-- C->Haskell Compiler: Lexer for CHS Files
--
-- Author : Manuel M T Chakravarty
-- Created: 13 August 99
--
-- Version $Revision: 1.1 $ from $Date: 2004/11/21 21:05:35 $
--
-- Copyright (c) [1999..2004] Manuel M T Chakravarty
--
-- This file is free software; you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation; either version 2 of the License, or
-- (at your option) any later version.
--
-- This file is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-- GNU General Public License for more details.
--
--- DESCRIPTION ---------------------------------------------------------------
--
-- Lexer for CHS files; the tokens are only partially recognised.
--
--- DOCU ----------------------------------------------------------------------
--
-- language: Haskell 98
--
-- * CHS files are assumed to be Haskell 98 files that include C2HS binding
-- hooks.
--
-- * Haskell code is not tokenised, but binding hooks (delimited by `{#'and
-- `#}') are analysed. Therefore the lexer operates in two states
-- (realised as two lexer coupled by meta actions) depending on whether
-- Haskell code or a binding hook is currently read. The lexer reading
-- Haskell code is called `base lexer'; the other one, `binding-hook
-- lexer'. In addition, there is a inline-c lexer, which, as the
-- binding-hook lexer, can be triggered from the base lexer.
--
-- * Base lexer:
--
-- haskell -> (inline \\ special)*
-- | special \\ `"'
-- | comment
-- | nested
-- | hstring
-- | '{#'
-- | cpp
-- special -> `(' | `{' | `-' | `"'
-- ctrl -> `\n' | `\f' | `\r' | `\t' | `\v'
--
-- inline -> any \\ ctrl
-- any -> '\0'..'\255'
--
-- Within the base lexer control codes appear as separate tokens in the
-- token list.
--
-- NOTE: It is important that `{' is an extra lexeme and not added as an
-- optional component at the end of the first alternative for
-- `haskell'. Otherwise, the principle of the longest match will
-- divide `foo {#' into the tokens `foo {' and `#' instead of `foo '
-- and `{#'.
--
-- One line comments are handled by
--
-- comment -> `--' (any \\ `\n')* `\n'
--
-- and nested comments by
--
-- nested -> `{-' any* `-}'
--
-- where `any*' may contain _balanced_ occurrences of `{-' and `-}'.
--
-- hstring -> `"' inhstr* `"'
-- inhstr -> ` '..`\127' \\ `"'
-- | `\"'
--
-- Pre-precessor directives as well as the switch to inline-C code are
-- formed as follows:
--
-- cpp -> `\n#' (inline | `\t')* `\n'
-- | `\n#c' (' ' | '\t')* `\n'
--
-- We allow whitespace between the `#' and the actual directive, but in `#c'
-- and `#endc' the directive must immediately follow the `#'. This might
-- be regarded as a not entirely orthogonal design, but simplifies matters
-- especially for `#endc'.
--
-- * On encountering the lexeme `{#', a meta action in the base lexer
-- transfers control to the following binding-hook lexer:
--
-- ident -> letter (letter | digit | `\'')*
-- | `\'' letter (letter | digit)* `\''
-- reservedid -> `as' | `call' | `class' | `context' | `deriving'
-- | `enum' | `foreign' | `fun' | `get' | `lib'
-- | `newtype' | `pointer' | `prefix' | `pure' | `set'
-- | `sizeof' | `stable' | `type' | `underscoreToCase'
-- | `unsafe' | `with' | 'lock' | 'unlock'
-- reservedsym -> `{#' | `#}' | `{' | `}' | `,' | `.' | `->' | `='
-- | `=>' | '-' | `*' | `&' | `^'
-- string -> `"' instr* `"'
-- verbhs -> `\`' instr* `\''
-- instr -> ` '..`\127' \\ `"'
-- comment -> `--' (any \\ `\n')* `\n'
--
-- Control characters, white space, and comments are discarded in the
-- binding-hook lexer. Nested comments are not allowed in a binding hook.
-- Identifiers can be enclosed in single quotes to avoid collision with
-- C->Haskell keywords.
