+-----------------------------------------------------------------------------
+-- (c) The University of Glasgow, 2003
+--
+-- 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
+-- file is maintained. Every token has a start and end SrcLoc attached to it.
+--
+-----------------------------------------------------------------------------
+
+-- ToDo / known bugs:
+-- - Unicode
+-- - 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
+
+{
+module Lexer (
+ Token(..), Token__(..), lexer, ExtFlags(..), mkPState, showPFailed,
+ P(..), ParseResult(..), setSrcLocFor, getSrcLoc,
+ failMsgP, failLocMsgP, srcParseFail,
+ popContext, pushCurrentContext,
+ ) where
+
+#include "HsVersions.h"
+
+import ForeignCall ( Safety(..) )
+import ErrUtils ( Message )
+import Outputable
+import StringBuffer
+import FastString
+import FastTypes
+import SrcLoc
+import UniqFM
+import Ctype
+import Util ( maybePrefixMatch )
+
+import DATA_BITS
+import Char
+import Ratio
+import TRACE
+}
+
+$whitechar = [\ \t\n\r\f\v]
+$white_no_nl = $whitechar # \n
+
+$ascdigit = 0-9
+$unidigit = \x01
+$digit = [$ascdigit $unidigit]
+
+$special = [\(\)\,\;\[\]\`\{\}]
+$ascsymbol = [\!\#\$\%\&\*\+\.\/\<\=\>\?\@\\\^\|\-\~]
+$unisymbol = \x02
+$symbol = [$ascsymbol $unisymbol] # [$special \_\:\"\']
+
+$unilarge = \x03
+$asclarge = [A-Z \xc0-\xd6 \xd8-\xde]
+$large = [$asclarge $unilarge]
+
+$unismall = \x04
+$ascsmall = [a-z \xdf-\xf6 \xf8-\xff]
+$small = [$ascsmall $unismall \_]
+
+$graphic = [$small $large $symbol $digit $special \:\"\']
+
+$octit = 0-7
+$hexit = [$digit A-F a-f]
+$symchar = [$symbol \:]
+$nl = [\n\r]
+$idchar = [$small $large $digit \']
+
+@varid = $small $idchar*
+@conid = $large $idchar*
+
+@varsym = $symbol $symchar*
+@consym = \: $symchar*
+
+@decimal = $digit+
+@octal = $octit+
+@hexadecimal = $hexit+
+@exponent = [eE] [\-\+]? @decimal
+
+-- we support the hierarchical module name extension:
+@qual = (@conid \.)+
+
+@floating_point = @decimal \. @decimal @exponent? | @decimal @exponent
+
+haskell :-
+
+-- everywhere: skip whitespace and comments
+$white_no_nl+ ;
+
+-- 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
+-- are).
+"{-" / { notFollowedBy '#' } { nested_comment }
+
+-- 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.
+-- The regex says: "munch all the characters after the dashes, as long as
+-- the first one is not a symbol".
+"--"\-* ([^$symbol] .*)? ;
+
+-- '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 }
+ () { 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> {
+ \{ / { notFollowedBy '-' } { pop_and open_brace }
+ -- 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 }
+
+<0,glaexts> \n { begin bol }
+
+"{-#" $whitechar* (line|LINE) { begin line_prag2 }
+
+-- single-line line pragmas, of the form
+-- # <line> "<file>" <extra-stuff> \n
+<line_prag1> $digit+ { set_line line_prag1a }
+<line_prag1a> \" $graphic* \" { set_file line_prag1b }
+<line_prag1b> .* { pop }
+
+-- Haskell-style line pragmas, of the form
+-- {-# LINE <line> "<file>" #-}
+<line_prag2> $digit+ { set_line line_prag2a }
+<line_prag2a> \" $graphic* \" { set_file line_prag2b }
+<line_prag2b> "#-}" { pop }
+
+<0,glaexts> {
+ "{-#" $whitechar* (SPECIALI[SZ]E|speciali[sz]e)
+ { token ITspecialise_prag }
+ "{-#" $whitechar* (SOURCE|source) { token ITsource_prag }
+ "{-#" $whitechar* (INLINE|inline) { token ITinline_prag }
+ "{-#" $whitechar* (NO(T?)INLINE|no(t?)inline)
+ { token ITnoinline_prag }
+ "{-#" $whitechar* (RULES|rules) { token ITrules_prag }
+ "{-#" $whitechar* (DEPRECATED|deprecated)
+ { token ITdeprecated_prag }
+ "{-#" $whitechar* (SCC|scc) { token ITscc_prag }
+ "{-#" $whitechar* (CORE|core) { token ITcore_prag }
+
+ "{-#" { nested_comment }
+
+ -- ToDo: should only be valid inside a pragma:
+ "#-}" { token ITclose_prag}
+}
+
+
+-- '0' state: ordinary lexemes
+-- 'glaexts' state: glasgow extensions (postfix '#', etc.)
