1 files changed, 32 insertions, 0 deletions
diff --git a/src/compiler/GF/Command/TreeOperations.hs b/src/compiler/GF/Command/TreeOperations.hs
new file mode 100644
index 000000000..941f03782
--- /dev/null
+++ b/src/compiler/GF/Command/TreeOperations.hs
@@ -0,0 +1,32 @@
+module GF.Command.TreeOperations (
+  treeOp,
+  allTreeOps
+  ) where
+
+import PGF
+import PGF.Data
+import Data.List
+
+type TreeOp = [Expr] -> [Expr]
+
+treeOp :: PGF -> String -> Maybe (Either TreeOp (CId -> TreeOp))
+treeOp pgf f = fmap snd $ lookup f $ allTreeOps pgf
+
+allTreeOps :: PGF -> [(String,(String,Either TreeOp (CId -> TreeOp)))]
+allTreeOps pgf = [
+   ("compute",("compute by using semantic definitions (def)",
+      Left  $ map (compute pgf))),
+   ("transfer",("syntactic transfer by applying function and computing",
+      Right $ \f -> map (compute pgf . EApp (EFun f)))),
+   ("paraphrase",("paraphrase by using semantic definitions (def)",
+      Left  $ nub . concatMap (paraphrase pgf))),
+   ("smallest",("sort trees from smallest to largest, in number of nodes",
+      Left  $ smallest))
+  ]
+
+smallest :: [Expr] -> [Expr]
+smallest = sortBy (\t u -> compare (size t) (size u)) where
+  size t = case t of
+    EAbs _ _ e -> size e + 1
+    EApp e1 e2 -> size e1 + size e2 + 1
+    _ -> 1