--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/pathcheck.sml	Sun Oct 19 12:12:59 2008 -0400
@@ -0,0 +1,64 @@
+(* Copyright (c) 2008, Adam Chlipala
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * - The names of contributors may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *)
+
+structure PathCheck :> PATH_CHECK = struct
+
+open Mono
+
+structure E = ErrorMsg
+
+structure SS = BinarySetFn(struct
+                           type ord_key = string
+                           val compare = String.compare
+                           end)
+
+fun checkDecl ((d, loc), (funcs, rels)) =
+    let
+        fun doRel s =
+            (if SS.member (rels, s) then
+                 E.errorAt loc ("Duplicate table/sequence path " ^ s)
+             else
+                 ();
+             (funcs, SS.add (rels, s)))
+    in
+        case d of
+            DExport (_, s, _, _) =>
+            (if SS.member (funcs, s) then
+                 E.errorAt loc ("Duplicate function path " ^ s)
+             else
+                 ();
+             (SS.add (funcs, s), rels))
+            
+          | DTable (s, _) => doRel s
+          | DSequence s => doRel s
+
+          | _ => (funcs, rels)
+    end
+
+fun check ds = ignore (foldl checkDecl (SS.empty, SS.empty) ds)
+
+end