checkpoint

[sbp.git] / src / edu / berkeley / sbp / Tree.java

diff --git a/src/edu/berkeley/sbp/Tree.java b/src/edu/berkeley/sbp/Tree.java
index cdd3b8b..bffc353 100644 (file)
--- a/src/edu/berkeley/sbp/Tree.java
+++ b/src/edu/berkeley/sbp/Tree.java
@@ -57,4 +57,25 @@ public class Tree<T>
     }
     public boolean isTransparent() { return false; }
     public boolean isHidden() { return false; }
+
+    public static interface TreeFunctor<T,R> extends Functor<Iterable<Tree<T>>, R> {
+    }
+
+    public static class ArrayBuildingTreeFunctor<T> implements TreeFunctor<T,T[]> {
+        public String toString() { return ""; }
+        public T[] invoke(Iterable<Tree<T>> t) {
+            ArrayList ret = new ArrayList();
+            for(Tree tc : t) {
+                if (tc.head() != null && tc.head() instanceof Functor)
+                    ret.add(((Functor<Iterable<Tree>,Object>)tc.head()).invoke(tc.children()));
+                else if (tc.numChildren() == 0)
+                    ret.add(tc.head());
+                else {
+                    System.err.println("FIXME: don't know what to do about " + tc);
+                    ret.add(null);
+                }
+            }
+            return (T[])ret.toArray(new Object[0]);
+        }
+    }
 }