1/*
2 [The "BSD licence"]
3 Copyright (c) 2005-2006 Terence Parr
4 All rights reserved.
5
6 Redistribution and use in source and binary forms, with or without
7 modification, are permitted provided that the following conditions
8 are met:
9 1. Redistributions of source code must retain the above copyright
10    notice, this list of conditions and the following disclaimer.
11 2. Redistributions in binary form must reproduce the above copyright
12    notice, this list of conditions and the following disclaimer in the
13    documentation and/or other materials provided with the distribution.
14 3. The name of the author may not be used to endorse or promote products
15    derived from this software without specific prior written permission.
16
17 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27*/
28package org.antlr.runtime.tree {
29
30    public class RewriteRuleSubtreeStream extends RewriteRuleElementStream {
31
32        public function RewriteRuleSubtreeStream(adaptor:TreeAdaptor, elementDescription:String, element:Object=null) {
33            super(adaptor, elementDescription, element);
34        }
35
36    	/** Treat next element as a single node even if it's a subtree.
37    	 *  This is used instead of next() when the result has to be a
38    	 *  tree root node.  Also prevents us from duplicating recently-added
39    	 *  children; e.g., ^(type ID)+ adds ID to type and then 2nd iteration
40    	 *  must dup the type node, but ID has been added.
41    	 *
42    	 *  Referencing a rule result twice is ok; dup entire tree as
43    	 *  we can't be adding trees as root; e.g., expr expr.
44    	 *
45    	 *  Hideous code duplication here with super.next().  Can't think of
46    	 *  a proper way to refactor.  This needs to always call dup node
47    	 *  and super.next() doesn't know which to call: dup node or dup tree.
48    	 */
49    	public function nextNode():Object {
50    		var n:int = size;
51    		var el:Object;
52    		if ( dirty || (cursor>=n && n==1) ) {
53    			// if out of elements and size is 1, dup (at most a single node
54    			// since this is for making root nodes).
55    			el = _next();
56    			return adaptor.dupNode(el);
57    		}
58    		// test size above then fetch
59    		el = _next();
60    		return el;
61    	}
62
63    	protected override function dup(el:Object):Object {
64    		return adaptor.dupTree(el);
65    	}
66    }
67}