+
+-- "special" symbols
+
+<glaexts> {
+ "(#" { token IToubxparen }
+ "#)" { token ITcubxparen }
+
+ "[:" { token ITopabrack }
+ ":]" { token ITcpabrack }
+
+ "{|" { token ITocurlybar }
+ "|}" { token ITccurlybar }
+
+ "[|" { token ITopenExpQuote }
+ "[e|" { token ITopenExpQuote }
+ "[p|" { token ITopenPatQuote }
+ "[d|" { token ITopenDecQuote }
+ "[t|" { token ITopenTypQuote }
+ "|]" { token ITcloseQuote }
+}
+
+<0,glaexts> {
+ "(|" / { \b _ _ _ -> arrowsEnabled b} { special IToparenbar }
+ "|)" / { \b _ _ _ -> arrowsEnabled b} { special ITcparenbar }
+ \( { special IToparen }
+ \) { special ITcparen }
+ \[ { special ITobrack }
+ \] { special ITcbrack }
+ \, { special ITcomma }
+ \; { special ITsemi }
+ \` { special ITbackquote }
+
+ \{ { open_brace }
+ \} { close_brace }
+}
+
+<glaexts> {
+ \? @varid { skip_one_varid ITdupipvarid }
+ \% @varid { skip_one_varid ITsplitipvarid }
+ \$ @varid { skip_one_varid ITidEscape }
+ "$(" { token ITparenEscape }
+}
+
+<0,glaexts> {
+ @qual @varid { check_qvarid }
+ @qual @conid { idtoken qconid }
+ @varid { varid }
+ @conid { idtoken conid }
+}
+
+-- after an illegal qvarid, such as 'M.let',
+-- we back up and try again in the bad_qvarid state:
+<bad_qvarid> {
+ @conid { pop_and (idtoken conid) }
+ @qual @conid { pop_and (idtoken qconid) }
+}
+
+<glaexts> {
+ @qual @varid "#"+ { idtoken qvarid }
+ @qual @conid "#"+ { idtoken qconid }
+ @varid "#"+ { varid }
+ @conid "#"+ { idtoken conid }
+}
+
+-- ToDo: M.(,,,)
+
+<0,glaexts> {
+ @qual @varsym { idtoken qvarsym }
+ @qual @consym { idtoken qconsym }
+ @varsym { varsym }
+ @consym { consym }
+}
+
+<0,glaexts> {
+ @decimal { tok_decimal }
+ 0[oO] @octal { tok_octal }
+ 0[xX] @hexadecimal { tok_hexadecimal }
+}
+
+<glaexts> {
+ @decimal \# { prim_decimal }
+ 0[oO] @octal \# { prim_octal }
+ 0[xX] @hexadecimal \# { prim_hexadecimal }
+}
+
+<0,glaexts> @floating_point { strtoken tok_float }
+<glaexts> @floating_point \# { init_strtoken 1 prim_float }
+<glaexts> @floating_point \# \# { init_strtoken 2 prim_double }
+
+-- Strings and chars are lexed by hand-written code. The reason is
+-- that even if we recognise the string or char here in the regex
+-- lexer, we would still have to parse the string afterward in order
+-- to convert it to a String.
+<0,glaexts> {
+ \' { lex_char_tok }
+ \" { lex_string_tok }
+}
+
+<glaexts> "``" (([$graphic $whitechar] # \') | \' ([$graphic $whitechar] # \'))*
+ "''" { clitlit }
+
+{
+-- work around bug in Alex 2.0
+#if __GLASGOW_HASKELL__ < 503
+unsafeAt arr i = arr ! i
+#endif
+
+-- -----------------------------------------------------------------------------
+-- The token type
+
+data Token = T SrcLoc{-start-} SrcLoc{-end-} Token__
+
+data Token__
+ = 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
+ | ITthreadsafe
+ | ITunsafe
+ | ITwith
+ | ITstdcallconv
+ | ITccallconv
+ | ITdotnet
+ | ITccall (Bool,Bool,Safety) -- (is_dyn, is_casm, may_gc)
+ | ITmdo
+
+ | ITspecialise_prag -- Pragmas
+ | ITsource_prag
+ | ITinline_prag
+ | ITnoinline_prag
+ | ITrules_prag
+ | ITdeprecated_prag
+ | ITline_prag
+ | ITscc_prag
+ | ITcore_prag -- hdaume: core annotations
+ | ITclose_prag
+
+ | 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
+ | ITopabrack -- [:, for parallel arrays with -fparr
+ | ITcpabrack -- :], for parallel arrays with -fparr
+ | 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)
+
+ | ITdupipvarid FastString -- GHC extension: implicit param: ?x
+ | ITsplitipvarid FastString -- GHC extension: implicit param: %x
+
+ | ITpragma StringBuffer
+
+ | ITchar Char
+ | ITstring FastString
+ | ITinteger Integer
+ | ITrational Rational
+
+ | ITprimchar Char
+ | ITprimstring FastString
+ | ITprimint Integer
+ | ITprimfloat Rational
+ | ITprimdouble Rational
+ | ITlitlit FastString
+
+ -- MetaHaskell extension tokens
+ | ITopenExpQuote -- [| or [e|
+ | ITopenPatQuote -- [p|
+ | ITopenDecQuote -- [d|
+ | ITopenTypQuote -- [t|
+ | ITcloseQuote -- |]
