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 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));
}
