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//
// Enumerable.cs
//
// Authors:
// Marek Safar (marek.safar@gmail.com)
// Antonello Provenzano <antonello@deveel.com>
// Alejandro Serrano "Serras" (trupill@yahoo.es)
// Jb Evain (jbevain@novell.com)
//
// Copyright (C) 2007 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
// precious: http://www.hookedonlinq.com
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
namespace System.Linq
{
public static class Enumerable
{
enum Fallback {
Default,
Throw
}
class PredicateOf<T> {
public static readonly Func<T, bool> Always = (t) => true;
}
class Function<T> {
public static readonly Func<T, T> Identity = (t) => t;
}
#region Aggregate
public static TSource Aggregate<TSource> (this IEnumerable<TSource> source, Func<TSource, TSource, TSource> func)
{
Check.SourceAndFunc (source, func);
// custom foreach so that we can efficiently throw an exception
// if zero elements and treat the first element differently
using (var enumerator = source.GetEnumerator ()) {
if (!enumerator.MoveNext ())
throw new InvalidOperationException ("No elements in source list");
TSource folded = enumerator.Current;
while (enumerator.MoveNext ())
folded = func (folded, enumerator.Current);
return folded;
}
}
public static TAccumulate Aggregate<TSource, TAccumulate> (this IEnumerable<TSource> source,
TAccumulate seed, Func<TAccumulate, TSource, TAccumulate> func)
{
Check.SourceAndFunc (source, func);
TAccumulate folded = seed;
foreach (TSource element in source)
folded = func (folded, element);
return folded;
}
public static TResult Aggregate<TSource, TAccumulate, TResult> (this IEnumerable<TSource> source, TAccumulate seed, Func<TAccumulate, TSource, TAccumulate> func, Func<TAccumulate, TResult> resultSelector)
{
Check.SourceAndFunc (source, func);
if (resultSelector == null)
throw new ArgumentNullException ("resultSelector");
var result = seed;
foreach (var e in source)
result = func (result, e);
return resultSelector (result);
}
#endregion
#region All
public static bool All<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
Check.SourceAndPredicate (source, predicate);
foreach (var element in source)
if (!predicate (element))
return false;
return true;
}
#endregion
#region Any
public static bool Any<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
var collection = source as ICollection<TSource>;
if (collection != null)
return collection.Count > 0;
using (var enumerator = source.GetEnumerator ())
return enumerator.MoveNext ();
}
public static bool Any<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
Check.SourceAndPredicate (source, predicate);
foreach (TSource element in source)
if (predicate (element))
return true;
return false;
}
#endregion
#region AsEnumerable
public static IEnumerable<TSource> AsEnumerable<TSource> (this IEnumerable<TSource> source)
{
return source;
}
#endregion
#region Average
public static double Average (this IEnumerable<int> source)
{
return Average<int, long, double> (source, (a, b) => a + b, (a, b) => (double) a / (double) b);
}
public static double Average (this IEnumerable<long> source)
{
return Average<long, long, double> (source, (a, b) => a + b, (a, b) => (double) a / (double) b);
}
public static double Average (this IEnumerable<double> source)
{
return Average<double, double, double> (source, (a, b) => a + b, (a, b) => a / b);
}
public static float Average (this IEnumerable<float> source)
{
return Average<float, double, float> (source, (a, b) => a + b, (a, b) => (float) a / (float) b);
}
public static decimal Average (this IEnumerable<decimal> source)
{
return Average<decimal, decimal, decimal> (source, (a, b) => a + b, (a, b) => a / b);
}
static TResult Average<TElement, TAggregate, TResult> (this IEnumerable<TElement> source,
Func<TAggregate, TElement, TAggregate> func, Func<TAggregate, long, TResult> result)
where TElement : struct
where TAggregate : struct
where TResult : struct
{
Check.Source (source);
var total = default (TAggregate);
long counter = 0;
foreach (var element in source) {
total = func (total, element);
++counter;
}
if (counter == 0)
throw new InvalidOperationException ();
return result (total, counter);
}
static TResult? AverageNullable<TElement, TAggregate, TResult> (this IEnumerable<TElement?> source,
Func<TAggregate, TElement, TAggregate> func, Func<TAggregate, long, TResult> result)
where TElement : struct
where TAggregate : struct
where TResult : struct
{
Check.Source (source);
var total = default (TAggregate);
long counter = 0;
foreach (var element in source) {
if (!element.HasValue)
continue;
total = func (total, element.Value);
counter++;
}
if (counter == 0)
return null;
return new TResult? (result (total, counter));
}
public static double? Average (this IEnumerable<int?> source)
{
Check.Source (source);
return source.AverageNullable<int, long, double> ((a, b) => a + b, (a, b) => (double) a / (double) b);
}
public static double? Average (this IEnumerable<long?> source)
{
Check.Source (source);
return source.AverageNullable<long, long, double> ((a, b) => a + b, (a, b) => (double) a / b);
}
public static double? Average (this IEnumerable<double?> source)
{
Check.Source (source);
return source.AverageNullable<double, double, double> ((a, b) => a + b, (a, b) => a / b);
}
public static decimal? Average (this IEnumerable<decimal?> source)
{
Check.Source (source);
return source.AverageNullable<decimal, decimal, decimal> ((a, b) => a + b, (a, b) => a / b);
}
public static float? Average (this IEnumerable<float?> source)
{
Check.Source (source);
return source.AverageNullable<float, double, float> ((a, b) => a + b, (a, b) => (float) a / (float) b);
}
public static double Average<TSource> (this IEnumerable<TSource> source, Func<TSource, int> selector)
{
Check.SourceAndSelector (source, selector);
return source.Select (selector).Average<int, long, double> ((a, b) => a + b, (a, b) => (double) a / (double) b);
}
public static double? Average<TSource> (this IEnumerable<TSource> source, Func<TSource, int?> selector)
{
Check.SourceAndSelector (source, selector);
return source.Select (selector).AverageNullable<int, long, double> ((a, b) => a + b, (a, b) => (double) a / (double) b);
}
public static double Average<TSource> (this IEnumerable<TSource> source, Func<TSource, long> selector)
{
Check.SourceAndSelector (source, selector);
return source.Select (selector).Average<long, long, double> ((a, b) => a + b, (a, b) => (double) a / (double) b);
}
public static double? Average<TSource> (this IEnumerable<TSource> source, Func<TSource, long?> selector)
{
Check.SourceAndSelector (source, selector);
return source.Select (selector).AverageNullable<long, long, double> ((a, b) => a + b, (a, b) => (double) a / (double) b);
}
public static double Average<TSource> (this IEnumerable<TSource> source, Func<TSource, double> selector)
{
Check.SourceAndSelector (source, selector);
return source.Select (selector).Average<double, double, double> ((a, b) => a + b, (a, b) => a / b);
}
public static double? Average<TSource> (this IEnumerable<TSource> source, Func<TSource, double?> selector)
{
Check.SourceAndSelector (source, selector);
return source.Select (selector).AverageNullable<double, double, double> ((a, b) => a + b, (a, b) => a / b);
}
public static float Average<TSource> (this IEnumerable<TSource> source, Func<TSource, float> selector)
{
Check.SourceAndSelector (source, selector);
