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, bangPatEnabled
33 #include "HsVersions.h"
35 import ErrUtils ( Message )
44 import Util ( maybePrefixMatch, readRational )
47 import Data.Char ( chr )
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 @varid = $small $idchar*
90 @conid = $large $idchar*
92 @varsym = $symbol $symchar*
93 @consym = \: $symchar*
97 @hexadecimal = $hexit+
98 @exponent = [eE] [\-\+]? @decimal
100 -- we support the hierarchical module name extension:
103 @floating_point = @decimal \. @decimal @exponent? | @decimal @exponent
107 -- everywhere: skip whitespace and comments
110 -- Everywhere: deal with nested comments. We explicitly rule out
111 -- pragmas, "{-#", so that we don't accidentally treat them as comments.
112 -- (this can happen even though pragmas will normally take precedence due to
113 -- longest-match, because pragmas aren't valid in every state, but comments
115 "{-" / { notFollowedBy '#' } { nested_comment }
117 -- Single-line comments are a bit tricky. Haskell 98 says that two or
118 -- more dashes followed by a symbol should be parsed as a varsym, so we
119 -- have to exclude those.
120 -- The regex says: "munch all the characters after the dashes, as long as
121 -- the first one is not a symbol".
122 "--"\-* [^$symbol :] .* ;
123 "--"\-* / { atEOL } ;
125 -- 'bol' state: beginning of a line. Slurp up all the whitespace (including
126 -- blank lines) until we find a non-whitespace character, then do layout
129 -- One slight wibble here: what if the line begins with {-#? In
130 -- theory, we have to lex the pragma to see if it's one we recognise,
131 -- and if it is, then we backtrack and do_bol, otherwise we treat it
132 -- as a nested comment. We don't bother with this: if the line begins
133 -- with {-#, then we'll assume it's a pragma we know about and go for do_bol.
136 ^\# (line)? { begin line_prag1 }
137 ^\# pragma .* \n ; -- GCC 3.3 CPP generated, apparently
138 ^\# \! .* \n ; -- #!, for scripts
142 -- after a layout keyword (let, where, do, of), we begin a new layout
143 -- context if the curly brace is missing.
144 -- Careful! This stuff is quite delicate.
145 <layout, layout_do> {
146 \{ / { notFollowedBy '-' } { pop_and open_brace }
147 -- we might encounter {-# here, but {- has been handled already
149 ^\# (line)? { begin line_prag1 }
152 -- do is treated in a subtly different way, see new_layout_context
153 <layout> () { new_layout_context True }
154 <layout_do> () { new_layout_context False }
156 -- after a new layout context which was found to be to the left of the
157 -- previous context, we have generated a '{' token, and we now need to
158 -- generate a matching '}' token.
159 <layout_left> () { do_layout_left }
161 <0,option_prags,glaexts> \n { begin bol }
163 "{-#" $whitechar* (line|LINE) { begin line_prag2 }
165 -- single-line line pragmas, of the form
166 -- # <line> "<file>" <extra-stuff> \n
167 <line_prag1> $decdigit+ { setLine line_prag1a }
168 <line_prag1a> \" [$graphic \ ]* \" { setFile line_prag1b }
169 <line_prag1b> .* { pop }
171 -- Haskell-style line pragmas, of the form
172 -- {-# LINE <line> "<file>" #-}
173 <line_prag2> $decdigit+ { setLine line_prag2a }
174 <line_prag2a> \" [$graphic \ ]* \" { setFile line_prag2b }
175 <line_prag2b> "#-}"|"-}" { pop }
176 -- NOTE: accept -} at the end of a LINE pragma, for compatibility
177 -- with older versions of GHC which generated these.
179 -- We only want RULES pragmas to be picked up when -fglasgow-exts
180 -- is on, because the contents of the pragma is always written using
181 -- glasgow-exts syntax (using forall etc.), so if glasgow exts are not
182 -- enabled, we're sure to get a parse error.
183 -- (ToDo: we should really emit a warning when ignoring pragmas)
185 "{-#" $whitechar* (RULES|rules) { token ITrules_prag }
187 <0,option_prags,glaexts> {
188 "{-#" $whitechar* (INLINE|inline) { token (ITinline_prag True) }
189 "{-#" $whitechar* (NO(T?)INLINE|no(t?)inline)
190 { token (ITinline_prag False) }
191 "{-#" $whitechar* (SPECIALI[SZ]E|speciali[sz]e)
192 { token ITspec_prag }
193 "{-#" $whitechar* (SPECIALI[SZ]E|speciali[sz]e)
194 $whitechar* (INLINE|inline) { token (ITspec_inline_prag True) }
195 "{-#" $whitechar* (SPECIALI[SZ]E|speciali[sz]e)
196 $whitechar* (NO(T?)INLINE|no(t?)inline)
197 { token (ITspec_inline_prag False) }
198 "{-#" $whitechar* (SOURCE|source) { token ITsource_prag }
199 "{-#" $whitechar* (DEPRECATED|deprecated)
200 { token ITdeprecated_prag }
201 "{-#" $whitechar* (SCC|scc) { token ITscc_prag }
202 "{-#" $whitechar* (CORE|core) { token ITcore_prag }
203 "{-#" $whitechar* (UNPACK|unpack) { token ITunpack_prag }
205 "{-#" { nested_comment }
207 -- ToDo: should only be valid inside a pragma:
208 "#-}" { token ITclose_prag}
212 "{-#" $whitechar* (OPTIONS|options) { lex_string_prag IToptions_prag }
213 "{-#" $whitechar* (OPTIONS_GHC|options_ghc)
214 { lex_string_prag IToptions_prag }
215 "{-#" $whitechar* (LANGUAGE|language) { token ITlanguage_prag }
216 "{-#" $whitechar* (INCLUDE|include) { lex_string_prag ITinclude_prag }
219 <0,option_prags,glaexts> {
220 -- This is to catch things like {-# OPTIONS OPTIONS_HUGS ...
