/// <summary>Parser standard (for all levels) prefix <n>. </summary>
/// <param name="ctx">parser context.</param>
/// <returns>True if prefix read correctly; otherwise, false.</returns>
public static bool ReadSyslogPrefix(this ParserContext ctx)
{
try
{
ctx.Position = 0;
ctx.ReadSymbol(SyslogChars.LT);
var digits = ctx.ReadDigits(3);
ctx.ReadSymbol(SyslogChars.GT);
ctx.Prefix = ctx.Text.Substring(0, ctx.Position);
return(true);
}
catch (Exception)
{
ctx.Position = 0;
return(false);
}
}
public static bool TryParseTimestamp(ParserContext ctx)
{
// sometimes there's starting space
if (ctx.Current == SyslogChars.Space)
{
ctx.SkipSpaces();
}
// some messages start with some numeric Id:
// <139>36177473: Mar 4 17:21:18 UTC:
if (char.IsDigit(ctx.Current))
{
// make sure it's not a year and at least 5 chars
var fiveDigits = ctx.Text.Substring(ctx.Position, 5).All(ch => char.IsDigit(ch));
if (fiveDigits)
{
var savePos = ctx.Position;
var digits = ctx.ReadDigits(20);
if (ctx.Match(": "))
{
// we swallowed this numeric prefix and ': ' after that, nothing to do
}
else
{
ctx.Position = savePos; // rollback, timestamp evaluation will go from string start
}
}
}
try
{
// quick guess - if it contains current month name
if (TryParseIfStartsWithYear(ctx) || TryParseTimestampWithMonthName(ctx) ||
TryParseIfStartsWithColonThenYear(ctx) || TryParseIfStartsWithSpace(ctx))
{
return(true);
}
}
catch (Exception ex)
{
ctx.ErrorMessages.Add(ex.ToString());
}
return(false);
}
public static int ReadNumber(this ParserContext ctx, int maxDigits = 10)
{
var digits = ctx.ReadDigits(maxDigits);
return(int.Parse(digits));
}
