mirror of
https://github.com/GrammaticalFramework/gf-core.git
synced 2026-04-18 01:09:32 -06:00
130 lines
4.1 KiB
Haskell
130 lines
4.1 KiB
Haskell
----------------------------------------------------------------------
|
|
-- |
|
|
-- Module : Trie
|
|
-- Maintainer : Markus Forsberg
|
|
-- Stability : Obsolete
|
|
-- Portability : Haskell 98
|
|
--
|
|
-- > CVS $Date: 2005/04/21 16:22:09 $
|
|
-- > CVS $Author: bringert $
|
|
-- > CVS $Revision: 1.6 $
|
|
--
|
|
-- (Description of the module)
|
|
-----------------------------------------------------------------------------
|
|
|
|
module GF.Data.Trie (
|
|
tcompile,
|
|
collapse,
|
|
Trie,
|
|
trieLookup,
|
|
decompose,
|
|
Attr,
|
|
atW, atP, atWP
|
|
) where
|
|
|
|
import GF.Data.Map
|
|
|
|
--- data Attr = W | P | WP deriving Eq
|
|
type Attr = Int
|
|
|
|
atW, atP, atWP :: Attr
|
|
(atW,atP,atWP) = (0,1,2)
|
|
|
|
newtype TrieT = TrieT ([(Char,TrieT)],[(Attr,String)])
|
|
|
|
newtype Trie = Trie (Map Char Trie, [(Attr,String)])
|
|
|
|
emptyTrie = TrieT ([],[])
|
|
|
|
optimize :: TrieT -> Trie
|
|
optimize (TrieT (xs,res)) = Trie ([(c,optimize t) | (c,t) <- xs] |->+ empty,
|
|
res)
|
|
|
|
collapse :: Trie -> [(String,[(Attr,String)])]
|
|
collapse trie = collapse' trie []
|
|
where collapse' (Trie (map,(x:xs))) s = if (isEmpty map) then [(reverse s,(x:xs))]
|
|
else (reverse s,(x:xs)):
|
|
concat [ collapse' trie (c:s) | (c,trie) <- flatten map]
|
|
collapse' (Trie (map,[])) s
|
|
= concat [ collapse' trie (c:s) | (c,trie) <- flatten map]
|
|
|
|
tcompile :: [(String,[(Attr,String)])] -> Trie
|
|
tcompile xs = optimize $ build xs emptyTrie
|
|
|
|
build :: [(String,[(Attr,String)])] -> TrieT -> TrieT
|
|
build [] trie = trie
|
|
build (x:xs) trie = build xs (insert x trie)
|
|
where
|
|
insert ([],ys) (TrieT (xs,res)) = TrieT (xs,ys ++ res)
|
|
insert ((s:ss),ys) (TrieT (xs,res))
|
|
= case (span (\(s',_) -> s' /= s) xs) of
|
|
(xs,[]) -> TrieT (((s,(insert (ss,ys) emptyTrie)):xs),res)
|
|
(xs,(y,trie):zs) -> TrieT (xs ++ ((y,insert (ss,ys) trie):zs),res)
|
|
|
|
trieLookup :: Trie -> String -> (String,[(Attr,String)])
|
|
trieLookup trie s = apply trie s s
|
|
|
|
apply :: Trie -> String -> String -> (String,[(Attr,String)])
|
|
apply (Trie (_,res)) [] inp = (inp,res)
|
|
apply (Trie (map,_)) (s:ss) inp
|
|
= case map ! s of
|
|
Just trie -> apply trie ss inp
|
|
Nothing -> (inp,[])
|
|
|
|
-- Composite analysis (Huet's unglue algorithm)
|
|
-- only legaldecompositions are accepted.
|
|
-- With legal means that the composite forms are ordered correctly
|
|
-- with respect to the attributes W,P and WP.
|
|
|
|
-- Composite analysis
|
|
|
|
testTrie = tcompile [("flick",[(atP,"P")]),("knopp",[(atW,"W")]),("flaggstångs",[(atWP,"WP")])]
|
|
|
|
decompose :: Trie -> String -> [String]
|
|
decompose trie sentence = legal trie $ backtrack [(sentence,[])] trie
|
|
|
|
-- The function legal checks if the decomposition is in fact a possible one.
|
|
|
|
legal :: Trie -> [String] -> [String]
|
|
legal _ [] = []
|
|
legal trie input = if (test (map ((map fst).snd.(trieLookup trie)) input)) then input else []
|
|
where
|
|
test [] = False
|
|
test [xs] = elem atW xs || elem atWP xs
|
|
test (xs:xss) = (elem atP xs || elem atWP xs) && test xss
|
|
|
|
react :: String -> [String] -> [(String,[String])] -> String -> Trie -> Trie -> [String]
|
|
react input output back occ (Trie (arcs,res)) init =
|
|
case res of -- Accept = non-empty res.
|
|
[] -> continue back
|
|
_ -> let pushout = (occ:output)
|
|
in case input of
|
|
[] -> reverse $ map reverse pushout
|
|
_ -> let pushback = ((input,pushout):back)
|
|
in continue pushback
|
|
where continue cont = case input of
|
|
[] -> backtrack cont init
|
|
(l:rest) -> case arcs ! l of
|
|
Just trie ->
|
|
react rest output cont (l:occ) trie init
|
|
Nothing -> backtrack cont init
|
|
|
|
backtrack :: [(String,[String])] -> Trie -> [String]
|
|
backtrack [] _ = []
|
|
backtrack ((input,output):back) trie
|
|
= react input output back [] trie trie
|
|
|
|
{-
|
|
-- The function legal checks if the decomposition is in fact a possible one.
|
|
legal :: Trie -> [String] -> [String]
|
|
legal _ [] = []
|
|
legal trie input
|
|
| test $
|
|
map ((map fst).snd.(trieLookup trie)) input = input
|
|
| otherwise = []
|
|
where -- test checks that the Attrs are in the correct order.
|
|
test [] = False -- This case should never happen.
|
|
test [xs] = elem W xs || elem WP xs
|
|
test (xs:xss) = (elem P xs || elem WP xs) && test xss
|
|
-}
|