--
-- * In the binding-hook lexer, the lexeme `#}' transfers control back to the
-- base lexer. An occurence of the lexeme `{#' inside the binding-hook
-- lexer triggers an error. The symbol `{#' is not explcitly represented
-- in the resulting token stream. However, the occurrence of a token
-- representing one of the reserved identifiers `call', `context', `enum',
-- and `field' marks the start of a binding hook. Strictly speaking, `#}'
-- need also not occur in the token stream, as the next `haskell' token
-- marks a hook's end. It is, however, useful for producing accurate error
-- messages (in case an hook is closed to early) to have a token
-- representing `#}'.
--
-- * The rule `ident' describes Haskell identifiers, but without
-- distinguishing between variable and constructor identifers (ie, those
-- starting with a lowercase and those starting with an uppercase letter).
-- However, we use it also to scan C identifiers; although, strictly
-- speaking, it is too general for them. In the case of C identifiers,
-- this should not have any impact on the range of descriptions accepted by
-- the tool, as illegal identifier will never occur in a C header file that
-- is accepted by the C lexer. In the case of Haskell identifiers, a
-- confusion between variable and constructor identifiers will be noted by
-- the Haskell compiler translating the code generated by c2hs. Moreover,
-- identifiers can be enclosed in single quotes to avoid collision with
-- C->Haskell keywords, but those may not contain apostrophes.
--
-- * Any line starting with the character `#' is regarded to be a C
-- preprocessor directive. With the exception of `#c' and `#endc', which
-- delimit a set of lines containing inline C code. Hence, in the base
-- lexer, the lexeme `#c' triggers a meta action transferring control to the
-- following inline-C lexer:
--
-- c -> inline* \\ `\n#endc'
--
-- We do neither treat C strings nor C comments specially. Hence, if the
-- string "\n#endc" occurs in a comment, we will mistakenly regard it as
-- the end of the inline C code. Note that the problem cannot happen with
-- strings, as C does not permit strings that extend over multiple lines.
-- At the moment, it just seems not to be worth the effort required to
-- treat this situation more accurately.
--
-- The inline-C lexer also doesn't handle pre-processor directives
-- specially. Hence, structural pre-processor directives (namely,
-- conditionals) may occur within inline-C code only properly nested.
--
-- Shortcomings
-- ~~~~~~~~~~~~
-- Some lexemes that include single and double quote characters are not lexed
-- correctly. See the implementation comment at `haskell' for details.
--
--
--- TODO ----------------------------------------------------------------------
--
-- * In `haskell', the case of a single `"' (without a matching second one)
-- is caught by an eplicit error raising rule. This shouldn't be
-- necessary, but for some strange reason, the lexer otherwise hangs when a
-- single `"' appears in the input.
--
-- * Comments in the "gap" of a string are not yet supported.
--
module CHSLexer (CHSToken(..), lexCHS)
where
import Data.List ((\\))
import Data.Char (isDigit)
import Control.Monad (liftM)
import Numeric (readDec, readOct, readHex)
import Position (Position(..), Pos(posOf), incPos, retPos, tabPos)
import Errors (ErrorLvl(..), Error, makeError)
import UNames (NameSupply, Name, names)
import Idents (Ident, lexemeToIdent, identToLexeme)
import Lexers (Regexp, Lexer, Action, epsilon, char, (+>), lexaction,
lexactionErr, lexmeta, (>|<), (>||<), ctrlLexer, star, plus,
quest, alt, string, LexerState, execLexer)
import C2HSState (CST, raise, raiseError, nop, getNameSupply)
-- token definition
-- ----------------
-- possible tokens (EXPORTED)
--
data CHSToken = CHSTokArrow Position -- `->'
| CHSTokDArrow Position -- `=>'
| CHSTokDot Position -- `.'
