Lexer.x 81.6 KB
Newer Older
1
-----------------------------------------------------------------------------
2
-- (c) The University of Glasgow, 2006
3 4 5 6 7 8 9
--
-- GHC's lexer.
--
-- This is a combination of an Alex-generated lexer from a regex
-- definition, with some hand-coded bits.
--
-- Completely accurate information about token-spans within the source
Ian Lynagh's avatar
Ian Lynagh committed
10 11
-- file is maintained.  Every token has a start and end RealSrcLoc
-- attached to it.
12 13 14 15 16 17 18 19 20 21 22
--
-----------------------------------------------------------------------------

--   ToDo / known bugs:
--    - parsing integers is a bit slow
--    - readRational is a bit slow
--
--   Known bugs, that were also in the previous version:
--    - M... should be 3 tokens, not 1.
--    - pragma-end should be only valid in a pragma

23 24 25 26 27 28 29 30 31 32 33
--   qualified operator NOTES.
--   
--   - If M.(+) is a single lexeme, then..
--     - Probably (+) should be a single lexeme too, for consistency.
--       Otherwise ( + ) would be a prefix operator, but M.( + ) would not be.
--     - But we have to rule out reserved operators, otherwise (..) becomes
--       a different lexeme.
--     - Should we therefore also rule out reserved operators in the qualified
--       form?  This is quite difficult to achieve.  We don't do it for
--       qualified varids.

34
{
35
-- XXX The above flags turn off warnings in the generated code:
36
{-# LANGUAGE BangPatterns #-}
37 38 39 40 41 42 43 44
{-# OPTIONS_GHC -fno-warn-unused-matches #-}
{-# OPTIONS_GHC -fno-warn-unused-binds #-}
{-# OPTIONS_GHC -fno-warn-unused-imports #-}
{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
-- But alex still generates some code that causes the "lazy unlifted bindings"
-- warning, and old compilers don't know about it so we can't easily turn
-- it off, so for now we use the sledge hammer:
{-# OPTIONS_GHC -w #-}
45

46 47
{-# OPTIONS_GHC -funbox-strict-fields #-}

48
module Lexer (
49
   Token(..), lexer, pragState, mkPState, PState(..),
50
   P(..), ParseResult(..), getSrcLoc, 
51
   getPState, getDynFlags, withThisPackage,
52
   failLocMsgP, failSpanMsgP, srcParseFail,
53
   getMessages, 
54
   popContext, pushCurrentContext, setLastToken, setSrcLoc,
vivian's avatar
vivian committed
55
   activeContext, nextIsEOF,
simonpj@microsoft.com's avatar
simonpj@microsoft.com committed
56
   getLexState, popLexState, pushLexState,
57
   extension, bangPatEnabled, datatypeContextsEnabled,
Jedai's avatar
Jedai committed
58 59
   addWarning,
   lexTokenStream
60 61
  ) where

62 63
import Bag
import ErrUtils
64 65 66 67 68
import Outputable
import StringBuffer
import FastString
import SrcLoc
import UniqFM
69
import DynFlags
70
import Module
71
import Ctype
72
import BasicTypes	( InlineSpec(..), RuleMatchInfo(..), FractionalLit(..) )
73
import Util		( readRational )
74

75
import Control.Monad
Simon Marlow's avatar
Simon Marlow committed
76
import Data.Bits
77
import Data.Char
78
import Data.List
Ian Lynagh's avatar
Ian Lynagh committed
79
import Data.Maybe
80 81
import Data.Map (Map)
import qualified Data.Map as Map
Simon Marlow's avatar
Simon Marlow committed
82
import Data.Ratio
83 84
}

85
$unispace    = \x05 -- Trick Alex into handling Unicode. See alexGetChar.
86
$whitechar   = [\ \n\r\f\v $unispace]
87
$white_no_nl = $whitechar # \n
88
$tab         = \t
89 90

$ascdigit  = 0-9
91
$unidigit  = \x03 -- Trick Alex into handling Unicode. See alexGetChar.
92
$decdigit  = $ascdigit -- for now, should really be $digit (ToDo)
93 94 95
$digit     = [$ascdigit $unidigit]

$special   = [\(\)\,\;\[\]\`\{\}]
96
$ascsymbol = [\!\#\$\%\&\*\+\.\/\<\=\>\?\@\\\^\|\-\~]
97
$unisymbol = \x04 -- Trick Alex into handling Unicode. See alexGetChar.
98 99
$symbol    = [$ascsymbol $unisymbol] # [$special \_\:\"\']

100
$unilarge  = \x01 -- Trick Alex into handling Unicode. See alexGetChar.
101
$asclarge  = [A-Z]
102 103
$large     = [$asclarge $unilarge]

104
$unismall  = \x02 -- Trick Alex into handling Unicode. See alexGetChar.
105
$ascsmall  = [a-z]
106 107
$small     = [$ascsmall $unismall \_]

108
$unigraphic = \x06 -- Trick Alex into handling Unicode. See alexGetChar.
109
$graphic   = [$small $large $symbol $digit $special $unigraphic \:\"\']
110 111

$octit	   = 0-7
112
$hexit     = [$decdigit A-F a-f]
113 114 115 116
$symchar   = [$symbol \:]
$nl        = [\n\r]
$idchar    = [$small $large $digit \']

117 118
$pragmachar = [$small $large $digit]

119 120
$docsym    = [\| \^ \* \$]

121 122 123 124 125 126
@varid     = $small $idchar*
@conid     = $large $idchar*

@varsym    = $symbol $symchar*
@consym    = \: $symchar*

127
@decimal     = $decdigit+
128 129 130 131 132 133 134 135 136
@octal       = $octit+
@hexadecimal = $hexit+
@exponent    = [eE] [\-\+]? @decimal

-- we support the hierarchical module name extension:
@qual = (@conid \.)+

@floating_point = @decimal \. @decimal @exponent? | @decimal @exponent

137 138 139 140 141
-- normal signed numerical literals can only be explicitly negative,
-- not explicitly positive (contrast @exponent)
@negative = \-
@signed = @negative ?

142 143 144 145
haskell :-

-- everywhere: skip whitespace and comments
$white_no_nl+ 				;
146
$tab+         { warn Opt_WarnTabs (text "Warning: Tab character") }
147 148 149 150 151

-- Everywhere: deal with nested comments.  We explicitly rule out
-- pragmas, "{-#", so that we don't accidentally treat them as comments.
-- (this can happen even though pragmas will normally take precedence due to
-- longest-match, because pragmas aren't valid in every state, but comments
152 153 154 155
-- are). We also rule out nested Haddock comments, if the -haddock flag is
-- set.

