223a14d767
The parser now gets a stream of tokens, rather than needing to worry about loading files itself. This also reworks the lexer's idea of what constitutes a Token -- it's now a pair (Meta, TokenType), so it's always easy to pull out/rewrite the metadata -- and adds proper support for lexing preprocessor directives, rather than just treating them as reserved words.
70 lines
2.5 KiB
Haskell
70 lines
2.5 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 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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-- | 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 ((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 [(emptyMeta, EndOfLine)]
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analyse prevCol prevLine (t@(m, tokType):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 = 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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