| CHSTokComma Position -- `,'
| CHSTokEqual Position -- `='
| CHSTokMinus Position -- `-'
| CHSTokStar Position -- `*'
| CHSTokAmp Position -- `&'
| CHSTokHat Position -- `^'
| CHSTokLBrace Position -- `{'
| CHSTokRBrace Position -- `}'
| CHSTokLParen Position -- `('
| CHSTokRParen Position -- `)'
| CHSTokEndHook Position -- `#}'
| CHSTokAs Position -- `as'
| CHSTokCall Position -- `call'
| CHSTokClass Position -- `class'
| CHSTokContext Position -- `context'
| CHSTokDerive Position -- `deriving'
| CHSTokEnum Position -- `enum'
| CHSTokForeign Position -- `foreign'
| CHSTokFun Position -- `fun'
| CHSTokGet Position -- `get'
| CHSTokImport Position -- `import'
| CHSTokLib Position -- `lib'
| CHSTokNewtype Position -- `newtype'
| CHSTokPointer Position -- `pointer'
| CHSTokPrefix Position -- `prefix'
| CHSTokPure Position -- `pure'
| CHSTokQualif Position -- `qualified'
| CHSTokSet Position -- `set'
| CHSTokSizeof Position -- `sizeof'
| CHSTokStable Position -- `stable'
| CHSTokType Position -- `type'
| CHSTok_2Case Position -- `underscoreToCase'
| CHSTokUnsafe Position -- `unsafe'
| CHSTokWith Position -- `with'
| CHSTokLock Position -- `lock'
| CHSTokNolock Position -- `nolock'
| CHSTokString Position String -- string
| CHSTokHSVerb Position String -- verbatim Haskell (`...')
| CHSTokIdent Position Ident -- identifier
| CHSTokHaskell Position String -- verbatim Haskell code
| CHSTokCPP Position String -- pre-processor directive
| CHSTokLine Position -- line pragma
| CHSTokC Position String -- verbatim C code
| CHSTokCtrl Position Char -- control code
| CHSTokPragma Position -- '{-# LANGUAGE' language pragma begin
| CHSTokPragEnd Position -- '#-}' language pragma end
instance Pos CHSToken where
posOf (CHSTokArrow pos ) = pos
posOf (CHSTokDArrow pos ) = pos
posOf (CHSTokDot pos ) = pos
posOf (CHSTokComma pos ) = pos
posOf (CHSTokEqual pos ) = pos
posOf (CHSTokMinus pos ) = pos
posOf (CHSTokStar pos ) = pos
posOf (CHSTokAmp pos ) = pos
posOf (CHSTokHat pos ) = pos
posOf (CHSTokLBrace pos ) = pos
posOf (CHSTokRBrace pos ) = pos
posOf (CHSTokLParen pos ) = pos
posOf (CHSTokRParen pos ) = pos
posOf (CHSTokEndHook pos ) = pos
posOf (CHSTokAs pos ) = pos
posOf (CHSTokCall pos ) = pos
posOf (CHSTokClass pos ) = pos
posOf (CHSTokContext pos ) = pos
posOf (CHSTokDerive pos ) = pos
posOf (CHSTokEnum pos ) = pos
posOf (CHSTokForeign pos ) = pos
posOf (CHSTokFun pos ) = pos
posOf (CHSTokGet pos ) = pos
posOf (CHSTokImport pos ) = pos
posOf (CHSTokLib pos ) = pos
posOf (CHSTokNewtype pos ) = pos
posOf (CHSTokPointer pos ) = pos
posOf (CHSTokPrefix pos ) = pos
posOf (CHSTokPure pos ) = pos
posOf (CHSTokQualif pos ) = pos
posOf (CHSTokSet pos ) = pos
posOf (CHSTokSizeof pos ) = pos
posOf (CHSTokStable pos ) = pos
posOf (CHSTokType pos ) = pos
