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 }
256 "(#" / { notFollowedBySymbol } { token IToubxparen }
257 "#)" { token ITcubxparen }
258 "{|" { token ITocurlybar }
259 "|}" { token ITccurlybar }
262 <0,option_prags,glaexts> {
263 \( { special IToparen }
264 \) { special ITcparen }
265 \[ { special ITobrack }
266 \] { special ITcbrack }
267 \, { special ITcomma }
268 \; { special ITsemi }
269 \` { special ITbackquote }
275 <0,option_prags,glaexts> {
276 @qual @varid { check_qvarid }
277 @qual @conid { idtoken qconid }
279 @conid { idtoken conid }
282 -- after an illegal qvarid, such as 'M.let',
283 -- we back up and try again in the bad_qvarid state:
285 @conid { pop_and (idtoken conid) }
286 @qual @conid { pop_and (idtoken qconid) }
290 @qual @varid "#"+ { idtoken qvarid }
291 @qual @conid "#"+ { idtoken qconid }
292 @varid "#"+ { varid }
293 @conid "#"+ { idtoken conid }
299 @qual @varsym { idtoken qvarsym }
300 @qual @consym { idtoken qconsym }
306 @decimal { tok_decimal }
307 0[oO] @octal { tok_octal }
308 0[xX] @hexadecimal { tok_hexadecimal }
312 @decimal \# { prim_decimal }
313 0[oO] @octal \# { prim_octal }
314 0[xX] @hexadecimal \# { prim_hexadecimal }
317 <0,glaexts> @floating_point { strtoken tok_float }
318 <glaexts> @floating_point \# { init_strtoken 1 prim_float }
319 <glaexts> @floating_point \# \# { init_strtoken 2 prim_double }
321 -- Strings and chars are lexed by hand-written code. The reason is
322 -- that even if we recognise the string or char here in the regex
323 -- lexer, we would still have to parse the string afterward in order
324 -- to convert it to a String.
327 \" { lex_string_tok }
331 -- work around bug in Alex 2.0
332 #if __GLASGOW_HASKELL__ < 503
333 unsafeAt arr i = arr ! i
336 -- -----------------------------------------------------------------------------
340 = ITas -- Haskell keywords
364 | ITscc -- ToDo: remove (we use {-# SCC "..." #-} now)
366 | ITforall -- GHC extension keywords
382 | ITinline_prag Bool -- True <=> INLINE, False <=> NOINLINE
383 | ITspec_prag -- SPECIALISE
384 | ITspec_inline_prag Bool -- SPECIALISE INLINE (or NOINLINE)
390 | ITcore_prag -- hdaume: core annotations
393 | IToptions_prag String
394 | ITinclude_prag String
397 | ITdotdot -- reserved symbols
413 | ITbiglam -- GHC-extension symbols
415 | ITocurly -- special symbols
417 | ITocurlybar -- {|, for type applications
418 | ITccurlybar -- |}, for type applications
422 | ITopabrack -- [:, for parallel arrays with -fparr
423 | ITcpabrack -- :], for parallel arrays with -fparr
434 | ITvarid FastString -- identifiers
436 | ITvarsym FastString
437 | ITconsym FastString
438 | ITqvarid (FastString,FastString)
439 | ITqconid (FastString,FastString)
440 | ITqvarsym (FastString,FastString)
441 | ITqconsym (FastString,FastString)
443 | ITdupipvarid 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
502 isSpecial ITiso = True
503 isSpecial ITfamily = True
506 -- the bitmap provided as the third component indicates whether the
507 -- corresponding extension keyword is valid under the extension options
508 -- provided to the compiler; if the extension corresponding to *any* of the
509 -- bits set in the bitmap is enabled, the keyword is valid (this setup
510 -- facilitates using a keyword in two different extensions that can be
511 -- activated independently)
513 reservedWordsFM = listToUFM $
514 map (\(x, y, z) -> (mkFastString x, (y, z)))
515 [( "_", ITunderscore, 0 ),
517 ( "case", ITcase, 0 ),
518 ( "class", ITclass, 0 ),
519 ( "data", ITdata, 0 ),
520 ( "default", ITdefault, 0 ),
521 ( "deriving", ITderiving, 0 ),
523 ( "else", ITelse, 0 ),