"{-" / { isNormalComment } { nested_comment lexToken }
156 157 158 159

-- Single-line comments are a bit tricky.  Haskell 98 says that two or
-- more dashes followed by a symbol should be parsed as a varsym, so we
-- have to exclude those.
160 161 162 163 164 165 166 167 168 169

-- Since Haddock comments aren't valid in every state, we need to rule them
-- out here.  

-- The following two rules match comments that begin with two dashes, but
-- continue with a different character. The rules test that this character
-- is not a symbol (in which case we'd have a varsym), and that it's not a
-- space followed by a Haddock comment symbol (docsym) (in which case we'd
-- have a Haddock comment). The rules then munch the rest of the line.

Jedai's avatar
Jedai committed
170 171
"-- " ~[$docsym \#] .* { lineCommentToken }
"--" [^$symbol : \ ] .* { lineCommentToken }
172 173 174

-- Next, match Haddock comments if no -haddock flag

Jedai's avatar
Jedai committed
175
"-- " [$docsym \#] .* / { ifExtension (not . haddockEnabled) } { lineCommentToken }
176 177 178 179 180 181 182

-- Now, when we've matched comments that begin with 2 dashes and continue
-- with a different character, we need to match comments that begin with three
-- or more dashes (which clearly can't be Haddock comments). We only need to
-- make sure that the first non-dash character isn't a symbol, and munch the
-- rest of the line.

Jedai's avatar
Jedai committed
183
"---"\-* [^$symbol :] .* { lineCommentToken }
184 185 186 187

-- Since the previous rules all match dashes followed by at least one
-- character, we also need to match a whole line filled with just dashes.

Jedai's avatar
Jedai committed
188
"--"\-* / { atEOL } { lineCommentToken }
189 190 191 192

-- We need this rule since none of the other single line comment rules
-- actually match this case.

Jedai's avatar
Jedai committed
193
"-- " / { atEOL } { lineCommentToken }
194 195 196 197 198 199 200 201 202 203 204 205 206

-- 'bol' state: beginning of a line.  Slurp up all the whitespace (including
-- blank lines) until we find a non-whitespace character, then do layout
-- processing.
--
-- One slight wibble here: what if the line begins with {-#? In
-- theory, we have to lex the pragma to see if it's one we recognise,
-- and if it is, then we backtrack and do_bol, otherwise we treat it
-- as a nested comment.  We don't bother with this: if the line begins
-- with {-#, then we'll assume it's a pragma we know about and go for do_bol.
<bol> {
  \n					;
  ^\# (line)?				{ begin line_prag1 }
207
  ^\# pragma .* \n			; -- GCC 3.3 CPP generated, apparently
208
  ^\# \! .* \n				; -- #!, for scripts
209 210 211 212 213 214 215
  ()					{ do_bol }
}

-- after a layout keyword (let, where, do, of), we begin a new layout
-- context if the curly brace is missing.
-- Careful! This stuff is quite delicate.
<layout, layout_do> {
216
  \{ / { notFollowedBy '-' }		{ hopefully_open_brace }
217 218 219 220 221 222 223 224 225 226 227 228 229 230
	-- we might encounter {-# here, but {- has been handled already
  \n					;
  ^\# (line)?				{ begin line_prag1 }
}

-- do is treated in a subtly different way, see new_layout_context
<layout>    ()				{ new_layout_context True }
<layout_do> ()				{ new_layout_context False }

-- after a new layout context which was found to be to the left of the
-- previous context, we have generated a '{' token, and we now need to
-- generate a matching '}' token.
<layout_left>  ()			{ do_layout_left }

231
<0,option_prags> \n				{ begin bol }
232

233 234
"{-#" $whitechar* $pragmachar+ / { known_pragma linePrags }
                                { dispatch_pragmas linePrags }
235 236 237

-- single-line line pragmas, of the form
--    # <line> "<file>" <extra-stuff> \n
238
<line_prag1> $decdigit+			{ setLine line_prag1a }
239
<line_prag1a> \" [$graphic \ ]* \"	{ setFile line_prag1b }
240 241 242 243
<line_prag1b> .*			{ pop }

-- Haskell-style line pragmas, of the form
--    {-# LINE <line> "<file>" #-}
244
<line_prag2> $decdigit+			{ setLine line_prag2a }
245
<line_prag2a> \" [$graphic \ ]* \"	{ setFile line_prag2b }
246 247 248
<line_prag2b> "#-}"|"-}"		{ pop }
   -- NOTE: accept -} at the end of a LINE pragma, for compatibility
   -- with older versions of GHC which generated these.
249

250
<0,option_prags> {
251 252 253 254 255 256
  "{-#" $whitechar* $pragmachar+ 
        $whitechar+ $pragmachar+ / { known_pragma twoWordPrags }
                                 { dispatch_pragmas twoWordPrags }

  "{-#" $whitechar* $pragmachar+ / { known_pragma oneWordPrags }
                                 { dispatch_pragmas oneWordPrags }
257

258
  -- We ignore all these pragmas, but don't generate a warning for them
259 260
  "{-#" $whitechar* $pragmachar+ / { known_pragma ignoredPrags }
                                 { dispatch_pragmas ignoredPrags }
261 262

  -- ToDo: should only be valid inside a pragma:
263
  "#-}" 				{ endPrag }
264 265
}

266
<option_prags> {
267 268 269
  "{-#"  $whitechar* $pragmachar+ / { known_pragma fileHeaderPrags }
                                   { dispatch_pragmas fileHeaderPrags }

David Waern's avatar
David Waern committed
270 271 272
  "-- #"                                 { multiline_doc_comment }
}

273 274
<0> {
  -- In the "0" mode we ignore these pragmas
275
  "{-#"  $whitechar* $pragmachar+ / { known_pragma fileHeaderPrags }
276 277 278
                     { nested_comment lexToken }
}

David Waern's avatar
David Waern committed
279
<0> {
Jedai's avatar
Jedai committed
280
  "-- #" .* { lineCommentToken }
281
}
282

283
<0,option_prags> {
284 285
  "{-#"  { warnThen Opt_WarnUnrecognisedPragmas (text "Unrecognised pragma")
                    (nested_comment lexToken) }
286 287
}

288 289
-- '0' state: ordinary lexemes

290 291
-- Haddock comments

292
<0,option_prags> {
David Waern's avatar
David Waern committed
293 294
  "-- " $docsym      / { ifExtension haddockEnabled } { multiline_doc_comment }
  "{-" \ ? $docsym   / { ifExtension haddockEnabled } { nested_doc_comment }
295 296
}

297 298
-- "special" symbols

299
<0> {
300 301 302 303
  "[:" / { ifExtension parrEnabled }	{ token ITopabrack }
  ":]" / { ifExtension parrEnabled }	{ token ITcpabrack }
}
  
