Started playing with label expressions.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@33616 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/model/LabelExpression.java

+package hudson.model;
+
+/**
+ * Boolean expression of labels.
+ * 
+ * @author Kohsuke Kawaguchi
+ * @since 1.COMPOSITELABEL
+ */
+public abstract class LabelExpression extends Label {
+
+
+    public static final class And extends LabelExpression {
+        private final Label lhs,rhs;
+    }
+}

core/src/main/java/hudson/model/LabelToken.java

+package hudson.model;
+
+/**
+ * Atomic single token label, like "foo" or "bar".
+ * 
+ * @author Kohsuke Kawaguchi
+ * @since 1.COMPOSITELABEL
+ */
+public class LabelToken extends Label {
+    public LabelToken(String name) {
+        super(name);
+    }
+}