524 ( "hiding", IThiding, 0 ),
526 ( "import", ITimport, 0 ),
528 ( "infix", ITinfix, 0 ),
529 ( "infixl", ITinfixl, 0 ),
530 ( "infixr", ITinfixr, 0 ),
531 ( "instance", ITinstance, 0 ),
533 ( "module", ITmodule, 0 ),
534 ( "newtype", ITnewtype, 0 ),
536 ( "qualified", ITqualified, 0 ),
537 ( "then", ITthen, 0 ),
538 ( "type", ITtype, 0 ),
539 ( "where", ITwhere, 0 ),
540 ( "_scc_", ITscc, 0 ), -- ToDo: remove
542 ( "forall", ITforall, bit tvBit),
543 ( "mdo", ITmdo, bit glaExtsBit),
544 ( "family", ITfamily, bit idxTysBit),
546 ( "foreign", ITforeign, bit ffiBit),
547 ( "export", ITexport, bit ffiBit),
548 ( "label", ITlabel, bit ffiBit),
549 ( "dynamic", ITdynamic, bit ffiBit),
550 ( "safe", ITsafe, bit ffiBit),
551 ( "threadsafe", ITthreadsafe, bit ffiBit),
552 ( "unsafe", ITunsafe, bit ffiBit),
553 ( "stdcall", ITstdcallconv, bit ffiBit),
554 ( "ccall", ITccallconv, bit ffiBit),
555 ( "dotnet", ITdotnet, bit ffiBit),
557 ( "rec", ITrec, bit arrowsBit),
558 ( "proc", ITproc, bit arrowsBit)
561 reservedSymsFM = listToUFM $
562 map (\ (x,y,z) -> (mkFastString x,(y,z)))
563 [ ("..", ITdotdot, 0)
564 ,(":", ITcolon, 0) -- (:) is a reserved op,
565 -- meaning only list cons
578 ,("*", ITstar, bit glaExtsBit .|.
579 bit idxTysBit) -- For data T (a::*) = MkT
580 ,(".", ITdot, bit tvBit) -- For 'forall a . t'
582 ,("-<", ITlarrowtail, bit arrowsBit)
583 ,(">-", ITrarrowtail, bit arrowsBit)
584 ,("-<<", ITLarrowtail, bit arrowsBit)
585 ,(">>-", ITRarrowtail, bit arrowsBit)
587 #if __GLASGOW_HASKELL__ >= 605
588 ,("λ", ITlam, bit glaExtsBit)
589 ,("∷", ITdcolon, bit glaExtsBit)
590 ,("⇒", ITdarrow, bit glaExtsBit)
591 ,("∀", ITforall, bit glaExtsBit)
592 ,("→", ITrarrow, bit glaExtsBit)
593 ,("←", ITlarrow, bit glaExtsBit)
594 ,("⋯", ITdotdot, bit glaExtsBit)
595 -- ToDo: ideally, → and ∷ should be "specials", so that they cannot
596 -- form part of a large operator. This would let us have a better
597 -- syntax for kinds: ɑ∷*→* would be a legal kind signature. (maybe).
601 -- -----------------------------------------------------------------------------
604 type Action = SrcSpan -> StringBuffer -> Int -> P (Located Token)
606 special :: Token -> Action
607 special tok span _buf len = return (L span tok)
609 token, layout_token :: Token -> Action
610 token t span buf len = return (L span t)
611 layout_token t span buf len = pushLexState layout >> return (L span t)
613 idtoken :: (StringBuffer -> Int -> Token) -> Action
614 idtoken f span buf len = return (L span $! (f buf len))
616 skip_one_varid :: (FastString -> Token) -> Action
617 skip_one_varid f span buf len
618 = return (L span $! f (lexemeToFastString (stepOn buf) (len-1)))
620 strtoken :: (String -> Token) -> Action
621 strtoken f span buf len =
622 return (L span $! (f $! lexemeToString buf len))
624 init_strtoken :: Int -> (String -> Token) -> Action
625 -- like strtoken, but drops the last N character(s)
626 init_strtoken drop f span buf len =
627 return (L span $! (f $! lexemeToString buf (len-drop)))
629 begin :: Int -> Action
630 begin code _span _str _len = do pushLexState code; lexToken
633 pop _span _buf _len = do popLexState; lexToken
635 pop_and :: Action -> Action
636 pop_and act span buf len = do popLexState; act span buf len
638 notFollowedBy char _ _ _ (AI _ _ buf) = atEnd buf || currentChar buf /= char
640 notFollowedBySymbol _ _ _ (AI _ _ buf)
641 = atEnd buf || currentChar buf `notElem` "!#$%&*+./<=>?@\\^|-~"
643 atEOL _ _ _ (AI _ _ buf) = atEnd buf || currentChar buf == '\n'
645 ifExtension pred bits _ _ _ = pred bits
648 nested comments require traversing by hand, they can't be parsed
649 using regular expressions.