return source.Select (selector).Average<float, double, float> ((a, b) => a + b, (a, b) => (float) a / (float) b);
}
public static float? Average<TSource> (this IEnumerable<TSource> source, Func<TSource, float?> selector)
{
Check.SourceAndSelector (source, selector);
return source.Select (selector).AverageNullable<float, double, float> ((a, b) => a + b, (a, b) => (float) a / (float) b);
}
public static decimal Average<TSource> (this IEnumerable<TSource> source, Func<TSource, decimal> selector)
{
Check.SourceAndSelector (source, selector);
return source.Select (selector).Average<decimal, decimal, decimal> ((a, b) => a + b, (a, b) => a / b);
}
public static decimal? Average<TSource> (this IEnumerable<TSource> source, Func<TSource, decimal?> selector)
{
Check.SourceAndSelector (source, selector);
return source.Select (selector).AverageNullable<decimal, decimal, decimal> ((a, b) => a + b, (a, b) => a / b);
}
#endregion
#region Cast
public static IEnumerable<TResult> Cast<TResult> (this IEnumerable source)
{
Check.Source (source);
var actual = source as IEnumerable<TResult>;
if (actual != null)
return actual;
return CreateCastIterator<TResult> (source);
}
static IEnumerable<TResult> CreateCastIterator<TResult> (IEnumerable source)
{
foreach (TResult element in source)
yield return element;
}
#endregion
#region Concat
public static IEnumerable<TSource> Concat<TSource> (this IEnumerable<TSource> first, IEnumerable<TSource> second)
{
Check.FirstAndSecond (first, second);
return CreateConcatIterator (first, second);
}
static IEnumerable<TSource> CreateConcatIterator<TSource> (IEnumerable<TSource> first, IEnumerable<TSource> second)
{
foreach (TSource element in first)
yield return element;
foreach (TSource element in second)
yield return element;
}
#endregion
#region Contains
public static bool Contains<TSource> (this IEnumerable<TSource> source, TSource value)
{
var collection = source as ICollection<TSource>;
if (collection != null)
return collection.Contains (value);
return Contains<TSource> (source, value, null);
}
public static bool Contains<TSource> (this IEnumerable<TSource> source, TSource value, IEqualityComparer<TSource> comparer)
{
Check.Source (source);
if (comparer == null)
comparer = EqualityComparer<TSource>.Default;
foreach (var element in source)
if (comparer.Equals (element, value))
return true;
return false;
}
#endregion
#region Count
public static int Count<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
var collection = source as ICollection<TSource>;
if (collection != null)
return collection.Count;
int counter = 0;
using (var enumerator = source.GetEnumerator ())
while (enumerator.MoveNext ())
counter++;
return counter;
}
public static int Count<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> selector)
{
Check.SourceAndSelector (source, selector);
int counter = 0;
foreach (var element in source)
if (selector (element))
counter++;
return counter;
}
#endregion
#region DefaultIfEmpty
public static IEnumerable<TSource> DefaultIfEmpty<TSource> (this IEnumerable<TSource> source)
{
return DefaultIfEmpty (source, default (TSource));
}
public static IEnumerable<TSource> DefaultIfEmpty<TSource> (this IEnumerable<TSource> source, TSource defaultValue)
{
Check.Source (source);
return CreateDefaultIfEmptyIterator (source, defaultValue);
}
static IEnumerable<TSource> CreateDefaultIfEmptyIterator<TSource> (IEnumerable<TSource> source, TSource defaultValue)
{
bool empty = true;
foreach (TSource item in source) {
empty = false;
yield return item;
}
if (empty)
yield return defaultValue;
}
#endregion
#region Distinct
public static IEnumerable<TSource> Distinct<TSource> (this IEnumerable<TSource> source)
{
return Distinct<TSource> (source, null);
}
public static IEnumerable<TSource> Distinct<TSource> (this IEnumerable<TSource> source, IEqualityComparer<TSource> comparer)
{
Check.Source (source);
if (comparer == null)
comparer = EqualityComparer<TSource>.Default;
return CreateDistinctIterator (source, comparer);
}
static IEnumerable<TSource> CreateDistinctIterator<TSource> (IEnumerable<TSource> source, IEqualityComparer<TSource> comparer)
{
var items = new HashSet<TSource> (comparer);
foreach (var element in source) {
if (! items.Contains (element)) {
items.Add (element);
yield return element;
}
}
}
#endregion
#region ElementAt
static TSource ElementAt<TSource> (this IEnumerable<TSource> source, int index, Fallback fallback)
{
long counter = 0L;
foreach (var element in source) {
if (index == counter++)
return element;
}
if (fallback == Fallback.Throw)
throw new ArgumentOutOfRangeException ();
return default (TSource);
}
public static TSource ElementAt<TSource> (this IEnumerable<TSource> source, int index)
{
Check.Source (source);
if (index < 0)
throw new ArgumentOutOfRangeException ();
var list = source as IList<TSource>;
if (list != null)
return list [index];
return source.ElementAt (index, Fallback.Throw);
}
#endregion
#region ElementAtOrDefault
public static TSource ElementAtOrDefault<TSource> (this IEnumerable<TSource> source, int index)
{
Check.Source (source);
if (index < 0)
return default (TSource);
var list = source as IList<TSource>;
if (list != null)
return index < list.Count ? list [index] : default (TSource);
return source.ElementAt (index, Fallback.Default);
}
#endregion
#region Empty
public static IEnumerable<TResult> Empty<TResult> ()
{
return new TResult [0];
}
#endregion
#region Except
public static IEnumerable<TSource> Except<TSource> (this IEnumerable<TSource> first, IEnumerable<TSource> second)
{
return Except (first, second, null);
}
public static IEnumerable<TSource> Except<TSource> (this IEnumerable<TSource> first, IEnumerable<TSource> second, IEqualityComparer<TSource> comparer)
{
Check.FirstAndSecond (first, second);
if (comparer == null)
comparer = EqualityComparer<TSource>.Default;
return CreateExceptIterator (first, second, comparer);
}
static IEnumerable<TSource> CreateExceptIterator<TSource> (IEnumerable<TSource> first, IEnumerable<TSource> second, IEqualityComparer<TSource> comparer)
{
var items = new HashSet<TSource> (second, comparer);
foreach (var element in first) {
if (!items.Contains (element, comparer))
yield return element;
}
}
#endregion
#region First
static TSource First<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> predicate, Fallback fallback)
{
foreach (var element in source)
if (predicate (element))
return element;
if (fallback == Fallback.Throw)
throw new InvalidOperationException ();
return default (TSource);
}
public static TSource First<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
var list = source as IList<TSource>;
if (list != null) {
if (list.Count != 0)
return list [0];
throw new InvalidOperationException ();
} else {
using (var enumerator = source.GetEnumerator ()) {
if (enumerator.MoveNext ())
return enumerator.Current;
}
}
throw new InvalidOperationException ();
}
public static TSource First<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
Check.SourceAndPredicate (source, predicate);
return source.First (predicate, Fallback.Throw);
}
#endregion
#region FirstOrDefault
public static TSource FirstOrDefault<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
return source.First (PredicateOf<TSource>.Always, Fallback.Default);
}
public static TSource FirstOrDefault<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
Check.SourceAndPredicate (source, predicate);
return source.First (predicate, Fallback.Default);
