From 673bc27755a6d026422cda29bf32d0c4711a7f82 Mon Sep 17 00:00:00 2001
From: aarne <aarne@cs.chalmers.se>
Date: Sun, 5 Oct 2008 18:01:42 +0000
Subject: [PATCH] adapted old AbsCompute for use with source GF terms

---
 src/GF/Compile/AbsCompute.hs | 145 +++++++++++++++++++++++++++++++++++
 src/GF/Compile/TypeCheck.hs  |   1 +
 2 files changed, 146 insertions(+)
 create mode 100644 src/GF/Compile/AbsCompute.hs

diff --git a/src/GF/Compile/AbsCompute.hs b/src/GF/Compile/AbsCompute.hs
new file mode 100644
index 000000000..f8a484ac8
--- /dev/null
+++ b/src/GF/Compile/AbsCompute.hs
@@ -0,0 +1,145 @@
+----------------------------------------------------------------------
+-- |
+-- Module      : AbsCompute
+-- Maintainer  : AR
+-- Stability   : (stable)
+-- Portability : (portable)
+--
+-- > CVS $Date: 2005/10/02 20:50:19 $ 
+-- > CVS $Author: aarne $
+-- > CVS $Revision: 1.8 $
+--
+-- computation in abstract syntax w.r.t. explicit definitions.
+--
+-- old GF computation; to be updated
+-----------------------------------------------------------------------------
+
+module GF.Compile.AbsCompute (LookDef,
+		   compute, 
+		   computeAbsTerm, 
+		   computeAbsTermIn, 
+		   beta
+		  ) where
+
+import GF.Data.Operations
+
+import GF.Grammar.Abstract
+import GF.Grammar.PrGrammar
+import GF.Grammar.Lookup
+import GF.Compile.Compute
+
+import Debug.Trace
+import Data.List(intersperse)
+import Control.Monad (liftM, liftM2)
+
+-- for debugging
+tracd m t = t 
+-- tracd = trace
+
+compute :: Grammar -> Exp -> Err Exp
+compute = computeAbsTerm
+
+computeAbsTerm :: Grammar -> Exp -> Err Exp
+computeAbsTerm gr = computeAbsTermIn (lookupAbsDef gr) []
+
+-- | a hack to make compute work on source grammar as well
+type LookDef = Ident -> Ident -> Err (Maybe Term)
+
+computeAbsTermIn :: LookDef -> [Ident] -> Exp -> Err Exp
+computeAbsTermIn lookd xs e = errIn ("computing" +++ prt e) $ compt xs e where
+  compt vv t = case t of
+--    Prod x a b  -> liftM2 (Prod x) (compt vv a) (compt (x:vv) b)
+--    Abs x b     -> liftM  (Abs  x)              (compt (x:vv) b)
+    _ -> do
+      let t' = beta vv t
+      (yy,f,aa) <- termForm t'
+      let vv' = yy ++ vv
+      aa'    <- mapM (compt vv') aa
+      case look f of
+        Just (Eqs eqs) -> tracd ("\nmatching" +++ prt f) $ 
+                          case findMatch eqs aa' of
+          Ok (d,g) -> do
+            --- let (xs,ts) = unzip g
+            --- ts' <- alphaFreshAll vv' ts
+            let g' = g --- zip xs ts'
+            d' <- compt vv' $ substTerm vv' g' d
+            tracd ("by Egs:" +++ prt d') $ return $ mkAbs yy $ d'
+          _ -> tracd ("no match" +++ prt t') $ 
+               do
+            let v = mkApp f aa'
+            return $ mkAbs yy $ v
+        Just d -> tracd ("define" +++ prt t') $ do
+          da <- compt vv' $ mkApp d aa' 
+          return $ mkAbs yy $ da
+        _ -> do
+          let t2 = mkAbs yy $ mkApp f aa'
+          tracd ("not defined" +++ prt_ t2) $ return t2
+
+  look t = case t of
+     (Q m f) -> case lookd m f of