651 nested_comment :: Action
652 nested_comment span _str _len = do
655 where go 0 input = do setInput input; lexToken
657 case alexGetChar input of
662 case alexGetChar input of
664 Just ('\125',input) -> go (n-1) input
665 Just (c,_) -> go n input
667 case alexGetChar input of
669 Just ('-',input') -> go (n+1) input'
670 Just (c,input) -> go n input
673 err (AI end _ _) = failLocMsgP (srcSpanStart span) end "unterminated `{-'"
675 open_brace, close_brace :: Action
676 open_brace span _str _len = do
678 setContext (NoLayout:ctx)
679 return (L span ITocurly)
680 close_brace span _str _len = do
682 return (L span ITccurly)
684 -- We have to be careful not to count M.<varid> as a qualified name
685 -- when <varid> is a keyword. We hack around this by catching
686 -- the offending tokens afterward, and re-lexing in a different state.
687 check_qvarid span buf len = do
688 case lookupUFM reservedWordsFM var of
690 | not (isSpecial keyword) ->
694 b <- extension (\i -> exts .&. i /= 0)
697 _other -> return token
699 (mod,var) = splitQualName buf len
700 token = L span (ITqvarid (mod,var))
703 (AI _ offs _) <- getInput
704 setInput (AI (srcSpanStart span) (offs-len) buf)
705 pushLexState bad_qvarid
708 qvarid buf len = ITqvarid $! splitQualName buf len
709 qconid buf len = ITqconid $! splitQualName buf len
711 splitQualName :: StringBuffer -> Int -> (FastString,FastString)
712 -- takes a StringBuffer and a length, and returns the module name
713 -- and identifier parts of a qualified name. Splits at the *last* dot,
714 -- because of hierarchical module names.
715 splitQualName orig_buf len = split orig_buf orig_buf
718 | orig_buf `byteDiff` buf >= len = done dot_buf
719 | c == '.' = found_dot buf'
720 | otherwise = split buf' dot_buf
722 (c,buf') = nextChar buf
724 -- careful, we might get names like M....
725 -- so, if the character after the dot is not upper-case, this is
726 -- the end of the qualifier part.
727 found_dot buf -- buf points after the '.'
728 | isUpper c = split buf' buf
729 | otherwise = done buf
731 (c,buf') = nextChar buf
734 (lexemeToFastString orig_buf (qual_size - 1),
735 lexemeToFastString dot_buf (len - qual_size))
737 qual_size = orig_buf `byteDiff` dot_buf
740 case lookupUFM reservedWordsFM fs of
741 Just (keyword,0) -> do
743 return (L span keyword)
744 Just (keyword,exts) -> do
745 b <- extension (\i -> exts .&. i /= 0)
746 if b then do maybe_layout keyword
747 return (L span keyword)
748 else return (L span (ITvarid fs))
749 _other -> return (L span (ITvarid fs))
751 fs = lexemeToFastString buf len
753 conid buf len = ITconid fs
754 where fs = lexemeToFastString buf len
756 qvarsym buf len = ITqvarsym $! splitQualName buf len
757 qconsym buf len = ITqconsym $! splitQualName buf len
759 varsym = sym ITvarsym
760 consym = sym ITconsym
762 sym con span buf len =
763 case lookupUFM reservedSymsFM fs of
764 Just (keyword,0) -> return (L span keyword)
765 Just (keyword,exts) -> do
766 b <- extension (\i -> exts .&. i /= 0)
767 if b then return (L span keyword)
768 else return (L span $! con fs)
769 _other -> return (L span $! con fs)
771 fs = lexemeToFastString buf len
773 tok_decimal span buf len
774 = return (L span (ITinteger $! parseInteger buf len 10 octDecDigit))
776 tok_octal span buf len
777 = return (L span (ITinteger $! parseInteger (offsetBytes 2 buf) (len-2) 8 octDecDigit))
779 tok_hexadecimal span buf len
780 = return (L span (ITinteger $! parseInteger (offsetBytes 2 buf) (len-2) 16 hexDigit))
782 prim_decimal span buf len
783 = return (L span (ITprimint $! parseInteger buf (len-1) 10 octDecDigit))
785 prim_octal span buf len
786 = return (L span (ITprimint $! parseInteger (offsetBytes 2 buf) (len-3) 8 octDecDigit))
788 prim_hexadecimal span buf len
789 = return (L span (ITprimint $! parseInteger (offsetBytes 2 buf) (len-3) 16 hexDigit))
791 tok_float str = ITrational $! readRational str
792 prim_float str = ITprimfloat $! readRational str
793 prim_double str = ITprimdouble $! readRational str
795 -- -----------------------------------------------------------------------------
798 -- we're at the first token on a line, insert layout tokens if necessary
800 do_bol span _str _len = do
804 --trace "layout: inserting '}'" $ do
806 -- do NOT pop the lex state, we might have a ';' to insert
807 return (L span ITvccurly)
809 --trace "layout: inserting ';'" $ do
811 return (L span ITsemi)
816 -- certain keywords put us in the "layout" state, where we might
817 -- add an opening curly brace.
