/// <summary>
/// Parses a header value into a value and a quality.
/// </summary>
/// <param name="headerValue"></param>
/// <returns></returns>
public static QualityValue Parse(string headerValue)
{
QualityValue result = null;
if (headerValue != null)
{
var qValueIdx = headerValue.IndexOf(";q=", StringComparison.OrdinalIgnoreCase);
double?quality = null;
if (qValueIdx != -1 &&
double.TryParse(
headerValue.Substring(qValueIdx + 3),
NumberStyles.AllowDecimalPoint | NumberStyles.AllowTrailingWhite,
CultureInfo.InvariantCulture,
out var qualityParsed
) &&
qualityParsed <= 1.0 &&
headerValue.Length - qValueIdx <= 8 && // Cannot exceed 3 decimal places
headerValue[qValueIdx + 3] != '.' // Must start with a digit
)
{
quality = qualityParsed;
}
else
{
qValueIdx = -1;
}
var value = qValueIdx == -1 ? headerValue : headerValue.Substring(0, qValueIdx);
result = new QualityValue(value, quality);
}
return(result);
}
/// <summary>
/// Parses a comma-separated list of q-value strings into a collection of <see cref="QualityValue"/>
/// objects.
/// </summary>
/// <param name="headerValue"></param>
/// <returns></returns>
public static IList <QualityValue> ParseCommaSeparated(string headerValue)
{
var result = new List <QualityValue>();
if (!String.IsNullOrWhiteSpace(headerValue))
{
foreach (var chunk in headerValue.Split(','))
{
result.Add(QualityValue.Parse(chunk.Trim()));
}
}
return(result);
}