/*
* [The "BSD license"]
* Copyright (c) 2010 Terence Parr
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
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* 2. Redistributions in binary form must reproduce the above copyright
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* documentation and/or other materials provided with the distribution.
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* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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package org.antlr.test;
import org.antlr.analysis.DFA;
import org.antlr.analysis.NFA;
import org.antlr.runtime.ANTLRStringStream;
import org.antlr.tool.Grammar;
import org.junit.Test;
public class TestDFAMatching extends BaseTest {
/** Public default constructor used by TestRig */
public TestDFAMatching() {
}
@Test public void testSimpleAltCharTest() throws Exception {
Grammar g = new Grammar(
"lexer grammar t;\n"+
"A : {;}'a' | 'b' | 'c';");
g.buildNFA();
g.createLookaheadDFAs(false);
DFA dfa = g.getLookaheadDFA(1);
checkPrediction(dfa,"a",1);
checkPrediction(dfa,"b",2);
checkPrediction(dfa,"c",3);
checkPrediction(dfa,"d", NFA.INVALID_ALT_NUMBER);
}
@Test public void testSets() throws Exception {
Grammar g = new Grammar(
"lexer grammar t;\n"+
"A : {;}'a'..'z' | ';' | '0'..'9' ;");
g.buildNFA();
g.createLookaheadDFAs(false);
DFA dfa = g.getLookaheadDFA(1);
checkPrediction(dfa,"a",1);
checkPrediction(dfa,"q",1);
checkPrediction(dfa,"z",1);
checkPrediction(dfa,";",2);
checkPrediction(dfa,"9",3);
}
@Test public void testFiniteCommonLeftPrefixes() throws Exception {
Grammar g = new Grammar(
"lexer grammar t;\n"+
"A : 'a' 'b' | 'a' 'c' | 'd' 'e' ;");
g.buildNFA();
g.createLookaheadDFAs(false);
DFA dfa = g.getLookaheadDFA(1);
checkPrediction(dfa,"ab",1);
checkPrediction(dfa,"ac",2);
checkPrediction(dfa,"de",3);
checkPrediction(dfa,"q", NFA.INVALID_ALT_NUMBER);
}
@Test public void testSimpleLoops() throws Exception {
Grammar g = new Grammar(
"lexer grammar t;\n"+
"A : (DIGIT)+ '.' DIGIT | (DIGIT)+ ;\n" +
"fragment DIGIT : '0'..'9' ;\n");
g.buildNFA();
g.createLookaheadDFAs(false);
DFA dfa = g.getLookaheadDFA(3);
checkPrediction(dfa,"32",2);
checkPrediction(dfa,"999.2",1);
checkPrediction(dfa,".2", NFA.INVALID_ALT_NUMBER);
}
protected void checkPrediction(DFA dfa, String input, int expected)
throws Exception
{
ANTLRStringStream stream = new ANTLRStringStream(input);
assertEquals(dfa.predict(stream), expected);
}
}