diff --git a/src/runtime/java/org/grammaticalframework/pgf/Completer.java b/src/runtime/java/org/grammaticalframework/pgf/Completer.java
new file mode 100644
index 000000000..21d3ea127
--- /dev/null
+++ b/src/runtime/java/org/grammaticalframework/pgf/Completer.java
@@ -0,0 +1,37 @@
+package org.grammaticalframework.pgf;
+
+import java.util.*;
+
+class Completer implements Iterable<TokenProb> {
+	private Concr concr;
+	private String s;
+	private String prefix;
+	private String startCat;
+	private TokenIterator iter;
+
+	public Completer(Concr concr, String startCat, String s, String prefix) throws ParseError {
+		this.concr    = concr;
+		this.startCat = startCat;
+		this.s        = s;
+		this.prefix   = prefix;
+		this.iter     = complete(concr, startCat, s, prefix);
+	}
+
+	public Iterator<TokenProb> iterator() {
+		if (iter == null) {
+			// If someone has asked for a second iterator over
+			// the same parse results then we have to parse again.
+			try {
+				return complete(concr, startCat, s, prefix);
+			} catch (ParseError e) {
+				return null;
+			}
+		} else {
+			TokenIterator tmp_iter = iter;
+			iter = null;
+			return tmp_iter;
+		}
+	}
+
+	static native TokenIterator complete(Concr concr, String startCat, String s, String prefix) throws ParseError;
+}