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 
33 namespace Antlr.Runtime.Tree
34 {
35     using IList = System.Collections.IList;
36 
37     [System.Serializable]
38     public class RewriteRuleSubtreeStream : RewriteRuleElementStream
39     {
RewriteRuleSubtreeStream( ITreeAdaptor adaptor, string elementDescription )40         public RewriteRuleSubtreeStream( ITreeAdaptor adaptor, string elementDescription )
41             : base( adaptor, elementDescription )
42         {
43         }
44 
45         /** <summary>Create a stream with one element</summary> */
RewriteRuleSubtreeStream( ITreeAdaptor adaptor, string elementDescription, object oneElement )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> */
RewriteRuleSubtreeStream( ITreeAdaptor adaptor, string elementDescription, IList elements )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          */
NextNode()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 
Dup( object el )94         protected override object Dup( object el )
95         {
96             return adaptor.DupTree( el );
97         }
98     }
99 }
100