221 "{-#" $whitechar* $idchar+ { nested_comment }
224 -- '0' state: ordinary lexemes
225 -- 'glaexts' state: glasgow extensions (postfix '#', etc.)
230 "[:" / { ifExtension parrEnabled } { token ITopabrack }
231 ":]" / { ifExtension parrEnabled } { token ITcpabrack }
235 "[|" / { ifExtension thEnabled } { token ITopenExpQuote }
236 "[e|" / { ifExtension thEnabled } { token ITopenExpQuote }
237 "[p|" / { ifExtension thEnabled } { token ITopenPatQuote }
238 "[d|" / { ifExtension thEnabled } { layout_token ITopenDecQuote }
239 "[t|" / { ifExtension thEnabled } { token ITopenTypQuote }
240 "|]" / { ifExtension thEnabled } { token ITcloseQuote }
241 \$ @varid / { ifExtension thEnabled } { skip_one_varid ITidEscape }
242 "$(" / { ifExtension thEnabled } { token ITparenEscape }
246 "(|" / { ifExtension arrowsEnabled `alexAndPred` notFollowedBySymbol }
247 { special IToparenbar }
248 "|)" / { ifExtension arrowsEnabled } { special ITcparenbar }
252 \? @varid / { ifExtension ipEnabled } { skip_one_varid ITdupipvarid }
253 \% @varid / { ifExtension ipEnabled } { skip_one_varid ITsplitipvarid }
257 "(#" / { notFollowedBySymbol } { token IToubxparen }
258 "#)" { token ITcubxparen }
259 "{|" { token ITocurlybar }
260 "|}" { token ITccurlybar }
263 <0,option_prags,glaexts> {
264 \( { special IToparen }
265 \) { special ITcparen }
266 \[ { special ITobrack }
267 \] { special ITcbrack }
268 \, { special ITcomma }
269 \; { special ITsemi }
270 \` { special ITbackquote }
276 <0,option_prags,glaexts> {
277 @qual @varid { check_qvarid }
278 @qual @conid { idtoken qconid }
280 @conid { idtoken conid }
283 -- after an illegal qvarid, such as 'M.let',
284 -- we back up and try again in the bad_qvarid state:
286 @conid { pop_and (idtoken conid) }
287 @qual @conid { pop_and (idtoken qconid) }
291 @qual @varid "#"+ { idtoken qvarid }
292 @qual @conid "#"+ { idtoken qconid }
293 @varid "#"+ { varid }
294 @conid "#"+ { idtoken conid }
300 @qual @varsym { idtoken qvarsym }
301 @qual @consym { idtoken qconsym }
307 @decimal { tok_decimal }
308 0[oO] @octal { tok_octal }
309 0[xX] @hexadecimal { tok_hexadecimal }
313 @decimal \# { prim_decimal }
314 0[oO] @octal \# { prim_octal }
315 0[xX] @hexadecimal \# { prim_hexadecimal }
318 <0,glaexts> @floating_point { strtoken tok_float }
319 <glaexts> @floating_point \# { init_strtoken 1 prim_float }
320 <glaexts> @floating_point \# \# { init_strtoken 2 prim_double }
322 -- Strings and chars are lexed by hand-written code. The reason is
323 -- that even if we recognise the string or char here in the regex
324 -- lexer, we would still have to parse the string afterward in order
325 -- to convert it to a String.
