+++ /dev/null
------------------------------------------------------------------------------
--- (c) The University of Glasgow, 2006
---
--- 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(..), lexer, pragState, mkPState, PState(..),
- P(..), ParseResult(..), getSrcLoc,
- failLocMsgP, failSpanMsgP, srcParseFail,
- popContext, pushCurrentContext, setLastToken, setSrcLoc,
- getLexState, popLexState, pushLexState,
- extension, bangPatEnabled
- ) where
-
-#include "HsVersions.h"
-
-import ErrUtils ( Message )
-import Outputable
-import StringBuffer
-import FastString
-import FastTypes
-import SrcLoc
-import UniqFM
-import DynFlags
-import Ctype
-import Util ( maybePrefixMatch, readRational )
-
-import DATA_BITS
-import Data.Char ( chr )
-import Ratio
---import TRACE
-
-#if __GLASGOW_HASKELL__ >= 605
-import Data.Char ( GeneralCategory(..), generalCategory, isPrint, isUpper )
-#else
-import Compat.Unicode ( GeneralCategory(..), generalCategory, isPrint, isUpper )
-#endif
-}
-
-$unispace = \x05
-$whitechar = [\ \t\n\r\f\v\xa0 $unispace]
-$white_no_nl = $whitechar # \n
-
-$ascdigit = 0-9
-$unidigit = \x03
-$decdigit = $ascdigit -- for now, should really be $digit (ToDo)
-$digit = [$ascdigit $unidigit]
-
-$special = [\(\)\,\;\[\]\`\{\}]
-$ascsymbol = [\!\#\$\%\&\*\+\.\/\<\=\>\?\@\\\^\|\-\~]
-$unisymbol = \x04
-$symbol = [$ascsymbol $unisymbol] # [$special \_\:\"\']
-
-$unilarge = \x01
-$asclarge = [A-Z \xc0-\xd6 \xd8-\xde]
-$large = [$asclarge $unilarge]
-
-$unismall = \x02
-$ascsmall = [a-z \xdf-\xf6 \xf8-\xff]
-$small = [$ascsmall $unismall \_]
-
-$unigraphic = \x06
-$graphic = [$small $large $symbol $digit $special $unigraphic \:\"\']
-
-$octit = 0-7
-$hexit = [$decdigit 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 = $decdigit+
-@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 :] .* ;
-"--"\-* / { atEOL } ;
-
--- '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 }
- ^\# pragma .* \n ; -- GCC 3.3 CPP generated, apparently
- ^\# \! .* \n ; -- #!, for scripts
- () { 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,option_prags,glaexts> \n { begin bol }
-
-"{-#" $whitechar* (line|LINE) { begin line_prag2 }
-
--- single-line line pragmas, of the form
--- # <line> "<file>" <extra-stuff> \n
-<line_prag1> $decdigit+ { setLine line_prag1a }
-<line_prag1a> \" [$graphic \ ]* \" { setFile line_prag1b }
-<line_prag1b> .* { pop }
-
--- Haskell-style line pragmas, of the form
--- {-# LINE <line> "<file>" #-}
-<line_prag2> $decdigit+ { setLine line_prag2a }
-<line_prag2a> \" [$graphic \ ]* \" { setFile line_prag2b }
-<line_prag2b> "#-}"|"-}" { pop }
- -- NOTE: accept -} at the end of a LINE pragma, for compatibility
- -- with older versions of GHC which generated these.
-
--- We only want RULES pragmas to be picked up when -fglasgow-exts
--- is on, because the contents of the pragma is always written using
--- glasgow-exts syntax (using forall etc.), so if glasgow exts are not
--- enabled, we're sure to get a parse error.
