public IComparer <T> CreateCompoundComparer(IComparer <T> comparer)
{
CompoundComparer <T> compoundComparer = new CompoundComparer <T>();
compoundComparer.AppendComparison(Comparer);
compoundComparer.AppendComparison(comparer);
return(KeyedNullPlacementComparer <T, TKey> .GetComparer(compoundComparer.Normalize(), _keySelector, NullFilter.NullsFirst));
}
/// <summary>
/// Composes a comparer that performs subsequent ordering using the key comparison.
/// </summary>
/// <typeparam name="T">The type being compared.</typeparam>
/// <typeparam name="TKey">The type of the key.</typeparam>
/// <param name="baseComparer">The comparer to extend.</param>
/// <param name="keySelector">The key of the type to use for comparison.</param>
/// <returns>A comparer that performs comparisons using both comparison operations.</returns>
/// <exception cref="System.ArgumentNullException">The base comparer is null.</exception>
/// <exception cref="System.ArgumentNullException">The key selector is null.</exception>
public static IComparer <T> ThenBy <T, TKey>(this IComparer <T> baseComparer, Func <T, TKey> keySelector)
{
if (baseComparer == null)
{
throw new ArgumentNullException("baseComparer");
}
KeyComparer <T> comparer = KeyComparer <T> .OrderBy(keySelector);
IComparer <T> compoundComparer = CompoundComparer <T> .GetComparer(baseComparer, comparer);
return(compoundComparer);
}
/// <summary>
/// Composes a comparer that performs subsequent ordering using the comparer.
/// </summary>
/// <typeparam name="T">The type being compared.</typeparam>
/// <param name="baseComparer">The comparer to extend.</param>
/// <param name="comparer">The comparer to use if two items compare as equal using the base comparer.</param>
/// <returns>A comparer that performs comparisons using both comparison operations.</returns>
/// <exception cref="System.ArgumentNullException">The base comparer is null.</exception>
/// <exception cref="System.ArgumentNullException">The comparer is null.</exception>
public static IComparer <T> ThenBy <T>(this IComparer <T> baseComparer, IComparer <T> comparer)
{
if (baseComparer == null)
{
throw new ArgumentNullException("baseComparer");
}
if (comparer == null)
{
throw new ArgumentNullException("comparer");
}
IComparer <T> compoundComparer = CompoundComparer <T> .GetComparer(baseComparer, comparer);
return(compoundComparer);
}
public void AppendComparison(IComparer <T> comparer)
{
if (comparer is NullComparer <T> )
{
return;
}
CompoundComparer <T> other = comparer as CompoundComparer <T>;
if (other != null)
{
_comparers.AddRange(other._comparers);
return;
}
_comparers.Add(comparer);
}
public static IComparer <T> GetComparer(IComparer <T> baseComparer, IComparer <T> nextComparer)
{
// make sure null comparer stays highest precedence
IPrecedenceEnforcer <T> nullComparer = baseComparer as IPrecedenceEnforcer <T>;
if (nullComparer != null)
{
return(nullComparer.CreateCompoundComparer(nextComparer));
}
CompoundComparer <T> comparer = new CompoundComparer <T>();
comparer.AppendComparison(baseComparer);
comparer.AppendComparison(nextComparer);
return(comparer.Normalize());
}
/// <summary>
/// Composes a comparer that performs subsequent ordering using the comparison.
/// </summary>
/// <typeparam name="T">The type being compared.</typeparam>
/// <param name="baseComparer">The comparer to extend.</param>
/// <param name="comparison">The comparison to use if two items compare as equal using the base comparer.</param>
/// <returns>A comparer that performs comparisons using both comparison operations.</returns>
/// <exception cref="System.ArgumentNullException">The base comparer is null.</exception>
/// <exception cref="System.ArgumentNullException">The comparison delegate is null.</exception>
public static IComparer <T> ThenBy <T>(this IComparer <T> baseComparer, Func <T, T, int> comparison)
{
if (baseComparer == null)
{
throw new ArgumentNullException("baseComparer");
}
if (comparison == null)
{
throw new ArgumentNullException("comparison");
}
IComparer <T> wrapper = ComparisonWrapper <T> .GetComparer(comparison);
IComparer <T> compoundComparer = CompoundComparer <T> .GetComparer(baseComparer, wrapper);
return(compoundComparer);
}