1 -----------------------------------------------------------------------------
2 -- (c) The University of Glasgow, 2003
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(..), Token__(..), lexer, mkPState, showPFailed,
26 P(..), ParseResult(..), setSrcLocFor, getSrcLoc,
27 failMsgP, failLocMsgP, srcParseFail,
28 popContext, pushCurrentContext,
31 #include "HsVersions.h"
33 import ForeignCall ( Safety(..) )
34 import ErrUtils ( Message )
43 import Util ( maybePrefixMatch )
51 $whitechar = [\ \t\n\r\f\v]
52 $white_no_nl = $whitechar # \n
56 $digit = [$ascdigit $unidigit]
58 $special = [\(\)\,\;\[\]\`\{\}]
59 $ascsymbol = [\!\#\$\%\&\*\+\.\/\<\=\>\?\@\\\^\|\-\~]
61 $symbol = [$ascsymbol $unisymbol] # [$special \_\:\"\']
64 $asclarge = [A-Z \xc0-\xd6 \xd8-\xde]
65 $large = [$asclarge $unilarge]
68 $ascsmall = [a-z \xdf-\xf6 \xf8-\xff]
69 $small = [$ascsmall $unismall \_]
71 $graphic = [$small $large $symbol $digit $special \:\"\']
74 $hexit = [$digit A-F a-f]
75 $symchar = [$symbol \:]
77 $idchar = [$small $large $digit \']
79 @varid = $small $idchar*
80 @conid = $large $idchar*
82 @varsym = $symbol $symchar*
83 @consym = \: $symchar*
87 @hexadecimal = $hexit+
88 @exponent = [eE] [\-\+]? @decimal
90 -- we support the hierarchical module name extension:
93 @floating_point = @decimal \. @decimal @exponent? | @decimal @exponent
97 -- everywhere: skip whitespace and comments
100 -- Everywhere: deal with nested comments. We explicitly rule out
101 -- pragmas, "{-#", so that we don't accidentally treat them as comments.
102 -- (this can happen even though pragmas will normally take precedence due to
103 -- longest-match, because pragmas aren't valid in every state, but comments
105 "{-" / { notFollowedBy '#' } { nested_comment }
107 -- Single-line comments are a bit tricky. Haskell 98 says that two or
108 -- more dashes followed by a symbol should be parsed as a varsym, so we
109 -- have to exclude those.
110 -- The regex says: "munch all the characters after the dashes, as long as
111 -- the first one is not a symbol".
112 "--"\-* ([^$symbol] .*)? ;
114 -- 'bol' state: beginning of a line. Slurp up all the whitespace (including
115 -- blank lines) until we find a non-whitespace character, then do layout
118 -- One slight wibble here: what if the line begins with {-#? In
119 -- theory, we have to lex the pragma to see if it's one we recognise,
120 -- and if it is, then we backtrack and do_bol, otherwise we treat it
121 -- as a nested comment. We don't bother with this: if the line begins
122 -- with {-#, then we'll assume it's a pragma we know about and go for do_bol.
125 ^\# (line)? { begin line_prag1 }
126 ^\# pragma .* \n ; -- GCC 3.3 CPP generated, apparently
130 -- after a layout keyword (let, where, do, of), we begin a new layout
131 -- context if the curly brace is missing.
132 -- Careful! This stuff is quite delicate.
133 <layout, layout_do> {
134 \{ / { notFollowedBy '-' } { pop_and open_brace }
135 -- we might encounter {-# here, but {- has been handled already
137 ^\# (line)? { begin line_prag1 }
140 -- do is treated in a subtly different way, see new_layout_context
141 <layout> () { new_layout_context True }
142 <layout_do> () { new_layout_context False }
144 -- after a new layout context which was found to be to the left of the
145 -- previous context, we have generated a '{' token, and we now need to
146 -- generate a matching '}' token.