328 \" { lex_string_tok }
332 -- work around bug in Alex 2.0
333 #if __GLASGOW_HASKELL__ < 503
334 unsafeAt arr i = arr ! i
337 -- -----------------------------------------------------------------------------
341 = ITas -- Haskell keywords
365 | ITscc -- ToDo: remove (we use {-# SCC "..." #-} now)
367 | ITforall -- GHC extension keywords
381 | ITinline_prag Bool -- True <=> INLINE, False <=> NOINLINE
382 | ITspec_prag -- SPECIALISE
383 | ITspec_inline_prag Bool -- SPECIALISE INLINE (or NOINLINE)
389 | ITcore_prag -- hdaume: core annotations
392 | IToptions_prag String
393 | ITinclude_prag String
396 | ITdotdot -- reserved symbols
412 | ITbiglam -- GHC-extension symbols
414 | ITocurly -- special symbols
416 | ITocurlybar -- {|, for type applications
417 | ITccurlybar -- |}, for type applications
421 | ITopabrack -- [:, for parallel arrays with -fparr
422 | ITcpabrack -- :], for parallel arrays with -fparr
433 | ITvarid FastString -- identifiers
435 | ITvarsym FastString
436 | ITconsym FastString
437 | ITqvarid (FastString,FastString)
438 | ITqconid (FastString,FastString)
439 | ITqvarsym (FastString,FastString)
440 | ITqconsym (FastString,FastString)
442 | ITdupipvarid FastString -- GHC extension: implicit param: ?x
443 | ITsplitipvarid FastString -- GHC extension: implicit param: %x
445 | ITpragma StringBuffer
448 | ITstring FastString
450 | ITrational Rational
453 | ITprimstring FastString
455 | ITprimfloat Rational
456 | ITprimdouble Rational
458 -- MetaHaskell extension tokens
459 | ITopenExpQuote -- [| or [e|
460 | ITopenPatQuote -- [p|
461 | ITopenDecQuote -- [d|
462 | ITopenTypQuote -- [t|
464 | ITidEscape FastString -- $x
465 | ITparenEscape -- $(
469 -- Arrow notation extension
476 | ITLarrowtail -- -<<
477 | ITRarrowtail -- >>-
479 | ITunknown String -- Used when the lexer can't make sense of it
480 | ITeof -- end of file token
482 deriving Show -- debugging
485 isSpecial :: Token -> Bool
486 -- If we see M.x, where x is a keyword, but
487 -- is special, we treat is as just plain M.x,
489 isSpecial ITas = True
490 isSpecial IThiding = True
491 isSpecial ITqualified = True
492 isSpecial ITforall = True
493 isSpecial ITexport = True
494 isSpecial ITlabel = True
495 isSpecial ITdynamic = True
496 isSpecial ITsafe = True
497 isSpecial ITthreadsafe = True
498 isSpecial ITunsafe = True
499 isSpecial ITccallconv = True
500 isSpecial ITstdcallconv = True
501 isSpecial ITmdo = True
504 -- the bitmap provided as the third component indicates whether the
505 -- corresponding extension keyword is valid under the extension options
506 -- provided to the compiler; if the extension corresponding to *any* of the
507 -- bits set in the bitmap is enabled, the keyword is valid (this setup
508 -- facilitates using a keyword in two different extensions that can be
509 -- activated independently)
511 reservedWordsFM = listToUFM $
512 map (\(x, y, z) -> (mkFastString x, (y, z)))
513 [( "_", ITunderscore, 0 ),
515 ( "case", ITcase, 0 ),
516 ( "class", ITclass, 0 ),
517 ( "data", ITdata, 0 ),
518 ( "default", ITdefault, 0 ),
519 ( "deriving", ITderiving, 0 ),
521 ( "else", ITelse, 0 ),
522 ( "hiding", IThiding, 0 ),
524 ( "import", ITimport, 0 ),
526 ( "infix", ITinfix, 0 ),
527 ( "infixl", ITinfixl, 0 ),
528 ( "infixr", ITinfixr, 0 ),
529 ( "instance", ITinstance, 0 ),
531 ( "module", ITmodule, 0 ),
532 ( "newtype", ITnewtype, 0 ),
534 ( "qualified", ITqualified, 0 ),
535 ( "then", ITthen, 0 ),
536 ( "type", ITtype, 0 ),
537 ( "where", ITwhere, 0 ),
538 ( "_scc_", ITscc, 0 ), -- ToDo: remove
540 ( "forall", ITforall, bit tvBit),
541 ( "mdo", ITmdo, bit glaExtsBit),
543 ( "foreign", ITforeign, bit ffiBit),
544 ( "export", ITexport, bit ffiBit),
545 ( "label", ITlabel, bit ffiBit),
546 ( "dynamic", ITdynamic, bit ffiBit),
547 ( "safe", ITsafe, bit ffiBit),
548 ( "threadsafe", ITthreadsafe, bit ffiBit),
549 ( "unsafe", ITunsafe, bit ffiBit),
550 ( "stdcall", ITstdcallconv, bit ffiBit),
551 ( "ccall", ITccallconv, bit ffiBit),
552 ( "dotnet", ITdotnet, bit ffiBit),
554 ( "rec", ITrec, bit arrowsBit),
555 ( "proc", ITproc, bit arrowsBit)
558 reservedSymsFM = listToUFM $
559 map (\ (x,y,z) -> (mkFastString x,(y,z)))
560 [ ("..", ITdotdot, 0)
561 ,(":", ITcolon, 0) -- (:) is a reserved op,
562 -- meaning only list cons
575 ,("*", ITstar, bit glaExtsBit) -- For data T (a::*) = MkT
576 ,(".", ITdot, bit tvBit) -- For 'forall a . t'
578 ,("-<", ITlarrowtail, bit arrowsBit)
579 ,(">-", ITrarrowtail, bit arrowsBit)
580 ,("-<<", ITLarrowtail, bit arrowsBit)
581 ,(">>-", ITRarrowtail, bit arrowsBit)
583 #if __GLASGOW_HASKELL__ >= 605
584 ,("λ", ITlam, bit glaExtsBit)
585 ,("∷", ITdcolon, bit glaExtsBit)
586 ,("⇒", ITdarrow, bit glaExtsBit)
587 ,("∀", ITforall, bit glaExtsBit)
588 ,("→", ITrarrow, bit glaExtsBit)
589 ,("←", ITlarrow, bit glaExtsBit)
590 ,("⋯", ITdotdot, bit glaExtsBit)
594 -- -----------------------------------------------------------------------------
597 type Action = SrcSpan -> StringBuffer -> Int -> P (Located Token)
599 special :: Token -> Action
600 special tok span _buf len = return (L span tok)
602 token, layout_token :: Token -> Action
603 token t span buf len = return (L span t)
604 layout_token t span buf len = pushLexState layout >> return (L span t)
606 idtoken :: (StringBuffer -> Int -> Token) -> Action
607 idtoken f span buf len = return (L span $! (f buf len))
609 skip_one_varid :: (FastString -> Token) -> Action
610 skip_one_varid f span buf len
611 = return (L span $! f (lexemeToFastString (stepOn buf) (len-1)))
613 strtoken :: (String -> Token) -> Action
614 strtoken f span buf len =
615 return (L span $! (f $! lexemeToString buf len))
617 init_strtoken :: Int -> (String -> Token) -> Action
618 -- like strtoken, but drops the last N character(s)
619 init_strtoken drop f span buf len =
620 return (L span $! (f $! lexemeToString buf (len-drop)))
622 begin :: Int -> Action
623 begin code _span _str _len = do pushLexState code; lexToken
626 pop _span _buf _len = do popLexState; lexToken
628 pop_and :: Action -> Action
629 pop_and act span buf len = do popLexState; act span buf len
631 notFollowedBy char _ _ _ (AI _ _ buf) = atEnd buf || currentChar buf /= char
633 notFollowedBySymbol _ _ _ (AI _ _ buf)
634 = atEnd buf || currentChar buf `notElem` "!#$%&*+./<=>?@\\^|-~"
636 atEOL _ _ _ (AI _ _ buf) = atEnd buf || currentChar buf == '\n'
638 ifExtension pred bits _ _ _ = pred bits
641 nested comments require traversing by hand, they can't be parsed
642 using regular expressions.
