1/*
2 * [The "BSD licence"]
3 * Copyright (c) 2005-2008 Terence Parr
4 * All rights reserved.
5 *
6 * Conversion to C#:
7 * Copyright (c) 2008-2009 Sam Harwell, Pixel Mine, Inc.
8 * All rights reserved.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. The name of the author may not be used to endorse or promote products
19 *    derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33namespace Antlr.Runtime.Tree {
34    using IList = System.Collections.IList;
35
36    [System.Serializable]
37    public class RewriteRuleSubtreeStream : RewriteRuleElementStream {
38        public RewriteRuleSubtreeStream(ITreeAdaptor adaptor, string elementDescription)
39            : base(adaptor, elementDescription) {
40        }
41
42        /** <summary>Create a stream with one element</summary> */
43        public RewriteRuleSubtreeStream(ITreeAdaptor adaptor, string elementDescription, object oneElement)
44            : base(adaptor, elementDescription, oneElement) {
45        }
46
47        /** <summary>Create a stream, but feed off an existing list</summary> */
48        public RewriteRuleSubtreeStream(ITreeAdaptor adaptor, string elementDescription, IList elements)
49            : base(adaptor, elementDescription, elements) {
50        }
51
52        /** <summary>
53         *  Treat next element as a single node even if it's a subtree.
54         *  This is used instead of next() when the result has to be a
55         *  tree root node.  Also prevents us from duplicating recently-added
56         *  children; e.g., ^(type ID)+ adds ID to type and then 2nd iteration
57         *  must dup the type node, but ID has been added.
58         *  </summary>
59         *
60         *  <remarks>
61         *  Referencing a rule result twice is ok; dup entire tree as
62         *  we can't be adding trees as root; e.g., expr expr.
63         *
64         *  Hideous code duplication here with super.next().  Can't think of
65         *  a proper way to refactor.  This needs to always call dup node
66         *  and super.next() doesn't know which to call: dup node or dup tree.
67         *  </remarks>
68         */
69        public virtual object NextNode() {
70            //System.Console.WriteLine("nextNode: elements={0}, singleElement={1}", elements, ((ITree)singleElement).ToStringTree());
71            int n = Count;
72            if (dirty || (cursor >= n && n == 1)) {
73                // if out of elements and size is 1, dup (at most a single node
74                // since this is for making root nodes).
75                object el = NextCore();
76                return adaptor.DupNode(el);
77            }
78            // test size above then fetch
79            object tree = NextCore();
80            while (adaptor.IsNil(tree) && adaptor.GetChildCount(tree) == 1)
81                tree = adaptor.GetChild(tree, 0);
82            //System.Console.WriteLine("_next={0}", ((ITree)tree).ToStringTree());
83            object el2 = adaptor.DupNode(tree); // dup just the root (want node here)
84            return el2;
85        }
86
87        protected override object Dup(object el) {
88            return adaptor.DupTree(el);
89        }
90    }
91}
92