147 <layout_left> () { do_layout_left }
149 <0,glaexts> \n { begin bol }
151 "{-#" $whitechar* (line|LINE) { begin line_prag2 }
153 -- single-line line pragmas, of the form
154 -- # <line> "<file>" <extra-stuff> \n
155 <line_prag1> $digit+ { set_line line_prag1a }
156 <line_prag1a> \" [$graphic \ ]* \" { set_file line_prag1b }
157 <line_prag1b> .* { pop }
159 -- Haskell-style line pragmas, of the form
160 -- {-# LINE <line> "<file>" #-}
161 <line_prag2> $digit+ { set_line line_prag2a }
162 <line_prag2a> \" [$graphic \ ]* \" { set_file line_prag2b }
163 <line_prag2b> "#-}" { pop }
166 "{-#" $whitechar* (SPECIALI[SZ]E|speciali[sz]e)
167 { token ITspecialise_prag }
168 "{-#" $whitechar* (SOURCE|source) { token ITsource_prag }
169 "{-#" $whitechar* (INLINE|inline) { token ITinline_prag }
170 "{-#" $whitechar* (NO(T?)INLINE|no(t?)inline)
171 { token ITnoinline_prag }
172 "{-#" $whitechar* (RULES|rules) { token ITrules_prag }
173 "{-#" $whitechar* (DEPRECATED|deprecated)
174 { token ITdeprecated_prag }
175 "{-#" $whitechar* (SCC|scc) { token ITscc_prag }
176 "{-#" $whitechar* (CORE|core) { token ITcore_prag }
178 "{-#" { nested_comment }
180 -- ToDo: should only be valid inside a pragma:
181 "#-}" { token ITclose_prag}
185 -- '0' state: ordinary lexemes
186 -- 'glaexts' state: glasgow extensions (postfix '#', etc.)
191 "[:" / { ifExtension parrEnabled } { token ITopabrack }
192 ":]" / { ifExtension parrEnabled } { token ITcpabrack }
196 "[|" / { ifExtension thEnabled } { token ITopenExpQuote }
197 "[e|" / { ifExtension thEnabled } { token ITopenExpQuote }
198 "[p|" / { ifExtension thEnabled } { token ITopenPatQuote }
199 "[d|" / { ifExtension thEnabled } { layout_token ITopenDecQuote }
200 "[t|" / { ifExtension thEnabled } { token ITopenTypQuote }
201 "|]" / { ifExtension thEnabled } { token ITcloseQuote }
202 \$ @varid / { ifExtension thEnabled } { skip_one_varid ITidEscape }
203 "$(" / { ifExtension thEnabled } { token ITparenEscape }
207 "(|" / { ifExtension arrowsEnabled } { special IToparenbar }
208 "|)" / { ifExtension arrowsEnabled } { special ITcparenbar }
212 \? @varid / { ifExtension ipEnabled } { skip_one_varid ITdupipvarid }
213 \% @varid / { ifExtension ipEnabled } { skip_one_varid ITsplitipvarid }
217 "(#" { token IToubxparen }
218 "#)" { token ITcubxparen }
219 "{|" { token ITocurlybar }
220 "|}" { token ITccurlybar }
224 \( { special IToparen }
225 \) { special ITcparen }
226 \[ { special ITobrack }
227 \] { special ITcbrack }
228 \, { special ITcomma }
229 \; { special ITsemi }
230 \` { special ITbackquote }
237 @qual @varid { check_qvarid }
238 @qual @conid { idtoken qconid }
240 @conid { idtoken conid }
243 -- after an illegal qvarid, such as 'M.let',
244 -- we back up and try again in the bad_qvarid state:
246 @conid { pop_and (idtoken conid) }
247 @qual @conid { pop_and (idtoken qconid) }
251 @qual @varid "#"+ { idtoken qvarid }
252 @qual @conid "#"+ { idtoken qconid }
253 @varid "#"+ { varid }
254 @conid "#"+ { idtoken conid }
260 @qual @varsym { idtoken qvarsym }
261 @qual @consym { idtoken qconsym }
267 @decimal { tok_decimal }
268 0[oO] @octal { tok_octal }
269 0[xX] @hexadecimal { tok_hexadecimal }
273 @decimal \# { prim_decimal }
274 0[oO] @octal \# { prim_octal }
275 0[xX] @hexadecimal \# { prim_hexadecimal }
278 <0,glaexts> @floating_point { strtoken tok_float }
279 <glaexts> @floating_point \# { init_strtoken 1 prim_float }
280 <glaexts> @floating_point \# \# { init_strtoken 2 prim_double }
282 -- Strings and chars are lexed by hand-written code. The reason is
283 -- that even if we recognise the string or char here in the regex
284 -- lexer, we would still have to parse the string afterward in order
285 -- to convert it to a String.
