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{
35    using IList = System.Collections.IList;
36
37    [System.Serializable]
38    public class RewriteRuleSubtreeStream : RewriteRuleElementStream
39    {
40        public RewriteRuleSubtreeStream( ITreeAdaptor adaptor, string elementDescription )
41            : base( adaptor, elementDescription )
42        {
43        }
44
45        /** <summary>Create a stream with one element</summary> */
46        public RewriteRuleSubtreeStream( ITreeAdaptor adaptor, string elementDescription, object oneElement )
47            : base( adaptor, elementDescription, oneElement )
48        {
49        }
50
51        /** <summary>Create a stream, but feed off an existing list</summary> */
52        public RewriteRuleSubtreeStream( ITreeAdaptor adaptor, string elementDescription, IList elements )
53            : base( adaptor, elementDescription, elements )
54        {
55        }
56
57        /** <summary>
58         *  Treat next element as a single node even if it's a subtree.
59         *  This is used instead of next() when the result has to be a
60         *  tree root node.  Also prevents us from duplicating recently-added
61         *  children; e.g., ^(type ID)+ adds ID to type and then 2nd iteration
62         *  must dup the type node, but ID has been added.
63         *  </summary>
64         *
65         *  <remarks>
66         *  Referencing a rule result twice is ok; dup entire tree as
67         *  we can't be adding trees as root; e.g., expr expr.
68         *
69         *  Hideous code duplication here with super.next().  Can't think of
70         *  a proper way to refactor.  This needs to always call dup node
71         *  and super.next() doesn't know which to call: dup node or dup tree.
72         *  </remarks>
73         */
74        public virtual object NextNode()
75        {
76            //System.Console.WriteLine("nextNode: elements={0}, singleElement={1}", elements, ((ITree)singleElement).ToStringTree());
77            int n = Count;
78            if ( dirty || ( cursor >= n && n == 1 ) )
79            {
80                // if out of elements and size is 1, dup (at most a single node
81                // since this is for making root nodes).
82                object el = NextCore();
83                return adaptor.DupNode( el );
84            }
85            // test size above then fetch
86            object tree = NextCore();
87            while (adaptor.IsNil(tree) && adaptor.GetChildCount(tree) == 1)
88                tree = adaptor.GetChild(tree, 0);
89            //System.Console.WriteLine("_next={0}", ((ITree)tree).ToStringTree());
90            object el2 = adaptor.DupNode(tree); // dup just the root (want node here)
91            return el2;
92        }
93
94        protected override object Dup( object el )
95        {
96            return adaptor.DupTree( el );
97        }
98    }
99}
100