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{
-- Tests the basic operation.
module Main where
import Data.Char (toUpper)
import Control.Monad
import System.Exit
import System.IO
}
%wrapper "monad"
@word = [A-Za-z]+
tokens :-
$white+ ;
<0> {
"magic" { magic } -- should override later patterns
^ @word $ { both } -- test both trailing and left context
@word $ { eol } -- test trailing context
^ @word { bol } -- test left context
@word { word }
}
<0> \( { begin parens }
<parens> [A-Za-z]+ { parenword }
<parens> \) { begin 0 }
{
{- we can now have comments in source code? -}
word (_,_,_,input) len = return (take len input)
both (_,_,_,input) len = return ("BOTH:"++ take len input)
eol (_,_,_,input) len = return ("EOL:"++ take len input)
bol (_,_,_,input) len = return ("BOL:"++ take len input)
parenword (_,_,_,input) len = return (map toUpper (take len input))
magic (_,_,_,_) _ = return "PING!"
alexEOF = return "stopped."
scanner str = runAlex str $ do
let loop = do tok <- alexMonadScan
if tok == "stopped." || tok == "error."
then return [tok]
else do toks <- loop
return (tok:toks)
loop
main = do
let test1 = scanner str1
when (test1 /= out1) $
do hPutStrLn stderr "Test 1 failed:"
print test1
exitFailure
let test2 = scanner str2
when (test2 /= out2) $
do hPutStrLn stderr "Test 2 failed:"
print test2
exitFailure
str1 = "a b c (d e f) magic (magic) eol\nbol \nboth\n"
out1 = Right ["BOL:a","b","c","D","E","F","PING!","MAGIC","EOL:eol", "BOL:bol", "BOTH:both", "stopped."]
str2 = "."
out2 = Left "lexical error at line 1, column 1"
}
|
