/// <summary>
/// The current token is unexpected, report an error and consume it.
/// </summary>
public static TextSpan UnexpectedToken(this ITokenIterator tokens)
{
// TODO shouldn't we ignore or combine unexpected token errors until we parse something successfully?
var span = tokens.Current.Span;
tokens.Context.Diagnostics.Add(ParseError.UnexpectedToken(tokens.Context.File, span));
tokens.Next();
return(span);
}
private Token ReadToken(int distance)
{
while (distance >= _readTokens.Count)
{
_readTokens.Add(_tokenIterator.Next());
}
return(_readTokens[distance]);
}
public static T?AcceptToken <T>(this ITokenIterator <IToken> tokens)
where T : class, IToken
{
if (tokens.Current is T token)
{
tokens.Next();
return(token);
}
return(null);
}
public static bool Accept <T>(this ITokenIterator <IToken> tokens)
where T : class, IToken
{
if (tokens.Current is T)
{
tokens.Next();
return(true);
}
return(false);
}
public bool Next()
{
do
{
if (!tokens.Next())
{
return(false);
}
} while (tokens.Current is ITriviaToken);
return(true);
}
public static (TextSpan, IIdentifierToken) ExpectIdentifier(this ITokenIterator tokens)
{
if (tokens.Current is IIdentifierToken identifier)
{
tokens.Next();
return(identifier.Span, identifier);
}
tokens.Context.Diagnostics.Add(
ParseError.MissingToken(tokens.Context.File, typeof(IIdentifierToken), tokens.Current));
return(new TextSpan(tokens.Current.Span.Start, 0), null);
}
public LexResult(ITokenIterator iterator)
{
var tokens = new List <IToken>();
do
{
tokens.Add(iterator.Current);
} while (iterator.Next());
File = iterator.Context.File;
Tokens = tokens.ToFixedList();
Diagnostics = iterator.Context.Diagnostics.Build();
}
public static T RequiredToken <T>(this ITokenIterator <IToken> tokens)
where T : IToken
{
if (tokens.Current is T token)
{
tokens.Next();
return(token);
}
tokens.Context.Diagnostics.Add(
ParseError.MissingToken(tokens.Context.File, typeof(T), tokens.Current));
throw new ParseFailedException($"Requires {typeof(T).GetFriendlyName()}, found {tokens.Current.GetType().GetFriendlyName()}");
}
public static TextSpan Expect <T>(this ITokenIterator <IToken> tokens)
where T : IToken
{
if (tokens.Current is T token)
{
tokens.Next();
return(token.Span);
}
tokens.Context.Diagnostics.Add(
ParseError.MissingToken(tokens.Context.File, typeof(T), tokens.Current));
// An empty span at the current location
return(new TextSpan(tokens.Current.Span.Start, 0));
}