Structure analyser for the new lexer.
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LexOccam.x
40
LexOccam.x
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@ -20,10 +20,10 @@ with this program. If not, see <http://www.gnu.org/licenses/>.
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module LexOccam where
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import Data.Generics
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import System
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import Errors
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import Metadata
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import PrettyShow
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import Pass
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}
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%wrapper "posn"
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@ -96,7 +96,13 @@ $white+ ;
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{
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-- | An occam source token.
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data Token = Token TokenType Meta String
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-- Only `Token` is generated by the lexer itself; the others are added later
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-- once the indentation has been analysed.
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data Token =
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Token TokenType Meta String -- ^ A real token read from the source
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| Indent -- ^ Indentation increase
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| Outdent -- ^ Indentation decrease
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| EndOfLine -- ^ End of line
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deriving (Show, Eq, Typeable, Data)
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-- | The type of a source token.
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@ -111,22 +117,19 @@ mkToken :: TokenType -> AlexPosn -> String -> Token
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mkToken tt (AlexPn _ line col) s = Token tt emptyMeta s
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-- | Run the lexer, returning either an error position or a list of tokens.
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-- (This is based on the `alexScanTokens` function that Alex provides, but it
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-- adds error reporting.)
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runLexer :: String -> String -> Either Meta [Token]
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-- (This is based on the `alexScanTokens` function that Alex provides.)
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runLexer :: String -> String -> PassM [Token]
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runLexer filename str = go (alexStartPos, '\n', str)
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where
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go inp@(pos@(AlexPn _ line col), _, str) =
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case alexScan inp 0 of
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AlexEOF -> Right []
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AlexError _ -> Left meta
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AlexEOF -> return []
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AlexError _ -> dieP meta "Unrecognised token"
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AlexSkip inp' len -> go inp'
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AlexToken inp' len act ->
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case go inp' of
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e@(Left _) -> e
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Right ts -> Right $ tok : ts
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where (Token tt _ s) = act pos (take len str)
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tok = Token tt meta s
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do ts <- go inp'
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let (Token tt _ s) = act pos (take len str)
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return $ (Token tt meta s) : ts
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where
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meta = emptyMeta {
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@ -134,16 +137,5 @@ runLexer filename str = go (alexStartPos, '\n', str)
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metaLine = line,
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metaColumn = col
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}
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-- | Main function for testing the lexer.
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main :: IO ()
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main
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= do (arg:_) <- getArgs
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s <- readFile arg
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let tokens =
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case runLexer arg s of
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Left m -> error $ "Lex error: " ++ show m
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Right ts -> ts
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putStrLn $ pshow tokens
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}
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2
Makefile
2
Makefile
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@ -21,7 +21,7 @@ tocktest: $(sources)
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ghc $(ghc_opts) -o tocktest -main-is TestMain --make TestMain
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lextest: $(sources)
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ghc $(ghc_opts) -o lextest -main-is LexOccam --make LexOccam
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ghc $(ghc_opts) -o lextest -main-is StructureOccam --make StructureOccam
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CFLAGS = \
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-O2 \
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84
StructureOccam.hs
Normal file
84
StructureOccam.hs
Normal file
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@ -0,0 +1,84 @@
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{-
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Tock: a compiler for parallel languages
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Copyright (C) 2007 University of Kent
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This program is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation, either version 2 of the License, or (at your
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option) any later version.
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This program is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program. If not, see <http://www.gnu.org/licenses/>.
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-}
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-- | Analyse syntactic structure of occam code.
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module StructureOccam where
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import Control.Monad.Error
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import Control.Monad.State
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import Data.Generics
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import System
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import CompState
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import Errors
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import LexOccam
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import Metadata
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import Pass
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import PrettyShow
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-- | Given the output of the lexer for a single file, add `Indent`, `Outdent`
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-- and `EndOfLine` markers.
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structureOccam :: [Token] -> PassM [Token]
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structureOccam [] = return []
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structureOccam ts = analyse 1 firstLine ts
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where
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-- Find the first line that's actually got something on it.
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firstLine
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= case ts of (Token _ m _:_) -> metaLine m
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analyse :: Int -> Int -> [Token] -> PassM [Token]
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-- Add extra EndOfLine at the end of the file.
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analyse _ _ [] = return [EndOfLine]
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analyse prevCol prevLine (t@(Token _ m _):ts)
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= if line /= prevLine
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then do rest <- analyse col line ts
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newLine $ t : rest
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else do rest <- analyse prevCol line ts
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return $ t : rest
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where
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col = metaColumn m
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line = metaLine m
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-- A new line -- look to see what's going on with the indentation.
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newLine rest
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| col == prevCol + 2 = return $ EndOfLine : Indent : rest
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-- FIXME: If col > prevCol, then look to see if there's a VALOF
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-- coming up before the next column change...
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| col < prevCol
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= if (prevCol - col) `mod` 2 == 0
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then return $ EndOfLine : (replicate steps Outdent ++ rest)
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else dieP m "Invalid indentation"
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| col == prevCol = return $ EndOfLine : rest
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| otherwise = dieP m "Invalid indentation"
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where
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steps = (prevCol - col) `div` 2
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-- | Main function for testing.
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main :: IO ()
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main
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= do (arg:_) <- getArgs
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s <- readFile arg
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e <- evalStateT (runErrorT (test arg s)) emptyState
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return ()
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where
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test :: String -> String -> PassM ()
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test arg s
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= do tokens <- runLexer arg s
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tokens' <- structureOccam tokens
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liftIO $ putStrLn $ pshow tokens'
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