/// <summary>
/// Get suitable tags
/// </summary>
/// <param name="languageTag"></param>
/// <returns></returns>
public IEnumerable <LanguageTag> GetSuitableTags(LanguageTag languageTag)
{
if (_cachedResults.TryGetValue(languageTag.GetHashCode(), out var results))
{
return(results.Select(s => s.Value));
}
if (!_items.Any())
{
return(Enumerable.Empty <LanguageTag>());
}
results = new List <FallbackItem>();
var orderedItems = _items.OrderByDescending(o => o.Priority).ToList();
var skipHashCodes = new List <int>();
//step.1 filter all results by this order: ExactMatch, DefaultRegion, ScriptMatch and LanguageMatch
foreach (var level in _matchLevels)
{
results.AddRange(Filter(orderedItems, languageTag, level, skipHashCodes));
}
//step.2 add all results which priority less than the min of the result that got from step.1
results.AddRange(Filter(orderedItems, results.Min(m => m.Priority), skipHashCodes));
//step.3 add default language tag (in this case, the most less priority) if need.
AddMostLessPriorityIfNeed(results, skipHashCodes);
//step.4 clear skipped hashcode cache
skipHashCodes.Clear();
return(Remember(languageTag, results));
}
/// <summary>
/// Register language tag
/// </summary>
/// <param name="languageTag"></param>
/// <exception cref="ArgumentNullException"></exception>
public void RegisterTag(LanguageTag languageTag)
{
if (languageTag == null)
{
throw new ArgumentNullException(nameof(languageTag));
}
var hashcode = languageTag.GetHashCode();
// ReSharper disable once InconsistentlySynchronizedField
if (_items.Any(x => x.HashCodeCached == hashcode))
{
return;
}
lock (_cacheLockObj) {
if (_items.Any(x => x.HashCodeCached == hashcode))
{
return;
}
//this will update all item's priority
_items.Add(new FallbackItem(languageTag));
}
}
/// <summary>
/// Has cached result
/// </summary>
/// <param name="languageTag"></param>
/// <returns></returns>
public bool HashCachedResult(LanguageTag languageTag)
{
if (languageTag == null)
{
return(false);
}
return(_cachedResults.ContainsKey(languageTag.GetHashCode()));
}
private IEnumerable <LanguageTag> Remember(LanguageTag left, List <FallbackItem> filteredItems)
{
lock (_cacheLockObj) {
var hashcode = left.GetHashCode();
if (_cachedResults.ContainsKey(hashcode))
{
_cachedResults[hashcode] = filteredItems;
}
else
{
_cachedResults.Add(hashcode, filteredItems);
}
}
return(filteredItems.Select(s => s.Value));
}
