// see comment about expecteds in ParseState.Error.cs
internal sealed override InternalResult <T> Parse(ref ParseState <TToken> state)
{
var firstTime = true;
var err = new InternalError <TToken>(
Maybe.Nothing <TToken>(),
false,
state.Location,
"OneOf had no arguments"
);
state.BeginExpectedTran();
foreach (var p in _parsers)
{
state.BeginExpectedTran();
var thisResult = p.Parse(ref state);
if (thisResult.Success)
{
// throw out all expecteds
state.EndExpectedTran(false);
state.EndExpectedTran(false);
return(thisResult);
}
// we'll usually return the error from the first parser that didn't backtrack,
// even if other parsers had a longer match.
// There is some room for improvement here.
if (thisResult.ConsumedInput)
{
// throw out all expecteds except this one
var expected = state.ExpectedTranState();
state.EndExpectedTran(false);
state.EndExpectedTran(false);
state.AddExpected(expected.AsSpan());
expected.Dispose(clearArray: true);
return(thisResult);
}
state.EndExpectedTran(true);
// choose the longest match, preferring the left-most error in a tie,
// except the first time (avoid returning "OneOf had no arguments").
if (firstTime || state.Error.ErrorLocation > err.ErrorLocation)
{
err = state.Error;
}
firstTime = false;
}
state.Error = err;
state.EndExpectedTran(true);
return(InternalResult.Failure <T>(false));
}
// see comment about expecteds in ParseState.Error.cs
internal override InternalResult <T> Parse(ref ParseState <TToken> state)
{
state.BeginExpectedTran();
var result = _parser.Parse(ref state);
if (result.Success)
{
state.EndExpectedTran(false);
return(result);
}
var parserExpecteds = state.ExpectedTranState();
state.EndExpectedTran(false);
var recoverParser = _errorHandler(state.BuildError(parserExpecteds.AsEnumerable()));
parserExpecteds.Dispose(clearArray: true);
return(recoverParser.Parse(ref state));
}
// see comment about expecteds in ParseState.Error.cs
internal override InternalResult <IEnumerable <T> > Parse(ref ParseState <TToken> state)
{
var ts = _keepResults ? new List <T>() : null;
var firstItemResult = _parser.Parse(ref state);
if (!firstItemResult.Success)
{
// state.Error set by _parser
return(InternalResult.Failure <IEnumerable <T> >(firstItemResult.ConsumedInput));
}
if (!firstItemResult.ConsumedInput)
{
throw new InvalidOperationException("Until() used with a parser which consumed no input");
}
ts?.Add(firstItemResult.Value);
while (true)
{
state.BeginExpectedTran();
var terminatorResult = _terminator.Parse(ref state);
if (terminatorResult.Success)
{
state.EndExpectedTran(false);
return(InternalResult.Success <IEnumerable <T> >(ts, true));
}
if (terminatorResult.ConsumedInput)
{
// state.Error set by _terminator
state.EndExpectedTran(true);
return(InternalResult.Failure <IEnumerable <T> >(true));
}
state.BeginExpectedTran();
var itemResult = _parser.Parse(ref state);
if (!itemResult.Success)
{
if (!itemResult.ConsumedInput)
{
// get the expected from both _terminator and _parser
state.EndExpectedTran(true);
state.EndExpectedTran(true);
}
else
{
// throw out the _terminator expecteds and keep only _parser
var itemExpected = state.ExpectedTranState();
state.EndExpectedTran(false);
state.EndExpectedTran(false);
state.AddExpected(itemExpected.AsSpan());
itemExpected.Dispose();
}
return(InternalResult.Failure <IEnumerable <T> >(true));
}
// throw out both sets of expecteds
state.EndExpectedTran(false);
state.EndExpectedTran(false);
if (!itemResult.ConsumedInput)
{
throw new InvalidOperationException("Until() used with a parser which consumed no input");
}
ts?.Add(itemResult.Value);
}
}