+       Ok (Just EData) -> Nothing  -- canonical --- should always be QC
+       Ok md -> md
+       _ -> Nothing
+     Eqs _ -> return t ---- for nested fn
+     _ -> Nothing
+
+beta :: [Ident] -> Exp -> Exp
+beta vv c = case c of
+  Let (x,(_,a)) b -> beta vv $ substTerm vv [(x,beta vv a)] (beta (x:vv) b) 
+  App f         a -> 
+    let (a',f') = (beta vv a, beta vv f) in 
+    case f' of
+      Abs x b -> beta vv $ substTerm vv [(x,a')] (beta (x:vv) b) 
+      _ ->               (if a'==a && f'==f then id else beta vv) $ App f' a'
+  Prod x a b      -> Prod x (beta vv a) (beta (x:vv) b)
+  Abs x b         -> Abs x (beta (x:vv) b)
+  _               -> c
+
+-- special version of pattern matching, to deal with comp under lambda
+
+findMatch :: [([Patt],Term)] -> [Term] -> Err (Term, Substitution)
+findMatch cases terms = case cases of
+  [] -> Bad $"no applicable case for" +++ unwords (intersperse "," (map prt terms))
+  (patts,_):_ | length patts /= length terms -> 
+       Bad ("wrong number of args for patterns :" +++ 
+            unwords (map prt patts) +++ "cannot take" +++ unwords (map prt terms))
+  (patts,val):cc -> case mapM tryMatch (zip patts terms) of
+     Ok substs -> return (tracd ("value" +++ prt_ val) val, concat substs)
+     _         -> findMatch cc terms
+
+tryMatch :: (Patt, Term) -> Err [(Ident, Term)]
+tryMatch (p,t) = do 
+  t' <- termForm t
+  trym p t'
+ where
+
+  trym p t' = err (\s -> tracd s (Bad s)) (\t -> tracd (prtm p t) (return t)) $ ---- 
+              case (p,t') of
+    (PV IW, _) | notMeta t -> return [] -- optimization with wildcard
+    (PV x,  _) | notMeta t -> return [(x,t)]
+    (PString s, ([],K i,[])) | s==i -> return []
+    (PInt s, ([],EInt i,[])) | s==i -> return []
+    (PFloat s,([],EFloat i,[])) | s==i -> return [] --- rounding?
+    (PP q p pp, ([], QC r f, tt)) | 
+       p `eqStrIdent` f && length pp == length tt -> do
+         matches <- mapM tryMatch (zip pp tt)
+         return (concat matches)
+    (PP q p pp, ([], Q r f, tt)) | 
+       p `eqStrIdent` f && length pp == length tt -> do
+         matches <- mapM tryMatch (zip pp tt)
+         return (concat matches)
+    (PT _ p',_) -> trym p' t'
+    (_, ([],Alias _ _ d,[])) -> tryMatch (p,d)
+    (PAs x p',_) -> do
+       subst <- trym p' t'
+       return $ (x,t) : subst
+    _ -> Bad ("no match in pattern" +++ prt p +++ "for" +++ prt t)
+
+  notMeta e = case e of
+    Meta _  -> False
+    App f a -> notMeta f &&  notMeta a  
+    Abs _ b -> notMeta b
+    _ -> True
+
+  prtm p g = 
+    prt p +++ ":" ++++ unwords ["  " ++ prt_ x +++ "=" +++ prt_ y +++ ";" | (x,y) <- g]
diff --git a/src/GF/Compile/TypeCheck.hs b/src/GF/Compile/TypeCheck.hs
index 568eb3846..04698ea89 100644
--- a/src/GF/Compile/TypeCheck.hs
+++ b/src/GF/Compile/TypeCheck.hs
@@ -24,6 +24,7 @@ import GF.Data.Zipper
 
 import GF.Grammar.Abstract
 import GF.Compile.Refresh
+import GF.Compile.AbsCompute
 import GF.Grammar.LookAbs
 import qualified GF.Grammar.Lookup as Lookup ---
 import GF.Grammar.Unify ---