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 org.antlr.runtime.IntStream;
31: import org.antlr.runtime.TokenStream;
32:
33: /** A stream of tree nodes, accessing nodes from a tree of some kind */
34: public interface TreeNodeStream extends IntStream {
35: /** Get a tree node at an absolute index i; 0..n-1.
36: * If you don't want to buffer up nodes, then this method makes no
37: * sense for you.
38: */
39: public Object get(int i);
40:
41: /** Get tree node at current input pointer + i ahead where i=1 is next node.
42: * i<0 indicates nodes in the past. So LT(-1) is previous node, but
43: * implementations are not required to provide results for k < -1.
44: * LT(0) is undefined. For i>=n, return null.
45: * Return null for LT(0) and any index that results in an absolute address
46: * that is negative.
47: *
48: * This is analogus to the LT() method of the TokenStream, but this
49: * returns a tree node instead of a token. Makes code gen identical
50: * for both parser and tree grammars. :)
51: */
52: public Object LT(int k);
53:
54: /** Where is this stream pulling nodes from? This is not the name, but
55: * the object that provides node objects.
56: */
57: public Object getTreeSource();
58:
59: /** If the tree associated with this stream was created from a TokenStream,
60: * you can specify it here. Used to do rule $text attribute in tree
61: * parser. Optional unless you use tree parser rule text attribute
62: * or output=template and rewrite=true options.
63: */
64: public TokenStream getTokenStream();
65:
66: /** What adaptor can tell me how to interpret/navigate nodes and
67: * trees. E.g., get text of a node.
68: */
69: public TreeAdaptor getTreeAdaptor();
70:
71: /** As we flatten the tree, we use UP, DOWN nodes to represent
72: * the tree structure. When debugging we need unique nodes
73: * so we have to instantiate new ones. When doing normal tree
74: * parsing, it's slow and a waste of memory to create unique
75: * navigation nodes. Default should be false;
76: */
77: public void setUniqueNavigationNodes(boolean uniqueNavigationNodes);
78:
79: /** Return the text of all nodes from start to stop, inclusive.
80: * If the stream does not buffer all the nodes then it can still
81: * walk recursively from start until stop. You can always return
82: * null or "" too, but users should not access $ruleLabel.text in
83: * an action of course in that case.
84: */
85: public String toString(Object start, Object stop);
86: }
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