X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2Ftib%2FTib.java;h=39f6071d01a576fa6539f62240125d40b822f052;hp=915158bc8139a99a5a831cb1b8400be9fbc46143;hb=0516ea34996c86664928ef948013b749876b87ec;hpb=0907ad8065e0d123e46fd00d87189a2fa9f10bf4

diff --git a/src/edu/berkeley/sbp/tib/Tib.java b/src/edu/berkeley/sbp/tib/Tib.java
index 915158b..39f6071 100644
--- a/src/edu/berkeley/sbp/tib/Tib.java
+++ b/src/edu/berkeley/sbp/tib/Tib.java
@@ -21,9 +21,7 @@ import java.io.*;
  *
  *   This was written as an ad-hoc parser to facilitate
  *   experimentation with the TIB spec.  Once the spec is finalized it
- *   should probably be rewritten using a parser-generator, if
- *   possible (it is unclear whether or not the associated grammar is
- *   context-free).
+ *   should probably be rewritten.
  */
 public class Tib implements Token.Stream<CharToken> {
 
@@ -129,7 +127,7 @@ public class Tib implements Token.Stream<CharToken> {
         }
     }
 
-    public static class Block /*implements Token*/ {
+    public static class Block {
                       Block  parent;
         public  final int    row;
         public  final int    col;
@@ -137,7 +135,6 @@ public class Tib implements Token.Stream<CharToken> {
         private final Vector children = new Vector();
         private       String pending  = "";
 
-        //public Location getLocation() { return /*new Location.Cartesian(row, col)*/null; }
         public int    size() { return children.size(); }
         public Object child(int i) { return children.elementAt(i); }
         public boolean isLiteral() {  return false; }
@@ -288,5 +285,37 @@ public class Tib implements Token.Stream<CharToken> {
         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);
+        }
+    }
+
 }