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using System.Collections.Generic; |
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using System.Linq; |
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using System.Text; |
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using System.Diagnostics; |
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namespace libxmltv |
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{ |
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public static class extensions |
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{ |
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/// <summary> |
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/// Break a list of items into chunks of a specific size |
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/// </summary> |
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public static IEnumerable<IEnumerable<T>> Chunk<T>(this IEnumerable<T> source, int chunksize) |
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public static IEnumerable<IEnumerable<T>> Chunk<T>(this IEnumerable<T> source, |
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int chunkSize) |
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{ |
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while (source.Any()) |
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// Validate parameters. |
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if (source == null) throw new ArgumentNullException("source"); |
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if (chunkSize <= 0) throw new ArgumentOutOfRangeException("chunkSize", |
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"The chunkSize parameter must be a positive value."); |
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// Call the internal implementation. |
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return source.ChunkInternal(chunkSize); |
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} |
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private static IEnumerable<IEnumerable<T>> ChunkInternal<T>(this IEnumerable<T> source, int chunkSize) |
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{ |
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// Validate parameters. |
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Debug.Assert(source != null); |
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Debug.Assert(chunkSize > 0); |
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// Get the enumerator. Dispose of when done. |
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using (IEnumerator<T> enumerator = source.GetEnumerator()) |
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do |
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{ |
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// Move to the next element. If there's nothing left |
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// then get out. |
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if (!enumerator.MoveNext()) yield break; |
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// Return the chunked sequence. |
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yield return ChunkSequence(enumerator, chunkSize); |
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} while (true); |
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} |
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private static IEnumerable<T> ChunkSequence<T>(IEnumerator<T> enumerator, int chunkSize) |
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{ |
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// Validate parameters. |
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Debug.Assert(enumerator != null); |
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Debug.Assert(chunkSize > 0); |
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// The count. |
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int count = 0; |
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// There is at least one item. Yield and then continue. |
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do |
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{ |
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yield return source.Take(chunksize); |
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source = source.Skip(chunksize); |
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} |
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// Yield the item. |
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yield return enumerator.Current; |
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} while (++count < chunkSize && enumerator.MoveNext()); |
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} |
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} |
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} |
