/// <summary>
/// Joins elements of an outer option with elements of an inner option having matching keys.
/// </summary>
/// <typeparam name="TOuter">The type of the elements of <paramref name="outer"/>.</typeparam>
/// <typeparam name="TInner">The type of the elements of <paramref name="inner"/>.</typeparam>
/// <typeparam name="TKey">The type of the key used to match elements.</typeparam>
/// <typeparam name="TResult">The type of the result value for each matched pair.</typeparam>
/// <param name="outer">The outer option to join.</param>
/// <param name="inner">The inner option to join.</param>
/// <param name="outerKeySelector">
/// A function to select the key that corresponds to an element of <paramref name="outer"/>.
/// </param>
/// <param name="innerKeySelector">
/// A function to select the key that corresponds to an element of <paramref name="inner"/>.
/// </param>
/// <param name="resultSelector">A function to select a result value for each matched pair.</param>
/// <param name="comparer">
/// A comparer to determine whether keys are equal. (If <see langword="null"/>, <see
/// cref="EqualityComparer{T}.Default"/> is used.)
/// </param>
/// <returns>
/// An option that contains the result of applying <paramref name="resultSelector"/> to the
/// element of <paramref name="outer"/> and the element of <paramref name="inner"/>, if both
/// options are full and their corresponding keys are equal according to <paramref
/// name="comparer"/>; otherwise, an empty option.
/// </returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="outer"/>, <paramref name="inner"/>, <paramref name="outerKeySelector"/>,
/// <paramref name="innerKeySelector"/>, or <paramref name="resultSelector"/> is <see langword="null"/>.
/// </exception>
public static IOpt <TResult> Join <TOuter, TInner, TKey, TResult>(this IOpt <TOuter> outer, IOpt <TInner> inner, Func <TOuter, TKey> outerKeySelector, Func <TInner, TKey> innerKeySelector, Func <TOuter, TInner, TResult> resultSelector, IEqualityComparer <TKey> comparer)
{
if (outer == null)
{
throw new ArgumentNullException(nameof(outer));
}
if (inner == null)
{
throw new ArgumentNullException(nameof(inner));
}
if (outerKeySelector == null)
{
throw new ArgumentNullException(nameof(outerKeySelector));
}
if (innerKeySelector == null)
{
throw new ArgumentNullException(nameof(innerKeySelector));
}
if (resultSelector == null)
{
throw new ArgumentNullException(nameof(resultSelector));
}
return(outer
.CrossJoinRaw(inner)
.WhereRaw(x => comparer.DefaultIfNull().Equals(outerKeySelector(x.first), innerKeySelector(x.second)))
.SelectRaw(x => resultSelector(x.first, x.second)));
}
/// <summary>
/// Joins each element of an outer option to a grouping of inner elements with matching keys,
/// then applies a transform to each grouping.
/// </summary>
/// <typeparam name="TOuter">The type of the elements of <paramref name="outer"/>.</typeparam>
/// <typeparam name="TInner">The type of the elements of <paramref name="inner"/>.</typeparam>
/// <typeparam name="TKey">The type of the key used to match and group elements.</typeparam>
/// <typeparam name="TResult">The type of the result value for each grouping.</typeparam>
/// <param name="outer">The outer option to join.</param>
/// <param name="inner">The inner option to join.</param>
/// <param name="outerKeySelector">
/// A function to select the key that corresponds to an element of <paramref name="outer"/>.
/// </param>
/// <param name="innerKeySelector">
/// A function to select the key that corresponds to an element of <paramref name="inner"/>.
/// </param>
/// <param name="resultSelector">A function to select a result value for each grouping.</param>
/// <param name="comparer">
/// A comparer to determine whether keys are equal. (If <see langword="null"/>, <see
/// cref="EqualityComparer{T}.Default"/> is used.)
/// </param>
/// <returns>
/// An option that contains the result of applying <paramref name="resultSelector"/> to the
/// grouping for the element of <paramref name="outer"/> and its corresponding elements of
/// <paramref name="inner"/>, if <paramref name="outer"/> is full; otherwise, an empty option.
/// </returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="outer"/>, <paramref name="inner"/>, <paramref name="outerKeySelector"/>,
/// <paramref name="innerKeySelector"/>, or <paramref name="resultSelector"/> is <see langword="null"/>.
/// </exception>
public static IOpt <TResult> GroupJoin <TOuter, TInner, TKey, TResult>(this IOpt <TOuter> outer, IOpt <TInner> inner, Func <TOuter, TKey> outerKeySelector, Func <TInner, TKey> innerKeySelector, Func <TOuter, IOpt <TInner>, TResult> resultSelector, IEqualityComparer <TKey> comparer)
{
if (outer == null)
{
throw new ArgumentNullException(nameof(outer));
}
if (inner == null)
{
throw new ArgumentNullException(nameof(inner));
}
if (outerKeySelector == null)
{
throw new ArgumentNullException(nameof(outerKeySelector));
}
if (innerKeySelector == null)
{
throw new ArgumentNullException(nameof(innerKeySelector));
}
if (resultSelector == null)
{
throw new ArgumentNullException(nameof(resultSelector));
}
return(outer.SelectRaw(outerValue =>
{
var comparerNonNull = comparer.DefaultIfNull();
var outerKey = outerKeySelector(outerValue);
var innerValues = inner.WhereOptRaw(innerValue => comparerNonNull.Equals(outerKey, innerKeySelector(innerValue)));
return resultSelector(outerValue, innerValues);
}));
}
/// <summary>
/// Determines whether an option has an equal length and sequence of elements to a sequence.
/// </summary>
/// <typeparam name="TSource">
/// The type of the elements of <paramref name="first"/> and <paramref name="second"/>.
/// </typeparam>
/// <param name="first">A source option.</param>
/// <param name="second">A sequence whose contents to compare with those of <paramref name="first"/>.</param>
/// <param name="comparer">
/// A comparer to determine whether values are equal. (If <see langword="null"/>, <see
/// cref="EqualityComparer{T}.Default"/> is used.)
/// </param>
/// <returns>
/// <see langword="true"/> if <paramref name="first"/> and <paramref name="second"/> are both
/// empty or each of <paramref name="first"/> and <paramref name="second"/> contains exactly
/// one element and those elements are equal; otherwise, <see langword="false"/>.
/// </returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="first"/> or <paramref name="second"/> is null.
/// </exception>
public static bool SequenceEqual <TSource>(this IOpt <TSource> first, IEnumerable <TSource> second, IEqualityComparer <TSource> comparer)
{
if (first == null)
{
throw new ArgumentNullException(nameof(first));
}
if (second == null)
{
throw new ArgumentNullException(nameof(second));
}
var opt = first.ToFixed();
if (opt.HasValue)
{
using (var secondEnumerator = second.GetEnumerator())
{
if (secondEnumerator.MoveNext())
{
var onlyValue = secondEnumerator.Current;
if (!secondEnumerator.MoveNext())
{
// second is same length
return(comparer.DefaultIfNull().Equals(opt.ValueOrDefault, onlyValue));
}
}
}
// Number of elements did not match
return(false);
}
else
{
using (var secondEnumerator = second.GetEnumerator())
{
return(!secondEnumerator.MoveNext());
}
}
}
