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| Imports System.Linq
Imports System.Linq.Expressions
Imports System.Collections.Generic
Imports System.Runtime.CompilerServices
Module PredicateBuilder
Sub New()
End Sub
Public Function [True](Of T)() As Expression(Of Func(Of T, Boolean))
Return Function(f) True
End Function
Public Function [False](Of T)() As Expression(Of Func(Of T, Boolean))
Return Function(f) False
End Function
<System.Runtime.CompilerServices.Extension()>
Public Function [Or](Of T)(expr1 As Expression(Of Func(Of T, Boolean)), expr2 As Expression(Of Func(Of T, Boolean))) As Expression(Of Func(Of T, Boolean))
Dim invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast(Of Expression)())
Return Expression.Lambda(Of Func(Of T, Boolean))(Expression.[OrElse](expr1.Body, invokedExpr), expr1.Parameters)
End Function
<System.Runtime.CompilerServices.Extension()>
Public Function [And](Of T)(expr1 As Expression(Of Func(Of T, Boolean)), expr2 As Expression(Of Func(Of T, Boolean))) As Expression(Of Func(Of T, Boolean))
Dim invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast(Of Expression)())
Return Expression.Lambda(Of Func(Of T, Boolean))(Expression.[AndAlso](expr1.Body, invokedExpr), expr1.Parameters)
End Function
End Module |
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