--- (ToDo: we should really emit a warning when ignoring pragmas)
-<glaexts>
- "{-#" $whitechar* (RULES|rules) { token ITrules_prag }
-
-<0,option_prags,glaexts> {
- "{-#" $whitechar* (INLINE|inline) { token (ITinline_prag True) }
- "{-#" $whitechar* (NO(T?)INLINE|no(t?)inline)
- { token (ITinline_prag False) }
- "{-#" $whitechar* (SPECIALI[SZ]E|speciali[sz]e)
- { token ITspec_prag }
- "{-#" $whitechar* (SPECIALI[SZ]E|speciali[sz]e)
- $whitechar* (INLINE|inline) { token (ITspec_inline_prag True) }
- "{-#" $whitechar* (SPECIALI[SZ]E|speciali[sz]e)
- $whitechar* (NO(T?)INLINE|no(t?)inline)
- { token (ITspec_inline_prag False) }
- "{-#" $whitechar* (SOURCE|source) { token ITsource_prag }
- "{-#" $whitechar* (DEPRECATED|deprecated)
- { token ITdeprecated_prag }
- "{-#" $whitechar* (SCC|scc) { token ITscc_prag }
- "{-#" $whitechar* (CORE|core) { token ITcore_prag }
- "{-#" $whitechar* (UNPACK|unpack) { token ITunpack_prag }
-
- "{-#" { nested_comment }
-
- -- ToDo: should only be valid inside a pragma:
- "#-}" { token ITclose_prag}
-}
-
-<option_prags> {
- "{-#" $whitechar* (OPTIONS|options) { lex_string_prag IToptions_prag }
- "{-#" $whitechar* (OPTIONS_GHC|options_ghc)
- { lex_string_prag IToptions_prag }
- "{-#" $whitechar* (LANGUAGE|language) { token ITlanguage_prag }
- "{-#" $whitechar* (INCLUDE|include) { lex_string_prag ITinclude_prag }
-}
-
--- '0' state: ordinary lexemes
--- 'glaexts' state: glasgow extensions (postfix '#', etc.)
-
--- "special" symbols
-
-<0,glaexts> {
- "[:" / { ifExtension parrEnabled } { token ITopabrack }
- ":]" / { ifExtension parrEnabled } { token ITcpabrack }
-}
-
-<0,glaexts> {
- "[|" / { ifExtension thEnabled } { token ITopenExpQuote }
- "[e|" / { ifExtension thEnabled } { token ITopenExpQuote }
- "[p|" / { ifExtension thEnabled } { token ITopenPatQuote }
- "[d|" / { ifExtension thEnabled } { layout_token ITopenDecQuote }
- "[t|" / { ifExtension thEnabled } { token ITopenTypQuote }
- "|]" / { ifExtension thEnabled } { token ITcloseQuote }
- \$ @varid / { ifExtension thEnabled } { skip_one_varid ITidEscape }
- "$(" / { ifExtension thEnabled } { token ITparenEscape }
-}
-
-<0,glaexts> {
- "(|" / { ifExtension arrowsEnabled `alexAndPred` notFollowedBySymbol }
- { special IToparenbar }
- "|)" / { ifExtension arrowsEnabled } { special ITcparenbar }
-}
-
-<0,glaexts> {
- \? @varid / { ifExtension ipEnabled } { skip_one_varid ITdupipvarid }
- \% @varid / { ifExtension ipEnabled } { skip_one_varid ITsplitipvarid }
-}
-
-<glaexts> {
- "(#" / { notFollowedBySymbol } { token IToubxparen }
- "#)" { token ITcubxparen }
- "{|" { token ITocurlybar }
- "|}" { token ITccurlybar }
-}
-
-<0,option_prags,glaexts> {
- \( { special IToparen }
- \) { special ITcparen }
- \[ { special ITobrack }
- \] { special ITcbrack }
- \, { special ITcomma }
- \; { special ITsemi }
- \` { special ITbackquote }
-
- \{ { open_brace }
- \} { close_brace }
-}
-
-<0,option_prags,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 }
-}
-
-{
--- work around bug in Alex 2.0
-#if __GLASGOW_HASKELL__ < 503
-unsafeAt arr i = arr ! i
-#endif
-
--- -----------------------------------------------------------------------------
--- The token type
-
-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
- | ITstdcallconv
- | ITccallconv
- | ITdotnet
- | ITmdo
-
- -- Pragmas
- | ITinline_prag Bool -- True <=> INLINE, False <=> NOINLINE
- | ITspec_prag -- SPECIALISE
- | ITspec_inline_prag Bool -- SPECIALISE INLINE (or NOINLINE)
- | ITsource_prag
- | ITrules_prag
- | ITdeprecated_prag
- | ITline_prag
- | ITscc_prag
- | ITcore_prag -- hdaume: core annotations
- | ITunpack_prag
- | ITclose_prag