}
#endregion
#region GroupBy
private static List<T> ContainsGroup<K, T> (
Dictionary<K, List<T>> items, K key, IEqualityComparer<K> comparer)
{
IEqualityComparer<K> comparerInUse = (comparer ?? EqualityComparer<K>.Default);
foreach (KeyValuePair<K, List<T>> value in items) {
if (comparerInUse.Equals (value.Key, key))
return value.Value;
}
return null;
}
public static IEnumerable<IGrouping<TKey, TSource>> GroupBy<TSource, TKey> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector)
{
return GroupBy<TSource, TKey> (source, keySelector, null);
}
public static IEnumerable<IGrouping<TKey, TSource>> GroupBy<TSource, TKey> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer)
{
Check.SourceAndKeySelector (source, keySelector);
return CreateGroupByIterator (source, keySelector, comparer);
}
static IEnumerable<IGrouping<TKey, TSource>> CreateGroupByIterator<TSource, TKey> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer)
{
Dictionary<TKey, List<TSource>> groups = new Dictionary<TKey, List<TSource>> ();
List<TSource> nullList = new List<TSource> ();
int counter = 0;
int nullCounter = -1;
foreach (TSource element in source) {
TKey key = keySelector (element);
if (key == null) {
nullList.Add (element);
if (nullCounter == -1) {
nullCounter = counter;
counter++;
}
} else {
List<TSource> group = ContainsGroup<TKey, TSource> (groups, key, comparer);
if (group == null) {
group = new List<TSource> ();
groups.Add (key, group);
counter++;
}
group.Add (element);
}
}
counter = 0;
foreach (KeyValuePair<TKey, List<TSource>> group in groups) {
if (counter == nullCounter) {
Grouping<TKey, TSource> nullGroup = new Grouping<TKey, TSource> (default (TKey), nullList);
yield return nullGroup;
counter++;
}
Grouping<TKey, TSource> grouping = new Grouping<TKey, TSource> (group.Key, group.Value);
yield return grouping;
counter++;
}
}
public static IEnumerable<IGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector)
{
return GroupBy<TSource, TKey, TElement> (source, keySelector, elementSelector, null);
}
public static IEnumerable<IGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey> comparer)
{
Check.SourceAndKeyElementSelectors (source, keySelector, elementSelector);
Dictionary<TKey, List<TElement>> groups = new Dictionary<TKey, List<TElement>> ();
List<TElement> nullList = new List<TElement> ();
int counter = 0;
int nullCounter = -1;
foreach (TSource item in source) {
TKey key = keySelector (item);
TElement element = elementSelector (item);
if (key == null) {
nullList.Add (element);
if (nullCounter == -1) {
nullCounter = counter;
counter++;
}
} else {
List<TElement> group = ContainsGroup<TKey, TElement> (groups, key, comparer);
if (group == null) {
group = new List<TElement> ();
groups.Add (key, group);
counter++;
}
group.Add (element);
}
}
counter = 0;
foreach (KeyValuePair<TKey, List<TElement>> group in groups) {
if (counter == nullCounter) {
Grouping<TKey, TElement> nullGroup = new Grouping<TKey, TElement> (default (TKey), nullList);
yield return nullGroup;
counter++;
}
Grouping<TKey, TElement> grouping = new Grouping<TKey, TElement> (group.Key, group.Value);
yield return grouping;
counter++;
}
}
public static IEnumerable<TResult> GroupBy<TSource, TKey, TElement, TResult> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector,
Func<TKey, IEnumerable<TElement>, TResult> resultSelector)
{
return GroupBy (source, keySelector, elementSelector, resultSelector, null);
}
public static IEnumerable<TResult> GroupBy<TSource, TKey, TElement, TResult> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector,
Func<TKey, IEnumerable<TElement>, TResult> resultSelector,
IEqualityComparer<TKey> comparer)
{
IEnumerable<IGrouping<TKey, TElement>> groups = GroupBy<TSource, TKey, TElement> (
source, keySelector, elementSelector, comparer);
foreach (IGrouping<TKey, TElement> group in groups)
yield return resultSelector (group.Key, group);
}
public static IEnumerable<TResult> GroupBy<TSource, TKey, TResult> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector,
Func<TKey, IEnumerable<TSource>, TResult> resultSelector)
{
return GroupBy (source, keySelector, resultSelector, null);
}
public static IEnumerable<TResult> GroupBy<TSource, TKey, TResult> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector,
Func<TKey, IEnumerable<TSource>, TResult> resultSelector,
IEqualityComparer<TKey> comparer)
{
IEnumerable<IGrouping<TKey,TSource>> groups = GroupBy<TSource, TKey> (source, keySelector, comparer);
foreach (IGrouping<TKey, TSource> group in groups)
yield return resultSelector (group.Key, group);
}
#endregion
# region GroupJoin
public static IEnumerable<TResult> GroupJoin<TOuter, TInner, TKey, TResult> (this IEnumerable<TOuter> outer,
IEnumerable<TInner> inner, Func<TOuter, TKey> outerKeySelector,
Func<TInner, TKey> innerKeySelector, Func<TOuter, IEnumerable<TInner>, TResult> resultSelector)
{
return GroupJoin (outer, inner, outerKeySelector, innerKeySelector, resultSelector, null);
}
public static IEnumerable<TResult> GroupJoin<TOuter, TInner, TKey, TResult> (this IEnumerable<TOuter> outer,
IEnumerable<TInner> inner, Func<TOuter, TKey> outerKeySelector,
Func<TInner, TKey> innerKeySelector, Func<TOuter, IEnumerable<TInner>, TResult> resultSelector,
IEqualityComparer<TKey> comparer)
{
Check.JoinSelectors (outer, inner, outerKeySelector, innerKeySelector, resultSelector);
if (comparer == null)
comparer = EqualityComparer<TKey>.Default;
return CreateGroupJoinIterator (outer, inner, outerKeySelector, innerKeySelector, resultSelector, comparer);
}
static IEnumerable<TResult> CreateGroupJoinIterator<TOuter, TInner, TKey, TResult> (this IEnumerable<TOuter> outer,
IEnumerable<TInner> inner, Func<TOuter, TKey> outerKeySelector,
Func<TInner, TKey> innerKeySelector, Func<TOuter, IEnumerable<TInner>, TResult> resultSelector,
IEqualityComparer<TKey> comparer)
{
ILookup<TKey, TInner> innerKeys = ToLookup<TInner, TKey> (inner, innerKeySelector, comparer);
/*Dictionary<K, List<U>> innerKeys = new Dictionary<K, List<U>> ();
foreach (U element in inner)
{
K innerKey = innerKeySelector (element);
if (!innerKeys.ContainsKey (innerKey))
innerKeys.Add (innerKey, new List<U> ());
innerKeys[innerKey].Add (element);
}*/
foreach (TOuter element in outer) {
TKey outerKey = outerKeySelector (element);
if (innerKeys.Contains (outerKey))
yield return resultSelector (element, innerKeys [outerKey]);
else
yield return resultSelector (element, Empty<TInner> ());
}
}
#endregion
#region Intersect
public static IEnumerable<TSource> Intersect<TSource> (this IEnumerable<TSource> first, IEnumerable<TSource> second)
{
return Intersect (first, second, null);
}
public static IEnumerable<TSource> Intersect<TSource> (this IEnumerable<TSource> first, IEnumerable<TSource> second, IEqualityComparer<TSource> comparer)
{
Check.FirstAndSecond (first, second);
if (comparer == null)
comparer = EqualityComparer<TSource>.Default;
return CreateIntersectIterator (first, second, comparer);
}
static IEnumerable<TSource> CreateIntersectIterator<TSource> (IEnumerable<TSource> first, IEnumerable<TSource> second, IEqualityComparer<TSource> comparer)
{
var items = new HashSet<TSource> (second, comparer);
foreach (TSource element in first) {
if (items.Remove (element))
yield return element;
}
}
#endregion
# region Join
public static IEnumerable<TResult> Join<TOuter, TInner, TKey, TResult> (this IEnumerable<TOuter> outer,
IEnumerable<TInner> inner, Func<TOuter, TKey> outerKeySelector,