304
<0> {
305 306 307 308 309 310 311 312
  "[|"	    / { ifExtension thEnabled }	{ token ITopenExpQuote }
  "[e|"	    / { ifExtension thEnabled }	{ token ITopenExpQuote }
  "[p|"	    / { ifExtension thEnabled }	{ token ITopenPatQuote }
  "[d|"	    / { ifExtension thEnabled }	{ layout_token ITopenDecQuote }
  "[t|"	    / { ifExtension thEnabled }	{ token ITopenTypQuote }
  "|]"	    / { ifExtension thEnabled }	{ token ITcloseQuote }
  \$ @varid / { ifExtension thEnabled }	{ skip_one_varid ITidEscape }
  "$("	    / { ifExtension thEnabled }	{ token ITparenEscape }
313

314 315 316 317
-- For backward compatibility, accept the old dollar syntax
  "[$" @varid "|"  / { ifExtension qqEnabled }
                     { lex_quasiquote_tok }

318
  "[" @varid "|"  / { ifExtension qqEnabled }
319
                     { lex_quasiquote_tok }
320 321
}

322
<0> {
ross's avatar
ross committed
323 324
  "(|" / { ifExtension arrowsEnabled `alexAndPred` notFollowedBySymbol }
					{ special IToparenbar }
325 326 327
  "|)" / { ifExtension arrowsEnabled }  { special ITcparenbar }
}

328
<0> {
329 330 331
  \? @varid / { ifExtension ipEnabled }	{ skip_one_varid ITdupipvarid }
}

332
<0> {
Ian Lynagh's avatar
Ian Lynagh committed
333 334 335 336 337 338
  "(#" / { ifExtension unboxedTuplesEnabled `alexAndPred` notFollowedBySymbol }
         { token IToubxparen }
  "#)" / { ifExtension unboxedTuplesEnabled }
         { token ITcubxparen }
}

339
<0,option_prags> {
340 341 342 343 344 345 346 347 348 349 350 351
  \(					{ special IToparen }
  \)					{ special ITcparen }
  \[					{ special ITobrack }
  \]					{ special ITcbrack }
  \,					{ special ITcomma }
  \;					{ special ITsemi }
  \`					{ special ITbackquote }
 				
  \{					{ open_brace }
  \}					{ close_brace }
}

352
<0,option_prags> {
353
  @qual @varid			{ idtoken qvarid }
354 355 356 357 358
  @qual @conid			{ idtoken qconid }
  @varid			{ varid }
  @conid			{ idtoken conid }
}

359
<0> {
360 361 362 363
  @qual @varid "#"+ / { ifExtension magicHashEnabled } { idtoken qvarid }
  @qual @conid "#"+ / { ifExtension magicHashEnabled } { idtoken qconid }
  @varid "#"+       / { ifExtension magicHashEnabled } { varid }
  @conid "#"+       / { ifExtension magicHashEnabled } { idtoken conid }
364 365
}

366 367
-- ToDo: - move `var` and (sym) into lexical syntax?
--       - remove backquote from $special?
368
<0> {
Ian Lynagh's avatar
Ian Lynagh committed
369 370
  @qual @varsym                                    { idtoken qvarsym }
  @qual @consym                                    { idtoken qconsym }
371 372
  @varsym                                          { varsym }
  @consym                                          { consym }
373 374
}

375 376
-- For the normal boxed literals we need to be careful
-- when trying to be close to Haskell98
377
<0> {
378
  -- Normal integral literals (:: Num a => a, from Integer)
Ian Lynagh's avatar
Ian Lynagh committed
379 380 381
  @decimal           { tok_num positive 0 0 decimal }
  0[oO] @octal       { tok_num positive 2 2 octal }
  0[xX] @hexadecimal { tok_num positive 2 2 hexadecimal }
382 383

  -- Normal rational literals (:: Fractional a => a, from Rational)
Ian Lynagh's avatar
Ian Lynagh committed
384
  @floating_point    { strtoken tok_float }
385 386
}

387
<0> {
Ian Lynagh's avatar
Ian Lynagh committed
388
  -- Unboxed ints (:: Int#) and words (:: Word#)
389 390
  -- It's simpler (and faster?) to give separate cases to the negatives,
  -- especially considering octal/hexadecimal prefixes.
Ian Lynagh's avatar
Ian Lynagh committed
391 392 393 394 395
  @decimal                     \# / { ifExtension magicHashEnabled } { tok_primint positive 0 1 decimal }
  0[oO] @octal                 \# / { ifExtension magicHashEnabled } { tok_primint positive 2 3 octal }
  0[xX] @hexadecimal           \# / { ifExtension magicHashEnabled } { tok_primint positive 2 3 hexadecimal }
  @negative @decimal           \# / { ifExtension magicHashEnabled } { tok_primint negative 1 2 decimal }
  @negative 0[oO] @octal       \# / { ifExtension magicHashEnabled } { tok_primint negative 3 4 octal }
396
  @negative 0[xX] @hexadecimal \# / { ifExtension magicHashEnabled } { tok_primint negative 3 4 hexadecimal }
397

Ian Lynagh's avatar
Ian Lynagh committed
398 399 400 401
  @decimal                     \# \# / { ifExtension magicHashEnabled } { tok_primword 0 2 decimal }
  0[oO] @octal                 \# \# / { ifExtension magicHashEnabled } { tok_primword 2 4 octal }
  0[xX] @hexadecimal           \# \# / { ifExtension magicHashEnabled } { tok_primword 2 4 hexadecimal }

402 403
  -- Unboxed floats and doubles (:: Float#, :: Double#)
  -- prim_{float,double} work with signed literals
404 405
  @signed @floating_point \# / { ifExtension magicHashEnabled } { init_strtoken 1 tok_primfloat }
  @signed @floating_point \# \# / { ifExtension magicHashEnabled } { init_strtoken 2 tok_primdouble }
406 407 408 409 410 411
}

-- Strings and chars are lexed by hand-written code.  The reason is
-- that even if we recognise the string or char here in the regex
-- lexer, we would still have to parse the string afterward in order
-- to convert it to a String.
412
<0> {
413 414 415 416 417 418 419 420
  \'				{ lex_char_tok }
  \" 				{ lex_string_tok }
}

{
-- -----------------------------------------------------------------------------
-- The token type