288 \" { lex_string_tok }
292 -- work around bug in Alex 2.0
293 #if __GLASGOW_HASKELL__ < 503
294 unsafeAt arr i = arr ! i
297 -- -----------------------------------------------------------------------------
300 data Token = T SrcLoc{-start-} SrcLoc{-end-} Token__
303 = ITas -- Haskell keywords
327 | ITscc -- ToDo: remove (we use {-# SCC "..." #-} now)
329 | ITforall -- GHC extension keywords
343 | ITspecialise_prag -- Pragmas
351 | ITcore_prag -- hdaume: core annotations
354 | ITdotdot -- reserved symbols
370 | ITbiglam -- GHC-extension symbols
372 | ITocurly -- special symbols
374 | ITocurlybar -- {|, for type applications
375 | ITccurlybar -- |}, for type applications
379 | ITopabrack -- [:, for parallel arrays with -fparr
380 | ITcpabrack -- :], for parallel arrays with -fparr
391 | ITvarid FastString -- identifiers
393 | ITvarsym FastString
394 | ITconsym FastString
395 | ITqvarid (FastString,FastString)
396 | ITqconid (FastString,FastString)
397 | ITqvarsym (FastString,FastString)
398 | ITqconsym (FastString,FastString)
400 | ITdupipvarid FastString -- GHC extension: implicit param: ?x
401 | ITsplitipvarid FastString -- GHC extension: implicit param: %x
403 | ITpragma StringBuffer
406 | ITstring FastString
408 | ITrational Rational
411 | ITprimstring FastString
413 | ITprimfloat Rational
414 | ITprimdouble Rational
416 -- MetaHaskell extension tokens
417 | ITopenExpQuote -- [| or [e|
418 | ITopenPatQuote -- [p|
419 | ITopenDecQuote -- [d|
420 | ITopenTypQuote -- [t|
422 | ITidEscape FastString -- $x
423 | ITparenEscape -- $(
428 -- Arrow notation extension
435 | ITLarrowtail -- -<<
436 | ITRarrowtail -- >>-
438 | ITunknown String -- Used when the lexer can't make sense of it
439 | ITeof -- end of file token
441 deriving Show -- debugging
444 isSpecial :: Token__ -> Bool
445 -- If we see M.x, where x is a keyword, but
446 -- is special, we treat is as just plain M.x,
448 isSpecial ITas = True
449 isSpecial IThiding = True
450 isSpecial ITqualified = True
451 isSpecial ITforall = True
452 isSpecial ITexport = True
453 isSpecial ITlabel = True
454 isSpecial ITdynamic = True
455 isSpecial ITsafe = True
456 isSpecial ITthreadsafe = True
457 isSpecial ITunsafe = True
458 isSpecial ITwith = True
459 isSpecial ITccallconv = True
460 isSpecial ITstdcallconv = True
461 isSpecial ITmdo = True
464 -- the bitmap provided as the third component indicates whether the
465 -- corresponding extension keyword is valid under the extension options
466 -- provided to the compiler; if the extension corresponding to *any* of the
467 -- bits set in the bitmap is enabled, the keyword is valid (this setup
468 -- facilitates using a keyword in two different extensions that can be
469 -- activated independently)
471 reservedWordsFM = listToUFM $
472 map (\(x, y, z) -> (mkFastString x, (y, z)))
473 [( "_", ITunderscore, 0 ),
475 ( "case", ITcase, 0 ),
476 ( "class", ITclass, 0 ),
477 ( "data", ITdata, 0 ),
478 ( "default", ITdefault, 0 ),
479 ( "deriving", ITderiving, 0 ),
481 ( "else", ITelse, 0 ),
482 ( "hiding", IThiding, 0 ),
484 ( "import", ITimport, 0 ),
486 ( "infix", ITinfix, 0 ),
487 ( "infixl", ITinfixl, 0 ),
488 ( "infixr", ITinfixr, 0 ),
489 ( "instance", ITinstance, 0 ),
491 ( "module", ITmodule, 0 ),
492 ( "newtype", ITnewtype, 0 ),
494 ( "qualified", ITqualified, 0 ),
495 ( "then", ITthen, 0 ),
496 ( "type", ITtype, 0 ),
497 ( "where", ITwhere, 0 ),
498 ( "_scc_", ITscc, 0 ), -- ToDo: remove
500 ( "forall", ITforall, bit glaExtsBit),
501 ( "mdo", ITmdo, bit glaExtsBit),
502 ( "reifyDecl", ITreifyDecl, bit thBit),
503 ( "reifyType", ITreifyType, bit thBit),
504 ( "reifyFixity",ITreifyFixity, bit thBit),
506 ( "foreign", ITforeign, bit ffiBit),
507 ( "export", ITexport, bit ffiBit),
508 ( "label", ITlabel, bit ffiBit),
509 ( "dynamic", ITdynamic, bit ffiBit),
510 ( "safe", ITsafe, bit ffiBit),
511 ( "threadsafe", ITthreadsafe, bit ffiBit),
512 ( "unsafe", ITunsafe, bit ffiBit),
513 ( "stdcall", ITstdcallconv, bit ffiBit),
514 ( "ccall", ITccallconv, bit ffiBit),
