public override Parser <TInput> VisitFails(FailsParser <TInput> parser)
{
if (state.State == 0)
{
if (source.IsEnd(state.InputStart))
{
state.InputLength = 0;
return(null);
}
else
{
state.State++;
return(parser.Pattern);
}
}
else
{
if (state.LastResult >= 0)
{
state.InputLength = -1;
}
else
{
state.InputLength = 0;
}
return(null);
}
}
public override Parser <TInput> VisitNot(NotParser <TInput> parser)
{
// for finding, allow not appear to succeed so that things that condition on it will continue to find.
if (source.IsEnd(state.InputStart))
{
state.InputLength = 0;
this.prevWasMissing = false;
return(null);
}
var len = parser.Pattern.Scan(source, state.InputStart);
if (len >= 0)
{
state.InputLength = -1;
this.prevWasMissing = false;
return(null);
}
else
{
state.InputLength = 1;
this.prevWasMissing = false;
return(null);
}
}
public override int VisitNot(NotParser <TInput> parser, int start)
{
_prevWasMissing = false;
// for finding, allow not appear to succeed so that things that condition on it will continue to find.
if (_source.IsEnd(start))
{
return(0);
}
var len = parser.Pattern.Scan(_source, start);
if (len >= 0)
{
return(-1);
}
else
{
return(1);
}
}
/// <summary>
/// Matches one or more lexical tokens to the corresponding text.
/// </summary>
private static int MatchesText(Source <LexicalToken> source, int start, string text)
{
// consume all lexical tokens with combined text that matches the specified text
int textOffset = 0;
int i = 0;
for (; !source.IsEnd(start + i); i++)
{
var token = source.Peek(start + i);
// only first token can have trivia
if (i > 0 && token.Trivia.Length > 0)
{
break;
}
// token has more text than remaining
if (token.Text.Length > text.Length - textOffset)
{
break;
}
// text parts must match exactly
if (string.Compare(token.Text, 0, text, textOffset, token.Text.Length) != 0)
{
break;
}
textOffset += token.Text.Length;
if (textOffset == text.Length)
{
return(i + 1);
}
}
return(-(i + 1));
}