+ | ITidEscape FastString -- $x
+ | ITparenEscape -- $(
+ | ITreifyType
+ | ITreifyDecl
+ | ITreifyFixity
+
+ -- Arrow notation extension
+ | ITproc
+ | ITrec
+ | IToparenbar -- (|
+ | ITcparenbar -- |)
+ | ITlarrowtail -- -<
+ | ITrarrowtail -- >-
+ | ITLarrowtail -- -<<
+ | ITRarrowtail -- >>-
+
+ | ITunknown String -- Used when the lexer can't make sense of it
+ | ITeof -- end of file token
+#ifdef DEBUG
+ deriving Show -- debugging
+#endif
+
+isSpecial :: Token__ -> Bool
+-- 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
+isSpecial ITthreadsafe = True
+isSpecial ITunsafe = True
+isSpecial ITwith = True
+isSpecial ITccallconv = True
+isSpecial ITstdcallconv = True
+isSpecial ITmdo = True
+isSpecial _ = False
+
+-- 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)
+--
+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
+
+ ( "forall", ITforall, bit glaExtsBit),
+ ( "mdo", ITmdo, bit glaExtsBit),
+ ( "reifyDecl", ITreifyDecl, bit glaExtsBit),
+ ( "reifyType", ITreifyType, bit glaExtsBit),
+ ( "reifyFixity",ITreifyFixity, bit glaExtsBit),
+
+ ( "foreign", ITforeign, bit ffiBit),
+ ( "export", ITexport, bit ffiBit),
+ ( "label", ITlabel, bit ffiBit),
+ ( "dynamic", ITdynamic, bit ffiBit),
+ ( "safe", ITsafe, bit ffiBit),
+ ( "threadsafe", ITthreadsafe, bit ffiBit),
+ ( "unsafe", ITunsafe, bit ffiBit),
+ ( "stdcall", ITstdcallconv, bit ffiBit),
+ ( "ccall", ITccallconv, bit ffiBit),
+ ( "dotnet", ITdotnet, bit ffiBit),
+
+ ( "with", ITwith, bit withBit),
+
+ ( "rec", ITrec, bit arrowsBit),
+ ( "proc", ITproc, bit arrowsBit),
+
+ -- On death row
+ ("_ccall_", ITccall (False, False, PlayRisky),
+ bit glaExtsBit),
+ ("_ccall_GC_", ITccall (False, False, PlaySafe False),
+ bit glaExtsBit),
+ ("_casm_", ITccall (False, True, PlayRisky),
+ bit glaExtsBit),
+ ("_casm_GC_", ITccall (False, True, PlaySafe False),
+ bit glaExtsBit)
+ ]
+
+reservedSymsFM = listToUFM $
+ map (\ (x,y,z) -> (mkFastString x,(y,z)))
+ [ ("..", ITdotdot, 0)
+ ,(":", ITcolon, 0) -- (:) is a reserved op,
+ -- meaning only list cons
+ ,("::", ITdcolon, 0)
+ ,("=", ITequal, 0)
+ ,("\\", ITlam, 0)
+ ,("|", ITvbar, 0)
+ ,("<-", ITlarrow, 0)
+ ,("->", ITrarrow, 0)
+ ,("@", ITat, 0)
+ ,("~", ITtilde, 0)
+ ,("=>", ITdarrow, 0)
+ ,("-", ITminus, 0)
+ ,("!", ITbang, 0)
+
+ ,("*", ITstar, bit glaExtsBit) -- For data T (a::*) = MkT
+ ,(".", ITdot, bit glaExtsBit) -- For 'forall a . t'
+
+ ,("-<", ITlarrowtail, bit arrowsBit)
+ ,(">-", ITrarrowtail, bit arrowsBit)
+ ,("-<<", ITLarrowtail, bit arrowsBit)
+ ,(">>-", ITRarrowtail, bit arrowsBit)
+ ]
+
+-- -----------------------------------------------------------------------------
+-- Lexer actions
+
+type Action = SrcLoc -> SrcLoc -> StringBuffer -> Int -> P Token
+
+special :: Token__ -> Action
+special tok loc end _buf len = return (T loc end tok)
+
+token :: Token__ -> Action
+token t loc end buf len = return (T loc end t)
+
+idtoken :: (StringBuffer -> Int -> Token__) -> Action
+idtoken f loc end buf len = return (T loc end $! (f buf len))
+
+skip_one_varid :: (FastString -> Token__) -> Action
+skip_one_varid f loc end buf len
+ = return (T loc end $! f (lexemeToFastString (stepOn buf) (len-1)))
+
+strtoken :: (String -> Token__) -> Action
+strtoken f loc end buf len =
+ return (T loc end $! (f $! lexemeToString buf len))
+
+init_strtoken :: Int -> (String -> Token__) -> Action
+-- like strtoken, but drops the last N character(s)
+init_strtoken drop f loc end buf len =
+ return (T loc end $! (f $! lexemeToString buf (len-drop)))
+
+begin :: Int -> Action
+begin code _loc _end _str _len = do pushLexState code; lexToken
+
+pop :: Action
+pop _loc _end _buf _len = do popLexState; lexToken
+
+pop_and :: Action -> Action
+pop_and act loc end buf len = do popLexState; act loc end buf len
+
+notFollowedBy char _ _ _ (_,buf) = atEnd buf || currentChar buf /= char
+
+{-
+ nested comments require traversing by hand, they can't be parsed
+ using regular expressions.
