public override Parser <TInput> VisitBest(BestParser <TInput> parser)
{
if (state.State == 0)
{
int minLength = -1;
int maxLength = -1;
int bestParser = -1;
// figure out which parser will consume most input
for (int i = 0; i < parser.Parsers.Count; i++)
{
var p = parser.Parsers[i];
var length = scanner.Scan(p, state.InputStart);
if (length > maxLength)
{
maxLength = length;
bestParser = i;
}
else if (length < minLength)
{
minLength = length;
}
}
if (maxLength >= 0)
{
state.State = 1;
state.NextOutputStart = state.OutputStart;
return(parser.Parsers[bestParser]);
}
else
{
state.InputLength = -1;
return(null);
}
}
else
{
state.InputLength = state.LastResult;
return(null);
}
}
/// <summary>
/// Parse using a state machine, does not use the call stack.
/// </summary>
public SearchResult Search(Parser <TInput> parser, int start, bool initialPrevWasMissing)
{
this.state = default(SearchState);
this.stackPosition = -1;
this.prevWasMissing = initialPrevWasMissing;
Push(parser, start, initialPrevWasMissing);
Parser <TInput> nextParser = null;
while (true)
{
if (this.state.Parser.IsHidden)
{
this.state.InputLength = scanner.Scan(this.state.Parser, this.state.InputStart);
nextParser = null;
}
else
{
if (this.state.State == 0)
{
beforeAction(this.state.Parser, source, this.state.InputStart, this.prevWasMissing);
}
nextParser = this.state.Parser.Accept(this);
}
if (nextParser != null)
{
Push(nextParser, inputStart: this.state.InputStart + this.state.InputLength, prevWasMissing: this.prevWasMissing);
}
else
{
var length = this.state.InputLength;
this.afterAction?.Invoke(this.state.Parser);
if (this.stackPosition == 0)
{
return(new SearchResult(length, this.prevWasMissing));
}
else
{
Pop();
this.state.LastResult = length;
}
}
}
}