1f490e9f7f
This is because the structure pass needs to be able to tell where new lines start, and if the line number changes in the middle of a token then it'll get confused.
86 lines
3.3 KiB
Haskell
86 lines
3.3 KiB
Haskell
{-
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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 (structureOccam) where
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import Data.Generics
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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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-- | Reserved words that, if found at the end of a line, indicate the next
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-- line is a continuation.
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continuationWords :: [String]
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continuationWords
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= [ "-", "~", "+", "-", "*", "/", "\\", "/\\", "\\/", "><", "=", "<>",
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"<", ">", ">=", "<=", ",", ";", ":=", "<<", ">>",
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"AFTER", "AND", "BITAND", "BITNOT", "BITOR", "FOR", "FROM",
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"IS", "MINUS", "MINUS", "NOT", "OR", "PLUS", "REM", "RESHAPES",
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"RETYPES", "SIZE", "TIMES" ]
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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 (emptyMeta, EndOfLine)
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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 ((m, _):_) -> metaLine m
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analyse :: Int -> Int -> [Token] -> Token -> PassM [Token]
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-- Add extra EndOfLine at the end of the file.
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analyse prevCol _ [] _ = return $ (emptyMeta, EndOfLine) : out
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where out = replicate (prevCol `div` 2) (emptyMeta, Outdent)
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analyse prevCol prevLine (t@(m, tokType):ts) prevTok
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= if (line /= prevLine) && (not isContinuation)
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then do rest <- analyse col line ts t
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newLine $ t : rest
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else do rest <- analyse prevCol line ts t
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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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isContinuation = case prevTok of
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(_, TokReserved s) -> s `elem` continuationWords
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(_, TokStringCont _) -> True
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_ -> False
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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 = withEOL $ (m, 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 withEOL $ replicate steps (m, Outdent) ++ rest
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else bad
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| col == prevCol = withEOL rest
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| otherwise = bad
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where
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steps = (prevCol - col) `div` 2
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bad = dieP m "Invalid indentation"
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-- This is actually the position at which the new line starts
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-- rather than the end of the previous line.
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withEOL ts = return $ (m, EndOfLine) : ts
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