+-}
+nested_comment :: Action
+nested_comment loc _end _str _len = do
+ input <- getInput
+ go 1 input
+ where go 0 input = do setInput input; lexToken
+ go n input = do
+ case alexGetChar input of
+ Nothing -> err input
+ Just (c,input) -> do
+ case c of
+ '-' -> do
+ case alexGetChar input of
+ Nothing -> err input
+ Just ('\125',input) -> go (n-1) input
+ Just (c,_) -> go n input
+ '\123' -> do
+ case alexGetChar input of
+ Nothing -> err input
+ Just ('-',input') -> go (n+1) input'
+ Just (c,input) -> go n input
+ c -> go n input
+
+ err input = do failLocMsgP loc (fst input) "unterminated `{-'"
+
+open_brace, close_brace :: Action
+open_brace loc end _str _len = do
+ ctx <- getContext
+ setContext (NoLayout:ctx)
+ return (T loc end ITocurly)
+close_brace loc end _str _len = do
+ popContext
+ return (T loc end ITccurly)
+
+-- We have to be careful not to count M.<varid> as a qualified name
+-- when <varid> is a keyword. We hack around this by catching
+-- the offending tokens afterward, and re-lexing in a different state.
+check_qvarid loc end buf len = do
+ case lookupUFM reservedWordsFM var of
+ Just (keyword,exts)
+ | not (isSpecial keyword) ->
+ if exts == 0
+ then try_again
+ else do
+ b <- extension (\i -> exts .&. i /= 0)
+ if b then try_again
+ else return token
+ _other -> return token
+ where
+ (mod,var) = splitQualName buf len
+ token = T loc end (ITqvarid (mod,var))
+
+ try_again = do
+ setInput (loc,buf)
+ pushLexState bad_qvarid
+ lexToken
+
+qvarid buf len = ITqvarid $! splitQualName buf len
+qconid buf len = ITqconid $! splitQualName buf len
+
+splitQualName :: StringBuffer -> Int -> (FastString,FastString)
+-- 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.
+splitQualName orig_buf len = split orig_buf 0 0
+ where
+ split buf dot_off n
+ | n == len = done dot_off
+ | lookAhead buf n == '.' = split2 buf n (n+1)
+ | otherwise = split buf dot_off (n+1)
+
+ -- 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.
+ split2 buf dot_off n
+ | isUpper (lookAhead buf n) = split buf dot_off (n+1)
+ | otherwise = done dot_off
+
+ done dot_off =
+ (lexemeToFastString orig_buf dot_off,
+ lexemeToFastString (stepOnBy (dot_off+1) orig_buf) (len - dot_off -1))
+
+varid loc end buf len =
+ case lookupUFM reservedWordsFM fs of
+ Just (keyword,0) -> do
+ maybe_layout keyword
+ return (T loc end keyword)
+ Just (keyword,exts) -> do
+ b <- extension (\i -> exts .&. i /= 0)
+ if b then do maybe_layout keyword
+ return (T loc end keyword)
+ else return (T loc end (ITvarid fs))
+ _other -> return (T loc end (ITvarid fs))
+ where
+ fs = lexemeToFastString buf len
+
+conid buf len = ITconid fs
+ where fs = lexemeToFastString buf len
+
+qvarsym buf len = ITqvarsym $! splitQualName buf len
+qconsym buf len = ITqconsym $! splitQualName buf len
+
+varsym = sym ITvarsym
+consym = sym ITconsym
+
+sym con loc end buf len =
+ case lookupUFM reservedSymsFM fs of
+ Just (keyword,0) -> return (T loc end keyword)
+ Just (keyword,exts) -> do
+ b <- extension (\i -> exts .&. i /= 0)
+ if b then return (T loc end keyword)
+ else return (T loc end $! con fs)
+ _other -> return (T loc end $! con fs)
+ where
+ fs = lexemeToFastString buf len
+
+tok_decimal loc end buf len
+ = return (T loc end (ITinteger $! parseInteger buf len 10 oct_or_dec))
+
+tok_octal loc end buf len
+ = return (T loc end (ITinteger $! parseInteger (stepOnBy 2 buf) (len-2) 8 oct_or_dec))
+
+tok_hexadecimal loc end buf len
+ = return (T loc end (ITinteger $! parseInteger (stepOnBy 2 buf) (len-2) 16 hex))
+
+prim_decimal loc end buf len
+ = return (T loc end (ITprimint $! parseInteger buf (len-1) 10 oct_or_dec))
+
+prim_octal loc end buf len
+ = return (T loc end (ITprimint $! parseInteger (stepOnBy 2 buf) (len-3) 8 oct_or_dec))
+
+prim_hexadecimal loc end buf len
+ = return (T loc end (ITprimint $! parseInteger (stepOnBy 2 buf) (len-3) 16 hex))
+
+tok_float str = ITrational $! readRational__ str
+prim_float str = ITprimfloat $! readRational__ str
+prim_double str = ITprimdouble $! readRational__ str
+
+parseInteger :: StringBuffer -> Int -> Integer -> (Char->Int) -> Integer
+parseInteger buf len radix to_int
+ = go 0 0
+ where go i x | i == len = x
+ | otherwise = go (i+1) (x * radix + toInteger (to_int (lookAhead buf i)))
+
+clitlit :: Action
+clitlit loc end buf len =
+ return (T loc end (ITlitlit $! lexemeToFastString (stepOnBy 2 buf) (len-4)))
+
+-- -----------------------------------------------------------------------------
+-- Layout processing
+
+-- we're at the first token on a line, insert layout tokens if necessary
+do_bol :: Action
+do_bol loc end _str _len = do
+ pos <- getOffside end
+ case pos of
+ LT -> do
+ --trace "layout: inserting '}'" $ do
+ popContext
+ -- do NOT pop the lex state, we might have a ';' to insert
+ return (T loc end ITvccurly)
+ EQ -> do
+ --trace "layout: inserting ';'" $ do
+ popLexState
+ return (T loc end ITsemi)
+ GT -> do
+ popLexState
+ lexToken
+
+-- certain keywords put us in the "layout" state, where we might
+-- add an opening curly brace.
