1 files changed, 77 insertions, 0 deletions
diff --git a/src/GF/Compile/Extend.hs b/src/GF/Compile/Extend.hs
new file mode 100644
index 000000000..66a632445
--- /dev/null
+++ b/src/GF/Compile/Extend.hs
@@ -0,0 +1,77 @@
+module Extend where
+
+import Grammar
+import Ident
+import PrGrammar
+import Modules
+import Update
+import Macros
+import Operations
+
+import Monad
+
+-- AR 14/5/2003
+
+-- The top-level function $extendModInfo$
+-- extends a module symbol table by indirections to the module it extends
+
+extendModInfo :: Ident -> SourceModInfo -> SourceModInfo -> Err SourceModInfo
+extendModInfo name old new = case (old,new) of
+  (ModMod m0, ModMod (Module mt fs _ ops js)) -> do
+    testErr (mtype m0 == mt) ("illegal extension type at module" +++ show name)
+    js' <- extendMod name (jments m0) js
+    return $ ModMod (Module mt fs Nothing ops js)
+
+-- this is what happens when extending a module: new information is inserted,
+-- and the process is interrupted if unification fails
+
+extendMod :: Ident -> BinTree (Ident,Info) -> BinTree (Ident,Info) -> 
+             Err (BinTree (Ident,Info))
+extendMod name old new = 
+  foldM (tryInsert (extendAnyInfo name) (indirInfo name)) new $ tree2list old
+
+indirInfo :: Ident -> Info -> Info
+indirInfo n info = AnyInd b n' where 
+  (b,n') = case info of
+    ResValue _ -> (True,n)
+    ResParam _ -> (True,n)
+    AnyInd b k -> (b,k)
+    _ -> (False,n) ---- canonical in Abs
+
+{- ----
+case info of
+  AbsFun pty ptr -> AbsFun (perhIndir n pty) (perhIndir n ptr)
+  ---- find a suitable indirection for cat info!
+
+  ResOper pty ptr -> ResOper (perhIndir n pty) (perhIndir n ptr)
+  ResParam pp -> ResParam (perhIndir n pp) 
+  _ -> info
+
+  CncCat pty ptr ppr -> CncCat (perhIndir n pty) (perhIndir n ptr) (perhIndir n ppr)
+  CncFun m ptr   ppr -> CncFun m (perhIndir n ptr)                 (perhIndir n ppr)
+-}
+
+perhIndir :: Ident -> Perh a -> Perh a
+perhIndir n p = case p of
+  Yes _ -> May n
+  _ -> p
+
+extendAnyInfo :: Ident -> Info -> Info -> Err Info
+extendAnyInfo n i j = case (i,j) of
+  (AbsCat mc1 mf1, AbsCat mc2 mf2) -> 
+    liftM2 AbsCat (updatePerhaps n mc1 mc2) (updatePerhaps n mf1 mf2) --- add cstrs
+  (AbsFun mt1 md1, AbsFun mt2 md2) -> 
+    liftM2 AbsFun (updatePerhaps n mt1 mt2) (updatePerhaps n md1 md2) --- add defs
+
+  (ResParam mt1, ResParam mt2) -> liftM ResParam $ updatePerhaps n mt1 mt2
+  (ResValue mt1, ResValue mt2) -> liftM ResValue $ updatePerhaps n mt1 mt2
+  (ResOper mt1 m1, ResOper mt2 m2) -> 
+    liftM2 ResOper (updatePerhaps n mt1 mt2) (updatePerhaps n m1 m2)
+
+  (CncCat mc1 mf1 mp1, CncCat mc2 mf2 mp2) -> 
+    liftM3 CncCat (updatePerhaps n mc1 mc2) 
+                  (updatePerhaps n mf1 mf2) (updatePerhaps n mp1 mp2)
+  (CncFun m mt1 md1, CncFun _ mt2 md2) -> 
+    liftM2 (CncFun m) (updatePerhaps n mt1 mt2) (updatePerhaps n md1 md2)
+
+  _ -> Bad $ "cannot unify information for" +++ show n