public void CanReadAhead_OnMovedEnumeratorWithinSequence_ReturnsTrue()
{
var enumerator = new ReadAheadEnumerator<char>("ab");
enumerator.MoveNext();
enumerator.CanReadAhead.Should().BeTrue();
}
public void CanReadAhead_OnLastItem_ReturnsFalse()
{
var enumerator = new ReadAheadEnumerator<char>("ab");
enumerator.MoveNext();
enumerator.MoveNext();
enumerator.CanReadAhead.Should().BeFalse();
}
private IToken GetToken(ReadAheadEnumerator<char> enumerator)
{
var c = enumerator.Current;
if (char.IsLetterOrDigit(c))
return new Character(c);
if (c == ' ' || c == '\t')
return new Character(c);
if (@".:,;-/\(){}#+*".Contains(c))
return new Character(c);
if (c == '\r' && enumerator.CanReadAhead && enumerator.ItemAhead == '\n')
{
enumerator.MoveNext();
return new EOL();
}
throw new ArgumentOutOfRangeException("c", string.Format("'{0}' is not a supported character.", c));
}
public IEnumerable<IToken> Tokenize(string inputText)
{
var enumer = new ReadAheadEnumerator<char>(inputText);
while (enumer.MoveNext())
{
yield return GetToken(enumer);
//if (enumer.ReadAhead(1) == '\n')
//{
// enumer.MoveNext();
// yield return
//}
}
//foreach (char c in inputText)
//{
// yield return GetToken(c);
//}
yield return new EOF();
}
public void ApiDemo()
{
var enumerator = new ReadAheadEnumerator<char>("ab");
bool thereIsAnItem;
Action moveNextAction = () => { enumerator.MoveNext(); };
char currentItem;
Action getCurrentAction = () => { var dummy = enumerator.Current; };
Action getItemAheadAction = () => { var dummy = enumerator.ItemAhead; };
// Enumerator has not been moved
getCurrentAction.ShouldThrow<InvalidOperationException>()
.WithMessage("Move next has never been called.");
// Move to the 1st item
thereIsAnItem = enumerator.MoveNext();
thereIsAnItem.Should().BeTrue();
currentItem = enumerator.Current;
currentItem.Should().Be('a');
enumerator.CanReadAhead.Should().BeTrue();
enumerator.ItemAhead.Should().Be('b');
// Move to the 2nd item
thereIsAnItem = enumerator.MoveNext();
thereIsAnItem.Should().BeTrue();
enumerator.Current.Should().Be('b');
enumerator.CanReadAhead.Should().BeFalse();
getItemAheadAction.ShouldThrow<InvalidOperationException>()
.WithMessage("The enumerator reached the last item of the sequence and thus cannot read ahead.");
// Move beyond the end
thereIsAnItem = enumerator.MoveNext();
thereIsAnItem.Should().BeFalse();
getCurrentAction.ShouldThrow<InvalidOperationException>()
.WithMessage("The enumerator reached the end of the sequence.");
moveNextAction.ShouldThrow<InvalidOperationException>()
.WithMessage("The enumerator reached the end of the sequence.");
}
public void Current_AfterTheFirstMoveNext_ReturnsTheFirstItem()
{
var enumerator = new ReadAheadEnumerator<char>("ab");
enumerator.MoveNext();
var actual = enumerator.Current;
actual.Should().Be('a');
}
public void MoveNext_ToTheLastItem_ReturnsTrue()
{
var enumerator = new ReadAheadEnumerator<char>("ab");
enumerator.MoveNext();
// Act
var actual = enumerator.MoveNext();
actual.Should().BeTrue();
}
public void MoveNext_OnNewEnumeratorWithNonEmptySequence_ReturnsTrue()
{
var enumerator = new ReadAheadEnumerator<char>("ab");
var actual = enumerator.MoveNext();
actual.Should().BeTrue();
}
public void ItemAhead_OnLastItem_ThrowsProperException()
{
var enumerator = new ReadAheadEnumerator<char>("ab");
enumerator.MoveNext();
enumerator.MoveNext();
new Action(() => { var dummy = enumerator.ItemAhead; }).ShouldThrow<InvalidOperationException>()
.WithMessage("The enumerator reached the last item of the sequence and thus cannot read ahead.");
}
public void FullScenarioWithEmptySequence()
{
var enumerator = new ReadAheadEnumerator<char>("");
Action moveNextAction = () => { enumerator.MoveNext(); };
Action getCurrentAction = () => { var dummy = enumerator.Current; };
Action getItemAheadAction = () => { var dummy = enumerator.ItemAhead; };
var thereIsAnItem = enumerator.MoveNext();
thereIsAnItem.Should().BeFalse();
enumerator.CanReadAhead.Should().BeFalse();
getCurrentAction.ShouldThrow<InvalidOperationException>();
getItemAheadAction.ShouldThrow<InvalidOperationException>();
moveNextAction.ShouldThrow<InvalidOperationException>();
}
public void Current_OnNewEnumeratorWithinSequence_ThrowsAProperException()
{
var enumerator = new ReadAheadEnumerator<char>("ab");
new Action(() => { var dummy = enumerator.Current; }).ShouldThrow<InvalidOperationException>()
.WithMessage("Move next has never been called.");
}
