internal sealed override bool TryParse(ref ParseState <TToken> state, ref ExpectedCollector <TToken> expecteds, out TToken result)
{
if (!state.HasCurrent)
{
state.Error = new InternalError <TToken>(
Maybe.Nothing <TToken>(),
true,
state.Location,
null
);
expecteds.Add(Expected);
result = default;
return(false);
}
var token = state.Current;
if (!EqualityComparer <TToken> .Default.Equals(token, _token))
{
state.Error = new InternalError <TToken>(
Maybe.Just(token),
false,
state.Location,
null
);
expecteds.Add(Expected);
result = default;
return(false);
}
state.Advance();
result = token;
return(true);
}
// see comment about expecteds in ParseState.Error.cs
internal sealed override bool TryParse(ref ParseState <TToken> state, ref ExpectedCollector <TToken> expecteds, out T result)
{
var firstTime = true;
var err = new InternalError <TToken>(
Maybe.Nothing <TToken>(),
false,
state.Location,
"OneOf had no arguments"
);
var childExpecteds = new ExpectedCollector <TToken>(); // the expecteds for all loop iterations
var grandchildExpecteds = new ExpectedCollector <TToken>(); // the expecteds for the current loop iteration
foreach (var p in _parsers)
{
var thisStartLoc = state.Location;
var success = p.TryParse(ref state, ref grandchildExpecteds, out result);
if (success)
{
// throw out all expecteds
grandchildExpecteds.Dispose();
childExpecteds.Dispose();
return(true);
}
// 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 (state.Location > thisStartLoc)
{
// throw out all expecteds except this one
expecteds.Add(ref grandchildExpecteds);
childExpecteds.Dispose();
grandchildExpecteds.Dispose();
result = default;
return(false);
}
childExpecteds.Add(ref grandchildExpecteds);
grandchildExpecteds.Clear();
// 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;
expecteds.Add(ref childExpecteds);
childExpecteds.Dispose();
grandchildExpecteds.Dispose();
result = default;
return(false);
}
internal sealed override bool TryParse(ref ParseState <TToken> state, ref ExpectedCollector <TToken> expecteds, out TEnumerable result)
{
var span = state.LookAhead(_valueTokens.Length); // span.Length <= _valueTokens.Length
var errorPos = -1;
for (var i = 0; i < span.Length; i++)
{
if (!EqualityComparer <TToken> .Default.Equals(span[i], _valueTokens[i]))
{
errorPos = i;
break;
}
}
if (errorPos != -1)
{
// strings didn't match
state.Advance(errorPos);
state.Error = new InternalError <TToken>(
Maybe.Just(span[errorPos]),
false,
state.Location,
null
);
expecteds.Add(new Expected <TToken>(_valueTokens));
result = default;
return(false);
}
if (span.Length < _valueTokens.Length)
{
// strings matched but reached EOF
state.Advance(span.Length);
state.Error = new InternalError <TToken>(
Maybe.Nothing <TToken>(),
true,
state.Location,
null
);
expecteds.Add(new Expected <TToken>(_valueTokens));
result = default;
return(false);
}
// OK
state.Advance(_valueTokens.Length);
result = _value;
return(true);
}
internal sealed override bool TryParse(ref ParseState <char> state, ref ExpectedCollector <char> expecteds, out string result)
{
var span = state.LookAhead(_value.Length); // span.Length <= _valueTokens.Length
var errorPos = -1;
for (var i = 0; i < span.Length; i++)
{
if (!char.ToLowerInvariant(span[i]).Equals(char.ToLowerInvariant(_value[i])))
{
errorPos = i;
break;
}
}
if (errorPos != -1)
{
// strings didn't match
state.Advance(errorPos);
state.Error = new InternalError <char>(
Maybe.Just(span[errorPos]),
false,
state.Location,
null
);
expecteds.Add(Expected);
result = null;
return(false);
}