421
data Token
422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453
  = ITas  			-- Haskell keywords
  | ITcase
  | ITclass
  | ITdata
  | ITdefault
  | ITderiving
  | ITdo
  | ITelse
  | IThiding
  | ITif
  | ITimport
  | ITin
  | ITinfix
  | ITinfixl
  | ITinfixr
  | ITinstance
  | ITlet
  | ITmodule
  | ITnewtype
  | ITof
  | ITqualified
  | ITthen
  | ITtype
  | ITwhere
  | ITscc			-- ToDo: remove (we use {-# SCC "..." #-} now)

  | ITforall			-- GHC extension keywords
  | ITforeign
  | ITexport
  | ITlabel
  | ITdynamic
  | ITsafe
454
  | ITinterruptible
455 456 457
  | ITunsafe
  | ITstdcallconv
  | ITccallconv
458
  | ITprimcallconv
459
  | ITmdo
460
  | ITfamily
461 462 463
  | ITgroup
  | ITby
  | ITusing
464

465
	-- Pragmas
466
  | ITinline_prag InlineSpec RuleMatchInfo
467 468
  | ITspec_prag			-- SPECIALISE	
  | ITspec_inline_prag Bool	-- SPECIALISE INLINE (or NOINLINE)
469 470
  | ITsource_prag
  | ITrules_prag
Ian Lynagh's avatar
Ian Lynagh committed
471
  | ITwarning_prag
472 473 474
  | ITdeprecated_prag
  | ITline_prag
  | ITscc_prag
andy@galois.com's avatar
andy@galois.com committed
475
  | ITgenerated_prag
476
  | ITcore_prag                 -- hdaume: core annotations
477
  | ITunpack_prag
478
  | ITann_prag
479
  | ITclose_prag
480 481 482
  | IToptions_prag String
  | ITinclude_prag String
  | ITlanguage_prag
483 484
  | ITvect_prag
  | ITvect_scalar_prag
485
  | ITnovect_prag
486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511

  | ITdotdot  			-- reserved symbols
  | ITcolon
  | ITdcolon
  | ITequal
  | ITlam
  | ITvbar
  | ITlarrow
  | ITrarrow
  | ITat
  | ITtilde
  | ITdarrow
  | ITminus
  | ITbang
  | ITstar
  | ITdot

  | ITbiglam			-- GHC-extension symbols

  | ITocurly  			-- special symbols
  | ITccurly
  | ITocurlybar                 -- {|, for type applications
  | ITccurlybar                 -- |}, for type applications
  | ITvocurly
  | ITvccurly
  | ITobrack
benl's avatar
benl committed
512 513
  | ITopabrack			-- [:, for parallel arrays with -XParallelArrays
  | ITcpabrack			-- :], for parallel arrays with -XParallelArrays
514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531
  | ITcbrack
  | IToparen
  | ITcparen
  | IToubxparen
  | ITcubxparen
  | ITsemi
  | ITcomma
  | ITunderscore
  | ITbackquote

  | ITvarid   FastString	-- identifiers
  | ITconid   FastString
  | ITvarsym  FastString
  | ITconsym  FastString
  | ITqvarid  (FastString,FastString)
  | ITqconid  (FastString,FastString)
  | ITqvarsym (FastString,FastString)
  | ITqconsym (FastString,FastString)
532 533
  | ITprefixqvarsym (FastString,FastString)
  | ITprefixqconsym (FastString,FastString)
534 535 536 537 538 539

  | ITdupipvarid   FastString	-- GHC extension: implicit param: ?x

  | ITchar       Char
  | ITstring     FastString
  | ITinteger    Integer
540
  | ITrational   FractionalLit
541 542 543 544

  | ITprimchar   Char
  | ITprimstring FastString
  | ITprimint    Integer
Ian Lynagh's avatar
Ian Lynagh committed
545
  | ITprimword   Integer
546 547
  | ITprimfloat  FractionalLit
  | ITprimdouble FractionalLit
548

549
  -- Template Haskell extension tokens
550 551 552 553 554 555 556 557 558
  | ITopenExpQuote  		--  [| or [e|
  | ITopenPatQuote		--  [p|
  | ITopenDecQuote		--  [d|
  | ITopenTypQuote		--  [t|         
  | ITcloseQuote		--  |]
  | ITidEscape   FastString	--  $x
  | ITparenEscape		--  $( 
  | ITvarQuote			--  '
  | ITtyQuote			--  ''
Ian Lynagh's avatar
Ian Lynagh committed
559
  | ITquasiQuote (FastString,FastString,RealSrcSpan) --  [:...|...|]
560 561 562 563

  -- Arrow notation extension
  | ITproc
  | ITrec
564 565 566 567 568 569
  | IToparenbar			--  (|
  | ITcparenbar			--  |)
  | ITlarrowtail		--  -<
  | ITrarrowtail		--  >-
  | ITLarrowtail		--  -<<
  | ITRarrowtail		--  >>-
570 571 572

  | ITunknown String		-- Used when the lexer can't make sense of it
  | ITeof			-- end of file token
573 574 575 576 577 578 579

  -- Documentation annotations
  | ITdocCommentNext  String     -- something beginning '-- |'
  | ITdocCommentPrev  String     -- something beginning '-- ^'
  | ITdocCommentNamed String     -- something beginning '-- $'
  | ITdocSection      Int String -- a section heading
  | ITdocOptions      String     -- doc options (prune, ignore-exports, etc)
David Waern's avatar
David Waern committed
580
  | ITdocOptionsOld   String     -- doc options declared "-- # ..."-style
Jedai's avatar
Jedai committed
581 582
  | ITlineComment     String     -- comment starting by "--"
  | ITblockComment    String     -- comment in {- -}
583

584 585 586 587
#ifdef DEBUG
  deriving Show -- debugging
#endif

twanvl's avatar
twanvl committed
588
{-
589
isSpecial :: Token -> Bool
590 591 592 593 594 595 596 597 598 599 600
-- If we see M.x, where x is a keyword, but
-- is special, we treat is as just plain M.x, 
-- not as a keyword.
isSpecial ITas        	= True
isSpecial IThiding    	= True
isSpecial ITqualified 	= True
isSpecial ITforall    	= True
isSpecial ITexport    	= True
isSpecial ITlabel     	= True
isSpecial ITdynamic   	= True
isSpecial ITsafe    	= True
601
isSpecial ITinterruptible = True
602 603 604
isSpecial ITunsafe    	= True
isSpecial ITccallconv   = True
isSpecial ITstdcallconv = True
605
isSpecial ITprimcallconv = True
606
isSpecial ITmdo		= True
607
isSpecial ITfamily	= True
608 609 610
isSpecial ITgroup   = True
isSpecial ITby      = True
isSpecial ITusing   = True
611
isSpecial _             = False
twanvl's avatar
twanvl committed
612
-}
613 614 615 616 617 618 619 620