644 nested_comment :: Action
645 nested_comment span _str _len = do
648 where go 0 input = do setInput input; lexToken
650 case alexGetChar input of
655 case alexGetChar input of
657 Just ('\125',input) -> go (n-1) input
658 Just (c,_) -> go n input
660 case alexGetChar input of
662 Just ('-',input') -> go (n+1) input'
663 Just (c,input) -> go n input
666 err (AI end _ _) = failLocMsgP (srcSpanStart span) end "unterminated `{-'"
668 open_brace, close_brace :: Action
669 open_brace span _str _len = do
671 setContext (NoLayout:ctx)
672 return (L span ITocurly)
673 close_brace span _str _len = do
675 return (L span ITccurly)
677 -- We have to be careful not to count M.<varid> as a qualified name
678 -- when <varid> is a keyword. We hack around this by catching
679 -- the offending tokens afterward, and re-lexing in a different state.
680 check_qvarid span buf len = do
681 case lookupUFM reservedWordsFM var of
683 | not (isSpecial keyword) ->
687 b <- extension (\i -> exts .&. i /= 0)
690 _other -> return token
692 (mod,var) = splitQualName buf len
693 token = L span (ITqvarid (mod,var))
696 (AI _ offs _) <- getInput
697 setInput (AI (srcSpanStart span) (offs-len) buf)
698 pushLexState bad_qvarid
701 qvarid buf len = ITqvarid $! splitQualName buf len
702 qconid buf len = ITqconid $! splitQualName buf len
704 splitQualName :: StringBuffer -> Int -> (FastString,FastString)
705 -- takes a StringBuffer and a length, and returns the module name
706 -- and identifier parts of a qualified name. Splits at the *last* dot,
707 -- because of hierarchical module names.
708 splitQualName orig_buf len = split orig_buf orig_buf
711 | orig_buf `byteDiff` buf >= len = done dot_buf
712 | c == '.' = found_dot buf'
713 | otherwise = split buf' dot_buf
715 (c,buf') = nextChar buf
717 -- careful, we might get names like M....
718 -- so, if the character after the dot is not upper-case, this is
719 -- the end of the qualifier part.
720 found_dot buf -- buf points after the '.'
721 | isUpper c = split buf' buf
722 | otherwise = done buf
724 (c,buf') = nextChar buf
727 (lexemeToFastString orig_buf (qual_size - 1),
728 lexemeToFastString dot_buf (len - qual_size))
730 qual_size = orig_buf `byteDiff` dot_buf
733 case lookupUFM reservedWordsFM fs of
734 Just (keyword,0) -> do
736 return (L span keyword)
737 Just (keyword,exts) -> do
738 b <- extension (\i -> exts .&. i /= 0)
739 if b then do maybe_layout keyword
740 return (L span keyword)
741 else return (L span (ITvarid fs))
742 _other -> return (L span (ITvarid fs))
744 fs = lexemeToFastString buf len
746 conid buf len = ITconid fs
747 where fs = lexemeToFastString buf len
749 qvarsym buf len = ITqvarsym $! splitQualName buf len
750 qconsym buf len = ITqconsym $! splitQualName buf len
752 varsym = sym ITvarsym
753 consym = sym ITconsym
755 sym con span buf len =
756 case lookupUFM reservedSymsFM fs of
757 Just (keyword,0) -> return (L span keyword)
758 Just (keyword,exts) -> do
759 b <- extension (\i -> exts .&. i /= 0)
760 if b then return (L span keyword)
761 else return (L span $! con fs)
762 _other -> return (L span $! con fs)
764 fs = lexemeToFastString buf len
766 tok_decimal span buf len
767 = return (L span (ITinteger $! parseInteger buf len 10 octDecDigit))
769 tok_octal span buf len
770 = return (L span (ITinteger $! parseInteger (offsetBytes 2 buf) (len-2) 8 octDecDigit))
772 tok_hexadecimal span buf len
773 = return (L span (ITinteger $! parseInteger (offsetBytes 2 buf) (len-2) 16 hexDigit))
775 prim_decimal span buf len
776 = return (L span (ITprimint $! parseInteger buf (len-1) 10 octDecDigit))
778 prim_octal span buf len
779 = return (L span (ITprimint $! parseInteger (offsetBytes 2 buf) (len-3) 8 octDecDigit))
781 prim_hexadecimal span buf len
782 = return (L span (ITprimint $! parseInteger (offsetBytes 2 buf) (len-3) 16 hexDigit))
784 tok_float str = ITrational $! readRational str
785 prim_float str = ITprimfloat $! readRational str
786 prim_double str = ITprimdouble $! readRational str
788 -- -----------------------------------------------------------------------------
791 -- we're at the first token on a line, insert layout tokens if necessary
793 do_bol span _str _len = do
797 --trace "layout: inserting '}'" $ do
799 -- do NOT pop the lex state, we might have a ';' to insert
800 return (L span ITvccurly)
802 --trace "layout: inserting ';'" $ do
804 return (L span ITsemi)
809 -- certain keywords put us in the "layout" state, where we might
810 -- add an opening curly brace.
