1/*
2 * [The "BSD license"]
3 *  Copyright (c) 2010 Terence Parr
4 *  All rights reserved.
5 *
6 *  Redistribution and use in source and binary forms, with or without
7 *  modification, are permitted provided that the following conditions
8 *  are met:
9 *  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 */
28package org.antlr.test;
29
30import org.antlr.analysis.DFA;
31import org.antlr.analysis.NFA;
32import org.antlr.runtime.ANTLRStringStream;
33import org.antlr.tool.Grammar;
34import org.junit.Test;
35
36public class TestDFAMatching extends BaseTest {
37
38    /** Public default constructor used by TestRig */
39    public TestDFAMatching() {
40    }
41
42    @Test public void testSimpleAltCharTest() throws Exception {
43        Grammar g = new Grammar(
44                "lexer grammar t;\n"+
45                "A : {;}'a' | 'b' | 'c';");
46		g.buildNFA();
47		g.createLookaheadDFAs(false);
48        DFA dfa = g.getLookaheadDFA(1);
49        checkPrediction(dfa,"a",1);
50        checkPrediction(dfa,"b",2);
51        checkPrediction(dfa,"c",3);
52        checkPrediction(dfa,"d", NFA.INVALID_ALT_NUMBER);
53    }
54
55    @Test public void testSets() throws Exception {
56        Grammar g = new Grammar(
57                "lexer grammar t;\n"+
58                "A : {;}'a'..'z' | ';' | '0'..'9' ;");
59		g.buildNFA();
60        g.createLookaheadDFAs(false);
61        DFA dfa = g.getLookaheadDFA(1);
62        checkPrediction(dfa,"a",1);
63        checkPrediction(dfa,"q",1);
64        checkPrediction(dfa,"z",1);
65        checkPrediction(dfa,";",2);
66        checkPrediction(dfa,"9",3);
67    }
68
69    @Test public void testFiniteCommonLeftPrefixes() throws Exception {
70        Grammar g = new Grammar(
71                "lexer grammar t;\n"+
72                "A : 'a' 'b' | 'a' 'c' | 'd' 'e' ;");
73		g.buildNFA();
74        g.createLookaheadDFAs(false);
75        DFA dfa = g.getLookaheadDFA(1);
76        checkPrediction(dfa,"ab",1);
77        checkPrediction(dfa,"ac",2);
78        checkPrediction(dfa,"de",3);
79        checkPrediction(dfa,"q", NFA.INVALID_ALT_NUMBER);
80    }
81
82    @Test public void testSimpleLoops() throws Exception {
83        Grammar g = new Grammar(
84                "lexer grammar t;\n"+
85                "A : (DIGIT)+ '.' DIGIT | (DIGIT)+ ;\n" +
86                "fragment DIGIT : '0'..'9' ;\n");
87		g.buildNFA();
88        g.createLookaheadDFAs(false);
89        DFA dfa = g.getLookaheadDFA(3);
90        checkPrediction(dfa,"32",2);
91        checkPrediction(dfa,"999.2",1);
92        checkPrediction(dfa,".2", NFA.INVALID_ALT_NUMBER);
93    }
94
95    protected void checkPrediction(DFA dfa, String input, int expected)
96        throws Exception
97    {
98        ANTLRStringStream stream = new ANTLRStringStream(input);
99        assertEquals(dfa.predict(stream), expected);
100    }
101
102}
103