+ else if ("grammar".equals(head)) { for(Tree<String> t : tree.children()) walk(t); return this; }
+ else if ("*".equals(head)) return Repeat.many0((Element)walk(tree.child(0)));
+ else if ("+".equals(head)) return Repeat.many1((Element)walk(tree.child(0)));
+ else if ("+/".equals(head)) return Repeat.many1((Element)walk(tree.child(0)), (Element)walk(tree.child(1)));
+ else if ("*/".equals(head)) return Repeat.many0((Element)walk(tree.child(0)), (Element)walk(tree.child(1)));
+ else if ("**".equals(head)) return Repeat.maximal(Repeat.many0((Element)walk(tree.child(0))));
+ else if ("++".equals(head)) return Repeat.maximal(Repeat.many1((Element)walk(tree.child(0))));
+ else if ("?".equals(head)) return Repeat.maybe((Element)walk(tree.child(0)));
+ else if ("&".equals(head))
+ return ((PreSequence)walk(tree,0)).and(new PreSequence((Element[])Reflection.lub((Object[])walk(tree, 1)), null).buildSequence(null, true, false));
+ else if ("&~".equals(head))
+ return ((PreSequence)walk(tree,0)).not(new PreSequence((Element[])Reflection.lub((Object[])walk(tree, 1)), null).buildSequence(null, true, false));
+ else if ("epsilon".equals(head)) return Union.epsilon;
+ else if ("()".equals(head)) return Union.epsilon;
+ else if (")".equals(head)) return SELF;
+ else if ("nonTerminal".equals(head)) return nonTerminal(string(tree.child(0)), null, false, false);
+ else if ("::=".equals(head)) return nonTerminal(string(tree.child(0)), (PreSequence[][])walk(tree, 1), false, false);
+ else if ("!::=".equals(head)) return nonTerminal(string(tree.child(0)), (PreSequence[][])walk(tree, 1), false, true);
+ else if ("(".equals(head)) return nonTerminal("anon"+(anon++), (PreSequence[][])walk(tree, 0), false, false);
+ else if ("literal".equals(head)) { Element ret = string(string(tree.child(0))); dropAll.add(ret); return ret; }
+ else if ("-".equals(head)) return new Range(walk(tree, 0).toString().charAt(0), walk(tree,1).toString().charAt(0));
+ else if ("range".equals(head)) return new Range(walk(tree, 0).toString().charAt(0), walk(tree,0).toString().charAt(0));
+ else if ("gram".equals(head)) return walk(tree, 1);
+ else if ("=>".equals(head)) { PreSequence p = (PreSequence)walk(tree, 0); p.tag = string(tree.child(1)); return p; }
+ else if ("/".equals(head)) return ((PreSequence)walk(tree, 0)).sparse((Element)walk(tree, 1));
+ else if ("ps".equals(head)) return new PreSequence((Element[])walk(tree, 0));
+ else if ("ps2".equals(head)) {
+ Object[] o1 = (Object[])walk(tree, 0);
+ String s = string(tree.child(1));
+ Object[] o2 = (Object[])walk(tree, 2);
+ if (o1==null) o1 = new Object[0];
+ if (o2==null) o2 = new Object[0];
+ Object[] o3 = new Object[o1.length + o2.length + 1];
+ System.arraycopy(o1, 0, o3, 0, o1.length);
+ o3[o1.length] = string(s);
+ System.arraycopy(o2, 0, o3, o1.length+1, o2.length);
+ PreSequence ret = new PreSequence(o3, s);
+ ret.drops[o1.length] = o3.length>1;
+ return ret;
+ } else if ("[".equals(head) || "[~".equals(head)) {
+ boolean positive = "[".equals(head);
+ Range[] rr = (Range[])walk(tree, 0);
+ Range.Set ret = positive ? new Range.Set() : new Range.Set(new Range(true, true));
+ if (rr != null)
+ for(Range r : rr)
+ if (positive) ret.add(r);
+ else ret.remove(r);
+ return set(ret);
+ }