811 maybe_layout ITdo = pushLexState layout_do
812 maybe_layout ITmdo = pushLexState layout_do
813 maybe_layout ITof = pushLexState layout
814 maybe_layout ITlet = pushLexState layout
815 maybe_layout ITwhere = pushLexState layout
816 maybe_layout ITrec = pushLexState layout
817 maybe_layout _ = return ()
819 -- Pushing a new implicit layout context. If the indentation of the
820 -- next token is not greater than the previous layout context, then
821 -- Haskell 98 says that the new layout context should be empty; that is
822 -- the lexer must generate {}.
824 -- We are slightly more lenient than this: when the new context is started
825 -- by a 'do', then we allow the new context to be at the same indentation as
826 -- the previous context. This is what the 'strict' argument is for.
828 new_layout_context strict span _buf _len = do
830 (AI _ offset _) <- getInput
833 Layout prev_off : _ |
834 (strict && prev_off >= offset ||
835 not strict && prev_off > offset) -> do
836 -- token is indented to the left of the previous context.
837 -- we must generate a {} sequence now.
838 pushLexState layout_left
839 return (L span ITvocurly)
841 setContext (Layout offset : ctx)
842 return (L span ITvocurly)
844 do_layout_left span _buf _len = do
846 pushLexState bol -- we must be at the start of a line
847 return (L span ITvccurly)
849 -- -----------------------------------------------------------------------------
852 setLine :: Int -> Action
853 setLine code span buf len = do
854 let line = parseInteger buf len 10 octDecDigit
855 setSrcLoc (mkSrcLoc (srcSpanFile span) (fromIntegral line - 1) 0)
856 -- subtract one: the line number refers to the *following* line
861 setFile :: Int -> Action
862 setFile code span buf len = do
863 let file = lexemeToFastString (stepOn buf) (len-2)
864 setSrcLoc (mkSrcLoc file (srcSpanEndLine span) (srcSpanEndCol span))
870 -- -----------------------------------------------------------------------------
871 -- Options, includes and language pragmas.
873 lex_string_prag :: (String -> Token) -> Action
874 lex_string_prag mkTok span buf len
875 = do input <- getInput
879 return (L (mkSrcSpan start end) tok)
881 = if isString input "#-}"
882 then do setInput input
883 return (mkTok (reverse acc))
884 else case alexGetChar input of
885 Just (c,i) -> go (c:acc) i
889 = case alexGetChar i of
890 Just (c,i') | c == x -> isString i' xs
892 err (AI end _ _) = failLocMsgP (srcSpanStart span) end "unterminated options pragma"
895 -- -----------------------------------------------------------------------------
898 -- This stuff is horrible. I hates it.
900 lex_string_tok :: Action
901 lex_string_tok span buf len = do
904 return (L (mkSrcSpan (srcSpanStart span) end) tok)
906 lex_string :: String -> P Token
909 case alexGetChar' i of
914 glaexts <- extension glaExtsEnabled
918 case alexGetChar' i of
922 then failMsgP "primitive string literal must contain only characters <= \'\\xFF\'"
923 else let s' = mkZFastString (reverse s) in
924 return (ITprimstring s')
925 -- mkZFastString is a hack to avoid encoding the
926 -- string in UTF-8. We just want the exact bytes.
928 return (ITstring (mkFastString (reverse s)))
930 return (ITstring (mkFastString (reverse s)))
933 | Just ('&',i) <- next -> do
934 setInput i; lex_string s
935 | Just (c,i) <- next, is_space c -> do
936 setInput i; lex_stringgap s
937 where next = alexGetChar' i
947 c | is_space c -> lex_stringgap s
951 lex_char_tok :: Action
952 -- Here we are basically parsing character literals, such as 'x' or '\n'
953 -- but, when Template Haskell is on, we additionally spot
954 -- 'x and ''T, returning ITvarQuote and ITtyQuote respectively,
955 -- but WIHTOUT CONSUMING the x or T part (the parser does that).