818 maybe_layout ITdo = pushLexState layout_do
819 maybe_layout ITmdo = pushLexState layout_do
820 maybe_layout ITof = pushLexState layout
821 maybe_layout ITlet = pushLexState layout
822 maybe_layout ITwhere = pushLexState layout
823 maybe_layout ITrec = pushLexState layout
824 maybe_layout _ = return ()
826 -- Pushing a new implicit layout context. If the indentation of the
827 -- next token is not greater than the previous layout context, then
828 -- Haskell 98 says that the new layout context should be empty; that is
829 -- the lexer must generate {}.
831 -- We are slightly more lenient than this: when the new context is started
832 -- by a 'do', then we allow the new context to be at the same indentation as
833 -- the previous context. This is what the 'strict' argument is for.
835 new_layout_context strict span _buf _len = do
837 (AI _ offset _) <- getInput
840 Layout prev_off : _ |
841 (strict && prev_off >= offset ||
842 not strict && prev_off > offset) -> do
843 -- token is indented to the left of the previous context.
844 -- we must generate a {} sequence now.
845 pushLexState layout_left
846 return (L span ITvocurly)
848 setContext (Layout offset : ctx)
849 return (L span ITvocurly)
851 do_layout_left span _buf _len = do
853 pushLexState bol -- we must be at the start of a line
854 return (L span ITvccurly)
856 -- -----------------------------------------------------------------------------
859 setLine :: Int -> Action
860 setLine code span buf len = do
861 let line = parseInteger buf len 10 octDecDigit
862 setSrcLoc (mkSrcLoc (srcSpanFile span) (fromIntegral line - 1) 0)
863 -- subtract one: the line number refers to the *following* line
868 setFile :: Int -> Action
869 setFile code span buf len = do
870 let file = lexemeToFastString (stepOn buf) (len-2)
871 setSrcLoc (mkSrcLoc file (srcSpanEndLine span) (srcSpanEndCol span))
877 -- -----------------------------------------------------------------------------
878 -- Options, includes and language pragmas.
880 lex_string_prag :: (String -> Token) -> Action
881 lex_string_prag mkTok span buf len
882 = do input <- getInput
886 return (L (mkSrcSpan start end) tok)
888 = if isString input "#-}"
889 then do setInput input
890 return (mkTok (reverse acc))
891 else case alexGetChar input of
892 Just (c,i) -> go (c:acc) i
896 = case alexGetChar i of
897 Just (c,i') | c == x -> isString i' xs
899 err (AI end _ _) = failLocMsgP (srcSpanStart span) end "unterminated options pragma"
902 -- -----------------------------------------------------------------------------
905 -- This stuff is horrible. I hates it.
907 lex_string_tok :: Action
908 lex_string_tok span buf len = do
911 return (L (mkSrcSpan (srcSpanStart span) end) tok)
913 lex_string :: String -> P Token
916 case alexGetChar' i of
921 glaexts <- extension glaExtsEnabled
925 case alexGetChar' i of
929 then failMsgP "primitive string literal must contain only characters <= \'\\xFF\'"
930 else let s' = mkZFastString (reverse s) in
931 return (ITprimstring s')
932 -- mkZFastString is a hack to avoid encoding the
933 -- string in UTF-8. We just want the exact bytes.