-- the bitmap provided as the third component indicates whether the
-- corresponding extension keyword is valid under the extension options
-- provided to the compiler; if the extension corresponding to *any* of the
-- bits set in the bitmap is enabled, the keyword is valid (this setup
-- facilitates using a keyword in two different extensions that can be
-- activated independently)
--
Ian Lynagh's avatar
Ian Lynagh committed
621
reservedWordsFM :: UniqFM (Token, Int)
622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650
reservedWordsFM = listToUFM $
	map (\(x, y, z) -> (mkFastString x, (y, z)))
       [( "_",		ITunderscore, 	0 ),
	( "as",		ITas, 		0 ),
	( "case",	ITcase, 	0 ),     
	( "class",	ITclass, 	0 ),    
	( "data",	ITdata, 	0 ),     
	( "default",	ITdefault, 	0 ),  
	( "deriving",	ITderiving, 	0 ), 
	( "do",		ITdo, 		0 ),       
	( "else",	ITelse, 	0 ),     
	( "hiding",	IThiding, 	0 ),
	( "if",		ITif, 		0 ),       
	( "import",	ITimport, 	0 ),   
	( "in",		ITin, 		0 ),       
	( "infix",	ITinfix, 	0 ),    
	( "infixl",	ITinfixl, 	0 ),   
	( "infixr",	ITinfixr, 	0 ),   
	( "instance",	ITinstance, 	0 ), 
	( "let",	ITlet, 		0 ),      
	( "module",	ITmodule, 	0 ),   
	( "newtype",	ITnewtype, 	0 ),  
	( "of",		ITof, 		0 ),       
	( "qualified",	ITqualified, 	0 ),
	( "then",	ITthen, 	0 ),     
	( "type",	ITtype, 	0 ),     
	( "where",	ITwhere, 	0 ),
	( "_scc_",	ITscc, 		0 ),		-- ToDo: remove

651
    ( "forall",	ITforall,	 bit explicitForallBit .|. bit inRulePragBit),
Ian Lynagh's avatar
Ian Lynagh committed
652
	( "mdo",	ITmdo,		 bit recursiveDoBit),
653
	( "family",	ITfamily,	 bit tyFamBit),
654 655 656
    ( "group",  ITgroup,     bit transformComprehensionsBit),
    ( "by",     ITby,        bit transformComprehensionsBit),
    ( "using",  ITusing,     bit transformComprehensionsBit),
657 658 659 660 661

	( "foreign",	ITforeign,	 bit ffiBit),
	( "export",	ITexport,	 bit ffiBit),
	( "label",	ITlabel,	 bit ffiBit),
	( "dynamic",	ITdynamic,	 bit ffiBit),
662
	( "safe",	ITsafe,		 bit ffiBit .|. bit safeHaskellBit),
663
	( "interruptible", ITinterruptible, bit interruptibleFfiBit),
664 665 666
	( "unsafe",	ITunsafe,	 bit ffiBit),
	( "stdcall",    ITstdcallconv,	 bit ffiBit),
	( "ccall",      ITccallconv,	 bit ffiBit),
667
	( "prim",       ITprimcallconv,	 bit ffiBit),
668

669
	( "rec",	ITrec,		 bit recBit),
670
	( "proc",	ITproc,		 bit arrowsBit)
671 672
     ]

Ian Lynagh's avatar
Ian Lynagh committed
673
reservedSymsFM :: UniqFM (Token, Int -> Bool)
674
reservedSymsFM = listToUFM $
Ian Lynagh's avatar
Ian Lynagh committed
675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691
    map (\ (x,y,z) -> (mkFastString x,(y,z)))
      [ ("..",  ITdotdot,   always)
        -- (:) is a reserved op, meaning only list cons
       ,(":",   ITcolon,    always)
       ,("::",  ITdcolon,   always)
       ,("=",   ITequal,    always)
       ,("\\",  ITlam,      always)
       ,("|",   ITvbar,     always)
       ,("<-",  ITlarrow,   always)
       ,("->",  ITrarrow,   always)
       ,("@",   ITat,       always)
       ,("~",   ITtilde,    always)
       ,("=>",  ITdarrow,   always)
       ,("-",   ITminus,    always)
       ,("!",   ITbang,     always)

        -- For data T (a::*) = MkT
692
       ,("*", ITstar, always) -- \i -> kindSigsEnabled i || tyFamEnabled i)
Ian Lynagh's avatar
Ian Lynagh committed
693
        -- For 'forall a . t'
694
       ,(".", ITdot,  always) -- \i -> explicitForallEnabled i || inRulePrag i)
Ian Lynagh's avatar
Ian Lynagh committed
695 696 697 698 699

       ,("-<",  ITlarrowtail, arrowsEnabled)
       ,(">-",  ITrarrowtail, arrowsEnabled)
       ,("-<<", ITLarrowtail, arrowsEnabled)
       ,(">>-", ITRarrowtail, arrowsEnabled)
700

Ian Lynagh's avatar
Ian Lynagh committed
701 702
       ,("∷",   ITdcolon, unicodeSyntaxEnabled)
       ,("⇒",   ITdarrow, unicodeSyntaxEnabled)
Ian Lynagh's avatar
Ian Lynagh committed
703 704
       ,("∀",   ITforall, \i -> unicodeSyntaxEnabled i &&
                                explicitForallEnabled i)
Ian Lynagh's avatar
Ian Lynagh committed
705 706
       ,("→",   ITrarrow, unicodeSyntaxEnabled)
       ,("←",   ITlarrow, unicodeSyntaxEnabled)
707 708 709 710 711 712 713 714

       ,("⤙",   ITlarrowtail, \i -> unicodeSyntaxEnabled i && arrowsEnabled i)
       ,("⤚",   ITrarrowtail, \i -> unicodeSyntaxEnabled i && arrowsEnabled i)
       ,("⤛",   ITLarrowtail, \i -> unicodeSyntaxEnabled i && arrowsEnabled i)
       ,("⤜",   ITRarrowtail, \i -> unicodeSyntaxEnabled i && arrowsEnabled i)

       ,("★", ITstar, unicodeSyntaxEnabled)

Simon Marlow's avatar
Simon Marlow committed
715 716 717
        -- ToDo: ideally, → and ∷ should be "specials", so that they cannot
        -- form part of a large operator.  This would let us have a better
        -- syntax for kinds: ɑ∷*→* would be a legal kind signature. (maybe).
718 719 720 721 722
       ]

-- -----------------------------------------------------------------------------
-- Lexer actions

Ian Lynagh's avatar
Ian Lynagh committed
723
type Action = RealSrcSpan -> StringBuffer -> Int -> P (RealLocated Token)
724

725
special :: Token -> Action
twanvl's avatar
twanvl committed
726
special tok span _buf _len = return (L span tok)
727

