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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Collections.Generic;
using System.Runtime.InteropServices;
namespace System.Linq
{
public static partial class Enumerable
{
private sealed partial class IEnumerableWhereIterator<TSource>
{
public override int GetCount(bool onlyIfCheap)
{
if (onlyIfCheap)
{
return -1;
}
int count = 0;
foreach (TSource item in _source)
{
if (_predicate(item))
{
checked
{
count++;
}
}
}
return count;
}
public override TSource[] ToArray()
{
SegmentedArrayBuilder<TSource>.ScratchBuffer scratch = default;
SegmentedArrayBuilder<TSource> builder = new(scratch);
Func<TSource, bool> predicate = _predicate;
foreach (TSource item in _source)
{
if (predicate(item))
{
builder.Add(item);
}
}
TSource[] result = builder.ToArray();
builder.Dispose();
return result;
}
public override List<TSource> ToList()
{
var list = new List<TSource>();
Func<TSource, bool> predicate = _predicate;
foreach (TSource item in _source)
{
if (predicate(item))
{
list.Add(item);
}
}
return list;
}
public override TSource? TryGetFirst(out bool found)
{
Func<TSource, bool> predicate = _predicate;
foreach (TSource item in _source)
{
if (predicate(item))
{
found = true;
return item;
}
}
found = false;
return default;
}
public override TSource? TryGetLast(out bool found)
{
using IEnumerator<TSource> e = _source.GetEnumerator();
if (e.MoveNext())
{
Func<TSource, bool> predicate = _predicate;
TSource? last = default;
do
{
TSource current = e.Current;
if (predicate(current))
{
last = current;
found = true;
while (e.MoveNext())
{
current = e.Current;
if (predicate(current))
{
last = current;
}
}
return last;
}
}
while (e.MoveNext());
}
found = false;
return default;
}
public override TSource? TryGetElementAt(int index, out bool found)
{
if (index >= 0)
{
Func<TSource, bool> predicate = _predicate;
foreach (TSource item in _source)
{
if (predicate(item))
{
if (index == 0)
{
found = true;
return item;
}
index--;
}
}
}
found = false;
return default;
}
}
private sealed partial class ArrayWhereIterator<TSource>
{
public override int GetCount(bool onlyIfCheap) => GetCount(onlyIfCheap, _source, _predicate);
public static int GetCount(bool onlyIfCheap, ReadOnlySpan<TSource> source, Func<TSource, bool> predicate)
{
// In case someone uses Count() to force evaluation of
// the selector, run it provided `onlyIfCheap` is false.
if (onlyIfCheap)
{
return -1;
}
int count = 0;
foreach (TSource item in source)
{
if (predicate(item))
{
checked { count++; }
}
}
return count;
}
public override TSource[] ToArray() => ToArray(_source, _predicate);
public static TSource[] ToArray(ReadOnlySpan<TSource> source, Func<TSource, bool> predicate)
{
SegmentedArrayBuilder<TSource>.ScratchBuffer scratch = default;
SegmentedArrayBuilder<TSource> builder = new(scratch);
foreach (TSource item in source)
{
if (predicate(item))
{
builder.Add(item);
}
}
TSource[] result = builder.ToArray();
builder.Dispose();
return result;
}
public override List<TSource> ToList() => ToList(_source, _predicate);
public static List<TSource> ToList(ReadOnlySpan<TSource> source, Func<TSource, bool> predicate)
{
var list = new List<TSource>();
foreach (TSource item in source)
{
if (predicate(item))
{
list.Add(item);
}
}
return list;
}
public override TSource? TryGetFirst(out bool found)
{
Func<TSource, bool> predicate = _predicate;
foreach (TSource item in _source)
{
if (predicate(item))
{
found = true;
return item;
}
}
found = false;
return default;
}
public override TSource? TryGetLast(out bool found)
{
TSource[] source = _source;
Func<TSource, bool> predicate = _predicate;
for (int i = source.Length - 1; i >= 0; i--)
{
if (predicate(source[i]))
{
found = true;
return source[i];
}
}
found = false;
return default;
}
