ClosePunctuation -> other_graphic
1425 InitialQuote -> other_graphic
1426 FinalQuote -> other_graphic
1427 OtherPunctuation -> other_graphic
1428 MathSymbol -> symbol
1429 CurrencySymbol -> symbol
1430 ModifierSymbol -> symbol
1431 OtherSymbol -> symbol
1433 _other -> non_graphic
1435 -- This version does not squash unicode characters, it is used when
1437 alexGetChar' :: AlexInput -> Maybe (Char,AlexInput)
1438 alexGetChar' (AI loc ofs s)
1440 | otherwise = c `seq` loc' `seq` ofs' `seq` s' `seq`
1441 --trace (show (ord c)) $
1442 Just (c, (AI loc' ofs' s'))
1443 where (c,s') = nextChar s
1444 loc' = advanceSrcLoc loc c
1445 ofs' = advanceOffs c ofs
1447 advanceOffs :: Char -> Int -> Int
1448 advanceOffs '\n' offs = 0
1449 advanceOffs '\t' offs = (offs `quot` 8 + 1) * 8
1450 advanceOffs _ offs = offs + 1
1452 getInput :: P AlexInput
1453 getInput = P $ \s@PState{ loc=l, last_offs=o, buffer=b } -> POk s (AI l o b)
1455 setInput :: AlexInput -> P ()
1456 setInput (AI l o b) = P $ \s -> POk s{ loc=l, last_offs=o, buffer=b } ()
1458 pushLexState :: Int -> P ()
1459 pushLexState ls = P $ \s@PState{ lex_state=l } -> POk s{lex_state=ls:l} ()
1461 popLexState :: P Int
1462 popLexState = P $ \s@PState{ lex_state=ls:l } -> POk s{ lex_state=l } ls
1464 getLexState :: P Int
1465 getLexState = P $ \s@PState{ lex_state=ls:l } -> POk s ls
1467 -- for reasons of efficiency, flags indicating language extensions (eg,
1468 -- -fglasgow-exts or -fparr) are represented by a bitmap stored in an unboxed
1471 glaExtsBit, ffiBit, parrBit :: Int
1478 tvBit = 7 -- Scoped type variables enables 'forall' keyword
1479 bangPatBit = 8 -- Tells the parser to understand bang-patterns
1480 -- (doesn't affect the lexer)
1481 idxTysBit = 9 -- indexed type families: 'family' keyword and kind sigs
1482 haddockBit = 10 -- Lex and parse Haddock comments
1484 glaExtsEnabled, ffiEnabled, parrEnabled :: Int -> Bool
1485 glaExtsEnabled flags = testBit flags glaExtsBit
1486 ffiEnabled flags = testBit flags ffiBit
1487 parrEnabled flags = testBit flags parrBit
1488 arrowsEnabled flags = testBit flags arrowsBit
1489 thEnabled flags = testBit flags thBit
1490 ipEnabled flags = testBit flags ipBit
1491 tvEnabled flags = testBit flags tvBit
1492 bangPatEnabled flags = testBit flags bangPatBit
1493 idxTysEnabled flags = testBit flags idxTysBit
1494 haddockEnabled flags = testBit flags haddockBit
1496 -- PState for parsing options pragmas
1498 pragState :: StringBuffer -> SrcLoc -> PState
1502 last_loc = mkSrcSpan loc loc,
1509 lex_state = [bol, option_prags, 0]
1513 -- create a parse state
1515 mkPState :: StringBuffer -> SrcLoc -> DynFlags -> PState
1516 mkPState buf loc flags =
1519 last_loc = mkSrcSpan loc loc,
1524 extsBitmap = fromIntegral bitmap,
1526 lex_state = [bol, if glaExtsEnabled bitmap then glaexts else 0]
1527 -- we begin in the layout state if toplev_layout is set
1530 bitmap = glaExtsBit `setBitIf` dopt Opt_GlasgowExts flags
1531 .|. ffiBit `setBitIf` dopt Opt_FFI flags
1532 .|. parrBit `setBitIf` dopt Opt_PArr flags
1533 .|. arrowsBit `setBitIf` dopt Opt_Arrows flags
1534 .|. thBit `setBitIf` dopt Opt_TH flags
1535 .|. ipBit `setBitIf` dopt Opt_ImplicitParams flags
1536 .|. tvBit `setBitIf` dopt Opt_ScopedTypeVariables flags
1537 .|. bangPatBit `setBitIf` dopt Opt_BangPatterns flags
1538 .|. idxTysBit `setBitIf` dopt Opt_IndexedTypes flags
1539 .|. haddockBit `setBitIf` dopt Opt_Haddock flags
1541 setBitIf :: Int -> Bool -> Int
1542 b `setBitIf` cond | cond = bit b
1545 getContext :: P [LayoutContext]
1546 getContext = P $ \s@PState{context=ctx} -> POk s ctx
1548 setContext :: [LayoutContext] -> P ()
1549 setContext ctx = P $ \s -> POk s{context=ctx} ()
1552 popContext = P $ \ s@(PState{ buffer = buf, context = ctx,
1553 loc = loc, last_len = len, last_loc = last_loc }) ->
1555 (_:tl) -> POk s{ context = tl } ()
1556 [] -> PFailed last_loc (srcParseErr buf len)
1558 -- Push a new layout context at the indentation of the last token read.
