using System.Collections.Generic; using System.Runtime.CompilerServices; namespace System.Collections.Frozen { public static class FrozenSet { [System.Runtime.CompilerServices.NullableContext(1)] public static FrozenSet<T> ToFrozenSet<[System.Runtime.CompilerServices.Nullable(2)] T>(this IEnumerable<T> source, [System.Runtime.CompilerServices.Nullable(new byte[] { 2, 1 })] IEqualityComparer<T> comparer = null) { HashSet<T> newSet; return GetExistingFrozenOrNewSet(source, comparer, out newSet) ?? CreateFromSet(newSet); } private static FrozenSet<T> GetExistingFrozenOrNewSet<T>(IEnumerable<T> source, IEqualityComparer<T> comparer, out HashSet<T> newSet) { ThrowHelper.ThrowIfNull(source, "source"); if (comparer == null) comparer = EqualityComparer<T>.Default; FrozenSet<T> frozenSet = source as FrozenSet<T>; if (frozenSet != null && frozenSet.Comparer.Equals(comparer)) { newSet = null; return frozenSet; } newSet = (source as HashSet<T>); if (newSet == null || (newSet.Count != 0 && !newSet.Comparer.Equals(comparer))) newSet = new HashSet<T>(source, comparer); if (newSet.Count == 0) { if (comparer != FrozenSet<T>.Empty.Comparer) return new EmptyFrozenSet<T>(comparer); return FrozenSet<T>.Empty; } return null; } private static FrozenSet<T> CreateFromSet<T>(HashSet<T> source) { IEqualityComparer<T> comparer = source.Comparer; if (typeof(T).IsValueType && comparer == EqualityComparer<T>.Default) { if (source.Count <= 10) { if (Constants.IsKnownComparable<T>()) return (FrozenSet<T>)new SmallValueTypeComparableFrozenSet<T>(source); return (FrozenSet<T>)new SmallValueTypeDefaultComparerFrozenSet<T>(source); } if (typeof(T) == typeof(int)) return (FrozenSet<T>)new Int32FrozenSet((HashSet<int>)source); return new ValueTypeDefaultComparerFrozenSet<T>(source); } if (typeof(T) == typeof(string) && !source.Contains(default(T)) && (comparer == EqualityComparer<T>.Default || comparer == StringComparer.Ordinal || comparer == StringComparer.OrdinalIgnoreCase)) { IEqualityComparer<string> equalityComparer = (IEqualityComparer<string>)comparer; HashSet<string> hashSet = (HashSet<string>)source; string[] array = new string[hashSet.Count]; hashSet.CopyTo(array); int num = 2147483647; int num2 = 0; string[] array2 = array; foreach (string text in array2) { if (text.Length < num) num = text.Length; if (text.Length > num2) num2 = text.Length; } FrozenSet<string> frozenSet = LengthBucketsFrozenSet.CreateLengthBucketsFrozenSetIfAppropriate(array, equalityComparer, num, num2); if (frozenSet != null) return (FrozenSet<T>)frozenSet; KeyAnalyzer.AnalysisResults analysisResults = KeyAnalyzer.Analyze(array, equalityComparer == StringComparer.OrdinalIgnoreCase, num, num2); frozenSet = (analysisResults.SubstringHashing ? (analysisResults.RightJustifiedSubstring ? ((!analysisResults.IgnoreCase) ? ((analysisResults.HashCount == 1) ? ((OrdinalStringFrozenSet)new OrdinalStringFrozenSet_RightJustifiedSingleChar(array, equalityComparer, analysisResults.MinimumLength, analysisResults.MaximumLengthDiff, analysisResults.HashIndex)) : ((OrdinalStringFrozenSet)new OrdinalStringFrozenSet_RightJustifiedSubstring(array, equalityComparer, analysisResults.MinimumLength, analysisResults.MaximumLengthDiff, analysisResults.HashIndex, analysisResults.HashCount))) : (analysisResults.AllAsciiIfIgnoreCase ? ((OrdinalStringFrozenSet)new OrdinalStringFrozenSet_RightJustifiedCaseInsensitiveAsciiSubstring(array, equalityComparer, analysisResults.MinimumLength, analysisResults.MaximumLengthDiff, analysisResults.HashIndex, analysisResults.HashCount)) : ((OrdinalStringFrozenSet)new OrdinalStringFrozenSet_RightJustifiedCaseInsensitiveSubstring(array, equalityComparer, analysisResults.MinimumLength, analysisResults.MaximumLengthDiff, analysisResults.HashIndex, analysisResults.HashCount)))) : ((!analysisResults.IgnoreCase) ? ((analysisResults.HashCount == 1) ? ((OrdinalStringFrozenSet)new OrdinalStringFrozenSet_LeftJustifiedSingleChar(array, equalityComparer, analysisResults.MinimumLength, analysisResults.MaximumLengthDiff, analysisResults.HashIndex)) : ((OrdinalStringFrozenSet)new OrdinalStringFrozenSet_LeftJustifiedSubstring(array, equalityComparer, analysisResults.MinimumLength, analysisResults.MaximumLengthDiff, analysisResults.HashIndex, analysisResults.HashCount))) : (analysisResults.AllAsciiIfIgnoreCase ? ((OrdinalStringFrozenSet)new OrdinalStringFrozenSet_LeftJustifiedCaseInsensitiveAsciiSubstring(array, equalityComparer, analysisResults.MinimumLength, analysisResults.MaximumLengthDiff, analysisResults.HashIndex, analysisResults.HashCount)) : ((OrdinalStringFrozenSet)new OrdinalStringFrozenSet_LeftJustifiedCaseInsensitiveSubstring(array, equalityComparer, analysisResults.MinimumLength, analysisResults.MaximumLengthDiff, analysisResults.HashIndex, analysisResults.HashCount))))) : ((!analysisResults.IgnoreCase) ? new OrdinalStringFrozenSet_Full(array, equalityComparer, analysisResults.MinimumLength, analysisResults.MaximumLengthDiff) : (analysisResults.AllAsciiIfIgnoreCase ? ((OrdinalStringFrozenSet)new OrdinalStringFrozenSet_FullCaseInsensitiveAscii(array, equalityComparer, analysisResults.MinimumLength, analysisResults.MaximumLengthDiff)) : ((OrdinalStringFrozenSet)new OrdinalStringFrozenSet_FullCaseInsensitive(array, equalityComparer, analysisResults.MinimumLength, analysisResults.MaximumLengthDiff))))); return (FrozenSet<T>)frozenSet; } if (source.Count <= 4) return new SmallFrozenSet<T>(source); return new DefaultFrozenSet<T>(source); } } }