- | IToptions_prag String
- | ITinclude_prag String
- | ITlanguage_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
-
- -- MetaHaskell extension tokens
- | ITopenExpQuote -- [| or [e|
- | ITopenPatQuote -- [p|
- | ITopenDecQuote -- [d|
- | ITopenTypQuote -- [t|
- | ITcloseQuote -- |]
- | ITidEscape FastString -- $x
- | ITparenEscape -- $(
- | ITvarQuote -- '
- | ITtyQuote -- ''
-
- -- 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 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 tvBit),
- ( "mdo", ITmdo, 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),
-
- ( "rec", ITrec, bit arrowsBit),
- ( "proc", ITproc, bit arrowsBit)
- ]
-
-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 tvBit) -- For 'forall a . t'
-
- ,("-<", ITlarrowtail, bit arrowsBit)
- ,(">-", ITrarrowtail, bit arrowsBit)
- ,("-<<", ITLarrowtail, bit arrowsBit)
- ,(">>-", ITRarrowtail, bit arrowsBit)
-
-#if __GLASGOW_HASKELL__ >= 605
- ,("λ", ITlam, bit glaExtsBit)
- ,("∷", ITdcolon, bit glaExtsBit)
- ,("⇒", ITdarrow, bit glaExtsBit)
- ,("∀", ITforall, bit glaExtsBit)
- ,("→", ITrarrow, bit glaExtsBit)
- ,("←", ITlarrow, bit glaExtsBit)
- ,("⋯", ITdotdot, bit glaExtsBit)
-#endif
- ]
-
--- -----------------------------------------------------------------------------
--- Lexer actions
-
-type Action = SrcSpan -> StringBuffer -> Int -> P (Located Token)
-
-special :: Token -> Action
-special tok span _buf len = return (L span tok)
-
-token, layout_token :: Token -> Action
-token t span buf len = return (L span t)
-layout_token t span buf len = pushLexState layout >> return (L span t)
-
-idtoken :: (StringBuffer -> Int -> Token) -> Action
-idtoken f span buf len = return (L span $! (f buf len))
-
-skip_one_varid :: (FastString -> Token) -> Action
-skip_one_varid f span buf len
- = return (L span $! f (lexemeToFastString (stepOn buf) (len-1)))
-
-strtoken :: (String -> Token) -> Action
-strtoken f span buf len =
- return (L span $! (f $! lexemeToString buf len))
-
-init_strtoken :: Int -> (String -> Token) -> Action
--- like strtoken, but drops the last N character(s)
-init_strtoken drop f span buf len =
- return (L span $! (f $! lexemeToString buf (len-drop)))
-
-begin :: Int -> Action
-begin code _span _str _len = do pushLexState code; lexToken
-
-pop :: Action
-pop _span _buf _len = do popLexState; lexToken
-
-pop_and :: Action -> Action
-pop_and act span buf len = do popLexState; act span buf len
-
-notFollowedBy char _ _ _ (AI _ _ buf) = atEnd buf || currentChar buf /= char
-
-notFollowedBySymbol _ _ _ (AI _ _ buf)
- = atEnd buf || currentChar buf `notElem` "!#$%&*+./<=>?@\\^|-~"
-
-atEOL _ _ _ (AI _ _ buf) = atEnd buf || currentChar buf == '\n'
-
-ifExtension pred bits _ _ _ = pred bits
-
-{-
- nested comments require traversing by hand, they can't be parsed
- using regular expressions.
--}
-nested_comment :: Action
-nested_comment span _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 (AI end _ _) = failLocMsgP (srcSpanStart span) end "unterminated `{-'"
-
-open_brace, close_brace :: Action
-open_brace span _str _len = do
- ctx <- getContext
- setContext (NoLayout:ctx)
- return (L span ITocurly)
-close_brace span _str _len = do
- popContext
- return (L span 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 span 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 = L span (ITqvarid (mod,var))
-
- try_again = do
- (AI _ offs _) <- getInput
- setInput (AI (srcSpanStart span) (offs-len) 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 orig_buf
- where
- 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
-
- -- 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.
