#if NET_4_0
//
// QueryDefaultEmptyNode.cs
//
// Author:
// Jrmie "Garuma" Laval <jeremie.laval@gmail.com>
//
// Copyright (c) 2010 Jrmie "Garuma" Laval
//
// 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.
using System;
using System.Threading;
using System.Collections;
using System.Collections.Generic;
namespace System.Linq{
internal class QueryDefaultEmptyNode<TSource> : QueryStreamNode<TSource, TSource>
{
TSource defaultValue;
internal QueryDefaultEmptyNode (QueryBaseNode<TSource> parent, TSource defaultValue)
: base (parent, false)
{
this.defaultValue = defaultValue;
}
internal override IEnumerable<TSource> GetSequential ()
{
return Parent.GetSequential ().DefaultIfEmpty (defaultValue);
}
internal override IList<IEnumerable<TSource>> GetEnumerables (QueryOptions options)
{
IList<IEnumerable<TSource>> enumerables = Parent.GetEnumerables (options);
CountdownEvent evt = new CountdownEvent (enumerables.Count);
IEnumerable<TSource>[] result = new IEnumerable<TSource>[enumerables.Count];
for (int i = 0; i < enumerables.Count; i++)
result[i] = GetEnumerableInternal<TSource> (enumerables[i], evt,
(s) => s);
return result;
}
internal override IList<IEnumerable<KeyValuePair<long, TSource>>> GetOrderedEnumerables (QueryOptions options)
{
IList<IEnumerable<KeyValuePair<long, TSource>>> enumerables = Parent.GetOrderedEnumerables (options);
CountdownEvent evt = new CountdownEvent (enumerables.Count);
IEnumerable<KeyValuePair<long, TSource>>[] result = new IEnumerable<KeyValuePair<long, TSource>>[enumerables.Count];
for (int i = 0; i < enumerables.Count; i++)
result[i] = GetEnumerableInternal<KeyValuePair<long, TSource>> (enumerables[i], evt,
(s) => new KeyValuePair<long, TSource> (0, s));
return result;
}
IEnumerable<TSecond> GetEnumerableInternal<TSecond> (IEnumerable<TSecond> source,
CountdownEvent evt,
Func<TSource, TSecond> converter)
{
bool processed = false;
foreach (TSecond second in source) {
processed = true;
yield return second;
}
if (!processed && evt.Signal ())
yield return converter (defaultValue);
}
}
}
#endif
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