+maybe_layout ITdo = pushLexState layout_do
+maybe_layout ITof = pushLexState layout
+maybe_layout ITlet = pushLexState layout
+maybe_layout ITwhere = pushLexState layout
+maybe_layout _ = return ()
+
+-- 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.
+--
+new_layout_context strict loc end _buf _len = do
+ popLexState
+ let offset = srcLocCol loc
+ ctx <- getContext
+ case ctx of
+ Layout prev_off : _ |
+ (strict && prev_off >= offset ||
+ not strict && prev_off > offset) -> do
+ -- token is indented to the left of the previous context.
+ -- we must generate a {} sequence now.
+ pushLexState layout_left
+ return (T loc end ITvocurly)
+ other -> do
+ setContext (Layout offset : ctx)
+ return (T loc end ITvocurly)
+
+do_layout_left loc end _buf _len = do
+ popLexState
+ pushLexState bol -- we must be at the start of a line
+ return (T loc end ITvccurly)
+
+-- -----------------------------------------------------------------------------
+-- LINE pragmas
+
+set_line :: Int -> Action
+set_line code loc end buf len = do
+ let line = parseInteger buf len 10 oct_or_dec
+ setSrcLoc (mkSrcLoc (srcLocFile end) (fromIntegral line - 1) 0)
+ -- subtract one: the line number refers to the *following* line
+ popLexState
+ pushLexState code
+ lexToken
+
+set_file :: Int -> Action
+set_file code loc end buf len = do
+ let file = lexemeToFastString (stepOn buf) (len-2)
+ setSrcLoc (mkSrcLoc file (srcLocLine end) (srcLocCol end))
+ popLexState
+ pushLexState code
+ lexToken
+
+-- -----------------------------------------------------------------------------
+-- Strings & Chars
+
+-- This stuff is horrible. I hates it.
+
+lex_string_tok :: Action
+lex_string_tok loc end buf len = do
+ tok <- lex_string ""
+ end <- getSrcLoc
+ return (T loc end tok)
+
+lex_string :: String -> P Token__
+lex_string s = do
+ i <- getInput
+ case alexGetChar i of
+ Nothing -> lit_error
+
+ Just ('"',i) -> do
+ setInput i
+ glaexts <- extension glaExtsEnabled
+ if glaexts
+ then do
+ i <- getInput
+ case alexGetChar i of
+ Just ('#',i) -> do
+ setInput i
+ if any (> '\xFF') s
+ then failMsgP "primitive string literal must contain only characters <= \'\\xFF\'"
+ else let s' = mkFastStringNarrow (reverse s) in
+ -- always a narrow string/byte array
+ return (ITprimstring s')
+ _other ->
+ return (ITstring (mkFastString (reverse s)))
+ else
+ return (ITstring (mkFastString (reverse s)))
+
+ Just ('\\',i)
+ | Just ('&',i) <- next -> do
+ setInput i; lex_string s
+ | Just (c,i) <- next, is_space c -> do
+ setInput i; lex_stringgap s
+ where next = alexGetChar i
+
+ Just _ -> do
+ c <- lex_char
+ lex_string (c:s)
+
+
+lex_stringgap s = do
+ c <- getCharOrFail
+ case c of
+ '\\' -> lex_string s
+ c | is_space c -> lex_stringgap s
+ _other -> lit_error
+
+
+lex_char_tok :: Action
+lex_char_tok loc _end buf len = do
+ c <- lex_char
+ mc <- getCharOrFail
+ case mc of
+ '\'' -> do
+ glaexts <- extension glaExtsEnabled
+ if glaexts
+ then do
+ i@(end,_) <- getInput
+ case alexGetChar i of
+ Just ('#',i@(end,_)) -> do
+ setInput i
+ return (T loc end (ITprimchar c))
+ _other ->
+ return (T loc end (ITchar c))
+ else do
+ end <- getSrcLoc
+ return (T loc end (ITchar c))
+
+ _other -> lit_error
+
+lex_char :: P Char
+lex_char = do
+ mc <- getCharOrFail
+ case mc of
+ '\\' -> lex_escape
+ c | is_any c -> return c
+ _other -> lit_error
+
+lex_escape :: P Char
+lex_escape = do
+ c <- getCharOrFail
+ case c of
+ 'a' -> return '\a'
+ 'b' -> return '\b'
+ 'f' -> return '\f'
+ 'n' -> return '\n'
+ 'r' -> return '\r'
+ 't' -> return '\t'
+ 'v' -> return '\v'
+ '\\' -> return '\\'
+ '"' -> return '\"'
+ '\'' -> return '\''
+ '^' -> do c <- getCharOrFail
+ if c >= '@' && c <= '_'
+ then return (chr (ord c - ord '@'))
+ else lit_error
+
+ 'x' -> readNum is_hexdigit 16 hex
+ 'o' -> readNum is_octdigit 8 oct_or_dec