if (span.Length < _value.Length)
{
// strings matched but reached EOF
state.Advance(span.Length);
state.Error = new InternalError <char>(
Maybe.Nothing <char>(),
true,
state.Location,
null
);
expecteds.Add(Expected);
result = null;
return(false);
}
// OK
state.Advance(_value.Length);
result = span.ToString();
return(true);
}
internal sealed override bool TryParse(ref ParseState <TToken> state, ref ExpectedCollector <TToken> expecteds, out T result)
{
var childExpecteds = new ExpectedCollector <TToken>();
var success = _parser.TryParse(ref state, ref childExpecteds, out result);
expecteds.AddIf(ref childExpecteds, success);
childExpecteds.Dispose();
if (!success)
{
return(false);
}
if (!_predicate(result))
{
state.Error = new InternalError <TToken>(
Maybe.Nothing <TToken>(),
false,
state.Location,
_message(result)
);
expecteds.Add(_expected);
result = default;
return(false);
}
return(true);
}
internal sealed override bool TryParse(ref ParseState <TToken> state, ref ExpectedCollector <TToken> expecteds, out T result)
{
state.Error = new InternalError <TToken>(
Maybe.Nothing <TToken>(),
false,
state.Location,
_message
);
expecteds.Add(_expected);
result = default;
return(false);
}
internal sealed override bool TryParse(ref ParseState <TToken> state, ref ExpectedCollector <TToken> expecteds, out T result)
{
var childExpecteds = new ExpectedCollector <TToken>(true);
var success = _parser.TryParse(ref state, ref childExpecteds, out result);
childExpecteds.Dispose();
if (!success)
{
expecteds.Add(_expected);
}
return(success);
}
// see comment about expecteds in ParseState.Error.cs
internal sealed override bool TryParse(ref ParseState <TToken> state, ref ExpectedCollector <TToken> expecteds, out IEnumerable <T>?result)
{
var ts = _keepResults ? new List <T>() : null;
var firstItemStartLoc = state.Location;
var firstItemSuccess = _parser.TryParse(ref state, ref expecteds, out var result1);
if (!firstItemSuccess)
{
// state.Error set by _parser
result = null;
return(false);
}
if (state.Location <= firstItemStartLoc)
{
throw new InvalidOperationException("Until() used with a parser which consumed no input");
}
ts?.Add(result1);
var terminatorExpecteds = new ExpectedCollector <TToken>();
var itemExpecteds = new ExpectedCollector <TToken>();
while (true)
{
var terminatorStartLoc = state.Location;
var terminatorSuccess = _terminator.TryParse(ref state, ref terminatorExpecteds, out var terminatorResult);
if (terminatorSuccess)
{
terminatorExpecteds.Dispose();
itemExpecteds.Dispose();
result = ts;
return(true);
}
if (state.Location > terminatorStartLoc)
{
// state.Error set by _terminator
expecteds.Add(ref terminatorExpecteds);
terminatorExpecteds.Dispose();
itemExpecteds.Dispose();
result = null;
return(false);
}
var itemStartLoc = state.Location;
var itemSuccess = _parser.TryParse(ref state, ref itemExpecteds, out var itemResult);
var itemConsumedInput = state.Location > itemStartLoc;
if (!itemSuccess)
{
if (!itemConsumedInput)
{
// get the expected from both _terminator and _parser
expecteds.Add(ref terminatorExpecteds);
expecteds.Add(ref itemExpecteds);
}
else
{
// throw out the _terminator expecteds and keep only _parser
expecteds.Add(ref itemExpecteds);
}
terminatorExpecteds.Dispose();
itemExpecteds.Dispose();
result = null;
return(false);
}
// throw out both sets of expecteds
terminatorExpecteds.Clear();
itemExpecteds.Clear();
if (!itemConsumedInput)
{
throw new InvalidOperationException("Until() used with a parser which consumed no input");
}
ts?.Add(itemResult);
}
}
