checkpoint

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

diff --git a/src/edu/berkeley/sbp/Sequence.java b/src/edu/berkeley/sbp/Sequence.java
index bb0ba48..2530a21 100644 (file)
--- a/src/edu/berkeley/sbp/Sequence.java
+++ b/src/edu/berkeley/sbp/Sequence.java
@@ -32,30 +32,33 @@ public abstract class Sequence extends Element implements Iterable<Element> {
         return ret;
     }
 
-    /** the empty sequence (matches the empty string) */
-    public static Sequence newEmptySequence() { return new Sequence.Constant.Empty(); }
+    /** create an empty sequence (matches the empty string) */
+    public static Sequence create() { return new Sequence.Constant.Empty(); }
 
-    /** after matching the sequence, do not add anything to the output tree */
-    public static Sequence newDropSequence(Element[] e) { return new Constant.Drop(e); }
+    /** create a sequence of one element */
+    public static Sequence create(Element e) { return create(new Element[] { e }, 0); }
+
+    /** create a sequence which drops the result of all but one of its element */
+    public static Sequence create(Element[] e, int idx) { return new Singleton(e, idx); }
 
     /** after matching the sequence, insert a constant into the output tree */
     public static Sequence newConstantSequence(Element[] e, Object o) { return new Constant(e, o); }
 
-    /** after matching the sequence, place the result of the <tt>idx</tt>th match in the output tree */
-    public static Sequence newSingletonSequence(Element[] e, int idx) { return new Singleton(e, idx); }
-    public static Sequence newSingletonSequence(Element e) { return newSingletonSequence(new Element[] { e }, 0); }
 
     /**
      *  after matching the sequence, create the specified output tree
-     *  @param tag   the tag for the output tree
-     *  @param e     the elements to match
-     *  @param drops only elements of <tt>e</tt> whose corresponding <tt>boolean</tt> in <tt>drops</tt>
-     *               is <i>false</i> will be included in the output tree
+     *  @param tag    the tag for the output tree
+     *  @param e      the elements to match
+     *  @param drops  only elements of <tt>e</tt> whose corresponding <tt>boolean</tt> in <tt>drops</tt>
+     *                is <i>false</i> will be included in the output tree
+     *  @param unwrap if true, all children of the last child (ie
+     *                grandchildren) are promoted to children of this node; this is very useful for matching repetitions
      **/
-    public static Sequence newRewritingSequence(Object tag, Element[] e, boolean[] drops) {
-        return new RewritingSequence(tag, e, drops); }
-
-    public static Sequence newUnwrapSequence(Element[] e, Object tag, boolean[] drops) { return new Unwrap(e, tag, drops); }
+    public static Sequence create(Object tag, Element[] e, boolean[] drops, boolean unwrap) {
+        return unwrap
+            ? new Unwrap(e, tag, drops)
+            : new RewritingSequence(tag, e, drops);
+    }
 
     ////////////////////////////////////////////////////////////////////////////////