728
token, layout_token :: Token -> Action
twanvl's avatar
twanvl committed
729 730
token t span _buf _len = return (L span t)
layout_token t span _buf _len = pushLexState layout >> return (L span t)
731

732 733
idtoken :: (StringBuffer -> Int -> Token) -> Action
idtoken f span buf len = return (L span $! (f buf len))
734

735 736 737
skip_one_varid :: (FastString -> Token) -> Action
skip_one_varid f span buf len 
  = return (L span $! f (lexemeToFastString (stepOn buf) (len-1)))
738

739 740 741
strtoken :: (String -> Token) -> Action
strtoken f span buf len = 
  return (L span $! (f $! lexemeToString buf len))
742

743
init_strtoken :: Int -> (String -> Token) -> Action
744
-- like strtoken, but drops the last N character(s)
745 746
init_strtoken drop f span buf len = 
  return (L span $! (f $! lexemeToString buf (len-drop)))
747 748

begin :: Int -> Action
749
begin code _span _str _len = do pushLexState code; lexToken
750 751

pop :: Action
Ian Lynagh's avatar
Ian Lynagh committed
752 753
pop _span _buf _len = do _ <- popLexState
                         lexToken
754

755 756 757 758 759 760 761 762 763 764 765
hopefully_open_brace :: Action
hopefully_open_brace span buf len
 = do relaxed <- extension relaxedLayout
      ctx <- getContext
      (AI l _) <- getInput
      let offset = srcLocCol l
          isOK = relaxed ||
                 case ctx of
                 Layout prev_off : _ -> prev_off < offset
                 _                   -> True
      if isOK then pop_and open_brace span buf len
Ian Lynagh's avatar
Ian Lynagh committed
766
              else failSpanMsgP (RealSrcSpan span) (text "Missing block")
767

768
pop_and :: Action -> Action
Ian Lynagh's avatar
Ian Lynagh committed
769 770
pop_and act span buf len = do _ <- popLexState
                              act span buf len
771

772
{-# INLINE nextCharIs #-}
Ian Lynagh's avatar
Ian Lynagh committed
773
nextCharIs :: StringBuffer -> (Char -> Bool) -> Bool
774 775
nextCharIs buf p = not (atEnd buf) && p (currentChar buf)

Ian Lynagh's avatar
Ian Lynagh committed
776
notFollowedBy :: Char -> AlexAccPred Int
777
notFollowedBy char _ _ _ (AI _ buf) 
778
  = nextCharIs buf (/=char)
779

Ian Lynagh's avatar
Ian Lynagh committed
780
notFollowedBySymbol :: AlexAccPred Int
781
notFollowedBySymbol _ _ _ (AI _ buf)
782
  = nextCharIs buf (`notElem` "!#$%&*+./<=>?@\\^|-~")
ross's avatar
ross committed
783

784 785 786 787 788
-- We must reject doc comments as being ordinary comments everywhere.
-- In some cases the doc comment will be selected as the lexeme due to
-- maximal munch, but not always, because the nested comment rule is
-- valid in all states, but the doc-comment rules are only valid in
-- the non-layout states.
Ian Lynagh's avatar
Ian Lynagh committed
789
isNormalComment :: AlexAccPred Int
790
isNormalComment bits _ _ (AI _ buf)
791 792 793 794 795 796
  | haddockEnabled bits = notFollowedByDocOrPragma
  | otherwise           = nextCharIs buf (/='#')
  where
    notFollowedByDocOrPragma
       = not $ spaceAndP buf (`nextCharIs` (`elem` "|^*$#"))

Ian Lynagh's avatar
Ian Lynagh committed
797
spaceAndP :: StringBuffer -> (StringBuffer -> Bool) -> Bool
798
spaceAndP buf p = p buf || nextCharIs buf (==' ') && p (snd (nextChar buf))
799

twanvl's avatar
twanvl committed
800
{-
801
haddockDisabledAnd p bits _ _ (AI _ buf)
802
  = if haddockEnabled bits then False else (p buf)
twanvl's avatar
twanvl committed
803
-}
804

Ian Lynagh's avatar
Ian Lynagh committed
805
atEOL :: AlexAccPred Int
806
atEOL _ _ _ (AI _ buf) = atEnd buf || currentChar buf == '\n'
807

Ian Lynagh's avatar
Ian Lynagh committed
808
ifExtension :: (Int -> Bool) -> AlexAccPred Int
809 810
ifExtension pred bits _ _ _ = pred bits

811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838
multiline_doc_comment :: Action
multiline_doc_comment span buf _len = withLexedDocType (worker "")
  where
    worker commentAcc input docType oneLine = case alexGetChar input of
      Just ('\n', input') 
        | oneLine -> docCommentEnd input commentAcc docType buf span
        | otherwise -> case checkIfCommentLine input' of
          Just input -> worker ('\n':commentAcc) input docType False
          Nothing -> docCommentEnd input commentAcc docType buf span
      Just (c, input) -> worker (c:commentAcc) input docType oneLine
      Nothing -> docCommentEnd input commentAcc docType buf span
      
    checkIfCommentLine input = check (dropNonNewlineSpace input)
      where
        check input = case alexGetChar input of
          Just ('-', input) -> case alexGetChar input of
            Just ('-', input) -> case alexGetChar input of
              Just (c, _) | c /= '-' -> Just input
              _ -> Nothing
            _ -> Nothing
          _ -> Nothing

        dropNonNewlineSpace input = case alexGetChar input of
          Just (c, input') 
            | isSpace c && c /= '\n' -> dropNonNewlineSpace input'
            | otherwise -> input
          Nothing -> input

Jedai's avatar
Jedai committed
839 840 841 842 843
lineCommentToken :: Action
lineCommentToken span buf len = do
  b <- extension rawTokenStreamEnabled
  if b then strtoken ITlineComment span buf len else lexToken

