92 lines
3.2 KiB
C#
92 lines
3.2 KiB
C#
//
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// QueryDefaultEmptyNode.cs
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//
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// Author:
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// Jérémie "Garuma" Laval <jeremie.laval@gmail.com>
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//
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// Copyright (c) 2010 Jérémie "Garuma" Laval
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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#if NET_4_0
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using System;
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using System.Threading;
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using System.Collections;
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using System.Collections.Generic;
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namespace System.Linq.Parallel.QueryNodes
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{
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internal class QueryDefaultEmptyNode<TSource> : QueryStreamNode<TSource, TSource>
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{
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TSource defaultValue;
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internal QueryDefaultEmptyNode (QueryBaseNode<TSource> parent, TSource defaultValue)
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: base (parent, false)
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{
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this.defaultValue = defaultValue;
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}
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internal override IEnumerable<TSource> GetSequential ()
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{
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return Parent.GetSequential ().DefaultIfEmpty (defaultValue);
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}
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internal override IList<IEnumerable<TSource>> GetEnumerables (QueryOptions options)
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{
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IList<IEnumerable<TSource>> enumerables = Parent.GetEnumerables (options);
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CountdownEvent evt = new CountdownEvent (enumerables.Count);
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return enumerables
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.Select ((e) => GetEnumerableInternal<TSource> (e,
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evt,
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(s) => s))
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.ToList ();
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}
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internal override IList<IEnumerable<KeyValuePair<long, TSource>>> GetOrderedEnumerables (QueryOptions options)
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{
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IList<IEnumerable<KeyValuePair<long, TSource>>> enumerables = Parent.GetOrderedEnumerables (options);
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CountdownEvent evt = new CountdownEvent (enumerables.Count);
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return enumerables
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.Select ((e) => GetEnumerableInternal<KeyValuePair<long, TSource>> (e,
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evt,
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(s) => new KeyValuePair<long, TSource> (0, s)))
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.ToList ();
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}
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IEnumerable<TSecond> GetEnumerableInternal<TSecond> (IEnumerable<TSecond> source,
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CountdownEvent evt,
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Func<TSource, TSecond> converter)
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{
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bool processed = false;
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foreach (TSecond second in source) {
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processed = true;
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yield return second;
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}
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if (!processed && evt.Signal ())
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yield return converter (defaultValue);
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}
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}
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}
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#endif
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