QuerySetNode.cs :  » 2.6.4-mono-.net-core » System.Linq » System » Linq » C# / CSharp Open Source

#if NET_4_0
//
// QueryMuxNode.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.Linq;
using System.Collections.Generic;
using System.Collections.Concurrent;

namespace System.Linq{
  internal class QuerySetNode<TSource> : QueryMuxNode<TSource, TSource, TSource>
  {
    readonly SetInclusion setInclusion;
    readonly IEqualityComparer<TSource> comparer;

    internal QuerySetNode (SetInclusion setInclusion, IEqualityComparer<TSource> comparer,
                           QueryBaseNode<TSource> first, QueryBaseNode<TSource> second)
      : base (first, second)
    {
      this.setInclusion = setInclusion;
      this.comparer = comparer;
    }

    internal override IEnumerable<TSource> GetSequential ()
    {
      IEnumerable<TSource> first = Parent.GetSequential ();
      IEnumerable<TSource> second = Second == null ? null : Second.GetSequential ();

      // We try to do some guessing based on the default
      switch (setInclusion) {
      case SetInclusionDefaults.Union:
        return first.Union (second, comparer);
      case SetInclusionDefaults.Intersect:
        return first.Intersect (second, comparer);
      case SetInclusionDefaults.Except:
        return first.Except (second, comparer);
      case SetInclusionDefaults.Distinct:
        return first.Distinct (comparer);
      }

      // Default is we return the bare source enumerable
      return first;
    }

    internal override IList<IEnumerable<TSource>> GetEnumerables (QueryOptions options)
    {
      IList<IEnumerable<TSource>> first = Parent.GetEnumerables (options);
      IList<IEnumerable<TSource>> second = Second.GetEnumerables (options);
      
      IEnumerable<TSource>[] result = new IEnumerable<TSource>[first.Count];
      ConcurrentSkipList<TSource> checker = new ConcurrentSkipList<TSource> (comparer);
      
      InitConcurrentSkipList (checker, second, (e) => e);

      for (int i = 0; i < result.Length; i++)
        result[i] = GetEnumerable<TSource> (first[i], second[i], checker, (e) => e);

      return result;
    }

    internal override IList<IEnumerable<KeyValuePair<long, TSource>>> GetOrderedEnumerables (QueryOptions options)
    {
      IList<IEnumerable<KeyValuePair<long, TSource>>> first = Parent.GetOrderedEnumerables (options);
      IList<IEnumerable<KeyValuePair<long, TSource>>> second = Second.GetOrderedEnumerables (options);

      IEnumerable<KeyValuePair<long, TSource>>[] result = new IEnumerable<KeyValuePair<long, TSource>>[first.Count];
      ConcurrentSkipList<TSource> checker = new ConcurrentSkipList<TSource> (comparer);
      
      InitConcurrentSkipList (checker, second, (e) => e.Value);

      for (int i = 0; i < result.Length; i++)
        result[i] = GetEnumerable<KeyValuePair<long, TSource>> (first[i], second[i], checker, (e) => e.Value);

      return result;
    }
        
    void InitConcurrentSkipList<TExtract> (ConcurrentSkipList<TSource> checker,
                                           IList<IEnumerable<TExtract>> feeds,
                                           Func<TExtract, TSource> extractor)
    {
      if ((setInclusion & SetInclusion.Preload) == 0)
        return;
      
      foreach (IEnumerable<TExtract> feed in feeds)
        foreach (TExtract item in feed)
          checker.TryAdd (extractor (item));
    }

    IEnumerable<TExtract> GetEnumerable<TExtract> (IEnumerable<TExtract> first,
                                                   IEnumerable<TExtract> second,
                                                   ConcurrentSkipList<TSource> checker,
                                                   Func<TExtract, TSource> extractor)
    {
      IEnumerator<TExtract> eFirst = first.GetEnumerator ();
      IEnumerator<TExtract> eSecond = second == null ? null : second.GetEnumerator ();

      IEnumerator<TExtract> current = eFirst;
      bool outInclusion = (setInclusion & SetInclusion.Out) > 0;
      bool preload = (setInclusion & SetInclusion.Preload) > 0;
      bool relaxed = (setInclusion & SetInclusion.Relaxed) > 0;

      while (current != null) {
        while (current.MoveNext ()) {
          bool result = relaxed ?
            checker.Contains (extractor (current.Current)) : checker.TryAdd (extractor (current.Current));

          if ((result && outInclusion)
              || (!result && !outInclusion))
            yield return current.Current;
        }

        if (current == eFirst && !preload)
          current = eSecond;
        else
          break;
      }
    }
  }
}

#endif