844 845 846 847
{-
  nested comments require traversing by hand, they can't be parsed
  using regular expressions.
-}
Ian Lynagh's avatar
Ian Lynagh committed
848
nested_comment :: P (RealLocated Token) -> Action
849
nested_comment cont span _str _len = do
850
  input <- getInput
Jedai's avatar
Jedai committed
851
  go "" (1::Int) input
852
  where
Jedai's avatar
Jedai committed
853 854 855 856 857 858
    go commentAcc 0 input = do setInput input
                               b <- extension rawTokenStreamEnabled
                               if b
                                 then docCommentEnd input commentAcc ITblockComment _str span
                                 else cont
    go commentAcc n input = case alexGetChar input of
859 860 861
      Nothing -> errBrace input span
      Just ('-',input) -> case alexGetChar input of
        Nothing  -> errBrace input span
Jedai's avatar
Jedai committed
862 863
        Just ('\125',input) -> go commentAcc (n-1) input
        Just (_,_)          -> go ('-':commentAcc) n input
864 865
      Just ('\123',input) -> case alexGetChar input of
        Nothing  -> errBrace input span
Jedai's avatar
Jedai committed
866 867 868
        Just ('-',input) -> go ('-':'\123':commentAcc) (n+1) input
        Just (_,_)       -> go ('\123':commentAcc) n input
      Just (c,input) -> go (c:commentAcc) n input
869 870 871 872 873 874 875 876

nested_doc_comment :: Action
nested_doc_comment span buf _len = withLexedDocType (go "")
  where
    go commentAcc input docType _ = case alexGetChar input of
      Nothing -> errBrace input span
      Just ('-',input) -> case alexGetChar input of
        Nothing -> errBrace input span
twanvl's avatar
twanvl committed
877
        Just ('\125',input) ->
878
          docCommentEnd input commentAcc docType buf span
twanvl's avatar
twanvl committed
879
        Just (_,_) -> go ('-':commentAcc) input docType False
880 881 882 883 884 885
      Just ('\123', input) -> case alexGetChar input of
        Nothing  -> errBrace input span
        Just ('-',input) -> do
          setInput input
          let cont = do input <- getInput; go commentAcc input docType False
          nested_comment cont span buf _len
twanvl's avatar
twanvl committed
886
        Just (_,_) -> go ('\123':commentAcc) input docType False
887 888
      Just (c,input) -> go (c:commentAcc) input docType False

Ian Lynagh's avatar
Ian Lynagh committed
889 890
withLexedDocType :: (AlexInput -> (String -> Token) -> Bool -> P (RealLocated Token))
                 -> P (RealLocated Token)
891
withLexedDocType lexDocComment = do
892
  input@(AI _ buf) <- getInput
893 894 895 896
  case prevChar buf ' ' of
    '|' -> lexDocComment input ITdocCommentNext False
    '^' -> lexDocComment input ITdocCommentPrev False
    '$' -> lexDocComment input ITdocCommentNamed False
David Waern's avatar
David Waern committed
897 898
    '*' -> lexDocSection 1 input
    '#' -> lexDocComment input ITdocOptionsOld False
Ian Lynagh's avatar
Ian Lynagh committed
899
    _ -> panic "withLexedDocType: Bad doc type"
900 901 902
 where 
    lexDocSection n input = case alexGetChar input of 
      Just ('*', input) -> lexDocSection (n+1) input
twanvl's avatar
twanvl committed
903
      Just (_,   _)     -> lexDocComment input (ITdocSection n) True
904 905
      Nothing -> do setInput input; lexToken -- eof reached, lex it normally

906 907 908
-- RULES pragmas turn on the forall and '.' keywords, and we turn them
-- off again at the end of the pragma.
rulePrag :: Action
909
rulePrag span _buf _len = do
910
  setExts (.|. bit inRulePragBit)
911 912 913
  return (L span ITrules_prag)

endPrag :: Action
914
endPrag span _buf _len = do
915 916 917
  setExts (.&. complement (bit inRulePragBit))
  return (L span ITclose_prag)

918 919 920 921 922 923 924 925 926
-- docCommentEnd
-------------------------------------------------------------------------------
-- This function is quite tricky. We can't just return a new token, we also
-- need to update the state of the parser. Why? Because the token is longer
-- than what was lexed by Alex, and the lexToken function doesn't know this, so 
-- it writes the wrong token length to the parser state. This function is
-- called afterwards, so it can just update the state. 

docCommentEnd :: AlexInput -> String -> (String -> Token) -> StringBuffer ->
Ian Lynagh's avatar
Ian Lynagh committed
927
                 RealSrcSpan -> P (RealLocated Token) 
928 929
docCommentEnd input commentAcc docType buf span = do
  setInput input
930
  let (AI loc nextBuf) = input
931
      comment = reverse commentAcc
Ian Lynagh's avatar
Ian Lynagh committed
932
      span' = mkRealSrcSpan (realSrcSpanStart span) loc
933 934
      last_len = byteDiff buf nextBuf
      
935
  span `seq` setLastToken span' last_len
936 937
  return (L span' (docType comment))
 
Ian Lynagh's avatar
Ian Lynagh committed
938 939
errBrace :: AlexInput -> RealSrcSpan -> P a
errBrace (AI end _) span = failLocMsgP (realSrcSpanStart span) end "unterminated `{-'"
Ian Lynagh's avatar
Ian Lynagh committed
940

941
open_brace, close_brace :: Action
942
open_brace span _str _len = do 
943 944
  ctx <- getContext
  setContext (NoLayout:ctx)
945 946
  return (L span ITocurly)
close_brace span _str _len = do 
947
  popContext
948
  return (L span ITccurly)
949

Ian Lynagh's avatar
Ian Lynagh committed
950
qvarid, qconid :: StringBuffer -> Int -> Token
951 952
qvarid buf len = ITqvarid $! splitQualName buf len False
qconid buf len = ITqconid $! splitQualName buf len False
953

954
splitQualName :: StringBuffer -> Int -> Bool -> (FastString,FastString)
955 956 957
-- takes a StringBuffer and a length, and returns the module name
-- and identifier parts of a qualified name.  Splits at the *last* dot,
-- because of hierarchical module names.
958
splitQualName orig_buf len parens = split orig_buf orig_buf
959
  where
960 961 962 963 964 965
    split buf dot_buf
	| orig_buf `byteDiff` buf >= len  = done dot_buf
	| c == '.'                	  = found_dot buf'
	| otherwise               	  = split buf' dot_buf
      where
       (c,buf') = nextChar buf
966 967 968 969
  
    -- careful, we might get names like M....
    -- so, if the character after the dot is not upper-case, this is
    -- the end of the qualifier part.
970 971 972 973 974 975 976 977
    found_dot buf -- buf points after the '.'
	| isUpper c    = split buf' buf
	| otherwise    = done buf
      where
       (c,buf') = nextChar buf

    done dot_buf =
	(lexemeToFastString orig_buf (qual_size - 1),
978 979 980
	 if parens -- Prelude.(+)
            then lexemeToFastString (stepOn dot_buf) (len - qual_size - 2)
            else lexemeToFastString dot_buf (len - qual_size))
981 982
      where
	qual_size = orig_buf `byteDiff` dot_buf
983

Ian Lynagh's avatar
Ian Lynagh committed
984 985
varid :: Action
varid span buf len =
Ian Lynagh's avatar
Ian Lynagh committed
986
  fs `seq`
987 988 989
  case lookupUFM reservedWordsFM fs of
	Just (keyword,0)    -> do
		maybe_layout keyword
990
		return (L span keyword)
991 992 993
	Just (keyword,exts) -> do
		b <- extension (\i -> exts .&. i /= 0)
		if b then do maybe_layout keyword
994 995 996
			     return (L span keyword)
		     else return (L span (ITvarid fs))
	_other -> return (L span (ITvarid fs))
997 998 999
  where
	fs = lexemeToFastString buf len