posOf (CHSTok_2Case pos ) = pos
posOf (CHSTokUnsafe pos ) = pos
posOf (CHSTokWith pos ) = pos
posOf (CHSTokLock pos ) = pos
posOf (CHSTokNolock pos ) = pos
posOf (CHSTokString pos _) = pos
posOf (CHSTokHSVerb pos _) = pos
posOf (CHSTokIdent pos _) = pos
posOf (CHSTokHaskell pos _) = pos
posOf (CHSTokCPP pos _) = pos
posOf (CHSTokC pos _) = pos
posOf (CHSTokCtrl pos _) = pos
posOf (CHSTokPragma pos ) = pos
posOf (CHSTokPragEnd pos ) = pos
instance Eq CHSToken where
(CHSTokArrow _ ) == (CHSTokArrow _ ) = True
(CHSTokDArrow _ ) == (CHSTokDArrow _ ) = True
(CHSTokDot _ ) == (CHSTokDot _ ) = True
(CHSTokComma _ ) == (CHSTokComma _ ) = True
(CHSTokEqual _ ) == (CHSTokEqual _ ) = True
(CHSTokMinus _ ) == (CHSTokMinus _ ) = True
(CHSTokStar _ ) == (CHSTokStar _ ) = True
(CHSTokAmp _ ) == (CHSTokAmp _ ) = True
(CHSTokHat _ ) == (CHSTokHat _ ) = True
(CHSTokLBrace _ ) == (CHSTokLBrace _ ) = True
(CHSTokRBrace _ ) == (CHSTokRBrace _ ) = True
(CHSTokLParen _ ) == (CHSTokLParen _ ) = True
(CHSTokRParen _ ) == (CHSTokRParen _ ) = True
(CHSTokEndHook _ ) == (CHSTokEndHook _ ) = True
(CHSTokAs _ ) == (CHSTokAs _ ) = True
(CHSTokCall _ ) == (CHSTokCall _ ) = True
(CHSTokClass _ ) == (CHSTokClass _ ) = True
(CHSTokContext _ ) == (CHSTokContext _ ) = True
(CHSTokDerive _ ) == (CHSTokDerive _ ) = True
(CHSTokEnum _ ) == (CHSTokEnum _ ) = True
(CHSTokForeign _ ) == (CHSTokForeign _ ) = True
(CHSTokFun _ ) == (CHSTokFun _ ) = True
(CHSTokGet _ ) == (CHSTokGet _ ) = True
(CHSTokImport _ ) == (CHSTokImport _ ) = True
(CHSTokLib _ ) == (CHSTokLib _ ) = True
(CHSTokNewtype _ ) == (CHSTokNewtype _ ) = True
(CHSTokPointer _ ) == (CHSTokPointer _ ) = True
(CHSTokPrefix _ ) == (CHSTokPrefix _ ) = True
(CHSTokPure _ ) == (CHSTokPure _ ) = True
(CHSTokQualif _ ) == (CHSTokQualif _ ) = True
(CHSTokSet _ ) == (CHSTokSet _ ) = True
(CHSTokSizeof _ ) == (CHSTokSizeof _ ) = True
(CHSTokStable _ ) == (CHSTokStable _ ) = True
(CHSTokType _ ) == (CHSTokType _ ) = True
(CHSTok_2Case _ ) == (CHSTok_2Case _ ) = True
(CHSTokUnsafe _ ) == (CHSTokUnsafe _ ) = True
(CHSTokWith _ ) == (CHSTokWith _ ) = True
(CHSTokLock _ ) == (CHSTokLock _ ) = True
(CHSTokNolock _ ) == (CHSTokNolock _ ) = True
(CHSTokString _ _) == (CHSTokString _ _) = True
(CHSTokHSVerb _ _) == (CHSTokHSVerb _ _) = True
(CHSTokIdent _ _) == (CHSTokIdent _ _) = True
(CHSTokHaskell _ _) == (CHSTokHaskell _ _) = True
(CHSTokCPP _ _) == (CHSTokCPP _ _) = True
(CHSTokC _ _) == (CHSTokC _ _) = True
(CHSTokCtrl _ _) == (CHSTokCtrl _ _) = True
(CHSTokPragma _ ) == (CHSTokPragma _ ) = True
(CHSTokPragEnd _ ) == (CHSTokPragEnd _ ) = True
_ == _ = False
instance Show CHSToken where
showsPrec _ (CHSTokArrow _ ) = showString "->"
showsPrec _ (CHSTokDArrow _ ) = showString "=>"
showsPrec _ (CHSTokDot _ ) = showString "."