Func<TInner, TKey> innerKeySelector, Func<TOuter, TInner, TResult> resultSelector, IEqualityComparer<TKey> comparer)
{
Check.JoinSelectors (outer, inner, outerKeySelector, innerKeySelector, resultSelector);
if (comparer == null)
comparer = EqualityComparer<TKey>.Default;
return CreateJoinIterator (outer, inner, outerKeySelector, innerKeySelector, resultSelector, comparer);
}
static IEnumerable<TResult> CreateJoinIterator<TOuter, TInner, TKey, TResult> (this IEnumerable<TOuter> outer,
IEnumerable<TInner> inner, Func<TOuter, TKey> outerKeySelector,
Func<TInner, TKey> innerKeySelector, Func<TOuter, TInner, TResult> resultSelector, IEqualityComparer<TKey> comparer)
{
ILookup<TKey, TInner> innerKeys = ToLookup<TInner, TKey> (inner, innerKeySelector, comparer);
/*Dictionary<K, List<U>> innerKeys = new Dictionary<K, List<U>> ();
foreach (U element in inner)
{
K innerKey = innerKeySelector (element);
if (!innerKeys.ContainsKey (innerKey))
innerKeys.Add (innerKey, new List<U> ());
innerKeys[innerKey].Add (element);
}*/
foreach (TOuter element in outer) {
TKey outerKey = outerKeySelector (element);
if (innerKeys.Contains (outerKey)) {
foreach (TInner innerElement in innerKeys [outerKey])
yield return resultSelector (element, innerElement);
}
}
}
public static IEnumerable<TResult> Join<TOuter, TInner, TKey, TResult> (this IEnumerable<TOuter> outer,
IEnumerable<TInner> inner, Func<TOuter, TKey> outerKeySelector,
Func<TInner, TKey> innerKeySelector, Func<TOuter, TInner, TResult> resultSelector)
{
return outer.Join (inner, outerKeySelector, innerKeySelector, resultSelector, null);
}
#endregion
#region Last
static TSource Last<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> predicate, Fallback fallback)
{
var empty = true;
var item = default (TSource);
foreach (var element in source) {
if (!predicate (element))
continue;
item = element;
empty = false;
}
if (!empty)
return item;
if (fallback == Fallback.Throw)
throw new InvalidOperationException ();
return item;
}
public static TSource Last<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
var collection = source as ICollection<TSource>;
if (collection != null && collection.Count == 0)
throw new InvalidOperationException ();
var list = source as IList<TSource>;
if (list != null)
return list [list.Count - 1];
return source.Last (PredicateOf<TSource>.Always, Fallback.Throw);
}
public static TSource Last<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
Check.SourceAndPredicate (source, predicate);
return source.Last (predicate, Fallback.Throw);
}
#endregion
#region LastOrDefault
public static TSource LastOrDefault<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
var list = source as IList<TSource>;
if (list != null)
return list.Count > 0 ? list [list.Count - 1] : default (TSource);
return source.Last (PredicateOf<TSource>.Always, Fallback.Default);
}
public static TSource LastOrDefault<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
Check.SourceAndPredicate (source, predicate);
return source.Last (predicate, Fallback.Default);
}
#endregion
#region LongCount
public static long LongCount<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
#if !NET_2_1
var array = source as TSource [];
if (array != null)
return array.LongLength;
#endif
long counter = 0;
using (var enumerator = source.GetEnumerator ())
while (enumerator.MoveNext ())
counter++;
return counter;
}
public static long LongCount<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> selector)
{
Check.SourceAndSelector (source, selector);
long counter = 0;
foreach (TSource element in source)
if (selector (element))
counter++;
return counter;
}
#endregion
#region Max
public static int Max (this IEnumerable<int> source)
{
Check.Source (source);
return Iterate (source, int.MinValue, (a, b) => Math.Max (a, b));
}
public static long Max (this IEnumerable<long> source)
{
Check.Source (source);
return Iterate (source, long.MinValue, (a, b) => Math.Max (a, b));
}
public static double Max (this IEnumerable<double> source)
{
Check.Source (source);
return Iterate (source, double.MinValue, (a, b) => Math.Max (a, b));
}
public static float Max (this IEnumerable<float> source)
{
Check.Source (source);
return Iterate (source, float.MinValue, (a, b) => Math.Max (a, b));
}
public static decimal Max (this IEnumerable<decimal> source)
{
Check.Source (source);
return Iterate (source, decimal.MinValue, (a, b) => Math.Max (a, b));
}
public static int? Max (this IEnumerable<int?> source)
{
Check.Source (source);
return IterateNullable (source, (a, b) => Math.Max (a, b));
}
public static long? Max (this IEnumerable<long?> source)
{
Check.Source (source);
return IterateNullable (source, (a, b) => Math.Max (a, b));
}
public static double? Max (this IEnumerable<double?> source)
{
Check.Source (source);
return IterateNullable (source, (a, b) => Math.Max (a, b));
}
public static float? Max (this IEnumerable<float?> source)
{
Check.Source (source);
return IterateNullable (source, (a, b) => Math.Max (a, b));
}
public static decimal? Max (this IEnumerable<decimal?> source)
{
Check.Source (source);
return IterateNullable (source, (a, b) => Math.Max (a, b));
}
static T? IterateNullable<T> (IEnumerable<T?> source, Func<T, T, T> selector) where T : struct
{
bool empty = true;
T? value = null;
foreach (var element in source) {
if (!element.HasValue)
continue;
if (!value.HasValue)
value = element.Value;
else
value = selector (element.Value, value.Value);
empty = false;
}
if (empty)
return null;
return value;
}
static TRet? IterateNullable<TSource, TRet> (
IEnumerable<TSource> source,
Func<TSource, TRet?> source_selector,
Func<TRet?, TRet?, bool> selector) where TRet : struct
{
bool empty = true;
TRet? value = null;
foreach (var element in source) {
TRet? item = source_selector (element);
if (!value.HasValue)
value = item;
else if (selector (item, value))
value = item;
empty = false;
}
if (empty)
return null;
return value;
}
public static TSource Max<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
bool notAssigned = true;
TSource maximum = default (TSource);
int counter = 0;
foreach (TSource element in source) {
if (notAssigned) {
maximum = element;
notAssigned = false;
} else {
int comparison;
if (element is IComparable<TSource>)
comparison = ((IComparable<TSource>) element).CompareTo (maximum);
else if (element is System.IComparable)
comparison = ((System.IComparable) element).CompareTo (maximum);
else
throw new ArgumentNullException ();
if (comparison > 0)
maximum = element;
}
counter++;
}
if (counter == 0)
throw new InvalidOperationException ();
else
return maximum;
}
public static int Max<TSource> (this IEnumerable<TSource> source, Func<TSource, int> selector)
{
Check.SourceAndSelector (source, selector);
return Iterate (source, int.MinValue, (a, b) => Math.Max (selector (a), b));
}
public static long Max<TSource> (this IEnumerable<TSource> source, Func<TSource, long> selector)
{
Check.SourceAndSelector (source, selector);
return Iterate (source, long.MinValue, (a, b) => Math.Max (selector (a), b));
}
public static double Max<TSource> (this IEnumerable<TSource> source, Func<TSource, double> selector)
{
Check.SourceAndSelector (source, selector);
return Iterate (source, double.MinValue, (a, b) => Math.Max (selector (a), b));
}
public static float Max<TSource> (this IEnumerable<TSource> source, Func<TSource, float> selector)
{
Check.SourceAndSelector (source, selector);