956 -- So we have to do two characters of lookahead: when we see 'x we need to
957 -- see if there's a trailing quote
958 lex_char_tok span buf len = do -- We've seen '
959 i1 <- getInput -- Look ahead to first character
960 let loc = srcSpanStart span
961 case alexGetChar' i1 of
964 Just ('\'', i2@(AI end2 _ _)) -> do -- We've seen ''
965 th_exts <- extension thEnabled
968 return (L (mkSrcSpan loc end2) ITtyQuote)
971 Just ('\\', i2@(AI end2 _ _)) -> do -- We've seen 'backslash
974 mc <- getCharOrFail -- Trailing quote
975 if mc == '\'' then finish_char_tok loc lit_ch
976 else do setInput i2; lit_error
978 Just (c, i2@(AI end2 _ _))
979 | not (isAny c) -> lit_error
982 -- We've seen 'x, where x is a valid character
983 -- (i.e. not newline etc) but not a quote or backslash
984 case alexGetChar' i2 of -- Look ahead one more character
986 Just ('\'', i3) -> do -- We've seen 'x'
988 finish_char_tok loc c
989 _other -> do -- We've seen 'x not followed by quote
990 -- If TH is on, just parse the quote only
991 th_exts <- extension thEnabled
992 let (AI end _ _) = i1
993 if th_exts then return (L (mkSrcSpan loc end) ITvarQuote)
994 else do setInput i2; lit_error
996 finish_char_tok :: SrcLoc -> Char -> P (Located Token)
997 finish_char_tok loc ch -- We've already seen the closing quote
998 -- Just need to check for trailing #
999 = do glaexts <- extension glaExtsEnabled
1000 i@(AI end _ _) <- getInput
1002 case alexGetChar' i of
1003 Just ('#',i@(AI end _ _)) -> do
1005 return (L (mkSrcSpan loc end) (ITprimchar ch))
1007 return (L (mkSrcSpan loc end) (ITchar ch))
1009 return (L (mkSrcSpan loc end) (ITchar ch))
1011 lex_char :: Char -> AlexInput -> P Char
1014 '\\' -> do setInput inp; lex_escape
1015 c | isAny c -> do setInput inp; return c
1018 isAny c | c > '\xff' = isPrint c
1019 | otherwise = is_any c
1021 lex_escape :: P Char
1035 '^' -> do c <- getCharOrFail
1036 if c >= '@' && c <= '_'
1037 then return (chr (ord c - ord '@'))
1040 'x' -> readNum is_hexdigit 16 hexDigit
1041 'o' -> readNum is_octdigit 8 octDecDigit
1042 x | is_digit x -> readNum2 is_digit 10 octDecDigit (octDecDigit x)
1046 case alexGetChar' i of
1047 Nothing -> lit_error
1049 case alexGetChar' i2 of
1050 Nothing -> do setInput i2; lit_error
1052 let str = [c1,c2,c3] in
1053 case [ (c,rest) | (p,c) <- silly_escape_chars,
1054 Just rest <- [maybePrefixMatch p str] ] of
1055 (escape_char,[]):_ -> do
1058 (escape_char,_:_):_ -> do
1063 readNum :: (Char -> Bool) -> Int -> (Char -> Int) -> P Char
1064 readNum is_digit base conv = do
1068 then readNum2 is_digit base conv (conv c)
1069 else do setInput i; lit_error
1071 readNum2 is_digit base conv i = do
1074 where read i input = do
1075 case alexGetChar' input of
1076 Just (c,input') | is_digit c -> do
1077 read (i*base + conv c) input'
1079 if i >= 0 && i <= 0x10FFFF
1080 then do setInput input; return (chr i)
1083 silly_escape_chars = [
1120 -- before calling lit_error, ensure that the current input is pointing to
1121 -- the position of the error in the buffer. This is so that we can report
1122 -- a correct location to the user, but also so we can detect UTF-8 decoding
1123 -- errors if they occur.
1124 lit_error = lexError "lexical error in string/character literal"
1126 getCharOrFail :: P Char
1129 case alexGetChar' i of
1130 Nothing -> lexError "unexpected end-of-file in string/character literal"
1131 Just (c,i) -> do setInput i; return c
1133 -- -----------------------------------------------------------------------------
1143 SrcSpan -- The start and end of the text span related to
1144 -- the error. Might be used in environments which can
1145 -- show this span, e.g. by highlighting it.
1146 Message -- The error message
1148 data PState = PState {
1149 buffer :: StringBuffer,
1150 last_loc :: SrcSpan, -- pos of previous token
1151 last_offs :: !Int, -- offset of the previous token from the
1152 -- beginning of the current line.
1153 -- \t is equal to 8 spaces.
1154 last_len :: !Int, -- len of previous token
1155 loc :: SrcLoc, -- current loc (end of prev token + 1)
1156 extsBitmap :: !Int, -- bitmap that determines permitted extensions
1157 context :: [LayoutContext],
1160 -- last_loc and last_len are used when generating error messages,
1161 -- and in pushCurrentContext only. Sigh, if only Happy passed the
1162 -- current token to happyError, we could at least get rid of last_len.
1163 -- Getting rid of last_loc would require finding another way to
1164 -- implement pushCurrentContext (which is only called from one place).