public override TSource? TryGetElementAt(int index, out bool found)
{
if (index >= 0)
{
Func<TSource, bool> predicate = _predicate;
foreach (TSource item in _source)
{
if (predicate(item))
{
if (index == 0)
{
found = true;
return item;
}
index--;
}
}
}
found = false;
return default;
}
}
private sealed partial class ListWhereIterator<TSource> : Iterator<TSource>
{
public override int GetCount(bool onlyIfCheap) => ArrayWhereIterator<TSource>.GetCount(onlyIfCheap, CollectionsMarshal.AsSpan(_source), _predicate);
public override TSource[] ToArray() => ArrayWhereIterator<TSource>.ToArray(CollectionsMarshal.AsSpan(_source), _predicate);
public override List<TSource> ToList() => ArrayWhereIterator<TSource>.ToList(CollectionsMarshal.AsSpan(_source), _predicate);
public override TSource? TryGetFirst(out bool found)
{
Func<TSource, bool> predicate = _predicate;
foreach (TSource item in CollectionsMarshal.AsSpan(_source))
{
if (predicate(item))
{
found = true;
return item;
}
}
found = false;
return default;
}
public override TSource? TryGetLast(out bool found)
{
ReadOnlySpan<TSource> source = CollectionsMarshal.AsSpan(_source);
Func<TSource, bool> predicate = _predicate;
for (int i = source.Length - 1; i >= 0; i--)
{
if (predicate(source[i]))
{
found = true;
return source[i];
}
}
found = false;
return default;
}
public override TSource? TryGetElementAt(int index, out bool found)
{
if (index >= 0)
{
Func<TSource, bool> predicate = _predicate;
foreach (TSource item in CollectionsMarshal.AsSpan(_source))
{
if (predicate(item))
{
if (index == 0)
{
found = true;
return item;
}
index--;
}
}
}
found = false;
return default;
}
}
private sealed partial class ArrayWhereSelectIterator<TSource, TResult>
{
public override int GetCount(bool onlyIfCheap) => GetCount(onlyIfCheap, _source, _predicate, _selector);
public static int GetCount(bool onlyIfCheap, ReadOnlySpan<TSource> source, Func<TSource, bool> predicate, Func<TSource, TResult> selector)
{
// In case someone uses Count() to force evaluation of
// the selector, run it provided `onlyIfCheap` is false.
if (onlyIfCheap)
{
return -1;
}
int count = 0;
foreach (TSource item in source)
{
if (predicate(item))
{
selector(item);
checked
{
count++;
}
}
}
return count;
}
public override TResult[] ToArray() => ToArray(_source, _predicate, _selector);
public static TResult[] ToArray(ReadOnlySpan<TSource> source, Func<TSource, bool> predicate, Func<TSource, TResult> selector)
{
SegmentedArrayBuilder<TResult>.ScratchBuffer scratch = default;
SegmentedArrayBuilder<TResult> builder = new(scratch);
foreach (TSource item in source)
{
if (predicate(item))
{
builder.Add(selector(item));
}
}
TResult[] result = builder.ToArray();
builder.Dispose();
return result;
}
public override List<TResult> ToList() => ToList(_source, _predicate, _selector);
public static List<TResult> ToList(ReadOnlySpan<TSource> source, Func<TSource, bool> predicate, Func<TSource, TResult> selector)
{
var list = new List<TResult>();
foreach (TSource item in source)
{
if (predicate(item))
{
list.Add(selector(item));
}
}
return list;
}
public override TResult? TryGetFirst(out bool found) => TryGetFirst(_source, _predicate, _selector, out found);
public static TResult? TryGetFirst(ReadOnlySpan<TSource> source, Func<TSource, bool> predicate, Func<TSource, TResult> selector, out bool found)
{
foreach (TSource item in source)
{
if (predicate(item))
{
found = true;
return selector(item);
}
}
found = false;
return default;
}
public override TResult? TryGetLast(out bool found) => TryGetLast(_source, _predicate, _selector, out found);
public static TResult? TryGetLast(ReadOnlySpan<TSource> source, Func<TSource, bool> predicate, Func<TSource, TResult> selector, out bool found)
{
for (int i = source.Length - 1; i >= 0; i--)
{
if (predicate(source[i]))
{
found = true;
