EnumerableExtensions.cs

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// Copyright 2005-2015 Giacomo Stelluti Scala & Contributors. All rights reserved. See License.md in the project root for license information.
 
using System;
using System.Collections.Generic;
using System.Linq;
 
namespace CommandLine.Infrastructure
{
    internal static class EnumerableExtensions
    {
        public static int IndexOf<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> predicate)
        {
            int index = -1;
 
            foreach (TSource item in source)
            {
                index++;
 
                if (predicate(item))
                {
                    break;
                }
            }
 
            return index;
        }
 
        public static object ToUntypedArray(this IEnumerable<object> value, Type type)
        {
            Array array = Array.CreateInstance(type, value.Count());
 
            value.ToArray()
                 .CopyTo(array, 0);
 
            return array;
        }
 
        public static bool Empty<TSource>(this IEnumerable<TSource> source)
        {
            return !source.Any();
        }
 
        public static IEnumerable<T[]> Group<T>(this IEnumerable<T> source, int groupSize)
        {
            if (groupSize < 1)
            {
                throw new ArgumentOutOfRangeException(nameof(groupSize));
            }
 
            T[] group = new T[groupSize];
            int groupIndex = 0;
 
            foreach (T item in source)
            {
                group[groupIndex++] = item;
 
                if (groupIndex == groupSize)
                {
                    yield return group;
 
                    group = new T[groupSize];
                    groupIndex = 0;
                }
            }
        }
    }
}