showsPrec _ (CHSTokComma _ ) = showString ","
showsPrec _ (CHSTokEqual _ ) = showString "="
showsPrec _ (CHSTokMinus _ ) = showString "-"
showsPrec _ (CHSTokStar _ ) = showString "*"
showsPrec _ (CHSTokAmp _ ) = showString "&"
showsPrec _ (CHSTokHat _ ) = showString "^"
showsPrec _ (CHSTokLBrace _ ) = showString "{"
showsPrec _ (CHSTokRBrace _ ) = showString "}"
showsPrec _ (CHSTokLParen _ ) = showString "("
showsPrec _ (CHSTokRParen _ ) = showString ")"
showsPrec _ (CHSTokEndHook _ ) = showString "#}"
showsPrec _ (CHSTokAs _ ) = showString "as"
showsPrec _ (CHSTokCall _ ) = showString "call"
showsPrec _ (CHSTokClass _ ) = showString "class"
showsPrec _ (CHSTokContext _ ) = showString "context"
showsPrec _ (CHSTokDerive _ ) = showString "deriving"
showsPrec _ (CHSTokEnum _ ) = showString "enum"
showsPrec _ (CHSTokForeign _ ) = showString "foreign"
showsPrec _ (CHSTokFun _ ) = showString "fun"
showsPrec _ (CHSTokGet _ ) = showString "get"
showsPrec _ (CHSTokImport _ ) = showString "import"
showsPrec _ (CHSTokLib _ ) = showString "lib"
showsPrec _ (CHSTokNewtype _ ) = showString "newtype"
showsPrec _ (CHSTokPointer _ ) = showString "pointer"
showsPrec _ (CHSTokPrefix _ ) = showString "prefix"
showsPrec _ (CHSTokPure _ ) = showString "pure"
showsPrec _ (CHSTokQualif _ ) = showString "qualified"
showsPrec _ (CHSTokSet _ ) = showString "set"
showsPrec _ (CHSTokSizeof _ ) = showString "sizeof"
showsPrec _ (CHSTokStable _ ) = showString "stable"
showsPrec _ (CHSTokType _ ) = showString "type"
showsPrec _ (CHSTok_2Case _ ) = showString "underscoreToCase"
showsPrec _ (CHSTokUnsafe _ ) = showString "unsafe"
showsPrec _ (CHSTokWith _ ) = showString "with"
showsPrec _ (CHSTokLock _ ) = showString "lock"
showsPrec _ (CHSTokNolock _ ) = showString "nolock"
showsPrec _ (CHSTokString _ s) = showString ("\"" ++ s ++ "\"")
showsPrec _ (CHSTokHSVerb _ s) = showString ("`" ++ s ++ "'")
showsPrec _ (CHSTokIdent _ i) = (showString . identToLexeme) i
showsPrec _ (CHSTokHaskell _ s) = showString s
showsPrec _ (CHSTokCPP _ s) = showString s
showsPrec _ (CHSTokC _ s) = showString s
showsPrec _ (CHSTokCtrl _ c) = showChar c
showsPrec _ (CHSTokPragma _ ) = showString "{-# LANGUAGE"
showsPrec _ (CHSTokPragEnd _ ) = showString "#-}"
-- lexer state
-- -----------
-- state threaded through the lexer
--
data CHSLexerState = CHSLS {
nestLvl :: Int, -- nesting depth of nested comments
inHook :: Bool, -- within a binding hook?
namesup :: [Name] -- supply of unique names
}
-- initial state
--
initialState :: CST s CHSLexerState
initialState = do
namesup <- liftM names getNameSupply
return $ CHSLS {
nestLvl = 0,
inHook = False,
namesup = namesup
}
-- raise an error if the given state is not a final state
--
assertFinalState :: Position -> CHSLexerState -> CST s ()
assertFinalState pos CHSLS {nestLvl = nestLvl, inHook = inHook}
| nestLvl > 0 = raiseError pos ["Unexpected end of file!",
"Unclosed nested comment."]
| inHook = raiseError pos ["Unexpected end of file!",
"Unclosed binding hook."]