935 return (ITstring (mkFastString (reverse s)))
937 return (ITstring (mkFastString (reverse s)))
940 | Just ('&',i) <- next -> do
941 setInput i; lex_string s
942 | Just (c,i) <- next, is_space c -> do
943 setInput i; lex_stringgap s
944 where next = alexGetChar' i
954 c | is_space c -> lex_stringgap s
958 lex_char_tok :: Action
959 -- Here we are basically parsing character literals, such as 'x' or '\n'
960 -- but, when Template Haskell is on, we additionally spot
961 -- 'x and ''T, returning ITvarQuote and ITtyQuote respectively,
962 -- but WIHTOUT CONSUMING the x or T part (the parser does that).
963 -- So we have to do two characters of lookahead: when we see 'x we need to
964 -- see if there's a trailing quote
965 lex_char_tok span buf len = do -- We've seen '
966 i1 <- getInput -- Look ahead to first character
967 let loc = srcSpanStart span
968 case alexGetChar' i1 of
971 Just ('\'', i2@(AI end2 _ _)) -> do -- We've seen ''
972 th_exts <- extension thEnabled
975 return (L (mkSrcSpan loc end2) ITtyQuote)
978 Just ('\\', i2@(AI end2 _ _)) -> do -- We've seen 'backslash
981 mc <- getCharOrFail -- Trailing quote
982 if mc == '\'' then finish_char_tok loc lit_ch
983 else do setInput i2; lit_error
985 Just (c, i2@(AI end2 _ _))
986 | not (isAny c) -> lit_error
989 -- We've seen 'x, where x is a valid character
990 -- (i.e. not newline etc) but not a quote or backslash
991 case alexGetChar' i2 of -- Look ahead one more character
993 Just ('\'', i3) -> do -- We've seen 'x'
995 finish_char_tok loc c
996 _other -> do -- We've seen 'x not followed by quote
997 -- If TH is on, just parse the quote only
998 th_exts <- extension thEnabled
999 let (AI end _ _) = i1
1000 if th_exts then return (L (mkSrcSpan loc end) ITvarQuote)
1001 else do setInput i2; lit_error
1003 finish_char_tok :: SrcLoc -> Char -> P (Located Token)
1004 finish_char_tok loc ch -- We've already seen the closing quote
1005 -- Just need to check for trailing #
1006 = do glaexts <- extension glaExtsEnabled
1007 i@(AI end _ _) <- getInput
1009 case alexGetChar' i of
1010 Just ('#',i@(AI end _ _)) -> do
1012 return (L (mkSrcSpan loc end) (ITprimchar ch))
1014 return (L (mkSrcSpan loc end) (ITchar ch))
1016 return (L (mkSrcSpan loc end) (ITchar ch))
1018 lex_char :: Char -> AlexInput -> P Char
1021 '\\' -> do setInput inp; lex_escape
1022 c | isAny c -> do setInput inp; return c
1025 isAny c | c > '\xff' = isPrint c
1026 | otherwise = is_any c
1028 lex_escape :: P Char
1042 '^' -> do c <- getCharOrFail
1043 if c >= '@' && c <= '_'
1044 then return (chr (ord c - ord '@'))
1047 'x' -> readNum is_hexdigit 16 hexDigit
1048 'o' -> readNum is_octdigit 8 octDecDigit
1049 x | is_digit x -> readNum2 is_digit 10 octDecDigit (octDecDigit x)
1053 case alexGetChar' i of
1054 Nothing -> lit_error
1056 case alexGetChar' i2 of
1057 Nothing -> do setInput i2; lit_error
1059 let str = [c1,c2,c3] in
1060 case [ (c,rest) | (p,c) <- silly_escape_chars,
1061 Just rest <- [maybePrefixMatch p str] ] of
1062 (escape_char,[]):_ -> do
1065 (escape_char,_:_):_ -> do
1070 readNum :: (Char -> Bool) -> Int -> (Char -> Int) -> P Char
1071 readNum is_digit base conv = do
1075 then readNum2 is_digit base conv (conv c)
1076 else do setInput i; lit_error
1078 readNum2 is_digit base conv i = do
1081 where read i input = do
1082 case alexGetChar' input of
1083 Just (c,input') | is_digit c -> do
1084 read (i*base + conv c) input'
1086 if i >= 0 && i <= 0x10FFFF
1087 then do setInput input; return (chr i)
1090 silly_escape_chars = [
1127 -- before calling lit_error, ensure that the current input is pointing to
1128 -- the position of the error in the buffer. This is so that we can report
1129 -- a correct location to the user, but also so we can detect UTF-8 decoding
1130 -- errors if they occur.