Ian Lynagh's avatar
Ian Lynagh committed
1000
conid :: StringBuffer -> Int -> Token
1001 1002 1003
conid buf len = ITconid fs
  where fs = lexemeToFastString buf len

Ian Lynagh's avatar
Ian Lynagh committed
1004
qvarsym, qconsym, prefixqvarsym, prefixqconsym :: StringBuffer -> Int -> Token
1005 1006 1007 1008
qvarsym buf len = ITqvarsym $! splitQualName buf len False
qconsym buf len = ITqconsym $! splitQualName buf len False
prefixqvarsym buf len = ITprefixqvarsym $! splitQualName buf len True
prefixqconsym buf len = ITprefixqconsym $! splitQualName buf len True
1009

Ian Lynagh's avatar
Ian Lynagh committed
1010
varsym, consym :: Action
1011 1012 1013
varsym = sym ITvarsym
consym = sym ITconsym

Ian Lynagh's avatar
Ian Lynagh committed
1014 1015
sym :: (FastString -> Token) -> RealSrcSpan -> StringBuffer -> Int
    -> P (RealLocated Token)
1016
sym con span buf len = 
1017 1018
  case lookupUFM reservedSymsFM fs of
	Just (keyword,exts) -> do
Ian Lynagh's avatar
Ian Lynagh committed
1019
		b <- extension exts
1020 1021 1022
		if b then return (L span keyword)
		     else return (L span $! con fs)
	_other -> return (L span $! con fs)
1023 1024 1025
  where
	fs = lexemeToFastString buf len

1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036
-- Variations on the integral numeric literal.
tok_integral :: (Integer -> Token)
     -> (Integer -> Integer)
 --    -> (StringBuffer -> StringBuffer) -> (Int -> Int)
     -> Int -> Int
     -> (Integer, (Char->Int)) -> Action
tok_integral itint transint transbuf translen (radix,char_to_int) span buf len =
  return $ L span $ itint $! transint $ parseUnsignedInteger
     (offsetBytes transbuf buf) (subtract translen len) radix char_to_int

-- some conveniences for use with tok_integral
Ian Lynagh's avatar
Ian Lynagh committed
1037 1038 1039
tok_num :: (Integer -> Integer)
        -> Int -> Int
        -> (Integer, (Char->Int)) -> Action
1040
tok_num = tok_integral ITinteger
Ian Lynagh's avatar
Ian Lynagh committed
1041 1042 1043
tok_primint :: (Integer -> Integer)
            -> Int -> Int
            -> (Integer, (Char->Int)) -> Action
1044
tok_primint = tok_integral ITprimint
Ian Lynagh's avatar
Ian Lynagh committed
1045 1046
tok_primword :: Int -> Int
             -> (Integer, (Char->Int)) -> Action
Ian Lynagh's avatar
Ian Lynagh committed
1047
tok_primword = tok_integral ITprimword positive
Ian Lynagh's avatar
Ian Lynagh committed
1048
positive, negative :: (Integer -> Integer)
1049 1050
positive = id
negative = negate
Ian Lynagh's avatar
Ian Lynagh committed
1051
decimal, octal, hexadecimal :: (Integer, Char -> Int)
1052 1053 1054 1055 1056
decimal = (10,octDecDigit)
octal = (8,octDecDigit)
hexadecimal = (16,hexDigit)

-- readRational can understand negative rationals, exponents, everything.
Ian Lynagh's avatar
Ian Lynagh committed
1057
tok_float, tok_primfloat, tok_primdouble :: String -> Token
1058 1059 1060 1061 1062 1063
tok_float        str = ITrational   $! readFractionalLit str
tok_primfloat    str = ITprimfloat  $! readFractionalLit str
tok_primdouble   str = ITprimdouble $! readFractionalLit str

readFractionalLit :: String -> FractionalLit
readFractionalLit str = (FL $! str) $! readRational str
1064 1065 1066 1067 1068 1069

-- -----------------------------------------------------------------------------
-- Layout processing

-- we're at the first token on a line, insert layout tokens if necessary
do_bol :: Action
1070
do_bol span _str _len = do
1071
	pos <- getOffside
1072 1073 1074 1075 1076
	case pos of
	    LT -> do
                --trace "layout: inserting '}'" $ do
		popContext
		-- do NOT pop the lex state, we might have a ';' to insert
1077
		return (L span ITvccurly)
1078 1079
	    EQ -> do
                --trace "layout: inserting ';'" $ do
Ian Lynagh's avatar
Ian Lynagh committed
1080
		_ <- popLexState
1081
		return (L span ITsemi)
1082
	    GT -> do
Ian Lynagh's avatar
Ian Lynagh committed
1083
		_ <- popLexState
1084 1085 1086 1087
		lexToken

-- certain keywords put us in the "layout" state, where we might
-- add an opening curly brace.
Ian Lynagh's avatar
Ian Lynagh committed
1088
maybe_layout :: Token -> P ()
1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104
maybe_layout t = do -- If the alternative layout rule is enabled then
                    -- we never create an implicit layout context here.
                    -- Layout is handled XXX instead.
                    -- The code for closing implicit contexts, or
                    -- inserting implicit semi-colons, is therefore
                    -- irrelevant as it only applies in an implicit
                    -- context.
                    alr <- extension alternativeLayoutRule
                    unless alr $ f t
    where f ITdo    = pushLexState layout_do
          f ITmdo   = pushLexState layout_do
          f ITof    = pushLexState layout
          f ITlet   = pushLexState layout
          f ITwhere = pushLexState layout
          f ITrec   = pushLexState layout
          f _       = return ()
1105 1106 1107 1108 1109 1110 1111 1112 1113 1114

-- Pushing a new implicit layout context.  If the indentation of the
-- next token is not greater than the previous layout context, then
-- Haskell 98 says that the new layout context should be empty; that is
-- the lexer must generate {}.
--
-- We are slightly more lenient than this: when the new context is started
-- by a 'do', then we allow the new context to be at the same indentation as
-- the previous context.  This is what the 'strict' argument is for.
--
Ian Lynagh's avatar
Ian Lynagh committed
1115
new_layout_context :: Bool -> Action
1116
new_layout_context strict span _buf _len = do
Ian Lynagh's avatar
Ian Lynagh committed
1117
    _ <- popLexState
1118 1119
    (AI l _) <- getInput
    let offset = srcLocCol l
1120
    ctx <- getContext