private static int GetSubtypeLength(string input, int offset, out StringSegment subType)
{
var current = offset;
// Parse the separator between type and subtype
if (current < 0 || current >= input.Length || input[current] != '/')
{
subType = default;
return(0);
}
current++; // skip delimiter.
current += HttpTokenParsingRules.GetWhitespaceLength(input, current);
var subtypeLength = HttpTokenParsingRules.GetTokenLength(input, current);
if (subtypeLength == 0)
{
subType = default;
return(0);
}
subType = new StringSegment(input, current, subtypeLength);
current += subtypeLength;
current += HttpTokenParsingRules.GetWhitespaceLength(input, current);
return(current - offset);
}
// All GetXXXLength methods work in the same way. They expect to be on the right position for
// the token they are parsing, for example, the beginning of the media type or the delimiter
// from a previous token, like '/', ';' or '='.
// Each method consumes the delimiter token if any, the leading whitespace, then the given token
// itself, and finally the trailing whitespace.
private static int GetTypeLength(string input, int offset, out StringSegment type)
{
if (offset < 0 || offset >= input.Length)
{
type = default;
return(0);
}
var current = offset + HttpTokenParsingRules.GetWhitespaceLength(input, offset);
// Parse the type, i.e. <type> in media type string "<type>/<subtype>; param1=value1; param2=value2"
var typeLength = HttpTokenParsingRules.GetTokenLength(input, current);
if (typeLength == 0)
{
type = default;
return(0);
}
type = new StringSegment(input, current, typeLength);
current += typeLength;
current += HttpTokenParsingRules.GetWhitespaceLength(input, current);
return(current - offset);
}
