X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2Fmisc%2FMetaGrammar.java;h=13da0cae7e6ac183576f1e23fbcc833f3ea955cb;hp=bc171da5b27891926668380c71226f606326c66b;hb=7e98c8cefa1a3d5501c7ab513ba37d4aefa291e6;hpb=a19f44a6cc6e3a2b0c2f3dadd7be2263d6ff0c3e

diff --git a/src/edu/berkeley/sbp/misc/MetaGrammar.java b/src/edu/berkeley/sbp/misc/MetaGrammar.java
index bc171da..13da0ca 100644
--- a/src/edu/berkeley/sbp/misc/MetaGrammar.java
+++ b/src/edu/berkeley/sbp/misc/MetaGrammar.java
@@ -152,16 +152,25 @@ public class MetaGrammar extends ReflectiveWalker {
 
         public PreSequence sparse(Object e) {
             Object[] ret;
-            if (o.length <= 1) ret = o;
-            else {
+            boolean[] drops;
+            if (o.length <= 1) {
+                ret = o;
+                drops = new boolean[this.drops.length];
+                System.arraycopy(this.drops, 0, drops, 0, this.drops.length);
+            } else {
                 ret = new Object[o.length * 2 - 1];
+                drops = new boolean[o.length * 2 - 1];
                 for(int i=0; i<o.length; i++) {
                     Object oi = o[i];
                     ret[i*2]   = oi;
-                    if (i*2+1<ret.length) ret[i*2+1] = new MyDrop(e);
+                    drops[i*2] = this.drops[i];
+                    if (i*2+1<ret.length) {
+                        ret[i*2+1] = new MyDrop(e);
+                        drops[i*2+1] = true;
+                    }
                 }
             }
-            PreSequence p = new PreSequence(ret, tag);
+            PreSequence p = new PreSequence(ret, tag, drops);
             p.not.addAll(not);
             p.and.addAll(and);
             return p;
@@ -170,9 +179,15 @@ public class MetaGrammar extends ReflectiveWalker {
         public PreSequence not(Sequence s) { not.add(s); return this; }
         public PreSequence and(Sequence s) { and.add(s); return this; }
 
+        boolean[] drops = null;
         public PreSequence(Object o) { this(new Object[] { o }, null); }
         public PreSequence(Object[] o) { this(o, null); }
-        public PreSequence(Object[] o, String tag) { this.o = o; this.tag = tag; }
+        public PreSequence(Object[] o, String tag) { this(o, tag, null); }
+        public PreSequence(Object[] o, String tag, boolean[] drops) {
+            this.o = o;
+            this.tag = tag;
+            this.drops = drops==null ? new boolean[o.length] : drops;
+        }
 
         public Union    buildUnion() {
             Union u = new Union("???");
@@ -186,9 +201,7 @@ public class MetaGrammar extends ReflectiveWalker {
             HashSet<Sequence> set = new HashSet<Sequence>();
             Element[] o2 = o==null ? new Element[0] : new Element[o.length];
             int nonDrop = 0;
-            boolean[] drops = null;
             if (o != null) {
-                drops = new boolean[o.length];
                 int j = 0;
                 for(int i=0; i<o.length; i++) {
                     Object oi = o[i];