| otherwise = nop
-- lexer and action type used throughout this specification
--
type CHSLexer = Lexer CHSLexerState CHSToken
type CHSAction = Action CHSToken
type CHSRegexp = Regexp CHSLexerState CHSToken
-- for actions that need a new unique name
--
infixl 3 `lexactionName`
lexactionName :: CHSRegexp
-> (String -> Position -> Name -> CHSToken)
-> CHSLexer
re `lexactionName` action = re `lexmeta` action'
where
action' str pos state = let name:ns = namesup state
in
(Just $ Right (action str pos name),
incPos pos (length str),
state {namesup = ns},
Nothing)
-- lexical specification
-- ---------------------
-- the lexical definition of the tokens (the base lexer)
--
--
chslexer :: CHSLexer
chslexer = pragma -- LANGUAGE pragma
>||< haskell -- Haskell code
>||< nested -- nested comments
>||< ctrl -- control code (that has to be preserved)
>||< hook -- start of a binding hook
>||< cpp -- a pre-processor directive (or `#c')
-- the LANGUAGE pragma
pragma :: CHSLexer
pragma = string "{-# LANGUAGE" `lexmeta` \_ pos s ->
(Just $ Right (CHSTokPragma pos), incPos pos 12, s, Just langLexer)
langLexer :: CHSLexer
langLexer = whitespace >||< identOrKW >||< symbol >||<
(string "#-}" `lexmeta` \_ pos s ->
(Just $ Right (CHSTokPragEnd pos), incPos pos 3, s, Just chslexer))
-- stream of Haskell code (terminated by a control character or binding hook)
--
haskell :: CHSLexer
--
-- NB: We need to make sure that '"' is not regarded as the beginning of a
-- string; however, we cannot really lex character literals properly
-- without lexing identifiers (as the latter may containing single quotes
-- as part of their lexeme). Thus, we special case '"'. This is still a
-- kludge, as a program fragment, such as
--
-- foo'"'strange string"
--
-- will not be handled correctly.
--
haskell = ( anyButSpecial`star` epsilon
>|< specialButQuotes
>|< char '"' +> inhstr`star` char '"'
>|< string "'\"'" -- special case of "
>|< string "--" +> anyButNL`star` epsilon -- comment
)
`lexaction` copyVerbatim
>||< char '"' -- this is a bad kludge
`lexactionErr`
\_ pos -> (Left $ makeError ErrorErr pos
["Lexical error!",
"Unclosed string."])
where
anyButSpecial = alt (inlineSet \\ specialSet)
specialButQuotes = alt (specialSet \\ ['"'])
anyButNL = alt (anySet \\ ['\n'])
inhstr = instr >|< char '\\' >|< string "\\\"" >|< gap
gap = char '\\' +> alt (' ':ctrlSet)`plus` char '\\'
-- action copying the input verbatim to `CHSTokHaskell' tokens
--
copyVerbatim :: CHSAction
copyVerbatim cs pos = Just $ CHSTokHaskell pos cs
-- nested comments
--
nested :: CHSLexer
nested =
string "{-" {- for Haskell emacs mode :-( -}
`lexmeta` enterComment
>||<
string "-}"
`lexmeta` leaveComment
where
enterComment cs pos s =
(copyVerbatim' cs pos, -- collect the lexeme
incPos pos 2, -- advance current position
s {nestLvl = nestLvl s + 1}, -- increase nesting level
Just $ inNestedComment) -- continue in comment lexer
--
leaveComment cs pos s =
case nestLvl s of
0 -> (commentCloseErr pos, -- 0: -} outside comment => err
incPos pos 2, -- advance current position
s,
Nothing)
1 -> (copyVerbatim' cs pos, -- collect the lexeme
incPos pos 2, -- advance current position
s {nestLvl = nestLvl s - 1}, -- decrease nesting level
Just chslexer) -- 1: continue with root lexer
_ -> (copyVerbatim' cs pos, -- collect the lexeme
incPos pos 2, -- advance current position
s {nestLvl = nestLvl s - 1}, -- decrease nesting level
Nothing) -- _: cont with comment lexer
--
copyVerbatim' cs pos = Just $ Right (CHSTokHaskell pos cs)
--
commentCloseErr pos =
Just $ Left (makeError ErrorErr pos
["Lexical error!",
"`-}' not preceded by a matching `{-'."])
