2 // QueryDefaultEmptyNode.cs
5 // Jérémie "Garuma" Laval <jeremie.laval@gmail.com>
7 // Copyright (c) 2010 Jérémie "Garuma" Laval
9 // Permission is hereby granted, free of charge, to any person obtaining a copy
10 // of this software and associated documentation files (the "Software"), to deal
11 // in the Software without restriction, including without limitation the rights
12 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
13 // copies of the Software, and to permit persons to whom the Software is
14 // furnished to do so, subject to the following conditions:
16 // The above copyright notice and this permission notice shall be included in
17 // all copies or substantial portions of the Software.
19 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
22 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
23 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
24 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
29 using System.Threading;
30 using System.Collections;
31 using System.Collections.Generic;
33 namespace System.Linq.Parallel.QueryNodes
35 internal class QueryDefaultEmptyNode<TSource> : QueryStreamNode<TSource, TSource>
39 internal QueryDefaultEmptyNode (QueryBaseNode<TSource> parent, TSource defaultValue)
40 : base (parent, false)
42 this.defaultValue = defaultValue;
45 internal override IEnumerable<TSource> GetSequential ()
47 return Parent.GetSequential ().DefaultIfEmpty (defaultValue);
50 internal override IList<IEnumerable<TSource>> GetEnumerables (QueryOptions options)
52 IList<IEnumerable<TSource>> enumerables = Parent.GetEnumerables (options);
53 CountdownEvent evt = new CountdownEvent (enumerables.Count);
56 .Select ((e) => GetEnumerableInternal<TSource> (e,
62 internal override IList<IEnumerable<KeyValuePair<long, TSource>>> GetOrderedEnumerables (QueryOptions options)
64 IList<IEnumerable<KeyValuePair<long, TSource>>> enumerables = Parent.GetOrderedEnumerables (options);
65 CountdownEvent evt = new CountdownEvent (enumerables.Count);
68 .Select ((e) => GetEnumerableInternal<KeyValuePair<long, TSource>> (e,
70 (s) => new KeyValuePair<long, TSource> (0, s)))
74 IEnumerable<TSecond> GetEnumerableInternal<TSecond> (IEnumerable<TSecond> source,
76 Func<TSource, TSecond> converter)
78 bool processed = false;
80 foreach (TSecond second in source) {
85 if (!processed && evt.Signal ())
86 yield return converter (defaultValue);