Tabulation.hs

module ADP.Multi.Tabulation where

import Data.Array
import ADP.Multi.Parser


-- four-dimensional tabulation
table2 :: Array Int a -> RichParser a b -> RichParser a b
table2 z (info,q) =
    let (_,n) = bounds z
        arr = ( array ((0,0,0,0),(n,n,n,n))
                      [ ((i,j,k,l),q z [i,j,k,l]) |
                        i <- [0..n]
                      , j <- [i..n]
                      , k <- [0..n]
                      , l <- [k..n]
                      ])
    in (info, 
          \ _ [i',j',k',l'] -> arr ! (i',j',k',l')
        )
        
-- two-dimensional tabulation
table1 :: Array Int a -> RichParser a b -> RichParser a b
table1 z (info,q) =
    let (_,n) = bounds z
        arr = ( array ((0,0),(n,n))
                      [ ((i,j),q z [i,j]) |
                        i <- [0..n]
                      , j <- [i..n]
                      ])
    in (info, 
          \ _ [i',j'] -> arr ! (i',j')
        )
        
-- TODO tabulation with diagonal arrays