1131 lit_error = lexError "lexical error in string/character literal"
1133 getCharOrFail :: P Char
1136 case alexGetChar' i of
1137 Nothing -> lexError "unexpected end-of-file in string/character literal"
1138 Just (c,i) -> do setInput i; return c
1140 -- -----------------------------------------------------------------------------
1150 SrcSpan -- The start and end of the text span related to
1151 -- the error. Might be used in environments which can
1152 -- show this span, e.g. by highlighting it.
1153 Message -- The error message
1155 data PState = PState {
1156 buffer :: StringBuffer,
1157 last_loc :: SrcSpan, -- pos of previous token
1158 last_offs :: !Int, -- offset of the previous token from the
1159 -- beginning of the current line.
1160 -- \t is equal to 8 spaces.
1161 last_len :: !Int, -- len of previous token
1162 loc :: SrcLoc, -- current loc (end of prev token + 1)
1163 extsBitmap :: !Int, -- bitmap that determines permitted extensions
1164 context :: [LayoutContext],
1167 -- last_loc and last_len are used when generating error messages,
1168 -- and in pushCurrentContext only. Sigh, if only Happy passed the
1169 -- current token to happyError, we could at least get rid of last_len.
1170 -- Getting rid of last_loc would require finding another way to
1171 -- implement pushCurrentContext (which is only called from one place).
1173 newtype P a = P { unP :: PState -> ParseResult a }
1175 instance Monad P where
1181 returnP a = P $ \s -> POk s a
1183 thenP :: P a -> (a -> P b) -> P b
1184 (P m) `thenP` k = P $ \ s ->
1186 POk s1 a -> (unP (k a)) s1
1187 PFailed span err -> PFailed span err
1189 failP :: String -> P a
1190 failP msg = P $ \s -> PFailed (last_loc s) (text msg)
1192 failMsgP :: String -> P a
1193 failMsgP msg = P $ \s -> PFailed (last_loc s) (text msg)
1195 failLocMsgP :: SrcLoc -> SrcLoc -> String -> P a
1196 failLocMsgP loc1 loc2 str = P $ \s -> PFailed (mkSrcSpan loc1 loc2) (text str)
1198 failSpanMsgP :: SrcSpan -> String -> P a
1199 failSpanMsgP span msg = P $ \s -> PFailed span (text msg)
1201 extension :: (Int -> Bool) -> P Bool
1202 extension p = P $ \s -> POk s (p $! extsBitmap s)
1205 getExts = P $ \s -> POk s (extsBitmap s)
1207 setSrcLoc :: SrcLoc -> P ()
1208 setSrcLoc new_loc = P $ \s -> POk s{loc=new_loc} ()
1210 getSrcLoc :: P SrcLoc
1211 getSrcLoc = P $ \s@(PState{ loc=loc }) -> POk s loc
1213 setLastToken :: SrcSpan -> Int -> P ()
1214 setLastToken loc len = P $ \s -> POk s{ last_loc=loc, last_len=len } ()
1216 data AlexInput = AI SrcLoc {-#UNPACK#-}!Int StringBuffer
1218 alexInputPrevChar :: AlexInput -> Char
1219 alexInputPrevChar (AI _ _ buf) = prevChar buf '\n'
1221 alexGetChar :: AlexInput -> Maybe (Char,AlexInput)
1222 alexGetChar (AI loc ofs s)
1224 | otherwise = adj_c `seq` loc' `seq` ofs' `seq` s' `seq`
1225 --trace (show (ord c)) $
1226 Just (adj_c, (AI loc' ofs' s'))
1227 where (c,s') = nextChar s
1228 loc' = advanceSrcLoc loc c
1229 ofs' = advanceOffs c ofs
1237 other_graphic = '\x6'
1240 | c <= '\x06' = non_graphic
1243 case generalCategory c of
1244 UppercaseLetter -> upper
1245 LowercaseLetter -> lower
1246 TitlecaseLetter -> upper
1247 ModifierLetter -> other_graphic
1248 OtherLetter -> other_graphic
1249 NonSpacingMark -> other_graphic
1250 SpacingCombiningMark -> other_graphic
1251 EnclosingMark -> other_graphic
