checkpoint

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

diff --git a/src/edu/berkeley/sbp/Repeat.java b/src/edu/berkeley/sbp/Repeat.java
index 4868135..b7e7e39 100644 (file)
--- a/src/edu/berkeley/sbp/Repeat.java
+++ b/src/edu/berkeley/sbp/Repeat.java
@@ -10,12 +10,12 @@ import java.lang.ref.*;
 /** currently this class exports only static methods to create repetitions; there are no public instance methods or constructors */
 class Repeat extends Union {
 
-    Repeat(final Element e, boolean zeroOkay, boolean manyOkay, final Element separator, boolean maximal) {
-        this(e, zeroOkay, manyOkay, separator, maximal, null); }
-    Repeat(final Element e, boolean zeroOkay, boolean manyOkay, final Element separator, boolean maximal, Object tag) {
+    public Repeat(final Element e, boolean zeroOkay, boolean manyOkay, Object tag) {
+        this(e, zeroOkay, manyOkay, null, false, tag); }
+    public Repeat(final Element e, boolean zeroOkay, boolean manyOkay, final Element separator, Object tag) {
+        this(e, zeroOkay, manyOkay, separator, false, tag); }
+    protected Repeat(final Element e, boolean zeroOkay, boolean manyOkay, final Element separator, boolean maximal, Object tag) {
         super(e+(!manyOkay ? "?" : (zeroOkay ? (maximal ? "**" : "*") : (maximal ? "++" : "+")))+(separator==null?"":("/"+separator)), true);
-        if (maximal && zeroOkay && separator != null)
-            throw new RuntimeException("cannot create a maximal repetition of zero or more items with a separator (yet): " + this);
         if (zeroOkay) {
             add(new Sequence.Constant.Empty());
             if (manyOkay) add(new Sequence.Singleton(Sequence.many1(e, separator)));
@@ -27,6 +27,29 @@ class Repeat extends Union {
             else
                 add(new Sequence.Unwrap(new Element[] { e, separator,      Repeat.this }, tag, new boolean[] { false, true, false }));
         }
-        if (maximal) for(Sequence s : this) s.noFollow = separator==null ? e : separator;
+    }
+
+    public static class Maximal extends Repeat {
+        public Maximal(final Element e, boolean zeroOkay, boolean manyOkay, final Atom separator, Object tag) {
+            super(e, zeroOkay, manyOkay, separator, true, tag);
+            if (zeroOkay && separator != null)
+                throw new RuntimeException("cannot create a maximal repetition of zero or more items with a separator (yet): " + this);
+            for(Sequence s : this)
+                s.follow = new Invert(separator);
+        }
+        public Maximal(final Atom e, boolean zeroOkay, boolean manyOkay, Object tag) {
+            super(e, zeroOkay, manyOkay, null, true, tag);
+            for(Sequence s : this)
+                s.follow = new Invert(e);
+        }
+    }
+
+
+    /** an atom which tracks the inverse of some other atom */
+    private 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 a.complement(); }
+        public String toString() { return "~"+a; }
     }
 }