1166 newtype P a = P { unP :: PState -> ParseResult a }
1168 instance Monad P where
1174 returnP a = P $ \s -> POk s a
1176 thenP :: P a -> (a -> P b) -> P b
1177 (P m) `thenP` k = P $ \ s ->
1179 POk s1 a -> (unP (k a)) s1
1180 PFailed span err -> PFailed span err
1182 failP :: String -> P a
1183 failP msg = P $ \s -> PFailed (last_loc s) (text msg)
1185 failMsgP :: String -> P a
1186 failMsgP msg = P $ \s -> PFailed (last_loc s) (text msg)
1188 failLocMsgP :: SrcLoc -> SrcLoc -> String -> P a
1189 failLocMsgP loc1 loc2 str = P $ \s -> PFailed (mkSrcSpan loc1 loc2) (text str)
1191 failSpanMsgP :: SrcSpan -> String -> P a
1192 failSpanMsgP span msg = P $ \s -> PFailed span (text msg)
1194 extension :: (Int -> Bool) -> P Bool
1195 extension p = P $ \s -> POk s (p $! extsBitmap s)
1198 getExts = P $ \s -> POk s (extsBitmap s)
1200 setSrcLoc :: SrcLoc -> P ()
1201 setSrcLoc new_loc = P $ \s -> POk s{loc=new_loc} ()
1203 getSrcLoc :: P SrcLoc
1204 getSrcLoc = P $ \s@(PState{ loc=loc }) -> POk s loc
1206 setLastToken :: SrcSpan -> Int -> P ()
1207 setLastToken loc len = P $ \s -> POk s{ last_loc=loc, last_len=len } ()
1209 data AlexInput = AI SrcLoc {-#UNPACK#-}!Int StringBuffer
1211 alexInputPrevChar :: AlexInput -> Char
1212 alexInputPrevChar (AI _ _ buf) = prevChar buf '\n'
1214 alexGetChar :: AlexInput -> Maybe (Char,AlexInput)
1215 alexGetChar (AI loc ofs s)
1217 | otherwise = adj_c `seq` loc' `seq` ofs' `seq` s' `seq`
1218 --trace (show (ord c)) $
1219 Just (adj_c, (AI loc' ofs' s'))
1220 where (c,s') = nextChar s
1221 loc' = advanceSrcLoc loc c
1222 ofs' = advanceOffs c ofs
1230 other_graphic = '\x6'
1233 | c <= '\x06' = non_graphic
1236 case generalCategory c of
1237 UppercaseLetter -> upper
1238 LowercaseLetter -> lower
1239 TitlecaseLetter -> upper
1240 ModifierLetter -> other_graphic
1241 OtherLetter -> other_graphic
1242 NonSpacingMark -> other_graphic
1243 SpacingCombiningMark -> other_graphic
1244 EnclosingMark -> other_graphic
1245 DecimalNumber -> digit
1246 LetterNumber -> other_graphic
1247 OtherNumber -> other_graphic
1248 ConnectorPunctuation -> other_graphic
1249 DashPunctuation -> other_graphic
1250 OpenPunctuation -> other_graphic
1251 ClosePunctuation -> other_graphic
1252 InitialQuote -> other_graphic
1253 FinalQuote -> other_graphic
1254 OtherPunctuation -> other_graphic
1255 MathSymbol -> symbol
1256 CurrencySymbol -> symbol
1257 ModifierSymbol -> symbol
1258 OtherSymbol -> symbol
1260 _other -> non_graphic
1262 -- This version does not squash unicode characters, it is used when
1264 alexGetChar' :: AlexInput -> Maybe (Char,AlexInput)
1265 alexGetChar' (AI loc ofs s)
1267 | otherwise = c `seq` loc' `seq` ofs' `seq` s' `seq`
1268 --trace (show (ord c)) $
1269 Just (c, (AI loc' ofs' s'))
1270 where (c,s') = nextChar s
1271 loc' = advanceSrcLoc loc c
1272 ofs' = advanceOffs c ofs
1274 advanceOffs :: Char -> Int -> Int
1275 advanceOffs '\n' offs = 0
1276 advanceOffs '\t' offs = (offs `quot` 8 + 1) * 8
1277 advanceOffs _ offs = offs + 1
1279 getInput :: P AlexInput
1280 getInput = P $ \s@PState{ loc=l, last_offs=o, buffer=b } -> POk s (AI l o b)
1282 setInput :: AlexInput -> P ()
1283 setInput (AI l o b) = P $ \s -> POk s{ loc=l, last_offs=o, buffer=b } ()
1285 pushLexState :: Int -> P ()
1286 pushLexState ls = P $ \s@PState{ lex_state=l } -> POk s{lex_state=ls:l} ()
1288 popLexState :: P Int
1289 popLexState = P $ \s@PState{ lex_state=ls:l } -> POk s{ lex_state=l } ls
1291 getLexState :: P Int
1292 getLexState = P $ \s@PState{ lex_state=ls:l } -> POk s ls
1294 -- for reasons of efficiency, flags indicating language extensions (eg,
1295 -- -fglasgow-exts or -fparr) are represented by a bitmap stored in an unboxed
1298 glaExtsBit, ffiBit, parrBit :: Int
1305 tvBit = 7 -- Scoped type variables enables 'forall' keyword
1306 bangPatBit = 8 -- Tells the parser to understand bang-patterns
1307 -- (doesn't affect the lexer)
1309 glaExtsEnabled, ffiEnabled, parrEnabled :: Int -> Bool
1310 glaExtsEnabled flags = testBit flags glaExtsBit
1311 ffiEnabled flags = testBit flags ffiBit
1312 parrEnabled flags = testBit flags parrBit
1313 arrowsEnabled flags = testBit flags arrowsBit
1314 thEnabled flags = testBit flags thBit