return Iterate (source, float.MinValue, (a, b) => Math.Max (selector (a), b));
}
public static decimal Max<TSource> (this IEnumerable<TSource> source, Func<TSource, decimal> selector)
{
Check.SourceAndSelector (source, selector);
return Iterate (source, decimal.MinValue, (a, b) => Math.Max (selector (a), b));
}
static U Iterate<T, U> (IEnumerable<T> source, U initValue, Func<T, U, U> selector)
{
bool empty = true;
foreach (var element in source) {
initValue = selector (element, initValue);
empty = false;
}
if (empty)
throw new InvalidOperationException ();
return initValue;
}
public static int? Max<TSource> (this IEnumerable<TSource> source, Func<TSource, int?> selector)
{
Check.SourceAndSelector (source, selector);
return IterateNullable (source, selector, (a, b) => a > b);
}
public static long? Max<TSource> (this IEnumerable<TSource> source, Func<TSource, long?> selector)
{
Check.SourceAndSelector (source, selector);
return IterateNullable (source, selector, (a, b) => a > b);
}
public static double? Max<TSource> (this IEnumerable<TSource> source, Func<TSource, double?> selector)
{
Check.SourceAndSelector (source, selector);
return IterateNullable (source, selector, (a, b) => a > b);
}
public static float? Max<TSource> (this IEnumerable<TSource> source, Func<TSource, float?> selector)
{
Check.SourceAndSelector (source, selector);
return IterateNullable (source, selector, (a, b) => a > b);
}
public static decimal? Max<TSource> (this IEnumerable<TSource> source, Func<TSource, decimal?> selector)
{
Check.SourceAndSelector (source, selector);
return IterateNullable (source, selector, (a, b) => a > b);
}
public static TResult Max<TSource, TResult> (this IEnumerable<TSource> source, Func<TSource, TResult> selector)
{
Check.SourceAndSelector (source, selector);
bool notAssigned = true;
TResult maximum = default (TResult);
int counter = 0;
foreach (TSource item in source) {
TResult element = selector (item);
if (notAssigned) {
maximum = element;
notAssigned = false;
} else {
int comparison;
if (element is IComparable<TResult>)
comparison = ((IComparable<TResult>) element).CompareTo (maximum);
else if (element is System.IComparable)
comparison = ((System.IComparable) element).CompareTo (maximum);
else
throw new ArgumentNullException ();
if (comparison > 0)
maximum = element;
}
counter++;
}
if (counter == 0)
throw new InvalidOperationException ();
else
return maximum;
}
#endregion
#region Min
public static int Min (this IEnumerable<int> source)
{
Check.Source (source);
return Iterate (source, int.MaxValue, (a, b) => Math.Min (a, b));
}
public static long Min (this IEnumerable<long> source)
{
Check.Source (source);
return Iterate (source, long.MaxValue, (a, b) => Math.Min (a, b));
}
public static double Min (this IEnumerable<double> source)
{
Check.Source (source);
return Iterate (source, double.MaxValue, (a, b) => Math.Min (a, b));
}
public static float Min (this IEnumerable<float> source)
{
Check.Source (source);
return Iterate (source, float.MaxValue, (a, b) => Math.Min (a, b));
}
public static decimal Min (this IEnumerable<decimal> source)
{
Check.Source (source);
return Iterate (source, decimal.MaxValue, (a, b) => Math.Min (a, b));
}
public static int? Min (this IEnumerable<int?> source)
{
Check.Source (source);
return IterateNullable (source, (a, b) => Math.Min (a, b));
}
public static long? Min (this IEnumerable<long?> source)
{
Check.Source (source);
return IterateNullable (source, (a, b) => Math.Min (a, b));
}
public static double? Min (this IEnumerable<double?> source)
{
Check.Source (source);
return IterateNullable (source, (a, b) => Math.Min (a, b));
}
public static float? Min (this IEnumerable<float?> source)
{
Check.Source (source);
return IterateNullable (source, (a, b) => Math.Min (a, b));
}
public static decimal? Min (this IEnumerable<decimal?> source)
{
Check.Source (source);
return IterateNullable (source, (a, b) => Math.Min (a, b));
}
public static TSource Min<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
bool notAssigned = true;
TSource minimum = default (TSource);
int counter = 0;
foreach (TSource element in source) {
if (notAssigned) {
minimum = element;
notAssigned = false;
} else {
int comparison;
if (element is IComparable<TSource>)
comparison = ((IComparable<TSource>) element).CompareTo (minimum);
else if (element is System.IComparable)
comparison = ((System.IComparable) element).CompareTo (minimum);
else
throw new ArgumentNullException ();
if (comparison < 0)
minimum = element;
}
counter++;
}
if (counter == 0)
throw new InvalidOperationException ();
else
return minimum;
}
public static int Min<TSource> (this IEnumerable<TSource> source, Func<TSource, int> selector)
{
Check.SourceAndSelector (source, selector);
return Iterate (source, int.MaxValue, (a, b) => Math.Min (selector (a), b));
}
public static long Min<TSource> (this IEnumerable<TSource> source, Func<TSource, long> selector)
{
Check.SourceAndSelector (source, selector);
return Iterate (source, long.MaxValue, (a, b) => Math.Min (selector (a), b));
}
public static double Min<TSource> (this IEnumerable<TSource> source, Func<TSource, double> selector)
{
Check.SourceAndSelector (source, selector);
return Iterate (source, double.MaxValue, (a, b) => Math.Min (selector (a), b));
}
public static float Min<TSource> (this IEnumerable<TSource> source, Func<TSource, float> selector)
{
Check.SourceAndSelector (source, selector);
return Iterate (source, float.MaxValue, (a, b) => Math.Min (selector (a), b));
}
public static decimal Min<TSource> (this IEnumerable<TSource> source, Func<TSource, decimal> selector)
{
Check.SourceAndSelector (source, selector);
return Iterate (source, decimal.MaxValue, (a, b) => Math.Min (selector (a), b));
}
public static int? Min<TSource> (this IEnumerable<TSource> source, Func<TSource, int?> selector)
{
Check.SourceAndSelector (source, selector);
return IterateNullable (source, selector, (a, b) => a < b);
}
public static long? Min<TSource> (this IEnumerable<TSource> source, Func<TSource, long?> selector)
{
Check.SourceAndSelector (source, selector);
return IterateNullable (source, selector, (a, b) => a < b);
}
public static float? Min<TSource> (this IEnumerable<TSource> source, Func<TSource, float?> selector)
{
Check.SourceAndSelector (source, selector);
return IterateNullable (source, selector, (a, b) => a < b);
}
public static double? Min<TSource> (this IEnumerable<TSource> source, Func<TSource, double?> selector)
{
Check.SourceAndSelector (source, selector);
return IterateNullable (source, selector, (a, b) => a < b);
}
public static decimal? Min<TSource> (this IEnumerable<TSource> source, Func<TSource, decimal?> selector)
{
Check.SourceAndSelector (source, selector);
return IterateNullable (source, selector, (a, b) => a < b);
}
public static TResult Min<TSource, TResult> (this IEnumerable<TSource> source, Func<TSource, TResult> selector)
{
Check.SourceAndSelector (source, selector);
bool notAssigned = true;
TResult minimum = default (TResult);
int counter = 0;
foreach (TSource item in source) {
TResult element = selector (item);
if (notAssigned) {
minimum = element;
notAssigned = false;
} else {
int comparison;
if (element is IComparable<TResult>)
comparison = ((IComparable<TResult>) element).CompareTo (minimum);
else if (element is System.IComparable)
comparison = ((System.IComparable) element).CompareTo (minimum);
else
throw new ArgumentNullException ();