515 ( "dotnet", ITdotnet, bit ffiBit),
517 ( "with", ITwith, bit withBit),
519 ( "rec", ITrec, bit arrowsBit),
520 ( "proc", ITproc, bit arrowsBit)
523 reservedSymsFM = listToUFM $
524 map (\ (x,y,z) -> (mkFastString x,(y,z)))
525 [ ("..", ITdotdot, 0)
526 ,(":", ITcolon, 0) -- (:) is a reserved op,
527 -- meaning only list cons
540 ,("*", ITstar, bit glaExtsBit) -- For data T (a::*) = MkT
541 ,(".", ITdot, bit glaExtsBit) -- For 'forall a . t'
543 ,("-<", ITlarrowtail, bit arrowsBit)
544 ,(">-", ITrarrowtail, bit arrowsBit)
545 ,("-<<", ITLarrowtail, bit arrowsBit)
546 ,(">>-", ITRarrowtail, bit arrowsBit)
549 -- -----------------------------------------------------------------------------
552 type Action = SrcLoc -> SrcLoc -> StringBuffer -> Int -> P Token
554 special :: Token__ -> Action
555 special tok loc end _buf len = return (T loc end tok)
557 token, layout_token :: Token__ -> Action
558 token t loc end buf len = return (T loc end t)
559 layout_token t loc end buf len = pushLexState layout >> return (T loc end t)
561 idtoken :: (StringBuffer -> Int -> Token__) -> Action
562 idtoken f loc end buf len = return (T loc end $! (f buf len))
564 skip_one_varid :: (FastString -> Token__) -> Action
565 skip_one_varid f loc end buf len
566 = return (T loc end $! f (lexemeToFastString (stepOn buf) (len-1)))
568 strtoken :: (String -> Token__) -> Action
569 strtoken f loc end buf len =
570 return (T loc end $! (f $! lexemeToString buf len))
572 init_strtoken :: Int -> (String -> Token__) -> Action
573 -- like strtoken, but drops the last N character(s)
574 init_strtoken drop f loc end buf len =
575 return (T loc end $! (f $! lexemeToString buf (len-drop)))
577 begin :: Int -> Action
578 begin code _loc _end _str _len = do pushLexState code; lexToken
581 pop _loc _end _buf _len = do popLexState; lexToken
583 pop_and :: Action -> Action
584 pop_and act loc end buf len = do popLexState; act loc end buf len
586 notFollowedBy char _ _ _ (_,buf) = atEnd buf || currentChar buf /= char
588 ifExtension pred bits _ _ _ = pred bits
591 nested comments require traversing by hand, they can't be parsed
592 using regular expressions.
594 nested_comment :: Action
595 nested_comment loc _end _str _len = do
598 where go 0 input = do setInput input; lexToken
600 case alexGetChar input of
605 case alexGetChar input of
607 Just ('\125',input) -> go (n-1) input
608 Just (c,_) -> go n input
610 case alexGetChar input of
612 Just ('-',input') -> go (n+1) input'
613 Just (c,input) -> go n input
616 err input = do failLocMsgP loc (fst input) "unterminated `{-'"
618 open_brace, close_brace :: Action
619 open_brace loc end _str _len = do
621 setContext (NoLayout:ctx)
622 return (T loc end ITocurly)
623 close_brace loc end _str _len = do
625 return (T loc end ITccurly)
627 -- We have to be careful not to count M.<varid> as a qualified name
628 -- when <varid> is a keyword. We hack around this by catching
629 -- the offending tokens afterward, and re-lexing in a different state.
630 check_qvarid loc end buf len = do
631 case lookupUFM reservedWordsFM var of
633 | not (isSpecial keyword) ->
637 b <- extension (\i -> exts .&. i /= 0)
640 _other -> return token
642 (mod,var) = splitQualName buf len
643 token = T loc end (ITqvarid (mod,var))
647 pushLexState bad_qvarid
650 qvarid buf len = ITqvarid $! splitQualName buf len
651 qconid buf len = ITqconid $! splitQualName buf len
653 splitQualName :: StringBuffer -> Int -> (FastString,FastString)
654 -- takes a StringBuffer and a length, and returns the module name
655 -- and identifier parts of a qualified name. Splits at the *last* dot,
656 -- because of hierarchical module names.
657 splitQualName orig_buf len = split orig_buf 0 0
660 | n == len = done dot_off
661 | lookAhead buf n == '.' = split2 buf n (n+1)
662 | otherwise = split buf dot_off (n+1)
664 -- careful, we might get names like M....
665 -- so, if the character after the dot is not upper-case, this is
666 -- the end of the qualifier part.
