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{
module Lexer (lex_tok) where
import Control.Monad.State (StateT, get)
import ParserM (ParserM (..), mkT, Token(..), St, start_code,
StartCode, Action, set_start_code,
show_pos, position, input,
AlexInput, alexGetByte, alexInputPrevChar)
}
words :-
<0> $white+ ;
<0> fork { mkT TFork }
<0> leaf { mkT TLeaf }
{
get_tok :: AlexInput -> StateT St (Either String) (Token, AlexInput)
get_tok = \i ->
do st <- get
case alexScan i (start_code st) of
AlexEOF -> return (TEOF, i)
AlexError _ -> fail $ "Lexical error at " ++ show_pos (position i)
AlexSkip i' _ -> get_tok i'
AlexToken i' l a -> a (i', take l (input i))
begin :: StartCode -> Action
begin sc (i, _) = do set_start_code sc
get_tok i
lex_tok :: (Token -> ParserM a) -> ParserM a
lex_tok cont = ParserM $ \i ->
do (tok, iz) <- get_tok i
case cont tok of
ParserM x -> x iz
}
|
