// Returns the length of a range list. E.g. "1-2, 3-4, 5-6" adds 3 ranges to 'rangeCollection'. Note that empty
// list segments are allowed, e.g. ",1-2, , 3-4,,".
internal static int GetRangeItemListLength(
StringSegment input,
int startIndex,
ICollection <RangeItemHeaderValue> rangeCollection)
{
Contract.Requires(rangeCollection != null);
Contract.Requires(startIndex >= 0);
Contract.Ensures((Contract.Result <int>() == 0) || (rangeCollection.Count > 0),
"If we can parse the string, then we expect to have at least one range item.");
if ((StringSegment.IsNullOrEmpty(input)) || (startIndex >= input.Length))
{
return(0);
}
// Empty segments are allowed, so skip all delimiter-only segments (e.g. ", ,").
var separatorFound = false;
var current = HeaderUtilities.GetNextNonEmptyOrWhitespaceIndex(input, startIndex, true, out separatorFound);
// It's OK if we didn't find leading separator characters. Ignore 'separatorFound'.
if (current == input.Length)
{
return(0);
}
RangeItemHeaderValue range = null;
while (true)
{
var rangeLength = GetRangeItemLength(input, current, out range);
if (rangeLength == 0)
{
return(0);
}
rangeCollection.Add(range);
current = current + rangeLength;
current = HeaderUtilities.GetNextNonEmptyOrWhitespaceIndex(input, current, true, out separatorFound);
// If the string is not consumed, we must have a delimiter, otherwise the string is not a valid
// range list.
if ((current < input.Length) && !separatorFound)
{
return(0);
}
if (current == input.Length)
{
return(current - startIndex);
}
}
}
public sealed override bool TryParseValue(StringSegment value, ref int index, out T parsedValue)
{
parsedValue = default(T);
// If multiple values are supported (i.e. list of values), then accept an empty string: The header may
// be added multiple times to the request/response message. E.g.
// Accept: text/xml; q=1
// Accept:
// Accept: text/plain; q=0.2
if (StringSegment.IsNullOrEmpty(value) || (index == value.Length))
{
return(SupportsMultipleValues);
}
var current = HeaderUtilities.GetNextNonEmptyOrWhitespaceIndex(value, index, SupportsMultipleValues,
out var separatorFound);
if (separatorFound && !SupportsMultipleValues)
{
return(false); // leading separators not allowed if we don't support multiple values.
}
if (current == value.Length)
{
if (SupportsMultipleValues)
{
index = current;
}
return(SupportsMultipleValues);
}
var length = GetParsedValueLength(value, current, out var result);
if (length == 0)
{
return(false);
}
current += length;
current = HeaderUtilities.GetNextNonEmptyOrWhitespaceIndex(value, current, SupportsMultipleValues,
out separatorFound);
// If we support multiple values and we've not reached the end of the string, then we must have a separator.
if ((separatorFound && !SupportsMultipleValues) || (!separatorFound && (current < value.Length)))
{
return(false);
}
index = current;
parsedValue = result;
return(true);
}
