mono/mcs/class/System.Core/System.Linq/Internal/QueryNodes/QuerySelectManyNode.cs

#if NET_4_0
//
// QueryConcatNode.cs
//
// Author:
//       Jérémie "Garuma" Laval <[email protected]>
//
// Copyright (c) 2010 Jérémie "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 QuerySelectManyNode<TSource, TCollection, TResult> : QueryStreamNode<TResult, TSource>
	{
		Func<TSource, IEnumerable<TCollection>> collectionSelector;
		Func<TSource, int, IEnumerable<TCollection>> collectionSelectorIndexed;
		Func<TSource, TCollection, TResult> resultSelector;
		
		internal QuerySelectManyNode (QueryBaseNode<TSource> parent,
		                              Func<TSource, int, IEnumerable<TCollection>> collectionSelectorIndexed,
		                              Func<TSource, TCollection, TResult> resultSelector)
			: base (parent, true)
		{
			this.collectionSelectorIndexed = collectionSelectorIndexed;
			this.resultSelector = resultSelector;
		}
		
		internal QuerySelectManyNode (QueryBaseNode<TSource> parent,
		                              Func<TSource, IEnumerable<TCollection>> collectionSelector,
		                              Func<TSource, TCollection, TResult> resultSelector)
			: base (parent, false)
		{
			this.collectionSelector = collectionSelector;
			this.resultSelector = resultSelector;
		}
		
		internal override IEnumerable<TResult> GetSequential ()
		{
			IEnumerable<TSource> source = Parent.GetSequential ();
			
			if (IsIndexed)
				return source.SelectMany (collectionSelectorIndexed, resultSelector);
			else
				return source.SelectMany (collectionSelector, resultSelector);
		}
		
		internal override IList<IEnumerable<TResult>> GetEnumerables (QueryOptions options)
		{
			IEnumerable<TResult>[] result = null;
			
			if (IsIndexed) {
				IList<IEnumerable<KeyValuePair<long, TSource>>> enumerables = Parent.GetOrderedEnumerables (options);
				result = new IEnumerable<TResult>[enumerables.Count];
				
				for (int i = 0; i < enumerables.Count; i++)
					result[i] = GetEnumerableInternal<KeyValuePair<long, TSource>> (enumerables[i],
					                                                                (kv) => collectionSelectorIndexed (kv.Value, (int)kv.Key),
					                                                                (e, c) => resultSelector (e.Value, c));
			} else {
				IList<IEnumerable<TSource>> enumerables = Parent.GetEnumerables (options);
				result = new IEnumerable<TResult>[enumerables.Count];
				
				for (int i = 0; i < enumerables.Count; i++)
					result[i] = GetEnumerableInternal<TSource> (enumerables[i],
					                                            collectionSelector,
					                                            (e, c) => resultSelector (e, c));
			}
			
			return result;
		}
		
		// This one is gonna be tricky
		internal override IList<IEnumerable<KeyValuePair<long, TResult>>> GetOrderedEnumerables (QueryOptions options)
		{
			throw new NotImplementedException ();
		}
		
		IEnumerable<TResult> GetEnumerableInternal<T> (IEnumerable<T> source,
		                                               Func<T, IEnumerable<TCollection>> collectionner,
		                                               Func<T, TCollection, TResult> packer)
		{
			foreach (T element in source)
				foreach (TCollection item in collectionner (element))
					yield return packer (element, item);
		}
		
		IEnumerable<KeyValuePair<long, TResult>> GetOrderedEnumerableInternal (IEnumerable<KeyValuePair<long, TSource>> source,
		                                                                       Barrier barrier)
		{
			foreach (KeyValuePair<long, TSource> element in source) {
				IEnumerable<TCollection> collection = collectionSelectorIndexed (element.Value, (int)element.Key);
				
				foreach (TCollection item in collection)
					yield return new KeyValuePair<long, TResult> (-1, resultSelector (element.Value, item));
			}
		}
	}
}

#endif