- 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),
- lexemeToFastString dot_buf (len - qual_size))
- where
- qual_size = orig_buf `byteDiff` dot_buf
-
-varid span buf len =
- case lookupUFM reservedWordsFM fs of
- Just (keyword,0) -> do
- maybe_layout keyword
- return (L span keyword)
- Just (keyword,exts) -> do
- b <- extension (\i -> exts .&. i /= 0)
- if b then do maybe_layout keyword
- return (L span keyword)
- else return (L span (ITvarid fs))
- _other -> return (L span (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 span buf len =
- case lookupUFM reservedSymsFM fs of
- Just (keyword,0) -> return (L span keyword)
- Just (keyword,exts) -> do
- b <- extension (\i -> exts .&. i /= 0)
- if b then return (L span keyword)
- else return (L span $! con fs)
- _other -> return (L span $! con fs)
- where
- fs = lexemeToFastString buf len
-
-tok_decimal span buf len
- = return (L span (ITinteger $! parseInteger buf len 10 octDecDigit))
-
-tok_octal span buf len
- = return (L span (ITinteger $! parseInteger (offsetBytes 2 buf) (len-2) 8 octDecDigit))
-
-tok_hexadecimal span buf len
- = return (L span (ITinteger $! parseInteger (offsetBytes 2 buf) (len-2) 16 hexDigit))
-
-prim_decimal span buf len
- = return (L span (ITprimint $! parseInteger buf (len-1) 10 octDecDigit))
-
-prim_octal span buf len
- = return (L span (ITprimint $! parseInteger (offsetBytes 2 buf) (len-3) 8 octDecDigit))
-
-prim_hexadecimal span buf len
- = return (L span (ITprimint $! parseInteger (offsetBytes 2 buf) (len-3) 16 hexDigit))
-
-tok_float str = ITrational $! readRational str
-prim_float str = ITprimfloat $! readRational str
-prim_double str = ITprimdouble $! readRational str
-
--- -----------------------------------------------------------------------------
--- Layout processing
-
--- we're at the first token on a line, insert layout tokens if necessary
-do_bol :: Action
-do_bol span _str _len = do
- pos <- getOffside
- case pos of
- LT -> do
- --trace "layout: inserting '}'" $ do
- popContext
- -- do NOT pop the lex state, we might have a ';' to insert
- return (L span ITvccurly)
- EQ -> do
- --trace "layout: inserting ';'" $ do
- popLexState
- return (L span 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 ITmdo = pushLexState layout_do
-maybe_layout ITof = pushLexState layout
-maybe_layout ITlet = pushLexState layout
-maybe_layout ITwhere = pushLexState layout
-maybe_layout ITrec = 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 span _buf _len = do
- popLexState
- (AI _ offset _) <- getInput
- 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 (L span ITvocurly)
- other -> do
- setContext (Layout offset : ctx)
- return (L span ITvocurly)
-
-do_layout_left span _buf _len = do
- popLexState
- pushLexState bol -- we must be at the start of a line
- return (L span ITvccurly)
-
--- -----------------------------------------------------------------------------
--- LINE pragmas
-
-setLine :: Int -> Action
-setLine code span buf len = do
- let line = parseInteger buf len 10 octDecDigit
- setSrcLoc (mkSrcLoc (srcSpanFile span) (fromIntegral line - 1) 0)
- -- subtract one: the line number refers to the *following* line
- popLexState
- pushLexState code
- lexToken
-
-setFile :: Int -> Action
-setFile code span buf len = do
- let file = lexemeToFastString (stepOn buf) (len-2)
- setSrcLoc (mkSrcLoc file (srcSpanEndLine span) (srcSpanEndCol span))
- popLexState
- pushLexState code
- lexToken
-
-
--- -----------------------------------------------------------------------------
--- Options, includes and language pragmas.
-
-lex_string_prag :: (String -> Token) -> Action
-lex_string_prag mkTok span buf len
- = do input <- getInput
- start <- getSrcLoc
- tok <- go [] input
- end <- getSrcLoc
- return (L (mkSrcSpan start end) tok)
- where go acc input
- = if isString input "#-}"
- then do setInput input
- return (mkTok (reverse acc))
- else case alexGetChar input of
- Just (c,i) -> go (c:acc) i
- Nothing -> err input
- isString i [] = True
- isString i (x:xs)
- = case alexGetChar i of
- Just (c,i') | c == x -> isString i' xs
- _other -> False
- err (AI end _ _) = failLocMsgP (srcSpanStart span) end "unterminated options pragma"
-
-
--- -----------------------------------------------------------------------------
--- Strings & Chars
-
--- This stuff is horrible. I hates it.
