01: /*
02: [The "BSD licence"]
03: Copyright (c) 2005-2006 Terence Parr
04: All rights reserved.
05:
06: Redistribution and use in source and binary forms, with or without
07: modification, are permitted provided that the following conditions
08: are met:
09: 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: */
28: package org.antlr.runtime.tree;
29:
30: import java.util.List;
31:
32: public class RewriteRuleSubtreeStream extends RewriteRuleElementStream {
33:
34: public RewriteRuleSubtreeStream(TreeAdaptor adaptor,
35: String elementDescription) {
36: super (adaptor, elementDescription);
37: }
38:
39: /** Create a stream with one element */
40: public RewriteRuleSubtreeStream(TreeAdaptor adaptor,
41: String elementDescription, Object oneElement) {
42: super (adaptor, elementDescription, oneElement);
43: }
44:
45: /** Create a stream, but feed off an existing list */
46: public RewriteRuleSubtreeStream(TreeAdaptor adaptor,
47: String elementDescription, List elements) {
48: super (adaptor, elementDescription, elements);
49: }
50:
51: /** Treat next element as a single node even if it's a subtree.
52: * This is used instead of next() when the result has to be a
53: * tree root node. Also prevents us from duplicating recently-added
54: * children; e.g., ^(type ID)+ adds ID to type and then 2nd iteration
55: * must dup the type node, but ID has been added.
56: *
57: * Referencing a rule result twice is ok; dup entire tree as
58: * we can't be adding trees as root; e.g., expr expr.
59: *
60: * Hideous code duplication here with super.next(). Can't think of
61: * a proper way to refactor. This needs to always call dup node
62: * and super.next() doesn't know which to call: dup node or dup tree.
63: */
64: public Object nextNode() {
65: int n = size();
66: if (dirty || (cursor >= n && n == 1)) {
67: // if out of elements and size is 1, dup (at most a single node
68: // since this is for making root nodes).
69: Object el = _next();
70: return adaptor.dupNode(el);
71: }
72: // test size above then fetch
73: Object el = _next();
74: return el;
75: }
76:
77: protected Object dup(Object el) {
78: return adaptor.dupTree(el);
79: }
80: }
|