83 lines
4.6 KiB
C#
83 lines
4.6 KiB
C#
/*
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BSD 3-Clause License
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Copyright (c) 2017, B. Wofter
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice, this
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list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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* Neither the name of the copyright holder nor the names of its
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contributors may be used to endorse or promote products derived from
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this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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namespace BWofter.Converters.Extensions
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{
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using System;
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using System.Collections.Generic;
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using System.Data;
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using System.Linq;
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/// <summary><para>A static class that provides LINQ extensions for the <see cref="DataColumnCollection"/> type.</para></summary>
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public static class DataColumnCollectionExtensions
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{
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/// <summary><para>Returns an <see cref="IEnumerable{T}"/> of <see cref="DataColumn"/> values that represents <paramref name="collection"/>.</para></summary>
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/// <param name="collection"><para>The target of the extension method.</para></param>
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/// <returns><para><see cref="IEnumerable{T}"/> of <see cref="DataColumn"/> values or <see cref="Enumerable.Empty{TResult}"/>.</para></returns>
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public static IEnumerable<DataColumn> Select(this DataColumnCollection collection) =>
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collection.Select(dc => dc);
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/// <summary><para>Returns an <see cref="IEnumerable{T}"/> of <see cref="DataColumn"/> values that represents <paramref name="collection"/>.</para></summary>
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/// <param name="collection"><para>The target of the extension method.</para></param>
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/// <param name="selector"><para>The selector of the extension method.</para></param>
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/// <returns><para><see cref="IEnumerable{T}"/> of <see cref="DataColumn"/> values or <see cref="Enumerable.Empty{TResult}"/>.</para></returns>
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public static IEnumerable<T> Select<T>(this DataColumnCollection collection, Func<DataColumn, T> selector)
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{
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if (collection == null) throw new ArgumentNullException(nameof(collection));
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if (selector == null) throw new ArgumentNullException(nameof(selector));
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//Determines if there are no entries in the collection. If not, return an empty enumerable. Otherwise, process the selector.
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if (collection.Count == 0)
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{
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return Enumerable.Empty<T>();
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}
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else
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{
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return collection.Cast<DataColumn>().Select(selector);
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}
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}
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/// <summary><para>Returns an <see cref="IEnumerable{T}"/> of <see cref="DataColumn"/> values that represents <paramref name="collection"/>.</para></summary>
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/// <param name="collection"><para>The target of the extension method.</para></param>
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/// <param name="predicate"><para>The predicate of the extension method.</para></param>
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/// <returns><para><see cref="IEnumerable{T}"/> of <see cref="DataColumn"/> values or <see cref="Enumerable.Empty{TResult}"/>.</para></returns>
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public static IEnumerable<DataColumn> Where(this DataColumnCollection collection, Func<DataColumn, bool> predicate)
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{
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if (collection == null) throw new ArgumentNullException(nameof(collection));
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if (predicate == null) throw new ArgumentNullException(nameof(predicate));
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if (collection.Count == 0)
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{
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return Enumerable.Empty<DataColumn>();
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}
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else
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{
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return collection.Cast<DataColumn>().Where(predicate);
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}
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}
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}
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}
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