if (comparison < 0)
minimum = element;
}
counter++;
}
if (counter == 0)
throw new InvalidOperationException ();
else
return minimum;
}
#endregion
#region OfType
public static IEnumerable<TResult> OfType<TResult> (this IEnumerable source)
{
Check.Source (source);
return CreateOfTypeIterator<TResult> (source);
}
static IEnumerable<TResult> CreateOfTypeIterator<TResult> (IEnumerable source)
{
foreach (object element in source)
if (element is TResult)
yield return (TResult) element;
}
#endregion
#region OrderBy
public static IOrderedEnumerable<TSource> OrderBy<TSource, TKey> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector)
{
return OrderBy<TSource, TKey> (source, keySelector, null);
}
public static IOrderedEnumerable<TSource> OrderBy<TSource, TKey> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector,
IComparer<TKey> comparer)
{
Check.SourceAndKeySelector (source, keySelector);
return new OrderedSequence<TSource, TKey> (source, keySelector, comparer, SortDirection.Ascending);
}
#endregion
#region OrderByDescending
public static IOrderedEnumerable<TSource> OrderByDescending<TSource, TKey> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector)
{
return OrderByDescending<TSource, TKey> (source, keySelector, null);
}
public static IOrderedEnumerable<TSource> OrderByDescending<TSource, TKey> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector, IComparer<TKey> comparer)
{
Check.SourceAndKeySelector (source, keySelector);
return new OrderedSequence<TSource, TKey> (source, keySelector, comparer, SortDirection.Descending);
}
#endregion
#region Range
public static IEnumerable<int> Range (int start, int count)
{
if (count < 0)
throw new ArgumentOutOfRangeException ("count");
long upto = ((long) start + count) - 1;
if (upto > int.MaxValue)
throw new ArgumentOutOfRangeException ();
return CreateRangeIterator (start, (int) upto);
}
static IEnumerable<int> CreateRangeIterator (int start, int upto)
{
for (int i = start; i <= upto; i++)
yield return i;
}
#endregion
#region Repeat
public static IEnumerable<TResult> Repeat<TResult> (TResult element, int count)
{
if (count < 0)
throw new ArgumentOutOfRangeException ();
return CreateRepeatIterator (element, count);
}
static IEnumerable<TResult> CreateRepeatIterator<TResult> (TResult element, int count)
{
for (int i = 0; i < count; i++)
yield return element;
}
#endregion
#region Reverse
public static IEnumerable<TSource> Reverse<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
var list = source as IList<TSource>;
if (list == null)
list = new List<TSource> (source);
return CreateReverseIterator (list);
}
static IEnumerable<TSource> CreateReverseIterator<TSource> (IList<TSource> source)
{
for (int i = source.Count; i > 0; --i)
yield return source [i - 1];
}
#endregion
#region Select
public static IEnumerable<TResult> Select<TSource, TResult> (this IEnumerable<TSource> source, Func<TSource, TResult> selector)
{
Check.SourceAndSelector (source, selector);
return CreateSelectIterator (source, selector);
}
static IEnumerable<TResult> CreateSelectIterator<TSource, TResult> (IEnumerable<TSource> source, Func<TSource, TResult> selector)
{
foreach (var element in source)
yield return selector (element);
}
public static IEnumerable<TResult> Select<TSource, TResult> (this IEnumerable<TSource> source, Func<TSource, int, TResult> selector)
{
Check.SourceAndSelector (source, selector);
return CreateSelectIterator (source, selector);
}
static IEnumerable<TResult> CreateSelectIterator<TSource, TResult> (IEnumerable<TSource> source, Func<TSource, int, TResult> selector)
{
int counter = 0;
foreach (TSource element in source) {
yield return selector (element, counter);
counter++;
}
}
#endregion
#region SelectMany
public static IEnumerable<TResult> SelectMany<TSource, TResult> (this IEnumerable<TSource> source, Func<TSource, IEnumerable<TResult>> selector)
{
Check.SourceAndSelector (source, selector);
return CreateSelectManyIterator (source, selector);
}
static IEnumerable<TResult> CreateSelectManyIterator<TSource, TResult> (IEnumerable<TSource> source, Func<TSource, IEnumerable<TResult>> selector)
{
foreach (TSource element in source)
foreach (TResult item in selector (element))
yield return item;
}
public static IEnumerable<TResult> SelectMany<TSource, TResult> (this IEnumerable<TSource> source, Func<TSource, int, IEnumerable<TResult>> selector)
{
Check.SourceAndSelector (source, selector);
return CreateSelectManyIterator (source, selector);
}
static IEnumerable<TResult> CreateSelectManyIterator<TSource, TResult> (IEnumerable<TSource> source, Func<TSource, int, IEnumerable<TResult>> selector)
{
int counter = 0;
foreach (TSource element in source) {
foreach (TResult item in selector (element, counter))
yield return item;
counter++;
}
}
public static IEnumerable<TResult> SelectMany<TSource, TCollection, TResult> (this IEnumerable<TSource> source,
Func<TSource, IEnumerable<TCollection>> collectionSelector, Func<TSource, TCollection, TResult> selector)
{
Check.SourceAndCollectionSelectors (source, collectionSelector, selector);
return CreateSelectManyIterator (source, collectionSelector, selector);
}
static IEnumerable<TResult> CreateSelectManyIterator<TSource, TCollection, TResult> (IEnumerable<TSource> source,
Func<TSource, IEnumerable<TCollection>> collectionSelector, Func<TSource, TCollection, TResult> selector)
{
foreach (TSource element in source)
foreach (TCollection collection in collectionSelector (element))
yield return selector (element, collection);
}
public static IEnumerable<TResult> SelectMany<TSource, TCollection, TResult> (this IEnumerable<TSource> source,
Func<TSource, int, IEnumerable<TCollection>> collectionSelector, Func<TSource, TCollection, TResult> selector)
{
Check.SourceAndCollectionSelectors (source, collectionSelector, selector);
return CreateSelectManyIterator (source, collectionSelector, selector);
}
static IEnumerable<TResult> CreateSelectManyIterator<TSource, TCollection, TResult> (IEnumerable<TSource> source,
Func<TSource, int, IEnumerable<TCollection>> collectionSelector, Func<TSource, TCollection, TResult> selector)
{
int counter = 0;
foreach (TSource element in source)
foreach (TCollection collection in collectionSelector (element, counter++))
yield return selector (element, collection);
}
#endregion
#region Single
static TSource Single<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> predicate, Fallback fallback)
{
var found = false;
var item = default (TSource);
foreach (var element in source) {
if (!predicate (element))
continue;
if (found)
throw new InvalidOperationException ();
found = true;
item = element;
}
if (!found && fallback == Fallback.Throw)
throw new InvalidOperationException ();
return item;
}
public static TSource Single<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
return source.Single (PredicateOf<TSource>.Always, Fallback.Throw);
}
public static TSource Single<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
Check.SourceAndPredicate (source, predicate);
return source.Single (predicate, Fallback.Throw);
}
#endregion
#region SingleOrDefault
public static TSource SingleOrDefault<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
return source.Single (PredicateOf<TSource>.Always, Fallback.Default);
}
public static TSource SingleOrDefault<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
Check.SourceAndPredicate (source, predicate);
