1 files changed, 69 insertions, 0 deletions
diff --git a/src/expressions/collect_sources.ml b/src/expressions/collect_sources.ml
new file mode 100755
index 0000000..d898b86
--- /dev/null
+++ b/src/expressions/collect_sources.ml
@@ -0,0 +1,69 @@
+module T = struct
+
+  type 'a t = unit
+
+  type 'a obs = ('a -> 'a)
+
+  let str s = ()
+
+  let num n = ()
+
+  let date d = ()
+
+  let bool b = ()
+
+  let observe () x = x
+
+end
+
+module R = struct
+
+  type 'a obs = Cell.Set.t -> Cell.Set.t
+
+  type 'a t = 'a obs
+
+  let cell (c:Cell.t) set = Cell.Set.add (Cell.to_pair c) set
+
+  let range c1 c2 set = begin
+
+    let x1, y1 = Cell.to_pair c1
+    and x2, y2 = Cell.to_pair c2 in
+
+    let f_x x acc = begin
+      let f_y y acc = begin
+        Cell.Set.add (x, y) acc
+      end in
+      Tools.fold_for f_y y1 y2 acc
+    end in
+    Tools.fold_for f_x x1 x2 set
+  end
+
+  let observe elem set = elem set
+
+
+end
+
+let observe f value = f value
+
+let value v () = T.observe v
+
+let ref r () = R.observe r
+
+let call0 ident () acc = acc
+
+let call1 ident p1 () acc = observe p1 acc
+
+let call2 ident p1 p2 () acc = observe p2 (observe p1 acc)
+
+let call3 ident p1 p2 p3 () acc = observe p3 (observe p2 (observe p1 acc))
+
+let callN ident params () acc = List.fold_left (fun acc p -> observe p acc) acc params
+
+let expression e () = e
+
+type obs =  Cell.Set.t -> Cell.Set.t
+
+type t = unit
+
+type repr = obs
+