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Add another unit test to show when to keep looking for lookahead during prediction

This commit is contained in:
Terence Parr 2012-10-13 15:41:42 -07:00
parent a9ccda48ab
commit 742887c9b1
1 changed files with 17 additions and 39 deletions
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56
tool/test/org/antlr/v4/test/TestATNParserPrediction.java
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@ -411,7 +411,7 @@ public class TestATNParserPrediction extends BaseTest {
checkDFAConstruction(lg, g, decision, inputs, dfa);
}
@Test public void testAmbigDef() throws Exception {
@Test public void testContinuePrediction() throws Exception {
// Sam found prev def of ambiguity was too restrictive.
// E.g., (13, 1, []), (13, 2, []), (12, 2, []) should not
// be declared ambig since (12, 2, []) can take us to
@ -429,45 +429,23 @@ public class TestATNParserPrediction extends BaseTest {
int decision = 1;
checkPredictedAlt(lg, g, decision, "a;", 1);
checkPredictedAlt(lg, g, decision, "ab;", 2);
}
// After matching these inputs for decision, what is DFA after each prediction?
// String[] inputs = {
// "34a",
// "34ab",
// "((34))a",
// "((34))ab",
// };
// String[] dfa = {
// "s0-INT->s1\n" +
// "s1-'a'->s2\n" +
// "s2-EOF->:s3=>1\n",
//
// "s0-INT->s1\n" +
// "s1-'a'->s2\n" +
// "s2-EOF->:s3=>1\n" +
// "s2-'b'->:s4=>2\n",
//
// "s0-'('->s5\n" +
// "s0-INT->s1\n" +
// "s1-'a'->s2\n" +
// "s2-EOF->:s3=>1\n" +
// "s2-'b'->:s4=>2\n" +
// "s5-'('->s6\n" +
// "s6-INT->s7\n" +
// "s7-')'->s8\n" +
// "s8-')'->s1\n",
//
// "s0-'('->s5\n" +
// "s0-INT->s1\n" +
// "s1-'a'->s2\n" +
// "s2-EOF->:s3=>1\n" +
// "s2-'b'->:s4=>2\n" +
// "s5-'('->s6\n" +
// "s6-INT->s7\n" +
// "s7-')'->s8\n" +
// "s8-')'->s1\n",
// };
// checkDFAConstruction(lg, g, decision, inputs, dfa);
@Test public void testContinuePrediction2() throws Exception {
// ID is ambig for first two alts, but ID SEMI lets us move forward with alt 3
LexerGrammar lg = new LexerGrammar(
"lexer grammar L;\n" +
"ID : 'a'..'z' ;\n" + // one char
"SEMI : ';' ;\n"+
"INT : '0'..'9'+ ;\n"
);
Grammar g = new Grammar(
"parser grammar T;\n"+
"tokens {ID,SEMI,INT}\n" +
"a : ID | ID | ID SEMI ;\n");
int decision = 0;
checkPredictedAlt(lg, g, decision, "a", 1);
checkPredictedAlt(lg, g, decision, "a;", 3);
}
/** first check that the ATN predicts right alt.