1252 DecimalNumber -> digit
1253 LetterNumber -> other_graphic
1254 OtherNumber -> other_graphic
1255 ConnectorPunctuation -> other_graphic
1256 DashPunctuation -> other_graphic
1257 OpenPunctuation -> other_graphic
1258 ClosePunctuation -> other_graphic
1259 InitialQuote -> other_graphic
1260 FinalQuote -> other_graphic
1261 OtherPunctuation -> other_graphic
1262 MathSymbol -> symbol
1263 CurrencySymbol -> symbol
1264 ModifierSymbol -> symbol
1265 OtherSymbol -> symbol
1267 _other -> non_graphic
1269 -- This version does not squash unicode characters, it is used when
1271 alexGetChar' :: AlexInput -> Maybe (Char,AlexInput)
1272 alexGetChar' (AI loc ofs s)
1274 | otherwise = c `seq` loc' `seq` ofs' `seq` s' `seq`
1275 --trace (show (ord c)) $
1276 Just (c, (AI loc' ofs' s'))
1277 where (c,s') = nextChar s
1278 loc' = advanceSrcLoc loc c
1279 ofs' = advanceOffs c ofs
1281 advanceOffs :: Char -> Int -> Int
1282 advanceOffs '\n' offs = 0
1283 advanceOffs '\t' offs = (offs `quot` 8 + 1) * 8
1284 advanceOffs _ offs = offs + 1
1286 getInput :: P AlexInput
1287 getInput = P $ \s@PState{ loc=l, last_offs=o, buffer=b } -> POk s (AI l o b)
1289 setInput :: AlexInput -> P ()
1290 setInput (AI l o b) = P $ \s -> POk s{ loc=l, last_offs=o, buffer=b } ()
1292 pushLexState :: Int -> P ()
1293 pushLexState ls = P $ \s@PState{ lex_state=l } -> POk s{lex_state=ls:l} ()
1295 popLexState :: P Int
1296 popLexState = P $ \s@PState{ lex_state=ls:l } -> POk s{ lex_state=l } ls
1298 getLexState :: P Int
1299 getLexState = P $ \s@PState{ lex_state=ls:l } -> POk s ls
1301 -- for reasons of efficiency, flags indicating language extensions (eg,
1302 -- -fglasgow-exts or -fparr) are represented by a bitmap stored in an unboxed
1305 glaExtsBit, ffiBit, parrBit :: Int
1312 tvBit = 7 -- Scoped type variables enables 'forall' keyword
1313 bangPatBit = 8 -- Tells the parser to understand bang-patterns
1314 -- (doesn't affect the lexer)
1315 idxTysBit = 9 -- indexed type families: 'family' keyword and kind sigs
1317 glaExtsEnabled, ffiEnabled, parrEnabled :: Int -> Bool
1318 glaExtsEnabled flags = testBit flags glaExtsBit
1319 ffiEnabled flags = testBit flags ffiBit
1320 parrEnabled flags = testBit flags parrBit
1321 arrowsEnabled flags = testBit flags arrowsBit
1322 thEnabled flags = testBit flags thBit
1323 ipEnabled flags = testBit flags ipBit
1324 tvEnabled flags = testBit flags tvBit
1325 bangPatEnabled flags = testBit flags bangPatBit
1326 idxTysEnabled flags = testBit flags idxTysBit
1328 -- PState for parsing options pragmas
1330 pragState :: StringBuffer -> SrcLoc -> PState
1334 last_loc = mkSrcSpan loc loc,
1340 lex_state = [bol, option_prags, 0]
1344 -- create a parse state
1346 mkPState :: StringBuffer -> SrcLoc -> DynFlags -> PState
1347 mkPState buf loc flags =
1350 last_loc = mkSrcSpan loc loc,
1354 extsBitmap = fromIntegral bitmap,
1356 lex_state = [bol, if glaExtsEnabled bitmap then glaexts else 0]
1357 -- we begin in the layout state if toplev_layout is set
1360 bitmap = glaExtsBit `setBitIf` dopt Opt_GlasgowExts flags
1361 .|. ffiBit `setBitIf` dopt Opt_FFI flags
1362 .|. parrBit `setBitIf` dopt Opt_PArr flags
1363 .|. arrowsBit `setBitIf` dopt Opt_Arrows flags
1364 .|. thBit `setBitIf` dopt Opt_TH flags
1365 .|. ipBit `setBitIf` dopt Opt_ImplicitParams flags
