private Tuple <string, List <NameValuePair> > ParseElement(ParserContext ctx)
{
if (ctx.Current != SyslogChars.Lbr)
{
return(null);
}
ctx.Position++;
var elemName = ctx.ReadWord();
ctx.SkipSpaces();
var paramList = new List <NameValuePair>();
var elem = new Tuple <string, List <NameValuePair> >(elemName, paramList);
while (ctx.Current != SyslogChars.Rbr)
{
var paramName = ctx.ReadWord();
ctx.ReadSymbol('=');
var paramValue = ctx.ReadQuotedString();
var prm = new NameValuePair()
{
Name = paramName, Value = paramValue
};
paramList.Add(prm);
ctx.SkipSpaces();
}
ctx.ReadSymbol(SyslogChars.Rbr);
return(elem);
}
public static string ReadQuotedString(this ParserContext ctx)
{
ctx.ReadSymbol(SyslogChars.DQuote);
string result = string.Empty;
int curr = ctx.Position;
while (true)
{
var next = ctx.Text.IndexOfAny(SyslogChars.QuoteOrEscape, curr);
var segment = ctx.Text.Substring(curr, next - curr);
result += segment;
switch (ctx.CharAt(next))
{
case SyslogChars.DQuote:
// we are done
ctx.Position = next + 1; // after dquote
return(result);
case SyslogChars.Escape:
// it is escape symbol, add next char to result, shift to next char and continue loop
result += ctx.CharAt(next + 1);
curr = next + 2;
break;
} //switch
} // loop
}
/// <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);
}
}
} //method
private List <NameValuePair> ReadKeyValuePairs(ParserContext ctx)
{
var prmList = new List <NameValuePair>();
NameValuePair lastPrm = null;
/*
* 2 troubles here:
*/
while (!ctx.Eof())
{
ctx.SkipSpaces();
var name = ctx.ReadWord();
if (!ctx.ReadSymbol('=', throwIfMismatch: false))
{
// Some entries are malformed: double quoted strings
// the result is that we do not find '=' after closing the quote. So we just add the rest to a separate param and exit
var text = ctx.Text.Substring(ctx.Position);
prmList.Add(new NameValuePair()
{
Name = "Message", Value = text
});
return(prmList);
}
ctx.SkipSpaces();
string value;
if (ctx.Current == SyslogChars.DQuote)
{
// For double-quoted values, some values are malformed - they contain nested d-quoted strings that are not escaped.
value = ctx.ReadQuotedString();
}
else
{
// Special case: non quoted empty values, ex: ' a= b=234 '; value of 'a' is Empty. We check the char after we read the value,
// and if it is '=', we back off, set value to empty.
var saveP = ctx.Position;
value = ctx.ReadWord();
if (ctx.Current == '=')
{
ctx.Position = saveP;
value = string.Empty;
}
}
lastPrm = new NameValuePair()
{
Name = name, Value = value
};
prmList.Add(lastPrm);
}
return(prmList);
}