+ x | is_digit x -> readNum2 is_digit 10 oct_or_dec (oct_or_dec x)
+
+ c1 -> do
+ i <- getInput
+ case alexGetChar i of
+ Nothing -> lit_error
+ Just (c2,i2) ->
+ case alexGetChar i2 of
+ Nothing -> lit_error
+ Just (c3,i3) ->
+ let str = [c1,c2,c3] in
+ case [ (c,rest) | (p,c) <- silly_escape_chars,
+ Just rest <- [maybePrefixMatch p str] ] of
+ (escape_char,[]):_ -> do
+ setInput i3
+ return escape_char
+ (escape_char,_:_):_ -> do
+ setInput i2
+ return escape_char
+ [] -> lit_error
+
+readNum :: (Char -> Bool) -> Int -> (Char -> Int) -> P Char
+readNum is_digit base conv = do
+ c <- getCharOrFail
+ if is_digit c
+ then readNum2 is_digit base conv (conv c)
+ else lit_error
+
+readNum2 is_digit base conv i = do
+ input <- getInput
+ read i input
+ where read i input = do
+ case alexGetChar input of
+ Just (c,input') | is_digit c -> do
+ read (i*base + conv c) input'
+ _other -> do
+ setInput input
+ if i >= 0 && i <= 0x10FFFF
+ then return (chr i)
+ else lit_error
+
+is_hexdigit c
+ = is_digit c
+ || (c >= 'a' && c <= 'f')
+ || (c >= 'A' && c <= 'F')
+
+hex c | is_digit c = ord c - ord '0'
+ | otherwise = ord (to_lower c) - ord 'a' + 10
+
+oct_or_dec c = ord c - ord '0'
+
+is_octdigit c = c >= '0' && c <= '7'
+
+to_lower c
+ | c >= 'A' && c <= 'Z' = chr (ord c - (ord 'A' - ord 'a'))
+ | otherwise = c
+
+silly_escape_chars = [
+ ("NUL", '\NUL'),
+ ("SOH", '\SOH'),
+ ("STX", '\STX'),
+ ("ETX", '\ETX'),
+ ("EOT", '\EOT'),
+ ("ENQ", '\ENQ'),
+ ("ACK", '\ACK'),
+ ("BEL", '\BEL'),
+ ("BS", '\BS'),
+ ("HT", '\HT'),
+ ("LF", '\LF'),
+ ("VT", '\VT'),
+ ("FF", '\FF'),
+ ("CR", '\CR'),
+ ("SO", '\SO'),
+ ("SI", '\SI'),
+ ("DLE", '\DLE'),
+ ("DC1", '\DC1'),
+ ("DC2", '\DC2'),
+ ("DC3", '\DC3'),
+ ("DC4", '\DC4'),
+ ("NAK", '\NAK'),
+ ("SYN", '\SYN'),
+ ("ETB", '\ETB'),
+ ("CAN", '\CAN'),
+ ("EM", '\EM'),
+ ("SUB", '\SUB'),
+ ("ESC", '\ESC'),
+ ("FS", '\FS'),
+ ("GS", '\GS'),
+ ("RS", '\RS'),
+ ("US", '\US'),
+ ("SP", '\SP'),
+ ("DEL", '\DEL')
+ ]
+
+lit_error = lexError "lexical error in string/character literal"
+
+getCharOrFail :: P Char
+getCharOrFail = do
+ i <- getInput
+ case alexGetChar i of
+ Nothing -> lexError "unexpected end-of-file in string/character literal"
+ Just (c,i) -> do setInput i; return c
+
+-- -----------------------------------------------------------------------------
+-- Floats
+
+readRational :: ReadS Rational -- NB: doesn't handle leading "-"
+readRational r = do
+ (n,d,s) <- readFix r
+ (k,t) <- readExp s
+ return ((n%1)*10^^(k-d), t)
+ where
+ readFix r = do
+ (ds,s) <- lexDecDigits r
+ (ds',t) <- lexDotDigits s
+ return (read (ds++ds'), length ds', t)
+
+ readExp (e:s) | e `elem` "eE" = readExp' s
+ readExp s = return (0,s)
+
+ readExp' ('+':s) = readDec s
+ readExp' ('-':s) = do
+ (k,t) <- readDec s
+ return (-k,t)
+ readExp' s = readDec s
+
+ readDec s = do
+ (ds,r) <- nonnull isDigit s
+ return (foldl1 (\n d -> n * 10 + d) [ ord d - ord '0' | d <- ds ],
+ r)
+
+ lexDecDigits = nonnull isDigit
+
+ lexDotDigits ('.':s) = return (span isDigit s)
+ lexDotDigits s = return ("",s)
+
+ nonnull p s = do (cs@(_:_),t) <- return (span p s)
+ return (cs,t)
+
+readRational__ :: String -> Rational -- NB: *does* handle a leading "-"
+readRational__ top_s
+ = case top_s of
+ '-' : xs -> - (read_me xs)
+ xs -> read_me xs
+ where
+ read_me s
+ = case (do { (x,"") <- readRational s ; return x }) of
+ [x] -> x
+ [] -> error ("readRational__: no parse:" ++ top_s)
+ _ -> error ("readRational__: ambiguous parse:" ++ top_s)
+
+-- -----------------------------------------------------------------------------
+-- The Parse Monad
+
+data LayoutContext
+ = NoLayout
+ | Layout !Int
+
+data ParseResult a
+ = POk PState a
+ | PFailed
+ SrcLoc SrcLoc -- The start and end of the text span related to
+ -- the error. Might be used in environments which can
+ -- show this span, e.g. by highlighting it.