{- for Haskell emacs mode :-( -}
-- lexer processing the inner of a comment
--
inNestedComment :: CHSLexer
inNestedComment = commentInterior -- inside a comment
>||< nested -- nested comments
>||< ctrl -- control code (preserved)
-- standard characters in a nested comment
--
commentInterior :: CHSLexer
commentInterior = ( anyButSpecial`star` epsilon
>|< special
)
`lexaction` copyVerbatim
where
anyButSpecial = alt (inlineSet \\ commentSpecialSet)
special = alt commentSpecialSet
-- control code in the base lexer (is turned into a token)
--
-- * this covers exactly the same set of characters as contained in `ctrlSet'
-- and `Lexers.ctrlLexer' and advances positions also like the `ctrlLexer'
--
ctrl :: CHSLexer
ctrl =
char '\n' `lexmeta` newline
>||< char '\r' `lexmeta` newline
>||< char '\v' `lexmeta` newline
>||< char '\f' `lexmeta` formfeed
>||< char '\t' `lexmeta` tab
where
newline [c] pos = ctrlResult pos c (retPos pos)
formfeed [c] pos = ctrlResult pos c (incPos pos 1)
tab [c] pos = ctrlResult pos c (tabPos pos)
ctrlResult pos c pos' s =
(Just $ Right (CHSTokCtrl pos c), pos', s, Nothing)
-- start of a binding hook (ie, enter the binding hook lexer)
--
hook :: CHSLexer
hook = string "{#"
`lexmeta` \_ pos s -> (Nothing, incPos pos 2, s, Just bhLexer)
-- pre-processor directives and `#c'
--
-- * we lex `#c' as a directive and special case it in the action
--
-- * we lex C line number pragmas and special case it in the action
--
cpp :: CHSLexer
cpp = directive
where
directive =
string "\n#" +> alt ('\t':inlineSet)`star` epsilon
`lexmeta`
\(_:_:dir) pos s -> -- strip off the "\n#"
case dir of
['c'] -> -- #c
(Nothing, retPos pos, s, Just cLexer)
-- a #c may be followed by whitespace
'c':sp:_ | sp `elem` " \t" -> -- #c
(Nothing, retPos pos, s, Just cLexer)
' ':line@(n:_) | isDigit n -> -- C line pragma
let pos' = adjustPosByCLinePragma line pos
in (Just $ Right (CHSTokLine pos'), pos', s, Nothing)
_ -> -- CPP directive
(Just $ Right (CHSTokCPP pos dir),
retPos pos, s, Nothing)
adjustPosByCLinePragma :: String -> Position -> Position
adjustPosByCLinePragma str (Position fname _ _) =
(Position fname' row' 0)
where
str' = dropWhite str
(rowStr, str'') = span isDigit str'
row' = read rowStr
str''' = dropWhite str''
fnameStr = takeWhile (/= '"') . drop 1 $ str'''
fname' | null str''' || head str''' /= '"' = fname
-- try and get more sharing of file name strings
| fnameStr == fname = fname
| otherwise = fnameStr
--
dropWhite = dropWhile (\c -> c == ' ' || c == '\t')
-- the binding hook lexer
--
bhLexer :: CHSLexer
bhLexer = identOrKW
>||< symbol
>||< strlit
>||< hsverb
>||< whitespace
>||< endOfHook
>||< string "--" +> anyButNL`star` char '\n' -- comment
`lexmeta` \_ pos s -> (Nothing, retPos pos, s, Nothing)
where
anyButNL = alt (anySet \\ ['\n'])
endOfHook = string "#}"
`lexmeta`
\_ pos s -> (Just $ Right (CHSTokEndHook pos),
incPos pos 2, s, Just chslexer)
-- the inline-C lexer
--
cLexer :: CHSLexer
cLexer = inlineC -- inline C code
>||< ctrl -- control code (preserved)
>||< string "\n#endc" -- end of inline C code...
