public override ParseResult Parse(ParseContext ctx)
{
var oldPos = ctx.CurrentPosition;
var matchedParseMark = 0;
ParseResult matchedChoiceResult = null;
var matchedChoice = Elements.FirstOrDefault(e =>
{
ctx.CurrentPosition = oldPos;
ctx.StartMatch();
var result = e.Element.Parse(ctx);
var resultIsSuccess = result?.IsSuccess ?? false;
if (resultIsSuccess)
{
ctx.EndMatch(SaveChoice, this);
}
else
{
ctx.UndoMatch();
}
matchedParseMark = !(result?.IsOptionallyMatched ?? false) ? result?.ParseMark ?? 0 : 0;
if (!resultIsSuccess)
{
ctx.CurrentPosition = oldPos;
}
if (resultIsSuccess)
{
matchedChoiceResult = result;
}
return(resultIsSuccess);
});
if (matchedChoice == null)
{
return(ParseResult.Failure(ctx));
}
var success = ParseResult.Success(ctx);
if (!(matchedChoiceResult?.IsOptionallyMatched ?? false))
{
success.ParseMark ^= matchedChoice.ParseMark ^ matchedParseMark;
}
return(success);
}
