public static class Grammar extends MetaGrammar {
private int anon = 0;
+ private final Element ws = Repeat.maximal(Repeat.many0(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))
- return nonTerminal("braced"+(anon++),
+ 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,
- Repeat.maximal(Repeat.many0(nonTerminal("w"))),
- ((PreSequence)walk(tree, 0)).buildUnion(),
- Repeat.maximal(Repeat.many0(nonTerminal("w"))),
+ ws,
+ u2,
+ ws,
CharToken.rightBrace
})
}
},
false,
false);
+ }
return super.walk(tree);
}
}