convered maximal to use character lookahead

[sbp.git] / src / edu / berkeley / sbp / tib / Tib.java

diff --git a/src/edu/berkeley/sbp/tib/Tib.java b/src/edu/berkeley/sbp/tib/Tib.java
index 7f9b913..39f6071 100644 (file)
--- a/src/edu/berkeley/sbp/tib/Tib.java
+++ b/src/edu/berkeley/sbp/tib/Tib.java
@@ -285,5 +285,37 @@ public class Tib implements Token.Stream<CharToken> {
         return ret.toString();
     }
 
         return ret.toString();
     }
 

+    // Grammar //////////////////////////////////////////////////////////////////////////////
+
+    public static class Grammar extends MetaGrammar {
+        private int anon = 0;
+        private final Element ws = Repeat.maximal0(nonTerminal("w"));
+        public Grammar() { dropAll.add(ws); }
+        public Object walk(Tree<String> tree) {
+            String head = tree.head();
+            if (tree.numChildren()==0) return super.walk(tree);
+            if ("{".equals(head)) {
+                String s = "braced"+(anon++);
+                Union u = nonTerminal(s);
+                Union u2 = ((PreSequence)walk(tree, 0)).sparse(ws).buildUnion();
+                u2.add(Sequence.singleton(new Element[] { u }, 0, null, null));
+                return nonTerminal(s,
+                                   new PreSequence[][] {
+                                       new PreSequence[] {
+                                           new PreSequence(new Element[] { CharToken.leftBrace,
+                                                                           ws,
+                                                                           u2,
+                                                                           ws,
+                                                                           CharToken.rightBrace
+                                           })
+                                       }
+                                   },
+                                   false,
+                                   false);
+            }
+            return super.walk(tree);
+        }
+    }
+

 }
 
 }