return source.Single (predicate, Fallback.Default);
}
#endregion
#region Skip
public static IEnumerable<TSource> Skip<TSource> (this IEnumerable<TSource> source, int count)
{
Check.Source (source);
return CreateSkipIterator (source, count);
}
static IEnumerable<TSource> CreateSkipIterator<TSource> (IEnumerable<TSource> source, int count)
{
int i = 0;
foreach (var element in source) {
if (i++ < count)
continue;
yield return element;
}
}
#endregion
#region SkipWhile
public static IEnumerable<TSource> SkipWhile<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
Check.SourceAndPredicate (source, predicate);
return CreateSkipWhileIterator (source, predicate);
}
static IEnumerable<TSource> CreateSkipWhileIterator<TSource> (IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
bool yield = false;
foreach (TSource element in source) {
if (yield)
yield return element;
else
if (!predicate (element)) {
yield return element;
yield = true;
}
}
}
public static IEnumerable<TSource> SkipWhile<TSource> (this IEnumerable<TSource> source, Func<TSource, int, bool> predicate)
{
Check.SourceAndPredicate (source, predicate);
return CreateSkipWhileIterator (source, predicate);
}
static IEnumerable<TSource> CreateSkipWhileIterator<TSource> (IEnumerable<TSource> source, Func<TSource, int, bool> predicate)
{
int counter = 0;
bool yield = false;
foreach (TSource element in source) {
if (yield)
yield return element;
else
if (!predicate (element, counter)) {
yield return element;
yield = true;
}
counter++;
}
}
#endregion
#region Sum
public static int Sum (this IEnumerable<int> source)
{
Check.Source (source);
return Sum<int, int> (source, (a, b) => checked (a + b));
}
public static int? Sum (this IEnumerable<int?> source)
{
Check.Source (source);
return source.SumNullable<int?, int?> (0, (total, element) => element.HasValue ? checked (total + element) : total);
}
public static int Sum<TSource> (this IEnumerable<TSource> source, Func<TSource, int> selector)
{
Check.SourceAndSelector (source, selector);
return Sum<TSource, int> (source, (a, b) => checked (a + selector (b)));
}
public static int? Sum<TSource> (this IEnumerable<TSource> source, Func<TSource, int?> selector)
{
Check.SourceAndSelector (source, selector);
return source.SumNullable<TSource, int?> (0, (a, b) => {
var value = selector (b);
return value.HasValue ? checked (a + value.Value) : a;
});
}
public static long Sum (this IEnumerable<long> source)
{
Check.Source (source);
return Sum<long, long> (source, (a, b) => checked (a + b));
}
public static long? Sum (this IEnumerable<long?> source)
{
Check.Source (source);
return source.SumNullable<long?, long?> (0, (total, element) => element.HasValue ? checked (total + element) : total);
}
public static long Sum<TSource> (this IEnumerable<TSource> source, Func<TSource, long> selector)
{
Check.SourceAndSelector (source, selector);
return Sum<TSource, long> (source, (a, b) => checked (a + selector (b)));
}
public static long? Sum<TSource> (this IEnumerable<TSource> source, Func<TSource, long?> selector)
{
Check.SourceAndSelector (source, selector);
return source.SumNullable<TSource, long?> (0, (a, b) => {
var value = selector (b);
return value.HasValue ? checked (a + value.Value) : a;
});
}
public static double Sum (this IEnumerable<double> source)
{
Check.Source (source);
return Sum<double, double> (source, (a, b) => checked (a + b));
}
public static double? Sum (this IEnumerable<double?> source)
{
Check.Source (source);
return source.SumNullable<double?, double?> (0, (total, element) => element.HasValue ? checked (total + element) : total);
}
public static double Sum<TSource> (this IEnumerable<TSource> source, Func<TSource, double> selector)
{
Check.SourceAndSelector (source, selector);
return Sum<TSource, double> (source, (a, b) => checked (a + selector (b)));
}
public static double? Sum<TSource> (this IEnumerable<TSource> source, Func<TSource, double?> selector)
{
Check.SourceAndSelector (source, selector);
return source.SumNullable<TSource, double?> (0, (a, b) => {
var value = selector (b);
return value.HasValue ? checked (a + value.Value) : a;
});
}
public static float Sum (this IEnumerable<float> source)
{
Check.Source (source);
return Sum<float, float> (source, (a, b) => checked (a + b));
}
public static float? Sum (this IEnumerable<float?> source)
{
Check.Source (source);
return source.SumNullable<float?, float?> (0, (total, element) => element.HasValue ? checked (total + element) : total);
}
public static float Sum<TSource> (this IEnumerable<TSource> source, Func<TSource, float> selector)
{
Check.SourceAndSelector (source, selector);
return Sum<TSource, float> (source, (a, b) => checked (a + selector (b)));
}
public static float? Sum<TSource> (this IEnumerable<TSource> source, Func<TSource, float?> selector)
{
Check.SourceAndSelector (source, selector);
return source.SumNullable<TSource, float?> (0, (a, b) => {
var value = selector (b);
return value.HasValue ? checked (a + value.Value) : a;
});
}
public static decimal Sum (this IEnumerable<decimal> source)
{
Check.Source (source);
return Sum<decimal, decimal> (source, (a, b) => checked (a + b));
}
public static decimal? Sum (this IEnumerable<decimal?> source)
{
Check.Source (source);
return source.SumNullable<decimal?, decimal?> (0, (total, element) => element.HasValue ? checked (total + element) : total);
}
public static decimal Sum<TSource> (this IEnumerable<TSource> source, Func<TSource, decimal> selector)
{
Check.SourceAndSelector (source, selector);
return Sum<TSource, decimal> (source, (a, b) => checked (a + selector (b)));
}
public static decimal? Sum<TSource> (this IEnumerable<TSource> source, Func<TSource, decimal?> selector)
{
Check.SourceAndSelector (source, selector);
return source.SumNullable<TSource, decimal?> (0, (a, b) => {
var value = selector (b);
return value.HasValue ? checked (a + value.Value) : a;
});
}
static TR Sum<TA, TR> (this IEnumerable<TA> source, Func<TR, TA, TR> selector)
{
TR total = default (TR);
long counter = 0;
foreach (var element in source) {
total = selector (total, element);
++counter;
}
return total;
}
static TR SumNullable<TA, TR> (this IEnumerable<TA> source, TR zero, Func<TR, TA, TR> selector)
{
TR total = zero;
foreach (var element in source) {
total = selector (total, element);
}
return total;
}
#endregion
#region Take
public static IEnumerable<TSource> Take<TSource> (this IEnumerable<TSource> source, int count)
{
Check.Source (source);
return CreateTakeIterator (source, count);
}
static IEnumerable<TSource> CreateTakeIterator<TSource> (IEnumerable<TSource> source, int count)
{
if (count <= 0)
yield break;
int counter = 0;
foreach (TSource element in source) {
yield return element;
if (++counter == count)
yield break;
}
}
#endregion
#region TakeWhile
public static IEnumerable<TSource> TakeWhile<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
Check.SourceAndPredicate (source, predicate);
return CreateTakeWhileIterator (source, predicate);
}
static IEnumerable<TSource> CreateTakeWhileIterator<TSource> (IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
foreach (var element in source) {
if (!predicate (element))
yield break;
yield return element;
}
}
public static IEnumerable<TSource> TakeWhile<TSource> (this IEnumerable<TSource> source, Func<TSource, int, bool> predicate)
{
Check.SourceAndPredicate (source, predicate);
return CreateTakeWhileIterator (source, predicate);
}