1315 ipEnabled flags = testBit flags ipBit
1316 tvEnabled flags = testBit flags tvBit
1317 bangPatEnabled flags = testBit flags bangPatBit
1319 -- PState for parsing options pragmas
1321 pragState :: StringBuffer -> SrcLoc -> PState
1325 last_loc = mkSrcSpan loc loc,
1331 lex_state = [bol, option_prags, 0]
1335 -- create a parse state
1337 mkPState :: StringBuffer -> SrcLoc -> DynFlags -> PState
1338 mkPState buf loc flags =
1341 last_loc = mkSrcSpan loc loc,
1345 extsBitmap = fromIntegral bitmap,
1347 lex_state = [bol, if glaExtsEnabled bitmap then glaexts else 0]
1348 -- we begin in the layout state if toplev_layout is set
1351 bitmap = glaExtsBit `setBitIf` dopt Opt_GlasgowExts flags
1352 .|. ffiBit `setBitIf` dopt Opt_FFI flags
1353 .|. parrBit `setBitIf` dopt Opt_PArr flags
1354 .|. arrowsBit `setBitIf` dopt Opt_Arrows flags
1355 .|. thBit `setBitIf` dopt Opt_TH flags
1356 .|. ipBit `setBitIf` dopt Opt_ImplicitParams flags
1357 .|. tvBit `setBitIf` dopt Opt_ScopedTypeVariables flags
1358 .|. bangPatBit `setBitIf` dopt Opt_BangPatterns flags
1360 setBitIf :: Int -> Bool -> Int
1361 b `setBitIf` cond | cond = bit b
1364 getContext :: P [LayoutContext]
1365 getContext = P $ \s@PState{context=ctx} -> POk s ctx
1367 setContext :: [LayoutContext] -> P ()
1368 setContext ctx = P $ \s -> POk s{context=ctx} ()
1371 popContext = P $ \ s@(PState{ buffer = buf, context = ctx,
1372 loc = loc, last_len = len, last_loc = last_loc }) ->
1374 (_:tl) -> POk s{ context = tl } ()
1375 [] -> PFailed last_loc (srcParseErr buf len)
1377 -- Push a new layout context at the indentation of the last token read.
1378 -- This is only used at the outer level of a module when the 'module'
1379 -- keyword is missing.
1380 pushCurrentContext :: P ()
1381 pushCurrentContext = P $ \ s@PState{ last_offs=offs, last_len=len, context=ctx } ->
1382 POk s{context = Layout (offs-len) : ctx} ()
1384 getOffside :: P Ordering
1385 getOffside = P $ \s@PState{last_offs=offs, context=stk} ->
1386 let ord = case stk of
1387 (Layout n:_) -> compare offs n
1391 -- ---------------------------------------------------------------------------
1392 -- Construct a parse error
1395 :: StringBuffer -- current buffer (placed just after the last token)
1396 -> Int -- length of the previous token
1399 = hcat [ if null token
1400 then ptext SLIT("parse error (possibly incorrect indentation)")
1401 else hcat [ptext SLIT("parse error on input "),
1402 char '`', text token, char '\'']
1404 where token = lexemeToString (offsetBytes (-len) buf) len
1406 -- Report a parse failure, giving the span of the previous token as
1407 -- the location of the error. This is the entry point for errors
1408 -- detected during parsing.
1410 srcParseFail = P $ \PState{ buffer = buf, last_len = len,
1411 last_loc = last_loc } ->
1412 PFailed last_loc (srcParseErr buf len)
1414 -- A lexical error is reported at a particular position in the source file,
1415 -- not over a token range.
1416 lexError :: String -> P a
1419 i@(AI end _ buf) <- getInput
1420 reportLexError loc end buf str
1422 -- -----------------------------------------------------------------------------
1423 -- This is the top-level function: called from the parser each time a
1424 -- new token is to be read from the input.
1426 lexer :: (Located Token -> P a) -> P a
1428 tok@(L _ tok__) <- lexToken
1429 --trace ("token: " ++ show tok__) $ do
1432 lexToken :: P (Located Token)
1434 inp@(AI loc1 _ buf) <- getInput
1437 case alexScanUser exts inp sc of
1438 AlexEOF -> do let span = mkSrcSpan loc1 loc1
1440 return (L span ITeof)
1441 AlexError (AI loc2 _ buf) -> do
1442 reportLexError loc1 loc2 buf "lexical error"
1443 AlexSkip inp2 _ -> do
1446 AlexToken inp2@(AI end _ buf2) len t -> do
1448 let span = mkSrcSpan loc1 end
1449 let bytes = byteDiff buf buf2
1450 span `seq` setLastToken span bytes
1453 reportLexError loc1 loc2 buf str
1454 | atEnd buf = failLocMsgP loc1 loc2 (str ++ " at end of input")
1457 c = fst (nextChar buf)
1459 if c == '\0' -- decoding errors are mapped to '\0', see utf8DecodeChar#
1460 then failLocMsgP loc2 loc2 (str ++ " (UTF-8 decoding error)")
1461 else failLocMsgP loc1 loc2 (str ++ " at character " ++ show c)