-
-lex_string_tok :: Action
-lex_string_tok span buf len = do
- tok <- lex_string ""
- end <- getSrcLoc
- return (L (mkSrcSpan (srcSpanStart span) 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' = mkZFastString (reverse s) in
- return (ITprimstring s')
- -- mkZFastString is a hack to avoid encoding the
- -- string in UTF-8. We just want the exact bytes.
- _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 (c, i) -> do
- c' <- lex_char c i
- 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
--- Here we are basically parsing character literals, such as 'x' or '\n'
--- but, when Template Haskell is on, we additionally spot
--- 'x and ''T, returning ITvarQuote and ITtyQuote respectively,
--- but WIHTOUT CONSUMING the x or T part (the parser does that).
--- So we have to do two characters of lookahead: when we see 'x we need to
--- see if there's a trailing quote
-lex_char_tok span buf len = do -- We've seen '
- i1 <- getInput -- Look ahead to first character
- let loc = srcSpanStart span
- case alexGetChar' i1 of
- Nothing -> lit_error
-
- Just ('\'', i2@(AI end2 _ _)) -> do -- We've seen ''
- th_exts <- extension thEnabled
- if th_exts then do
- setInput i2
- return (L (mkSrcSpan loc end2) ITtyQuote)
- else lit_error
-
- Just ('\\', i2@(AI end2 _ _)) -> do -- We've seen 'backslash
- setInput i2
- lit_ch <- lex_escape
- mc <- getCharOrFail -- Trailing quote
- if mc == '\'' then finish_char_tok loc lit_ch
- else do setInput i2; lit_error
-
- Just (c, i2@(AI end2 _ _))
- | not (isAny c) -> lit_error
- | otherwise ->
-
- -- We've seen 'x, where x is a valid character
- -- (i.e. not newline etc) but not a quote or backslash
- case alexGetChar' i2 of -- Look ahead one more character
- Nothing -> lit_error
- Just ('\'', i3) -> do -- We've seen 'x'
- setInput i3
- finish_char_tok loc c
- _other -> do -- We've seen 'x not followed by quote
- -- If TH is on, just parse the quote only
- th_exts <- extension thEnabled
- let (AI end _ _) = i1
- if th_exts then return (L (mkSrcSpan loc end) ITvarQuote)
- else do setInput i2; lit_error
-
-finish_char_tok :: SrcLoc -> Char -> P (Located Token)
-finish_char_tok loc ch -- We've already seen the closing quote
- -- Just need to check for trailing #
- = do glaexts <- extension glaExtsEnabled
- i@(AI end _ _) <- getInput
- if glaexts then do
- case alexGetChar' i of
- Just ('#',i@(AI end _ _)) -> do
- setInput i
- return (L (mkSrcSpan loc end) (ITprimchar ch))
- _other ->
- return (L (mkSrcSpan loc end) (ITchar ch))
- else do
- return (L (mkSrcSpan loc end) (ITchar ch))
-
-lex_char :: Char -> AlexInput -> P Char
-lex_char c inp = do
- case c of
- '\\' -> do setInput inp; lex_escape
- c | isAny c -> do setInput inp; return c
- _other -> lit_error
-
-isAny c | c > '\xff' = isPrint c
- | otherwise = is_any c
-
-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 hexDigit
- 'o' -> readNum is_octdigit 8 octDecDigit
- x | is_digit x -> readNum2 is_digit 10 octDecDigit (octDecDigit x)
-
- c1 -> do
- i <- getInput
- case alexGetChar' i of
- Nothing -> lit_error
- Just (c2,i2) ->
- case alexGetChar' i2 of
- Nothing -> do setInput i2; 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
- i <- getInput
- c <- getCharOrFail
- if is_digit c
- then readNum2 is_digit base conv (conv c)
- else do setInput i; 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
- if i >= 0 && i <= 0x10FFFF
- then do setInput input; return (chr i)
- else lit_error
-
-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')
- ]
-
--- before calling lit_error, ensure that the current input is pointing to
--- the position of the error in the buffer. This is so that we can report
--- a correct location to the user, but also so we can detect UTF-8 decoding
--- errors if they occur.
-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
-
--- -----------------------------------------------------------------------------
--- The Parse Monad
-
-data LayoutContext
- = NoLayout
- | Layout !Int
-
-data ParseResult a
- = POk PState a
- | PFailed
- SrcSpan -- 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
-
-data PState = PState {
- buffer :: StringBuffer,
- last_loc :: SrcSpan, -- pos of previous token
- last_offs :: !Int, -- offset of the previous token from the
- -- beginning of the current line.
