checkpoint

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

diff --git a/src/edu/berkeley/sbp/Atom.java b/src/edu/berkeley/sbp/Atom.java
index cb7a379..55be283 100644 (file)
--- a/src/edu/berkeley/sbp/Atom.java
+++ b/src/edu/berkeley/sbp/Atom.java
@@ -12,8 +12,7 @@ public abstract class Atom<T> extends Element implements Topology<T> {
 
     protected abstract Topology<T> top();
     public    abstract String toString();
-
-    public Topology toAtom() { return this; }
+    public             StringBuffer toString(StringBuffer sb) { sb.append(this); return sb; }
 
     // Topology Thunks //////////////////////////////////////////////////////////////////////////////
 
@@ -31,18 +30,29 @@ public abstract class Atom<T> extends Element implements Topology<T> {
 
     // Subclasses //////////////////////////////////////////////////////////////////////////////
 
+    /** an atom which tracks the possible tokenset of some element, provided that element can only match single-token sequences */
     public static class Infer<T extends Input> extends Atom<T> {
         private final Element e;
         public Infer(Element e) { this.e = e; }
-        public Topology<T> top() { return (Topology<T>)e.toAtom(); }
-        public String toString() { return e.toString(); /* FIXME should be toAtom() */ }
+        public Topology<T> top() { return (Topology<T>)toAtom(e); }
+        public String toString() { return e.toString(); }
     }
     
+    /** an atom which tracks the inverse of some other atom */
     public static class Invert<T extends Input> extends Atom<T> {
         private final Atom<T> a;
         public Invert(Atom<T> a) { this.a = a; }
         public Topology<T> top() { return ((Topology<T>)a.top()).complement(); }
         public String toString() { return "~"+a; }
     }
+
+    static Topology toAtom(Element e) {
+        if (e instanceof Atom) return (Atom)e;
+        if (e instanceof Sequence) return ((Sequence)e).toAtom();
+        Topology ret = null;
+        for(Sequence s : (Union)e)
+            ret = ret==null ? toAtom(s) : ret.union(s.toAtom());
+        return ret;
+    }
 }