public static void ThrowScanException(IScanner scanner, string errorMessage)
{
var token = scanner.Peek();
var helpMessage = scanner.GetHelpMessage(token);
throw new ScanException($"{errorMessage}\r\n{helpMessage}");
}
public static TextSpan ConsumeAny <TTokenType>(this IScanner scanner, params TTokenType[] tokenTypes)
where TTokenType : struct
{
for (var i = 0; i < tokenTypes.Length; i++)
{
var tokenType = tokenTypes[i].ToString();
var token = scanner.Peek();
if (token.Type == tokenType)
{
scanner.Consume();
return(token);
}
}
var helpMessage = scanner.GetHelpMessage(scanner.Peek());
var tokenTypesStr = string.Join(",", tokenTypes.Select(x => x.ToString()));
throw new ScanException($"Expect one of {tokenTypesStr}.\r\n{helpMessage}");
}
public SqlDom ParseExp(int ctxPrecedence)
{
var prefixToken = _scanner.Consume();
if (prefixToken.IsEmpty)
{
throw new Exception($"expect token but found NONE");
}
PrefixParselet prefixParse = null;
try
{
prefixParse = SqlSpec.Instance.Prefix(prefixToken.Type);
}
catch (KeyNotFoundException)
{
var tokenStr = _scanner.GetSpanString(prefixToken);
var message = _scanner.GetHelpMessage(prefixToken);
throw new ParseException($"Prefix '{tokenStr}' Parse fail.\r\n" + message);
}
return(ProcessPrefix(prefixToken, prefixParse, ctxPrecedence));
}
public static string GetHelpMessage(this IScanner scanner)
{
var token = scanner.Peek();
return(scanner.GetHelpMessage(token));
}
