public Token <T> MatchNext(TokenizableDataStream <T> data, ref SourcePosition streamPos, MessageLog log)
{
data.PushSnapshot();
Token <T> token = Match(data, ref streamPos, log);
if (token == null)
{
data.PopSnapshot();
}
else
{
data.DiscardSnapshot();
}
return(token);
}
public void TestStreamTokenizer()
{
String source = "123456789ABCDEF";
Func<List<String>> input = () => source.ToCharArray()
.Select(i => i.ToString(CultureInfo.InvariantCulture))
.ToList();
TokenizableDataStream<String> data = new TokenizableDataStream<String>(input);
// Take base snapshot for later match
data.PushSnapshot();
// Match CurrentItem result
Assert.AreEqual(data.CurrentItem, "1");
// Match advance
data.Advance(3);
Assert.AreEqual(data.CurrentItem, "4");
// Snapshot and advance and then pop and ensure result
data.PushSnapshot();
data.Advance();
data.PopSnapshot();
Assert.AreEqual(data.CurrentItem, "4");
// Snapshot, advance, discard snapshot and ensure result
data.PushSnapshot();
data.Advance(3);
data.DiscardSnapshot();
Assert.AreEqual(data.CurrentItem, "7");
// Pop snapshot and assert that we are once again at the start
data.PopSnapshot();
Assert.AreEqual(data.CurrentItem, "1");
// Test AtEnd for non-eof
Assert.IsFalse(data.AtEnd());
// Advance too far and ensure that AtEnd returns
data.PushSnapshot();
data.Advance(23);
Assert.IsTrue(data.AtEnd());
// Assert that currentItem is null when out of range
Assert.IsNull(data.CurrentItem);
// Pop back to start and assert that LookAhead returns desired item
data.PopSnapshot();
Assert.AreEqual(data.LookAhead(4), "5");
// Assert that LookAhead returns null once out of range
Assert.IsNull(data.LookAhead(42));
}
public void TestStreamTokenizer()
{
String source = "123456789ABCDEF";
Func <List <String> > input = () => source.ToCharArray()
.Select(i => i.ToString(CultureInfo.InvariantCulture))
.ToList();
TokenizableDataStream <String> data = new TokenizableDataStream <String>(input);
// Take base snapshot for later match
data.PushSnapshot();
// Match CurrentItem result
Assert.AreEqual(data.CurrentItem, "1");
// Match advance
data.Advance(3);
Assert.AreEqual(data.CurrentItem, "4");
// Snapshot and advance and then pop and ensure result
data.PushSnapshot();
data.Advance();
data.PopSnapshot();
Assert.AreEqual(data.CurrentItem, "4");
// Snapshot, advance, discard snapshot and ensure result
data.PushSnapshot();
data.Advance(3);
data.DiscardSnapshot();
Assert.AreEqual(data.CurrentItem, "7");
// Pop snapshot and assert that we are once again at the start
data.PopSnapshot();
Assert.AreEqual(data.CurrentItem, "1");
// Test AtEnd for non-eof
Assert.IsFalse(data.AtEnd());
// Advance too far and ensure that AtEnd returns
data.PushSnapshot();
data.Advance(23);
Assert.IsTrue(data.AtEnd());
// Assert that currentItem is null when out of range
Assert.IsNull(data.CurrentItem);
// Pop back to start and assert that LookAhead returns desired item
data.PopSnapshot();
Assert.AreEqual(data.LookAhead(4), "5");
// Assert that LookAhead returns null once out of range
Assert.IsNull(data.LookAhead(42));
}