- -- \t is equal to 8 spaces.
- 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. Sigh, if only Happy passed the
- -- current token to happyError, we could at least get rid of last_len.
- -- Getting rid of last_loc would require finding another way to
- -- implement pushCurrentContext (which is only called from one place).
-
-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 span err -> PFailed span err
-
-failP :: String -> P a
-failP msg = P $ \s -> PFailed (last_loc s) (text msg)
-
-failMsgP :: String -> P a
-failMsgP msg = P $ \s -> PFailed (last_loc s) (text msg)
-
-failLocMsgP :: SrcLoc -> SrcLoc -> String -> P a
-failLocMsgP loc1 loc2 str = P $ \s -> PFailed (mkSrcSpan loc1 loc2) (text str)
-
-failSpanMsgP :: SrcSpan -> String -> P a
-failSpanMsgP span msg = P $ \s -> PFailed span (text msg)
-
-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} ()
-
-getSrcLoc :: P SrcLoc
-getSrcLoc = P $ \s@(PState{ loc=loc }) -> POk s loc
-
-setLastToken :: SrcSpan -> Int -> P ()
-setLastToken loc len = P $ \s -> POk s{ last_loc=loc, last_len=len } ()
-
-data AlexInput = AI SrcLoc {-#UNPACK#-}!Int StringBuffer
-
-alexInputPrevChar :: AlexInput -> Char
-alexInputPrevChar (AI _ _ buf) = prevChar buf '\n'
-
-alexGetChar :: AlexInput -> Maybe (Char,AlexInput)
-alexGetChar (AI loc ofs s)
- | atEnd s = Nothing
- | otherwise = adj_c `seq` loc' `seq` ofs' `seq` s' `seq`
- Just (adj_c, (AI loc' ofs' s'))
- where (c,s') = nextChar s
- loc' = advanceSrcLoc loc c
- ofs' = advanceOffs c ofs
-
- non_graphic = '\x0'
- upper = '\x1'
- lower = '\x2'
- digit = '\x3'
- symbol = '\x4'
- space = '\x5'
- other_graphic = '\x6'
-
- adj_c
- | c <= '\x06' = non_graphic
- | c <= '\xff' = c
- | otherwise =
- case generalCategory c of
- UppercaseLetter -> upper
- LowercaseLetter -> lower
- TitlecaseLetter -> upper
- ModifierLetter -> other_graphic
- OtherLetter -> other_graphic
- NonSpacingMark -> other_graphic
- SpacingCombiningMark -> other_graphic
- EnclosingMark -> other_graphic
- DecimalNumber -> digit
- LetterNumber -> other_graphic
- OtherNumber -> other_graphic
- ConnectorPunctuation -> other_graphic
- DashPunctuation -> other_graphic
- OpenPunctuation -> other_graphic
- ClosePunctuation -> other_graphic
- InitialQuote -> other_graphic
- FinalQuote -> other_graphic
- OtherPunctuation -> other_graphic
- MathSymbol -> symbol
- CurrencySymbol -> symbol
- ModifierSymbol -> symbol
- OtherSymbol -> symbol
- Space -> space
- _other -> non_graphic
-
--- This version does not squash unicode characters, it is used when
--- lexing strings.