+ Message -- The error message
+
+showPFailed loc1 loc2 err
+ = showSDoc (hcat [ppr loc1, text ": ", err])
+
+data PState = PState {
+ buffer :: StringBuffer,
+ last_loc :: SrcLoc, -- pos of previous token
+ last_len :: !Int, -- len of previous token
+ loc :: SrcLoc, -- current loc (end of prev token + 1)
+ extsBitmap :: !Int, -- bitmap that determines permitted extensions
+ context :: [LayoutContext],
+ lex_state :: [Int]
+ }
+ -- last_loc and last_len are used when generating error messages,
+ -- and in pushCurrentContext only.
+
+newtype P a = P { unP :: PState -> ParseResult a }
+
+instance Monad P where
+ return = returnP
+ (>>=) = thenP
+ fail = failP
+
+returnP :: a -> P a
+returnP a = P $ \s -> POk s a
+
+thenP :: P a -> (a -> P b) -> P b
+(P m) `thenP` k = P $ \ s ->
+ case m s of
+ POk s1 a -> (unP (k a)) s1
+ PFailed l1 l2 err -> PFailed l1 l2 err
+
+failP :: String -> P a
+failP msg = P $ \s -> PFailed (last_loc s) (loc s) (text msg)
+
+failMsgP :: String -> P a
+failMsgP msg = P $ \s -> PFailed (last_loc s) (loc s) (text msg)
+
+failLocMsgP :: SrcLoc -> SrcLoc -> String -> P a
+failLocMsgP loc1 loc2 str = P $ \s -> PFailed loc1 loc2 (text str)
+
+extension :: (Int -> Bool) -> P Bool
+extension p = P $ \s -> POk s (p $! extsBitmap s)
+
+getExts :: P Int
+getExts = P $ \s -> POk s (extsBitmap s)
+
+setSrcLoc :: SrcLoc -> P ()
+setSrcLoc new_loc = P $ \s -> POk s{loc=new_loc} ()
+
+-- tmp, for supporting stuff in RdrHsSyn. The scope better not include
+-- any calls to the lexer, because it assumes things about the SrcLoc.
+setSrcLocFor :: SrcLoc -> P a -> P a
+setSrcLocFor new_loc scope = P $ \s@PState{ loc = old_loc } ->
+ case unP scope s{loc=new_loc} of
+ PFailed l1 l2 msg -> PFailed l1 l2 msg
+ POk _ r -> POk s r
+
+getSrcLoc :: P SrcLoc
+getSrcLoc = P $ \s@(PState{ loc=loc }) -> POk s loc
+
+setLastToken :: SrcLoc -> Int -> P ()
+setLastToken loc len = P $ \s -> POk s{ last_loc=loc, last_len=len } ()
+
+type AlexInput = (SrcLoc,StringBuffer)
+
+alexInputPrevChar :: AlexInput -> Char
+alexInputPrevChar (_,s) = prevChar s '\n'
+
+alexGetChar :: AlexInput -> Maybe (Char,AlexInput)
+alexGetChar (loc,s)
+ | atEnd s = Nothing
+ | otherwise = c `seq` loc' `seq` s' `seq` Just (c, (loc', s'))
+ where c = currentChar s
+ loc' = advanceSrcLoc loc c
+ s' = stepOn s
+
+getInput :: P AlexInput
+getInput = P $ \s@PState{ loc=l, buffer=b } -> POk s (l,b)
+
+setInput :: AlexInput -> P ()
+setInput (l,b) = P $ \s -> POk s{ loc=l, buffer=b } ()
+
+pushLexState :: Int -> P ()
+pushLexState ls = P $ \s@PState{ lex_state=l } -> POk s{lex_state=ls:l} ()
+
+popLexState :: P Int
+popLexState = P $ \s@PState{ lex_state=ls:l } -> POk s{ lex_state=l } ls
+
+getLexState :: P Int
+getLexState = P $ \s@PState{ lex_state=ls:l } -> POk s ls
+
+-- for reasons of efficiency, flags indicating language extensions (eg,
+-- -fglasgow-exts or -fparr) are represented by a bitmap stored in an unboxed
+-- integer
+
+glaExtsBit, ffiBit, parrBit :: Int
+glaExtsBit = 0
+ffiBit = 1
+parrBit = 2
+withBit = 3
+arrowsBit = 4
+
+glaExtsEnabled, ffiEnabled, parrEnabled :: Int -> Bool
+glaExtsEnabled flags = testBit flags glaExtsBit
+ffiEnabled flags = testBit flags ffiBit
+withEnabled flags = testBit flags withBit
+parrEnabled flags = testBit flags parrBit
+arrowsEnabled flags = testBit flags arrowsBit
+
+-- convenient record-based bitmap for the interface to the rest of the world
+--
+-- NB: `glasgowExtsEF' implies `ffiEF' (see `mkPState' below)
+--
+data ExtFlags = ExtFlags {
+ glasgowExtsEF :: Bool,
+ ffiEF :: Bool,
+ withEF :: Bool,
+ parrEF :: Bool,
+ arrowsEF :: Bool