1366 .|. tvBit `setBitIf` dopt Opt_ScopedTypeVariables flags
1367 .|. bangPatBit `setBitIf` dopt Opt_BangPatterns flags
1368 .|. idxTysBit `setBitIf` dopt Opt_IndexedTypes flags
1370 setBitIf :: Int -> Bool -> Int
1371 b `setBitIf` cond | cond = bit b
1374 getContext :: P [LayoutContext]
1375 getContext = P $ \s@PState{context=ctx} -> POk s ctx
1377 setContext :: [LayoutContext] -> P ()
1378 setContext ctx = P $ \s -> POk s{context=ctx} ()
1381 popContext = P $ \ s@(PState{ buffer = buf, context = ctx,
1382 loc = loc, last_len = len, last_loc = last_loc }) ->
1384 (_:tl) -> POk s{ context = tl } ()
1385 [] -> PFailed last_loc (srcParseErr buf len)
1387 -- Push a new layout context at the indentation of the last token read.
1388 -- This is only used at the outer level of a module when the 'module'
1389 -- keyword is missing.
1390 pushCurrentContext :: P ()
1391 pushCurrentContext = P $ \ s@PState{ last_offs=offs, last_len=len, context=ctx } ->
1392 POk s{context = Layout (offs-len) : ctx} ()
1394 getOffside :: P Ordering
1395 getOffside = P $ \s@PState{last_offs=offs, context=stk} ->
1396 let ord = case stk of
1397 (Layout n:_) -> compare offs n
1401 -- ---------------------------------------------------------------------------
1402 -- Construct a parse error
1405 :: StringBuffer -- current buffer (placed just after the last token)
1406 -> Int -- length of the previous token
1409 = hcat [ if null token
1410 then ptext SLIT("parse error (possibly incorrect indentation)")
1411 else hcat [ptext SLIT("parse error on input "),
1412 char '`', text token, char '\'']
1414 where token = lexemeToString (offsetBytes (-len) buf) len
1416 -- Report a parse failure, giving the span of the previous token as
1417 -- the location of the error. This is the entry point for errors
1418 -- detected during parsing.
1420 srcParseFail = P $ \PState{ buffer = buf, last_len = len,
1421 last_loc = last_loc } ->
1422 PFailed last_loc (srcParseErr buf len)
1424 -- A lexical error is reported at a particular position in the source file,
1425 -- not over a token range.
1426 lexError :: String -> P a
1429 i@(AI end _ buf) <- getInput
1430 reportLexError loc end buf str
1432 -- -----------------------------------------------------------------------------
1433 -- This is the top-level function: called from the parser each time a
1434 -- new token is to be read from the input.
1436 lexer :: (Located Token -> P a) -> P a
1438 tok@(L _ tok__) <- lexToken
1439 --trace ("token: " ++ show tok__) $ do
1442 lexToken :: P (Located Token)
1444 inp@(AI loc1 _ buf) <- getInput
1447 case alexScanUser exts inp sc of
1448 AlexEOF -> do let span = mkSrcSpan loc1 loc1
1450 return (L span ITeof)
1451 AlexError (AI loc2 _ buf) -> do
1452 reportLexError loc1 loc2 buf "lexical error"
1453 AlexSkip inp2 _ -> do
1456 AlexToken inp2@(AI end _ buf2) len t -> do
1458 let span = mkSrcSpan loc1 end
1459 let bytes = byteDiff buf buf2
1460 span `seq` setLastToken span bytes
1463 reportLexError loc1 loc2 buf str
1464 | atEnd buf = failLocMsgP loc1 loc2 (str ++ " at end of input")
1467 c = fst (nextChar buf)
1469 if c == '\0' -- decoding errors are mapped to '\0', see utf8DecodeChar#
1470 then failLocMsgP loc2 loc2 (str ++ " (UTF-8 decoding error)")
1471 else failLocMsgP loc1 loc2 (str ++ " at character " ++ show c)