-alexGetChar' :: AlexInput -> Maybe (Char,AlexInput)
-alexGetChar' (AI loc ofs s)
- | atEnd s = Nothing
- | otherwise = c `seq` loc' `seq` ofs' `seq` s' `seq`
- Just (c, (AI loc' ofs' s'))
- where (c,s') = nextChar s
- loc' = advanceSrcLoc loc c
- ofs' = advanceOffs c ofs
-
-advanceOffs :: Char -> Int -> Int
-advanceOffs '\n' offs = 0
-advanceOffs '\t' offs = (offs `quot` 8 + 1) * 8
-advanceOffs _ offs = offs + 1
-
-getInput :: P AlexInput
-getInput = P $ \s@PState{ loc=l, last_offs=o, buffer=b } -> POk s (AI l o b)
-
-setInput :: AlexInput -> P ()
-setInput (AI l o b) = P $ \s -> POk s{ loc=l, last_offs=o, 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
-arrowsBit = 4
-thBit = 5
-ipBit = 6
-tvBit = 7 -- Scoped type variables enables 'forall' keyword
-bangPatBit = 8 -- Tells the parser to understand bang-patterns
- -- (doesn't affect the lexer)
-
-glaExtsEnabled, ffiEnabled, parrEnabled :: Int -> Bool
-glaExtsEnabled flags = testBit flags glaExtsBit
-ffiEnabled flags = testBit flags ffiBit
-parrEnabled flags = testBit flags parrBit
-arrowsEnabled flags = testBit flags arrowsBit
-thEnabled flags = testBit flags thBit
-ipEnabled flags = testBit flags ipBit
-tvEnabled flags = testBit flags tvBit
-bangPatEnabled flags = testBit flags bangPatBit
-
--- PState for parsing options pragmas
---
-pragState :: StringBuffer -> SrcLoc -> PState
-pragState buf loc =
- PState {
- buffer = buf,
- last_loc = mkSrcSpan loc loc,
- last_offs = 0,
- last_len = 0,
- loc = loc,
- extsBitmap = 0,
- context = [],
- lex_state = [bol, option_prags, 0]
- }
-
-
--- create a parse state
---
-mkPState :: StringBuffer -> SrcLoc -> DynFlags -> PState
-mkPState buf loc flags =
- PState {
- buffer = buf,
- last_loc = mkSrcSpan loc loc,
- last_offs = 0,
- 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` dopt Opt_GlasgowExts flags
- .|. ffiBit `setBitIf` dopt Opt_FFI flags
- .|. parrBit `setBitIf` dopt Opt_PArr flags
- .|. arrowsBit `setBitIf` dopt Opt_Arrows flags
- .|. thBit `setBitIf` dopt Opt_TH flags
- .|. ipBit `setBitIf` dopt Opt_ImplicitParams flags
- .|. tvBit `setBitIf` dopt Opt_ScopedTypeVariables flags
- .|. bangPatBit `setBitIf` dopt Opt_BangPatterns flags
- --
- 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 (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_offs=offs, last_len=len, context=ctx } ->
- POk s{context = Layout (offs-len) : ctx} ()
-
-getOffside :: P Ordering
-getOffside = P $ \s@PState{last_offs=offs, context=stk} ->
- let ord = case stk of
- (Layout n:_) -> compare offs 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 (offsetBytes (-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 } ->
- PFailed last_loc (srcParseErr buf len)
-
--- A lexical error is reported at a particular position in the source file,
--- not over a token range.
-lexError :: String -> P a
-lexError str = do
- loc <- getSrcLoc
- i@(AI end _ buf) <- getInput
- reportLexError loc end buf str
-
--- -----------------------------------------------------------------------------
--- This is the top-level function: called from the parser each time a
--- new token is to be read from the input.
-
-lexer :: (Located Token -> P a) -> P a
-lexer cont = do
- tok@(L _ tok__) <- lexToken
- --trace ("token: " ++ show tok__) $ do
- cont tok
-
-lexToken :: P (Located Token)
-lexToken = do
- inp@(AI loc1 _ buf) <- getInput
- sc <- getLexState
- exts <- getExts
- case alexScanUser exts inp sc of
- AlexEOF -> do let span = mkSrcSpan loc1 loc1
- setLastToken span 0
- return (L span ITeof)
- AlexError (AI loc2 _ buf) -> do
- reportLexError loc1 loc2 buf "lexical error"
- AlexSkip inp2 _ -> do
- setInput inp2
- lexToken
- AlexToken inp2@(AI end _ buf2) len t -> do
- setInput inp2
- let span = mkSrcSpan loc1 end
- let bytes = byteDiff buf buf2
- span `seq` setLastToken span bytes
- t span buf bytes
-
--- ToDo: Alex reports the buffer at the start of the erroneous lexeme,
--- but it would be more informative to report the location where the
--- error was actually discovered, especially if this is a decoding
--- error.
-reportLexError loc1 loc2 buf str =
- let
- c = fst (nextChar buf)
- in
- if c == '\0' -- decoding errors are mapped to '\0', see utf8DecodeChar#
- then failLocMsgP loc2 loc2 "UTF-8 decoding error"
- else failLocMsgP loc1 loc2 (str ++ " at character " ++ show c)
-}
projects / ghc-hetmet.git / blobdiff