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51 lines
1.4 KiB
Haskell
51 lines
1.4 KiB
Haskell
----------------------------------------------------------------------
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-- |
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-- Maintainer : PL
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-- Stability : (stable)
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-- Portability : (portable)
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--
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-- > CVS $Date: 2005/04/11 13:52:49 $
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-- > CVS $Author: peb $
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-- > CVS $Revision: 1.1 $
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--
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-- CFG formalism
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-----------------------------------------------------------------------------
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module GF.Formalism.CFG where
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import GF.Formalism.Utilities
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import GF.Infra.Print
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import GF.Data.Assoc (accumAssoc)
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import GF.Data.SortedList (groupPairs)
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import GF.Data.Utilities (mapSnd)
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------------------------------------------------------------
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-- type definitions
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type CFGrammar c n t = [CFRule c n t]
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data CFRule c n t = CFRule c [Symbol c t] n
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deriving (Eq, Ord, Show)
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type CFChart c n t = CFGrammar (Edge c) n t
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------------------------------------------------------------
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-- building syntax charts from grammars
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grammar2chart :: (Ord n, Ord e) => CFGrammar e n t -> SyntaxChart n e
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grammar2chart cfchart = accumAssoc groupSyntaxNodes $
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[ (lhs, SNode name (filterCats rhs)) |
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CFRule lhs rhs name <- cfchart ]
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----------------------------------------------------------------------
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-- pretty-printing
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instance (Print n, Print c, Print t) => Print (CFRule c n t) where
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prt (CFRule cat rhs name) = prt name ++ " : " ++ prt cat ++
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( if null rhs then ""
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else " --> " ++ prtSep " " rhs )
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prtList = prtSep "\n"
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