668 | isUpper (lookAhead buf n) = split buf dot_off (n+1)
669 | otherwise = done dot_off
672 (lexemeToFastString orig_buf dot_off,
673 lexemeToFastString (stepOnBy (dot_off+1) orig_buf) (len - dot_off -1))
675 varid loc end buf len =
676 case lookupUFM reservedWordsFM fs of
677 Just (keyword,0) -> do
679 return (T loc end keyword)
680 Just (keyword,exts) -> do
681 b <- extension (\i -> exts .&. i /= 0)
682 if b then do maybe_layout keyword
683 return (T loc end keyword)
684 else return (T loc end (ITvarid fs))
685 _other -> return (T loc end (ITvarid fs))
687 fs = lexemeToFastString buf len
689 conid buf len = ITconid fs
690 where fs = lexemeToFastString buf len
692 qvarsym buf len = ITqvarsym $! splitQualName buf len
693 qconsym buf len = ITqconsym $! splitQualName buf len
695 varsym = sym ITvarsym
696 consym = sym ITconsym
698 sym con loc end buf len =
699 case lookupUFM reservedSymsFM fs of
700 Just (keyword,0) -> return (T loc end keyword)
701 Just (keyword,exts) -> do
702 b <- extension (\i -> exts .&. i /= 0)
703 if b then return (T loc end keyword)
704 else return (T loc end $! con fs)
705 _other -> return (T loc end $! con fs)
707 fs = lexemeToFastString buf len
709 tok_decimal loc end buf len
710 = return (T loc end (ITinteger $! parseInteger buf len 10 oct_or_dec))
712 tok_octal loc end buf len
713 = return (T loc end (ITinteger $! parseInteger (stepOnBy 2 buf) (len-2) 8 oct_or_dec))
715 tok_hexadecimal loc end buf len
716 = return (T loc end (ITinteger $! parseInteger (stepOnBy 2 buf) (len-2) 16 hex))
718 prim_decimal loc end buf len
719 = return (T loc end (ITprimint $! parseInteger buf (len-1) 10 oct_or_dec))
721 prim_octal loc end buf len
722 = return (T loc end (ITprimint $! parseInteger (stepOnBy 2 buf) (len-3) 8 oct_or_dec))
724 prim_hexadecimal loc end buf len
725 = return (T loc end (ITprimint $! parseInteger (stepOnBy 2 buf) (len-3) 16 hex))
727 tok_float str = ITrational $! readRational__ str
728 prim_float str = ITprimfloat $! readRational__ str
729 prim_double str = ITprimdouble $! readRational__ str
731 parseInteger :: StringBuffer -> Int -> Integer -> (Char->Int) -> Integer
732 parseInteger buf len radix to_int
734 where go i x | i == len = x
735 | otherwise = go (i+1) (x * radix + toInteger (to_int (lookAhead buf i)))
737 -- -----------------------------------------------------------------------------
740 -- we're at the first token on a line, insert layout tokens if necessary
742 do_bol loc end _str _len = do
743 pos <- getOffside end
746 --trace "layout: inserting '}'" $ do
748 -- do NOT pop the lex state, we might have a ';' to insert
749 return (T loc end ITvccurly)
751 --trace "layout: inserting ';'" $ do
753 return (T loc end ITsemi)
758 -- certain keywords put us in the "layout" state, where we might
759 -- add an opening curly brace.
760 maybe_layout ITdo = pushLexState layout_do
761 maybe_layout ITmdo = pushLexState layout_do
762 maybe_layout ITof = pushLexState layout
763 maybe_layout ITlet = pushLexState layout
764 maybe_layout ITwhere = pushLexState layout
765 maybe_layout ITrec = pushLexState layout
766 maybe_layout _ = return ()
768 -- Pushing a new implicit layout context. If the indentation of the
769 -- next token is not greater than the previous layout context, then
770 -- Haskell 98 says that the new layout context should be empty; that is
771 -- the lexer must generate {}.
773 -- We are slightly more lenient than this: when the new context is started
774 -- by a 'do', then we allow the new context to be at the same indentation as
775 -- the previous context. This is what the 'strict' argument is for.
777 new_layout_context strict loc end _buf _len = do
779 let offset = srcLocCol loc
782 Layout prev_off : _ |
783 (strict && prev_off >= offset ||
784 not strict && prev_off > offset) -> do
785 -- token is indented to the left of the previous context.
786 -- we must generate a {} sequence now.
