/// <summary>
/// Creates new Cache Digest value from urls collection.
/// </summary>
/// <param name="urls">The collection of URLs with ETag. URLs should be converted to an ASCII string by percent-encoding as appropriate per RFC3986 and ETags should include both the weak indicator (if present) and double quotes.</param>
/// <param name="probability">The probability of hashes collision.</param>
/// <param name="validators">The value indicating that the validators should be included in the digest.</param>
/// <returns>Cache Digest value.</returns>
public static CacheDigestValue FromUrls(IDictionary <string, string> urls, uint probability = DefaultProbability, bool validators = false)
{
// Let N be the count of URLs’ members, rounded to the nearest power of 2 smaller than 2**32.
int count = CalculateCount(urls?.Count ?? 0);
try
{
ValidateProbability(probability);
}
catch (FormatException)
{
probability = DefaultProbability;
}
// Let hash-values be an empty array of integers.
HashSet <uint> hashes = new HashSet <uint>();
if (urls != null)
{
// For each (URL, ETag) in URLs, compute a hash value (Section 2.1.2) and append the result to hash-values.
foreach (KeyValuePair <string, string> url in urls)
{
hashes.Add(CacheDigestHashAlgorithm.ComputeHash(url.Key, count, probability, validators, url.Value));
}
}
return(new CacheDigestValue
{
Count = count,
Probability = probability,
Hashes = hashes
});
}
/// <summary>
/// Checks if digest value contains given URL.
/// </summary>
/// <param name="url">The URL, converted to an ASCII string by percent-encoding as appropriate per RFC3986.</param>
/// <param name="validators">Flag indicating if digest value is expected to contain validators.</param>
/// <param name="entityTag">The ETag, including both the weak indicator (if present) and double quotes, as per RFC7232 Section 2.3.</param>
/// <returns>True if there is a match in the digest value, otherwise false.</returns>
public bool Contains(string url, bool validators = false, string entityTag = null)
{
uint hash = CacheDigestHashAlgorithm.ComputeHash(url, Count, Probability, validators, entityTag);
return(Contains(hash));
}