static IEnumerable<TSource> CreateTakeWhileIterator<TSource> (IEnumerable<TSource> source, Func<TSource, int, bool> predicate)
{
int counter = 0;
foreach (var element in source) {
if (!predicate (element, counter))
yield break;
yield return element;
counter++;
}
}
#endregion
#region ThenBy
public static IOrderedEnumerable<TSource> ThenBy<TSource, TKey> (this IOrderedEnumerable<TSource> source, Func<TSource, TKey> keySelector)
{
return ThenBy<TSource, TKey> (source, keySelector, null);
}
public static IOrderedEnumerable<TSource> ThenBy<TSource, TKey> (this IOrderedEnumerable<TSource> source,
Func<TSource, TKey> keySelector, IComparer<TKey> comparer)
{
Check.SourceAndKeySelector (source, keySelector);
return source.CreateOrderedEnumerable (keySelector, comparer, false);
}
#endregion
#region ThenByDescending
public static IOrderedEnumerable<TSource> ThenByDescending<TSource, TKey> (this IOrderedEnumerable<TSource> source,
Func<TSource, TKey> keySelector)
{
return ThenByDescending<TSource, TKey> (source, keySelector, null);
}
public static IOrderedEnumerable<TSource> ThenByDescending<TSource, TKey> (this IOrderedEnumerable<TSource> source,
Func<TSource, TKey> keySelector, IComparer<TKey> comparer)
{
Check.SourceAndKeySelector (source, keySelector);
return source.CreateOrderedEnumerable (keySelector, comparer, true);
}
#endregion
#region ToArray
public static TSource [] ToArray<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
var collection = source as ICollection<TSource>;
if (collection != null) {
var array = new TSource [collection.Count];
collection.CopyTo (array, 0);
return array;
}
return new List<TSource> (source).ToArray ();
}
#endregion
#region ToDictionary
public static Dictionary<TKey, TElement> ToDictionary<TSource, TKey, TElement> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector)
{
return ToDictionary<TSource, TKey, TElement> (source, keySelector, elementSelector, null);
}
public static Dictionary<TKey, TElement> ToDictionary<TSource, TKey, TElement> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey> comparer)
{
Check.SourceAndKeyElementSelectors (source, keySelector, elementSelector);
if (comparer == null)
comparer = EqualityComparer<TKey>.Default;
var dict = new Dictionary<TKey, TElement> (comparer);
foreach (var e in source)
dict.Add (keySelector (e), elementSelector (e));
return dict;
}
public static Dictionary<TKey, TSource> ToDictionary<TSource, TKey> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector)
{
return ToDictionary (source, keySelector, null);
}
public static Dictionary<TKey, TSource> ToDictionary<TSource, TKey> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer)
{
return ToDictionary<TSource, TKey, TSource> (source, keySelector, Function<TSource>.Identity, comparer);
}
#endregion
#region ToList
public static List<TSource> ToList<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
return new List<TSource> (source);
}
#endregion
#region ToLookup
public static ILookup<TKey, TSource> ToLookup<TSource, TKey> (this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
{
return ToLookup<TSource, TKey, TSource> (source, keySelector, Function<TSource>.Identity, null);
}
public static ILookup<TKey, TSource> ToLookup<TSource, TKey> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer)
{
return ToLookup<TSource, TKey, TSource> (source, keySelector, element => element, comparer);
}
public static ILookup<TKey, TElement> ToLookup<TSource, TKey, TElement> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector)
{
return ToLookup<TSource, TKey, TElement> (source, keySelector, elementSelector, null);
}
public static ILookup<TKey, TElement> ToLookup<TSource, TKey, TElement> (this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey> comparer)
{
Check.SourceAndKeyElementSelectors (source, keySelector, elementSelector);
var dictionary = new Dictionary<TKey, List<TElement>> (comparer ?? EqualityComparer<TKey>.Default);
foreach (var element in source) {
var key = keySelector (element);
if (key == null)
throw new ArgumentNullException ("key");
List<TElement> list;
if (!dictionary.TryGetValue (key, out list)) {
list = new List<TElement> ();
dictionary.Add (key, list);
}
list.Add (elementSelector (element));
}
return new Lookup<TKey, TElement> (dictionary);
}
#endregion
#region SequenceEqual
public static bool SequenceEqual<TSource> (this IEnumerable<TSource> first, IEnumerable<TSource> second)
{
return first.SequenceEqual (second, null);
}
public static bool SequenceEqual<TSource> (this IEnumerable<TSource> first, IEnumerable<TSource> second, IEqualityComparer<TSource> comparer)
{
Check.FirstAndSecond (first, second);
if (comparer == null)
comparer = EqualityComparer<TSource>.Default;
using (IEnumerator<TSource> first_enumerator = first.GetEnumerator (),
second_enumerator = second.GetEnumerator ()) {
while (first_enumerator.MoveNext ()) {
if (!second_enumerator.MoveNext ())
return false;
if (!comparer.Equals (first_enumerator.Current, second_enumerator.Current))
return false;
}
return !second_enumerator.MoveNext ();
}
}
#endregion
#region Union
public static IEnumerable<TSource> Union<TSource> (this IEnumerable<TSource> first, IEnumerable<TSource> second)
{
Check.FirstAndSecond (first, second);
return first.Union (second, null);
}
public static IEnumerable<TSource> Union<TSource> (this IEnumerable<TSource> first, IEnumerable<TSource> second, IEqualityComparer<TSource> comparer)
{
Check.FirstAndSecond (first, second);
if (comparer == null)
comparer = EqualityComparer<TSource>.Default;
return CreateUnionIterator (first, second, comparer);
}
static IEnumerable<TSource> CreateUnionIterator<TSource> (IEnumerable<TSource> first, IEnumerable<TSource> second, IEqualityComparer<TSource> comparer)
{
var items = new HashSet<TSource> (comparer);
foreach (var element in first) {
if (! items.Contains (element)) {
items.Add (element);
yield return element;
}
}
foreach (var element in second) {
if (! items.Contains (element, comparer)) {
items.Add (element);
yield return element;
}
}
}
#endregion
#region Where
public static IEnumerable<TSource> Where<TSource> (this IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
Check.SourceAndPredicate (source, predicate);
return CreateWhereIterator (source, predicate);
}
static IEnumerable<TSource> CreateWhereIterator<TSource> (IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
foreach (TSource element in source)
if (predicate (element))
yield return element;
}
public static IEnumerable<TSource> Where<TSource> (this IEnumerable<TSource> source, Func<TSource, int, bool> predicate)
{
Check.SourceAndPredicate (source, predicate);
return CreateWhereIterator (source, predicate);
}
static IEnumerable<TSource> CreateWhereIterator<TSource> (this IEnumerable<TSource> source, Func<TSource, int, bool> predicate)
{
int counter = 0;
foreach (TSource element in source) {
if (predicate (element, counter))
yield return element;
counter++;
}
}
#endregion
class ReadOnlyCollectionOf<T> {
public static readonly ReadOnlyCollection<T> Empty = new ReadOnlyCollection<T> (new T [0]);
}
internal static ReadOnlyCollection<TSource> ToReadOnlyCollection<TSource> (this IEnumerable<TSource> source)
{
if (source == null)
return ReadOnlyCollectionOf<TSource>.Empty;
var ro = source as ReadOnlyCollection<TSource>;
if (ro != null)
return ro;
return new ReadOnlyCollection<TSource> (source.ToArray<TSource> ());
}
}
}
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