787 pushLexState layout_left
788 return (T loc end ITvocurly)
790 setContext (Layout offset : ctx)
791 return (T loc end ITvocurly)
793 do_layout_left loc end _buf _len = do
795 pushLexState bol -- we must be at the start of a line
796 return (T loc end ITvccurly)
798 -- -----------------------------------------------------------------------------
801 set_line :: Int -> Action
802 set_line code loc end buf len = do
803 let line = parseInteger buf len 10 oct_or_dec
804 setSrcLoc (mkSrcLoc (srcLocFile end) (fromIntegral line - 1) 0)
805 -- subtract one: the line number refers to the *following* line
810 set_file :: Int -> Action
811 set_file code loc end buf len = do
812 let file = lexemeToFastString (stepOn buf) (len-2)
813 setSrcLoc (mkSrcLoc file (srcLocLine end) (srcLocCol end))
818 -- -----------------------------------------------------------------------------
821 -- This stuff is horrible. I hates it.
823 lex_string_tok :: Action
824 lex_string_tok loc end buf len = do
827 return (T loc end tok)
829 lex_string :: String -> P Token__
832 case alexGetChar i of
837 glaexts <- extension glaExtsEnabled
841 case alexGetChar i of
845 then failMsgP "primitive string literal must contain only characters <= \'\\xFF\'"
846 else let s' = mkFastStringNarrow (reverse s) in
847 -- always a narrow string/byte array
848 return (ITprimstring s')
850 return (ITstring (mkFastString (reverse s)))
852 return (ITstring (mkFastString (reverse s)))
855 | Just ('&',i) <- next -> do
856 setInput i; lex_string s
857 | Just (c,i) <- next, is_space c -> do
858 setInput i; lex_stringgap s
859 where next = alexGetChar i
870 c | is_space c -> lex_stringgap s
874 lex_char_tok :: Action
875 lex_char_tok loc _end buf len = do
880 glaexts <- extension glaExtsEnabled
883 i@(end,_) <- getInput
884 case alexGetChar i of
885 Just ('#',i@(end,_)) -> do
887 return (T loc end (ITprimchar c))
889 return (T loc end (ITchar c))
892 return (T loc end (ITchar c))
901 c | is_any c -> return c
918 '^' -> do c <- getCharOrFail
919 if c >= '@' && c <= '_'
920 then return (chr (ord c - ord '@'))
923 'x' -> readNum is_hexdigit 16 hex
924 'o' -> readNum is_octdigit 8 oct_or_dec
925 x | is_digit x -> readNum2 is_digit 10 oct_or_dec (oct_or_dec x)
929 case alexGetChar i of
932 case alexGetChar i2 of
935 let str = [c1,c2,c3] in
936 case [ (c,rest) | (p,c) <- silly_escape_chars,
937 Just rest <- [maybePrefixMatch p str] ] of
938 (escape_char,[]):_ -> do
941 (escape_char,_:_):_ -> do
946 readNum :: (Char -> Bool) -> Int -> (Char -> Int) -> P Char
947 readNum is_digit base conv = do
950 then readNum2 is_digit base conv (conv c)
953 readNum2 is_digit base conv i = do
956 where read i input = do
957 case alexGetChar input of
958 Just (c,input') | is_digit c -> do
959 read (i*base + conv c) input'
962 if i >= 0 && i <= 0x10FFFF
968 || (c >= 'a' && c <= 'f')
969 || (c >= 'A' && c <= 'F')
971 hex c | is_digit c = ord c - ord '0'
972 | otherwise = ord (to_lower c) - ord 'a' + 10
974 oct_or_dec c = ord c - ord '0'
976 is_octdigit c = c >= '0' && c <= '7'
979 | c >= 'A' && c <= 'Z' = chr (ord c - (ord 'A' - ord 'a'))
982 silly_escape_chars = [
1019 lit_error = lexError "lexical error in string/character literal"
1021 getCharOrFail :: P Char
1024 case alexGetChar i of
1025 Nothing -> lexError "unexpected end-of-file in string/character literal"
1026 Just (c,i) -> do setInput i; return c
1028 -- -----------------------------------------------------------------------------
1031 readRational :: ReadS Rational -- NB: doesn't handle leading "-"
1033 (n,d,s) <- readFix r
1035 return ((n%1)*10^^(k-d), t)
1038 (ds,s) <- lexDecDigits r
1039 (ds',t) <- lexDotDigits s
1040 return (read (ds++ds'), length ds', t)
1042 readExp (e:s) | e `elem` "eE" = readExp' s
1043 readExp s = return (0,s)
1045 readExp' ('+':s) = readDec s
1046 readExp' ('-':s) = do
1049 readExp' s = readDec s
1052 (ds,r) <- nonnull isDigit s
1053 return (foldl1 (\n d -> n * 10 + d) [ ord d - ord '0' | d <- ds ],
1056 lexDecDigits = nonnull isDigit
1058 lexDotDigits ('.':s) = return (span isDigit s)
1059 lexDotDigits s = return ("",s)
1061 nonnull p s = do (cs@(_:_),t) <- return (span p s)
1064 readRational__ :: String -> Rational -- NB: *does* handle a leading "-"
1065 readRational__ top_s
1067 '-' : xs -> - (read_me xs)
1071 = case (do { (x,"") <- readRational s ; return x }) of
1073 [] -> error ("readRational__: no parse:" ++ top_s)
1074 _ -> error ("readRational__: ambiguous parse:" ++ top_s)
1076 -- -----------------------------------------------------------------------------
1086 SrcLoc SrcLoc -- The start and end of the text span related to
1087 -- the error. Might be used in environments which can
1088 -- show this span, e.g. by highlighting it.
