01.Imports System.Collections.Generic
02.Imports System.Linq
03.Imports System.Reflection
04.Imports System.Linq.Expressions
05.
06.Public Module IEnumerableHelper
07.
08. Sub New()
09. End Sub
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11. Private orderBy_ As MethodInfo = GetType(Enumerable).GetMethods(BindingFlags.[Static] Or BindingFlags.[Public]) _
12. .Where(Function(x) x.Name = "OrderBy" AndAlso x.GetParameters().Length = 2).First()
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21. <System.Runtime.CompilerServices.Extension()> _
22. Public Function OrderBy(Of TSource)(source As IEnumerable(Of TSource), propertyName As String) As IEnumerable(Of TSource)
23. Dim pi = GetType(TSource).GetProperty(propertyName, BindingFlags.[Public] Or BindingFlags.FlattenHierarchy Or BindingFlags.Instance)
24. Dim selectorParam = Expression.Parameter(GetType(TSource), "keySelector")
25. Dim sourceParam = Expression.Parameter(GetType(IEnumerable(Of TSource)), "source")
26. Return Expression.Lambda(Of Func(Of IEnumerable(Of TSource),
27. IOrderedEnumerable(Of TSource)))(Expression.[Call](orderBy_.MakeGenericMethod(GetType(TSource), pi.PropertyType),
28. sourceParam, Expression.Lambda(GetType(Func(Of ,)).MakeGenericType(GetType(TSource), pi.PropertyType),
29. Expression.[Property](selectorParam, pi), selectorParam)), sourceParam).Compile()(source)
30. End Function
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40. <System.Runtime.CompilerServices.Extension()> _
41. Public Function OrderBy(Of TSource)(source As IEnumerable(Of TSource), propertyName As String, ascending As Boolean) As IEnumerable(Of TSource)
42. Return If(ascending, source.OrderBy(propertyName), source.OrderBy(propertyName).Reverse())
43. End Function
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54. <System.Runtime.CompilerServices.Extension> _
55. Public Function DistinctBy(Of T, TKey)(items As IEnumerable(Of T), [property] As Func(Of T, TKey)) As IEnumerable(Of T)
56. Return items.GroupBy([property]).[Select](Function(x) x.First())
57. End Function
58.End Module
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