private static int GetRangeConditionLength(string input, int startIndex, out RangeConditionHeaderValue parsedValue)
{
Contract.Requires(startIndex >= 0);
parsedValue = null;
// Make sure we have at least 2 characters
if (string.IsNullOrEmpty(input) || (startIndex + 1 >= input.Length))
{
return(0);
}
var current = startIndex;
// Caller must remove leading whitespaces.
DateTimeOffset date = DateTimeOffset.MinValue;
EntityTagHeaderValue entityTag = null;
// Entity tags are quoted strings optionally preceded by "W/". By looking at the first two character we
// can determine whether the string is en entity tag or a date.
var firstChar = input[current];
var secondChar = input[current + 1];
if ((firstChar == '\"') || (((firstChar == 'w') || (firstChar == 'W')) && (secondChar == '/')))
{
// trailing whitespaces are removed by GetEntityTagLength()
var entityTagLength = EntityTagHeaderValue.GetEntityTagLength(input, current, out entityTag);
if (entityTagLength == 0)
{
return(0);
}
current = current + entityTagLength;
// RangeConditionHeaderValue only allows 1 value. There must be no delimiter/other chars after an
// entity tag.
if (current != input.Length)
{
return(0);
}
}
else
{
if (!HttpRuleParser.TryStringToDate(input.Substring(current), out date))
{
return(0);
}
// If we got a valid date, then the parser consumed the whole string (incl. trailing whitespaces).
current = input.Length;
}
parsedValue = new RangeConditionHeaderValue();
if (entityTag == null)
{
parsedValue._lastModified = date;
}
else
{
parsedValue._entityTag = entityTag;
}
return(current - startIndex);
}
public static bool TryParse(string input, out RangeConditionHeaderValue parsedValue)
{
var index = 0;
return(Parser.TryParseValue(input, ref index, out parsedValue));
}