1089 Message -- The error message
1091 showPFailed loc1 loc2 err
1092 = showSDoc (hcat [ppr loc1, text ": ", err])
1094 data PState = PState {
1095 buffer :: StringBuffer,
1096 last_loc :: SrcLoc, -- pos of previous token
1097 last_len :: !Int, -- len of previous token
1098 loc :: SrcLoc, -- current loc (end of prev token + 1)
1099 extsBitmap :: !Int, -- bitmap that determines permitted extensions
1100 context :: [LayoutContext],
1103 -- last_loc and last_len are used when generating error messages,
1104 -- and in pushCurrentContext only.
1106 newtype P a = P { unP :: PState -> ParseResult a }
1108 instance Monad P where
1114 returnP a = P $ \s -> POk s a
1116 thenP :: P a -> (a -> P b) -> P b
1117 (P m) `thenP` k = P $ \ s ->
1119 POk s1 a -> (unP (k a)) s1
1120 PFailed l1 l2 err -> PFailed l1 l2 err
1122 failP :: String -> P a
1123 failP msg = P $ \s -> PFailed (last_loc s) (loc s) (text msg)
1125 failMsgP :: String -> P a
1126 failMsgP msg = P $ \s -> PFailed (last_loc s) (loc s) (text msg)
1128 failLocMsgP :: SrcLoc -> SrcLoc -> String -> P a
1129 failLocMsgP loc1 loc2 str = P $ \s -> PFailed loc1 loc2 (text str)
1131 extension :: (Int -> Bool) -> P Bool
1132 extension p = P $ \s -> POk s (p $! extsBitmap s)
1135 getExts = P $ \s -> POk s (extsBitmap s)
1137 setSrcLoc :: SrcLoc -> P ()
1138 setSrcLoc new_loc = P $ \s -> POk s{loc=new_loc} ()
1140 -- tmp, for supporting stuff in RdrHsSyn. The scope better not include
1141 -- any calls to the lexer, because it assumes things about the SrcLoc.
1142 setSrcLocFor :: SrcLoc -> P a -> P a
1143 setSrcLocFor new_loc scope = P $ \s@PState{ loc = old_loc } ->
1144 case unP scope s{loc=new_loc} of
1145 PFailed l1 l2 msg -> PFailed l1 l2 msg
1148 getSrcLoc :: P SrcLoc
1149 getSrcLoc = P $ \s@(PState{ loc=loc }) -> POk s loc
1151 setLastToken :: SrcLoc -> Int -> P ()
1152 setLastToken loc len = P $ \s -> POk s{ last_loc=loc, last_len=len } ()
1154 type AlexInput = (SrcLoc,StringBuffer)
1156 alexInputPrevChar :: AlexInput -> Char
1157 alexInputPrevChar (_,s) = prevChar s '\n'
1159 alexGetChar :: AlexInput -> Maybe (Char,AlexInput)
1162 | otherwise = c `seq` loc' `seq` s' `seq` Just (c, (loc', s'))
1163 where c = currentChar s
1164 loc' = advanceSrcLoc loc c
1167 getInput :: P AlexInput
1168 getInput = P $ \s@PState{ loc=l, buffer=b } -> POk s (l,b)
1170 setInput :: AlexInput -> P ()
1171 setInput (l,b) = P $ \s -> POk s{ loc=l, buffer=b } ()
1173 pushLexState :: Int -> P ()
1174 pushLexState ls = P $ \s@PState{ lex_state=l } -> POk s{lex_state=ls:l} ()
1176 popLexState :: P Int
1177 popLexState = P $ \s@PState{ lex_state=ls:l } -> POk s{ lex_state=l } ls
1179 getLexState :: P Int
1180 getLexState = P $ \s@PState{ lex_state=ls:l } -> POk s ls
1182 -- for reasons of efficiency, flags indicating language extensions (eg,
1183 -- -fglasgow-exts or -fparr) are represented by a bitmap stored in an unboxed
1186 glaExtsBit, ffiBit, parrBit :: Int
1195 glaExtsEnabled, ffiEnabled, parrEnabled :: Int -> Bool
1196 glaExtsEnabled flags = testBit flags glaExtsBit
1197 ffiEnabled flags = testBit flags ffiBit
1198 withEnabled flags = testBit flags withBit
1199 parrEnabled flags = testBit flags parrBit
1200 arrowsEnabled flags = testBit flags arrowsBit
1201 thEnabled flags = testBit flags thBit
1202 ipEnabled flags = testBit flags ipBit
1204 -- create a parse state
