private static bool TryParseInternal(string value, HttpRangeSpecifier specifier, out string parseFailureReason)
{
if (specifier == null)
{
throw new ArgumentNullException("specifier");
}
HttpRangeSpecifier.StrSegment strSegment = new HttpRangeSpecifier.StrSegment(value);
HttpRangeSpecifier.ParseState parseState = HttpRangeSpecifier.ParseState.Start;
parseFailureReason = string.Empty;
int i = 0;
int length = value.Length;
long rangeStart = -1L;
while (i < length)
{
char c = value[i];
switch (parseState)
{
case HttpRangeSpecifier.ParseState.Start:
if (c != ' ' && c != '\t')
{
if (strSegment.Start == -1)
{
strSegment.Start = i;
}
if (c == '=')
{
strSegment.SetLengthFromTerminatingIndex(i);
strSegment.Trim();
specifier.RangeUnitSpecifier = strSegment.ToString();
parseState = HttpRangeSpecifier.ParseState.RangeStart;
rangeStart = -1L;
strSegment.Reset();
}
}
break;
case HttpRangeSpecifier.ParseState.RangeStart:
if (c != ' ' && c != '\t')
{
if (strSegment.Start == -1)
{
strSegment.Start = i;
}
if (c == '-' || c == ',')
{
strSegment.SetLengthFromTerminatingIndex(i);
strSegment.Trim();
if (c != '-')
{
parseFailureReason = "Invalid range, missing '-' character at " + (strSegment.Start + strSegment.Length);
return(false);
}
if (strSegment.Length > 0 && !long.TryParse(strSegment.ToString(), NumberStyles.Integer, CultureInfo.InvariantCulture, out rangeStart))
{
parseFailureReason = "Could not parse first-byte-pos at " + strSegment.Start;
return(false);
}
parseState = HttpRangeSpecifier.ParseState.RangeEnd;
strSegment.Reset();
}
}
break;
case HttpRangeSpecifier.ParseState.RangeEnd:
if (c != ' ' && c != '\t')
{
if (strSegment.Start == -1)
{
strSegment.Start = i;
}
if (c == ',')
{
strSegment.SetLengthFromTerminatingIndex(i);
strSegment.Trim();
if (!HttpRangeSpecifier.ProcessRangeEnd(specifier, ref parseFailureReason, strSegment, rangeStart))
{
return(false);
}
rangeStart = -1L;
parseState = HttpRangeSpecifier.ParseState.RangeStart;
strSegment.Reset();
}
}
break;
}
i++;
}
if (strSegment.Start != -1)
{
strSegment.SetLengthFromTerminatingIndex(i);
strSegment.Trim();
if (parseState == HttpRangeSpecifier.ParseState.Start)
{
specifier.RangeUnitSpecifier = strSegment.ToString();
}
if (parseState == HttpRangeSpecifier.ParseState.RangeStart)
{
parseFailureReason = "Invalid range, missing '-' character at " + (strSegment.Start + strSegment.Length);
return(false);
}
}
else
{
if (parseState == HttpRangeSpecifier.ParseState.Start)
{
parseFailureReason = "Did not find range unit specifier";
return(false);
}
if (parseState == HttpRangeSpecifier.ParseState.RangeStart)
{
parseFailureReason = "Expected range value at the end.";
return(false);
}
}
if (parseState == HttpRangeSpecifier.ParseState.RangeEnd && !HttpRangeSpecifier.ProcessRangeEnd(specifier, ref parseFailureReason, strSegment, rangeStart))
{
return(false);
}
if (specifier.RangeCollection.Count == 0)
{
parseFailureReason = "No ranges found.";
return(false);
}
return(true);
}
private static bool ProcessRangeEnd(HttpRangeSpecifier specifier, ref string parseFailureReason, HttpRangeSpecifier.StrSegment currentSegment, long rangeStart)
{
long rangeEnd = -1L;
if (currentSegment.Start >= 0 && currentSegment.Length > 0 && !long.TryParse(currentSegment.ToString(), NumberStyles.Integer, CultureInfo.InvariantCulture, out rangeEnd))
{
parseFailureReason = "Could not parse last-byte-pos at " + currentSegment.Start;
return(false);
}
if (!HttpRangeSpecifier.AddRange(specifier, rangeStart, rangeEnd))
{
parseFailureReason = "Invalid range specification near " + currentSegment.Start;
return(false);
}
return(true);
}