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

#if NET_4_0
//
// QueryWhereNode.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.Threading;
using System.Collections.Generic;

namespace System.Linq{

  internal class QueryWhereNode<TSource> : QueryStreamNode<TSource, TSource>
  {
    Func<TSource, int, bool> indexedPredicate;
    Func<TSource, bool> predicate;

    internal QueryWhereNode (QueryBaseNode<TSource> parent, Func<TSource, bool> predicate)
      : base (parent, false)
    {
      this.predicate = predicate;
    }

    internal QueryWhereNode (QueryBaseNode<TSource> parent, Func<TSource, int, bool> predicate)
      : base (parent, true)
    {
      this.indexedPredicate = predicate;
    }

    internal override IEnumerable<TSource> GetSequential ()
    {
      IEnumerable<TSource> parent = Parent.GetSequential ();

      if (indexedPredicate != null)
        return parent.Where (indexedPredicate);
      else
        return parent.Where (predicate);
    }

    internal override IList<IEnumerable<TSource>> GetEnumerables (QueryOptions options)
    {
      if (IsIndexed) {
        IList<IEnumerable<KeyValuePair<long, TSource>>> sources = Parent.GetOrderedEnumerables (options);
        IEnumerable<TSource>[] results = new IEnumerable<TSource>[sources.Count];

        for (int i = 0; i < results.Length; i++)
          results[i] =
            sources[i].Where ((e) => indexedPredicate (e.Value, (int)e.Key)).Select ((e) => e.Value);
        return results;
      } else {
        IList<IEnumerable<TSource>> sources = Parent.GetEnumerables (options);
        IEnumerable<TSource>[] results = new IEnumerable<TSource>[sources.Count];

        for (int i = 0; i < results.Length; i++)
          results[i] = sources[i].Where (predicate);
        return results;
      }
    }

    internal override IList<IEnumerable<KeyValuePair<long, TSource>>> GetOrderedEnumerables (QueryOptions options)
    {
      IList<IEnumerable<KeyValuePair<long, TSource>>> sources = Parent.GetOrderedEnumerables (options);
      IEnumerable<KeyValuePair<long, TSource>>[] results = new IEnumerable<KeyValuePair<long, TSource>>[sources.Count];

      Tuple<TSource, long, bool>[] store = new Tuple<TSource, long, bool>[results.Length];
      long lastIndex = 0;

      Barrier barrier = new Barrier (results.Length, delegate (Barrier b) {
        // Sort the store
        Array.Sort (store, ArraySortMethod);

        // Reassign a good index
        int i = 0;

        for (i = 0; i < store.Length && store[i].Item3; i++) {
          Tuple<TSource, long, bool> old = store[i];
          store[i] = Tuple.Create (old.Item1, lastIndex + i, old.Item3);
        }

        // Update lastIndex for next round
        lastIndex += i;
      });

      for (int j = 0; j < results.Length; j++)
        results[j] = GetEnumerator (sources[j], barrier, store, j);

      return results;
    }

    static int ArraySortMethod (Tuple<TSource, long, bool> lhs, Tuple<TSource, long, bool> rhs)
    {
      if (lhs.Item3 && !rhs.Item3)
        return -1;
      if (!lhs.Item3 && rhs.Item3)
        return 1;
      if (!lhs.Item3 && !rhs.Item3)
        return 0;

      return (lhs.Item2 < rhs.Item2) ? -1 : 1;
    }

    IEnumerable<KeyValuePair<long, TSource>> GetEnumerator (IEnumerable<KeyValuePair<long, TSource>> source,
                                                            Barrier barrier,
                                                            Tuple<TSource, long, bool>[] store, int index)
    {
      IEnumerator<KeyValuePair<long, TSource>> current = source.GetEnumerator ();
      bool result;

      while (current.MoveNext ()) {
        KeyValuePair<long, TSource> curr = current.Current;

        if (IsIndexed)
          result = indexedPredicate (curr.Value, (int)curr.Key);
        else
          result = predicate (curr.Value);

        store[index] = Tuple.Create (curr.Value, curr.Key, result);
        barrier.SignalAndWait ();

        Tuple<TSource, long, bool> value = store [index];

        if (value.Item3)
          yield return new KeyValuePair<long, TSource> (value.Item2, value.Item1);

        // Reset
        store[index] = Tuple.Create (default (TSource), long.MaxValue, false);
      }

      // Remove our participation
      barrier.RemoveParticipant ();
    }
  }
}
#endif