+ }
+
+-- create a parse state
+--
+mkPState :: StringBuffer -> SrcLoc -> ExtFlags -> PState
+mkPState buf loc exts =
+ PState {
+ buffer = buf,
+ last_loc = loc,
+ last_len = 0,
+ loc = loc,
+ extsBitmap = fromIntegral bitmap,
+ context = [],
+ lex_state = [bol, if glaExtsEnabled bitmap then glaexts else 0]
+ -- we begin in the layout state if toplev_layout is set
+ }
+ where
+ bitmap = glaExtsBit `setBitIf` glasgowExtsEF exts
+ .|. ffiBit `setBitIf` (ffiEF exts
+ || glasgowExtsEF exts)
+ .|. withBit `setBitIf` withEF exts
+ .|. parrBit `setBitIf` parrEF exts
+ .|. arrowsBit `setBitIf` arrowsEF exts
+ --
+ setBitIf :: Int -> Bool -> Int
+ b `setBitIf` cond | cond = bit b
+ | otherwise = 0
+
+getContext :: P [LayoutContext]
+getContext = P $ \s@PState{context=ctx} -> POk s ctx
+
+setContext :: [LayoutContext] -> P ()
+setContext ctx = P $ \s -> POk s{context=ctx} ()
+
+popContext :: P ()
+popContext = P $ \ s@(PState{ buffer = buf, context = ctx,
+ loc = loc, last_len = len, last_loc = last_loc }) ->
+ case ctx of
+ (_:tl) -> POk s{ context = tl } ()
+ [] -> PFailed last_loc loc (srcParseErr buf len)
+
+-- Push a new layout context at the indentation of the last token read.
+-- This is only used at the outer level of a module when the 'module'
+-- keyword is missing.
+pushCurrentContext :: P ()
+pushCurrentContext = P $ \ s@PState{ last_loc=loc, context=ctx } ->
+ POk s{ context = Layout (srcLocCol loc) : ctx} ()
+
+getOffside :: SrcLoc -> P Ordering
+getOffside loc = P $ \s@PState{context=stk} ->
+ let ord = case stk of
+ (Layout n:_) -> compare (srcLocCol loc) n
+ _ -> GT
+ in POk s ord
+
+-- ---------------------------------------------------------------------------
+-- Construct a parse error
+
+srcParseErr
+ :: StringBuffer -- current buffer (placed just after the last token)
+ -> Int -- length of the previous token
+ -> Message
+srcParseErr buf len
+ = hcat [ if null token
+ then ptext SLIT("parse error (possibly incorrect indentation)")
+ else hcat [ptext SLIT("parse error on input "),
+ char '`', text token, char '\'']
+ ]
+ where token = lexemeToString (stepOnBy (-len) buf) len
+
+-- Report a parse failure, giving the span of the previous token as
+-- the location of the error. This is the entry point for errors
+-- detected during parsing.
+srcParseFail :: P a
+srcParseFail = P $ \PState{ buffer = buf, last_len = len,
+ last_loc = last_loc, loc = loc } ->
+ PFailed last_loc loc (srcParseErr buf len)
+
+-- A lexical error is reported at a particular position in the source file,
+-- not over a token range. TODO: this is slightly wrong, because we record
+-- the error at the character position following the one which caused the
+-- error. We should somehow back up by one character.
+lexError :: String -> P a
+lexError str = do
+ loc <- getSrcLoc
+ failLocMsgP loc loc str
+
+-- -----------------------------------------------------------------------------
+-- This is the top-level function: called from the parser each time a
+-- new token is to be read from the input.
+
+lexer :: (Token -> P a) -> P a
+lexer cont = do
+ tok@(T _ _ tok__) <- lexToken
+ --trace ("token: " ++ show tok__) $ do
+ cont tok
+
+lexToken :: P Token
+lexToken = do
+ inp@(loc1,buf) <- getInput
+ sc <- getLexState
+ exts <- getExts
+ case alexScanUser exts inp sc of
+ AlexEOF -> do setLastToken loc1 0
+ return (T loc1 loc1 ITeof)
+ AlexError (loc2,_) -> do failLocMsgP loc1 loc2 "lexical error"
+ AlexSkip inp2 _ -> do
+ setInput inp2
+ lexToken
+ AlexToken inp2@(end,buf2) len t -> do
+ setInput inp2
+ setLastToken loc1 len
+ t loc1 end buf len
+}