return selector(source[i]);
}
}
found = false;
return default;
}
public override TResult? TryGetElementAt(int index, out bool found) => TryGetElementAt(_source, _predicate, _selector, index, out found);
public static TResult? TryGetElementAt(ReadOnlySpan<TSource> source, Func<TSource, bool> predicate, Func<TSource, TResult> selector, int index, out bool found)
{
if (index >= 0)
{
foreach (TSource item in source)
{
if (predicate(item))
{
if (index == 0)
{
found = true;
return selector(item);
}
index--;
}
}
}
found = false;
return default;
}
}
private sealed partial class ListWhereSelectIterator<TSource, TResult>
{
public override int GetCount(bool onlyIfCheap) => ArrayWhereSelectIterator<TSource, TResult>.GetCount(onlyIfCheap, CollectionsMarshal.AsSpan(_source), _predicate, _selector);
public override TResult[] ToArray() => ArrayWhereSelectIterator<TSource, TResult>.ToArray(CollectionsMarshal.AsSpan(_source), _predicate, _selector);
public override List<TResult> ToList() => ArrayWhereSelectIterator<TSource, TResult>.ToList(CollectionsMarshal.AsSpan(_source), _predicate, _selector);
public override TResult? TryGetElementAt(int index, out bool found) => ArrayWhereSelectIterator<TSource, TResult>.TryGetElementAt(CollectionsMarshal.AsSpan(_source), _predicate, _selector, index, out found);
public override TResult? TryGetFirst(out bool found) => ArrayWhereSelectIterator<TSource, TResult>.TryGetFirst(CollectionsMarshal.AsSpan(_source), _predicate, _selector, out found);
public override TResult? TryGetLast(out bool found) => ArrayWhereSelectIterator<TSource, TResult>.TryGetLast(CollectionsMarshal.AsSpan(_source), _predicate, _selector, out found);
}
private sealed partial class IEnumerableWhereSelectIterator<TSource, TResult>
{
public override int GetCount(bool onlyIfCheap)
{
// In case someone uses Count() to force evaluation of
// the selector, run it provided `onlyIfCheap` is false.
if (onlyIfCheap)
{
return -1;
}
int count = 0;
foreach (TSource item in _source)
{
if (_predicate(item))
{
_selector(item);
checked
{
count++;
}
}
}
return count;
}
public override TResult[] ToArray()
{
SegmentedArrayBuilder<TResult>.ScratchBuffer scratch = default;
SegmentedArrayBuilder<TResult> builder = new(scratch);
Func<TSource, bool> predicate = _predicate;
Func<TSource, TResult> selector = _selector;
foreach (TSource item in _source)
{
if (predicate(item))
{
builder.Add(selector(item));
}
}
TResult[] result = builder.ToArray();
builder.Dispose();
return result;
}
public override List<TResult> ToList()
{
var list = new List<TResult>();
Func<TSource, bool> predicate = _predicate;
Func<TSource, TResult> selector = _selector;
foreach (TSource item in _source)
{
if (predicate(item))
{
list.Add(selector(item));
}
}
return list;
}
public override TResult? TryGetFirst(out bool found)
{
Func<TSource, bool> predicate = _predicate;
foreach (TSource item in _source)
{
if (predicate(item))
{
found = true;
return _selector(item);
}
}
found = false;
return default;
}
public override TResult? TryGetLast(out bool found)
{
using IEnumerator<TSource> e = _source.GetEnumerator();
if (e.MoveNext())
{
Func<TSource, bool> predicate = _predicate;
TSource? last = default;
do
{
TSource current = e.Current;
if (predicate(current))
{
last = current;
found = true;
while (e.MoveNext())
{
current = e.Current;
if (predicate(current))
{
last = current;
}
}
return _selector(last);
}
}
while (e.MoveNext());
}
found = false;
return default;
}
public override TResult? TryGetElementAt(int index, out bool found)
{
if (index >= 0)
{
Func<TSource, bool> predicate = _predicate;
foreach (TSource item in _source)
{
if (predicate(item))
{
if (index == 0)
{
found = true;
return _selector(item);
}
index--;
}
}
}
found = false;
return default;
}
}
}
}
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