1559 -- This is only used at the outer level of a module when the 'module'
1560 -- keyword is missing.
1561 pushCurrentContext :: P ()
1562 pushCurrentContext = P $ \ s@PState{ last_offs=offs, last_line_len=len, context=ctx } ->
1563 POk s{context = Layout (offs-len) : ctx} ()
1564 --trace ("off: " ++ show offs ++ ", len: " ++ show len) $ POk s{context = Layout (offs-len) : ctx} ()
1566 getOffside :: P Ordering
1567 getOffside = P $ \s@PState{last_offs=offs, context=stk} ->
1568 let ord = case stk of
1569 (Layout n:_) -> compare offs n
1573 -- ---------------------------------------------------------------------------
1574 -- Construct a parse error
1577 :: StringBuffer -- current buffer (placed just after the last token)
1578 -> Int -- length of the previous token
1581 = hcat [ if null token
1582 then ptext SLIT("parse error (possibly incorrect indentation)")
1583 else hcat [ptext SLIT("parse error on input "),
1584 char '`', text token, char '\'']
1586 where token = lexemeToString (offsetBytes (-len) buf) len
1588 -- Report a parse failure, giving the span of the previous token as
1589 -- the location of the error. This is the entry point for errors
1590 -- detected during parsing.
1592 srcParseFail = P $ \PState{ buffer = buf, last_len = len,
1593 last_loc = last_loc } ->
1594 PFailed last_loc (srcParseErr buf len)
1596 -- A lexical error is reported at a particular position in the source file,
1597 -- not over a token range.
1598 lexError :: String -> P a
1601 i@(AI end _ buf) <- getInput
1602 reportLexError loc end buf str
1604 -- -----------------------------------------------------------------------------
1605 -- This is the top-level function: called from the parser each time a
1606 -- new token is to be read from the input.
1608 lexer :: (Located Token -> P a) -> P a
1610 tok@(L span tok__) <- lexToken
1611 -- trace ("token: " ++ show tok__) $ do
1614 lexToken :: P (Located Token)
1616 inp@(AI loc1 _ buf) <- getInput
1619 case alexScanUser exts inp sc of
1620 AlexEOF -> do let span = mkSrcSpan loc1 loc1
1621 setLastToken span 0 0
1622 return (L span ITeof)
1623 AlexError (AI loc2 _ buf) -> do
1624 reportLexError loc1 loc2 buf "lexical error"
1625 AlexSkip inp2 _ -> do
1628 AlexToken inp2@(AI end _ buf2) len t -> do
1630 let span = mkSrcSpan loc1 end
1631 let bytes = byteDiff buf buf2
1632 span `seq` setLastToken span bytes bytes
1635 reportLexError loc1 loc2 buf str
1636 | atEnd buf = failLocMsgP loc1 loc2 (str ++ " at end of input")
1639 c = fst (nextChar buf)
1641 if c == '\0' -- decoding errors are mapped to '\0', see utf8DecodeChar#
1642 then failLocMsgP loc2 loc2 (str ++ " (UTF-8 decoding error)")
1643 else failLocMsgP loc1 loc2 (str ++ " at character " ++ show c)