`lexmeta` -- ...preserve '\n' as control token
\_ pos s -> (Just $ Right (CHSTokCtrl pos '\n'), retPos pos, s,
Just chslexer)
where
inlineC = alt inlineSet `lexaction` copyVerbatimC
--
copyVerbatimC :: CHSAction
copyVerbatimC cs pos = Just $ CHSTokC pos cs
-- whitespace
--
-- * horizontal and vertical tabs, newlines, and form feeds are filter out by
-- `Lexers.ctrlLexer'
--
whitespace :: CHSLexer
whitespace = (char ' ' `lexaction` \_ _ -> Nothing)
>||< ctrlLexer
-- identifiers and keywords
--
identOrKW :: CHSLexer
--
-- the strictness annotations seem to help a bit
--
identOrKW =
-- identifier or keyword
(letter +> (letter >|< digit >|< char '\'')`star` epsilon
`lexactionName` \cs pos name -> (idkwtok $!pos) cs name)
>||< -- identifier in single quotes
(char '\'' +> letter +> (letter >|< digit)`star` char '\''
`lexactionName` \cs pos name -> (mkid $!pos) cs name)
-- NB: quotes are removed by lexemeToIdent
where
idkwtok pos "as" _ = CHSTokAs pos
idkwtok pos "call" _ = CHSTokCall pos
idkwtok pos "class" _ = CHSTokClass pos
idkwtok pos "context" _ = CHSTokContext pos
idkwtok pos "deriving" _ = CHSTokDerive pos
idkwtok pos "enum" _ = CHSTokEnum pos
idkwtok pos "foreign" _ = CHSTokForeign pos
idkwtok pos "fun" _ = CHSTokFun pos
idkwtok pos "get" _ = CHSTokGet pos
idkwtok pos "import" _ = CHSTokImport pos
idkwtok pos "lib" _ = CHSTokLib pos
idkwtok pos "newtype" _ = CHSTokNewtype pos
idkwtok pos "pointer" _ = CHSTokPointer pos
idkwtok pos "prefix" _ = CHSTokPrefix pos
idkwtok pos "pure" _ = CHSTokPure pos
idkwtok pos "qualified" _ = CHSTokQualif pos
idkwtok pos "set" _ = CHSTokSet pos
idkwtok pos "sizeof" _ = CHSTokSizeof pos
idkwtok pos "stable" _ = CHSTokStable pos
idkwtok pos "type" _ = CHSTokType pos
idkwtok pos "underscoreToCase" _ = CHSTok_2Case pos
idkwtok pos "unsafe" _ = CHSTokUnsafe pos
idkwtok pos "with" _ = CHSTokWith pos
idkwtok pos "lock" _ = CHSTokLock pos
idkwtok pos "nolock" _ = CHSTokNolock pos
idkwtok pos cs name = mkid pos cs name
--
mkid pos cs name = CHSTokIdent pos (lexemeToIdent pos cs name)
-- reserved symbols
--
symbol :: CHSLexer
symbol = sym "->" CHSTokArrow
>||< sym "=>" CHSTokDArrow
>||< sym "." CHSTokDot
>||< sym "," CHSTokComma
>||< sym "=" CHSTokEqual
>||< sym "-" CHSTokMinus
>||< sym "*" CHSTokStar
>||< sym "&" CHSTokAmp
>||< sym "^" CHSTokHat
>||< sym "{" CHSTokLBrace
>||< sym "}" CHSTokRBrace
>||< sym "(" CHSTokLParen
>||< sym ")" CHSTokRParen
where
sym cs con = string cs `lexaction` \_ pos -> Just (con pos)
-- string
--
strlit :: CHSLexer
strlit = char '"' +> (instr >|< char '\\')`star` char '"'
`lexaction` \cs pos -> Just (CHSTokString pos (init . tail $ cs))
-- verbatim code
--
hsverb :: CHSLexer
hsverb = char '`' +> inhsverb`star` char '\''
`lexaction` \cs pos -> Just (CHSTokHSVerb pos (init . tail $ cs))
-- regular expressions
--
letter, digit, instr, inchar, inhsverb :: Regexp s t
letter = alt ['a'..'z'] >|< alt ['A'..'Z'] >|< char '_'
digit = alt ['0'..'9']
instr = alt ([' '..'\127'] \\ "\"\\")
inchar = alt ([' '..'\127'] \\ "\'")
inhsverb = alt ([' '..'\127'] \\ "\'")
-- character sets
--
anySet, inlineSet, specialSet, commentSpecialSet, ctrlSet :: [Char]
anySet = ['\0'..'\255']
inlineSet = anySet \\ ctrlSet
specialSet = ['{', '-', '"', '\'']
commentSpecialSet = ['{', '-']
ctrlSet = ['\n', '\f', '\r', '\t', '\v']
-- main lexing routine
-- -------------------
-- generate a token sequence out of a string denoting a CHS file
-- (EXPORTED)
--
-- * the given position is attributed to the first character in the string
--
-- * errors are entered into the compiler state
--
lexCHS :: String -> Position -> CST s [CHSToken]
lexCHS cs pos =
do
state <- initialState
let (ts, lstate, errs) = execLexer chslexer (cs, pos, state)
(_, pos', state') = lstate
mapM raise errs
assertFinalState pos' state'
return ts