1206 mkPState :: StringBuffer -> SrcLoc -> DynFlags -> PState
1207 mkPState buf loc flags =
1213 extsBitmap = fromIntegral bitmap,
1215 lex_state = [bol, if glaExtsEnabled bitmap then glaexts else 0]
1216 -- we begin in the layout state if toplev_layout is set
1219 bitmap = glaExtsBit `setBitIf` dopt Opt_GlasgowExts flags
1220 .|. ffiBit `setBitIf` dopt Opt_FFI flags
1221 .|. withBit `setBitIf` dopt Opt_With flags
1222 .|. parrBit `setBitIf` dopt Opt_PArr flags
1223 .|. arrowsBit `setBitIf` dopt Opt_Arrows flags
1224 .|. thBit `setBitIf` dopt Opt_TH flags
1225 .|. ipBit `setBitIf` dopt Opt_ImplicitParams flags
1227 setBitIf :: Int -> Bool -> Int
1228 b `setBitIf` cond | cond = bit b
1231 getContext :: P [LayoutContext]
1232 getContext = P $ \s@PState{context=ctx} -> POk s ctx
1234 setContext :: [LayoutContext] -> P ()
1235 setContext ctx = P $ \s -> POk s{context=ctx} ()
1238 popContext = P $ \ s@(PState{ buffer = buf, context = ctx,
1239 loc = loc, last_len = len, last_loc = last_loc }) ->
1241 (_:tl) -> POk s{ context = tl } ()
1242 [] -> PFailed last_loc loc (srcParseErr buf len)
1244 -- Push a new layout context at the indentation of the last token read.
1245 -- This is only used at the outer level of a module when the 'module'
1246 -- keyword is missing.
1247 pushCurrentContext :: P ()
1248 pushCurrentContext = P $ \ s@PState{ last_loc=loc, context=ctx } ->
1249 POk s{ context = Layout (srcLocCol loc) : ctx} ()
1251 getOffside :: SrcLoc -> P Ordering
1252 getOffside loc = P $ \s@PState{context=stk} ->
1253 let ord = case stk of
1254 (Layout n:_) -> compare (srcLocCol loc) n
1258 -- ---------------------------------------------------------------------------
1259 -- Construct a parse error
1262 :: StringBuffer -- current buffer (placed just after the last token)
1263 -> Int -- length of the previous token
1266 = hcat [ if null token
1267 then ptext SLIT("parse error (possibly incorrect indentation)")
1268 else hcat [ptext SLIT("parse error on input "),
1269 char '`', text token, char '\'']
1271 where token = lexemeToString (stepOnBy (-len) buf) len
1273 -- Report a parse failure, giving the span of the previous token as
1274 -- the location of the error. This is the entry point for errors
1275 -- detected during parsing.
1277 srcParseFail = P $ \PState{ buffer = buf, last_len = len,
1278 last_loc = last_loc, loc = loc } ->
1279 PFailed last_loc loc (srcParseErr buf len)
1281 -- A lexical error is reported at a particular position in the source file,
1282 -- not over a token range. TODO: this is slightly wrong, because we record
1283 -- the error at the character position following the one which caused the
1284 -- error. We should somehow back up by one character.
1285 lexError :: String -> P a
1288 failLocMsgP loc loc str
1290 -- -----------------------------------------------------------------------------
1291 -- This is the top-level function: called from the parser each time a
1292 -- new token is to be read from the input.
1294 lexer :: (Token -> P a) -> P a
1296 tok@(T _ _ tok__) <- lexToken
1297 --trace ("token: " ++ show tok__) $ do
1302 inp@(loc1,buf) <- getInput
1305 case alexScanUser exts inp sc of
1306 AlexEOF -> do setLastToken loc1 0
1307 return (T loc1 loc1 ITeof)
1308 AlexError (loc2,_) -> do failLocMsgP loc1 loc2 "lexical error"
1309 AlexSkip inp2 _ -> do
1312 AlexToken inp2@(end,buf2) len t -> do
1314 setLastToken loc1 len