Founding the newly structured GF2.0 cvs archive.

1 files changed, 166 insertions, 0 deletions

diff --git a/src/GF/CF/ChartParser.hs b/src/GF/CF/ChartParser.hs
new file mode 100644
index 000000000..09d538244
--- /dev/null
+++ b/src/GF/CF/ChartParser.hs
@@ -0,0 +1,166 @@
+
+module ChartParser (chartParser) where
+
+import Operations
+import CF
+import CFIdent
+import PPrCF (prCFItem)
+
+import OrdSet
+import OrdMap2
+
+import List (groupBy)
+
+type Token      = CFTok
+type Name       = CFFun
+type Category   = CFItem
+type Grammar    = ([Production], Terminal)
+type Production = (Name, Category, [Category])
+type Terminal   = Token -> [(Category, Maybe Name)]
+type GParser    = Grammar -> Category -> [Token] -> ([ParseTree],String)
+data ParseTree  = Node Name Category [ParseTree] | Leaf Token
+
+--------------------------------------------------
+-- converting between GF parsing and CFG parsing
+
+buildParser :: GParser -> CF -> CFCat -> CFParser
+buildParser gparser cf = parse
+  where 
+    parse = \start input -> 
+            let parse2 = parse' (CFNonterm start) input in 
+            ([(parse2tree t, []) | t <- fst parse2], snd parse2) 
+    parse' = gparser (cf2grammar cf)
+
+cf2grammar :: CF -> Grammar
+cf2grammar cf = (productions, terminal)
+  where 
+    productions  = [ (name, CFNonterm cat, rhs) | 
+		     (name, (cat, rhs)) <- cfRules ]
+    terminal tok = [ (CFNonterm cat, Just name) |
+		     (cat, name) <- cfPredef tok ] 
+		   ++
+		   [ (item, Nothing) |
+		     item <- elems rhsItems,
+		     matchCFTerm item tok ]
+    cfRules  = rulesOfCF cf
+    cfPredef = predefOfCF cf
+    rhsItems :: Set Category
+    rhsItems = union [ makeSet rhs | (_, (_, rhs)) <- cfRules ]
+
+parse2tree :: ParseTree -> CFTree
+parse2tree (Node name (CFNonterm cat) trees) = CFTree (name, (cat, trees')) 
+  where
+    trees' = [ parse2tree t | t@(Node _ _ _) <- trees ]   -- ignore leafs
+
+maybeNode :: Maybe Name -> Category -> Token -> ParseTree
+maybeNode (Just name) cat tok = Node name cat [Leaf tok]
+maybeNode Nothing     _   tok = Leaf tok
+
+
+--------------------------------------------------
+-- chart parsing (bottom up kilbury-like)
+
+type Chart   = [CState]
+type CState  = Set Edge 
+type Edge    = (Int, Category, [Category])
+type Passive = (Int, Int, Category)
+
+chartParser :: CF -> CFCat -> CFParser
+chartParser = buildParser chartParser0
+
+chartParser0 :: GParser
+chartParser0 (productions, terminal) = cparse
+  where
+    emptyCats :: Set Category
+    emptyCats = empties emptySet
+      where 
+        empties cats | cats==cats' = cats
+		     | otherwise   = empties cats'
+	  where cats' = makeSet [ cat | (_, cat, rhs) <- productions,
+				        all (`elemSet` cats) rhs ]
+
+    grammarMap :: Map Category [(Name, [Category])]
+    grammarMap = makeMapWith (++) 
+		 [ (cat, [(name,rhs)]) | (name, cat, rhs) <- productions ]
+
+    leftCornerMap :: Map Category (Set (Category,[Category]))
+    leftCornerMap = makeMapWith (<++>) [ (a, unitSet (b, bs)) | 
+					 (_, b, abs) <- productions, 
+					 (a : bs) <- removeNullable abs ]
+
+    removeNullable :: [Category] -> [[Category]]
+    removeNullable [] = []
+    removeNullable cats@(cat:cats')
+	| cat `elemSet` emptyCats = cats : removeNullable cats'
+	| otherwise               = [cats]
+
+    cparse :: Category -> [Token] -> ([ParseTree], String)
+    cparse start input = case lookup (0, length input, start) edgeTrees of
+			   Just trees -> (trees, "Chart:" ++++ prChart passiveEdges)
+			   Nothing    -> ([],    "Chart:" ++++ prChart passiveEdges)
+      where 
+        finalChart :: Chart
+        finalChart = map buildState initialChart
+
+        finalChartMap :: [Map Category (Set Edge)]
+	finalChartMap = map stateMap finalChart
+
+        stateMap :: CState -> Map Category (Set Edge)
+	stateMap state = makeMapWith (<++>) [ (a, unitSet (i,b,bs)) |
+					      (i, b, a:bs) <- elems state ]
+
+        initialChart :: Chart
+        initialChart = emptySet : map initialState (zip [0..] input)
+          where initialState (j, sym) = makeSet [ (j, cat, []) | 
+						  (cat, _) <- terminal sym ]
+
+        buildState :: CState -> CState
+	buildState = limit more
+	  where more (j, a, [])   = ordSet [ (j, b, bs) |
+				             (b, bs) <- elems (lookupWith emptySet leftCornerMap a) ]
+				    <++>
+				    lookupWith emptySet (finalChartMap !! j) a
+		more (j, b, a:bs) = ordSet [ (j, b, bs) |
+					     a `elemSet` emptyCats ]
+
+        passiveEdges :: [Passive]
+	passiveEdges = [ (i, j, cat) |
+			 (j, state) <- zip [0..] finalChart,
+			 (i, cat, []) <- elems state ]
+		       ++
+		       [ (i, i, cat) |
+			 i <- [0 .. length input],
+			 cat <- elems emptyCats ]
+
+        edgeTrees :: [ (Passive, [ParseTree]) ]
+	edgeTrees = [ (edge, treesFor edge) | edge <- passiveEdges ]
+
+        edgeTreesMap :: Map (Int, Category) [(Int, [ParseTree])]
+	edgeTreesMap = makeMapWith (++) [ ((i,c), [(j,trees)]) |
+					  ((i,j,c), trees) <- edgeTrees ]
+
+        treesFor :: Passive -> [ParseTree]
+	treesFor (i, j, cat) = [ Node name cat trees |
+				 (name, rhs) <- lookupWith [] grammarMap cat,
+				 trees <- children rhs i j ]
+			       ++
+			       [ maybeNode name cat tok |
+				 i == j-1,
+				 let tok = input !! i,
+				 Just name <- [lookup cat (terminal tok)] ]
+
+        children :: [Category] -> Int -> Int -> [[ParseTree]]
+	children []     i k = [ [] | i == k ]
+	children (c:cs) i k = [ tree : rest |
+				i <= k,
+				(j, trees) <- lookupWith [] edgeTreesMap (i,c),
+				rest <- children cs j k,
+				tree <- trees ]
+
+
+-- AR 10/12/2002
+
+prChart :: [Passive] -> String
+prChart = unlines . map (unwords . map prOne) . positions where
+  prOne (i,j,it) = show i ++ "-" ++ show j ++ "-" ++ prCFItem it
+  positions = groupBy (\ (i,_,_) (j,_,_) -> i == j)