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.analysis;
29:
30: import org.antlr.misc.IntervalSet;
31: import org.antlr.misc.IntSet;
32: import org.antlr.tool.Grammar;
33:
34: /** An LL(1) lookahead set; contains a set of token types and a "hasEOF"
35: * condition when the set contains EOF. Since EOF is -1 everywhere and -1
36: * cannot be stored in my BitSet, I set a condition here. There may be other
37: * reasons in the future to abstract a LookaheadSet over a raw BitSet.
38: */
39: public class LookaheadSet {
40: public IntSet tokenTypeSet;
41: public boolean hasEOF;
42:
43: public LookaheadSet() {
44: tokenTypeSet = new IntervalSet();
45: }
46:
47: public LookaheadSet(IntSet s) {
48: this ();
49: tokenTypeSet.addAll(s);
50: }
51:
52: public LookaheadSet(int atom) {
53: tokenTypeSet = IntervalSet.of(atom);
54: }
55:
56: public void orInPlace(LookaheadSet other) {
57: this .tokenTypeSet.addAll(other.tokenTypeSet);
58: this .hasEOF = this .hasEOF || other.hasEOF;
59: }
60:
61: public boolean member(int a) {
62: return tokenTypeSet.member(a);
63: }
64:
65: public void remove(int a) {
66: tokenTypeSet = tokenTypeSet.subtract(IntervalSet.of(a));
67: }
68:
69: public String toString(Grammar g) {
70: if (tokenTypeSet == null) {
71: if (hasEOF) {
72: return "EOF";
73: }
74: return "";
75: }
76: String r = tokenTypeSet.toString(g);
77: if (hasEOF) {
78: return r + "+EOF";
79: }
80: return r;
81: }
82:
83: public static LookaheadSet EOF() {
84: LookaheadSet eof = new LookaheadSet();
85: eof.hasEOF = true;
86: return eof;
87: }
88:
89: public String toString() {
90: return toString(null);
91: }
92: }
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