internal sealed override InternalResult <TToken> Parse(ref ParseState <TToken> state)
{
var x = state.Peek();
if (!x.HasValue)
{
state.Error = new ParseError <TToken>(
x,
true,
Expected,
state.SourcePos,
null
);
return(InternalResult.Failure <TToken>(false));
}
var val = x.GetValueOrDefault();
if (!_predicate(val))
{
state.Error = new ParseError <TToken>(
x,
false,
Expected,
state.SourcePos,
null
);
return(InternalResult.Failure <TToken>(false));
}
state.Advance();
return(InternalResult.Success <TToken>(val, true));
}
internal sealed override InternalResult <TEnumerable> Parse(ref ParseState <TToken> state)
{
var span = state.Peek(_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.SourcePos,
null
);
state.AddExpected(new Expected <TToken>(_valueTokens));
return(InternalResult.Failure <TEnumerable>(errorPos > 0));
}
if (span.Length < _valueTokens.Length)
{
// strings matched but reached EOF
state.Advance(span.Length);
state.Error = new InternalError <TToken>(
Maybe.Nothing <TToken>(),
true,
state.SourcePos,
null
);
state.AddExpected(new Expected <TToken>(_valueTokens));
return(InternalResult.Failure <TEnumerable>(span.Length > 0));
}
// OK
state.Advance(_valueTokens.Length);
return(InternalResult.Success <TEnumerable>(_value, _valueTokens.Length > 0));
}
internal sealed override InternalResult <Unit> Parse(ref ParseState <TToken> state)
{
var result = state.Peek();
if (result.HasValue)
{
state.Error = new ParseError <TToken>(
result,
false,
Expected,
state.SourcePos,
null
);
return(InternalResult.Failure <Unit>(false));
}
return(InternalResult.Success(Unit.Value, false));
}
internal sealed override InternalResult <string> Parse(ref ParseState <char> state)
{
var consumedInput = false;
var builder = new PooledStringBuilder(_value.Length);
foreach (var c in _value)
{
var result = state.Peek();
if (!result.HasValue)
{
state.Error = new ParseError <char>(
result,
true,
Expected,
state.SourcePos,
null
);
return(InternalResult.Failure <string>(consumedInput));
}
var token = result.GetValueOrDefault();
if (char.ToLowerInvariant(token) != c)
{
state.Error = new ParseError <char>(
result,
false,
Expected,
state.SourcePos,
null
);
return(InternalResult.Failure <string>(consumedInput));
}
consumedInput = true;
builder.Append(token);
state.Advance();
}
return(InternalResult.Success <string>(builder.GetStringAndClear(), consumedInput));
}
internal sealed override InternalResult <Unit> Parse(ref ParseState <TToken> state)
{
var startingPosition = state.SourcePos;
var token = state.Peek();
var result = _parser.Parse(ref state);
if (result.Success)
{
state.Error = new ParseError <TToken>(
token,
false,
null,
startingPosition,
null
);
return(InternalResult.Failure <Unit>(result.ConsumedInput));
}
return(InternalResult.Success(
Unit.Value,
result.ConsumedInput
));
}
internal sealed override InternalResult <TEnumerable> Parse(ref ParseState <TToken> state)
{
var consumedInput = false;
foreach (var x in _valueTokens)
{
var result = state.Peek();
if (!result.HasValue)
{
state.Error = new ParseError <TToken>(
result,
true,
Expected,
state.SourcePos,
null
);
return(InternalResult.Failure <TEnumerable>(consumedInput));
}
TToken token = result.GetValueOrDefault();
if (!EqualityComparer <TToken> .Default.Equals(token, x))
{
state.Error = new ParseError <TToken>(
result,
false,
Expected,
state.SourcePos,
null
);
return(InternalResult.Failure <TEnumerable>(consumedInput));
}
consumedInput = true;
state.Advance();
}
return(InternalResult.Success <TEnumerable>(_value, consumedInput));
}
