added the Expr.unMeta method in the Java binding

src/runtime/java/jpgf.c

@@ -1399,6 +1399,19 @@ Java_org_grammaticalframework_pgf_Expr_unApply(JNIEnv* env, jobject self)
 	return japp;
 }
 
+JNIEXPORT jint JNICALL
+Java_org_grammaticalframework_pgf_Expr_unMeta(JNIEnv* env, jobject self)
+{
+	PgfExpr expr = gu_variant_from_ptr(get_ref(env, self));
+
+	PgfExprMeta* pmeta = pgf_expr_unmeta(expr);
+	if (pmeta != NULL) {
+		return pmeta->id;
+	}
+
+	return -1;
+}
+
 JNIEXPORT jboolean JNICALL
 Java_org_grammaticalframework_pgf_Expr_equals(JNIEnv* env, jobject self, jobject other)
 {

src/runtime/java/org/grammaticalframework/pgf/Expr.java

@@ -89,6 +89,11 @@ public class Expr implements Serializable {
 		 * an application then the result is null. */
 		public native ExprApplication unApply();
 
+		/** If the method is called on an expression which is 
+		 * a meta variable, then it will return the variable's id.
+		 * If this is not a meta variable then the result is -1. */
+		public native int unMeta();
+
 		/** Returns the expression as a string in the GF syntax */
 		public String toString() {
 			return showExpr(ref);