从Func构建条件表达式... [英] Building Conditional Expressions from Func...

问题描述

试图进入表达式，IL生成的代表等。



我有这个原型用于组合'比较'，但我认为它很慢，即使只需2-3个功能：



（我用VB - 抱歉;））

Trying to get into Expressions, IL-Generated Delegates etc.

I have this prototype for combining 'Comparisons', but I think it's quite slow, even with just 2-3 Funcs:

(I use VB -- sorry ;) )

Public Function BuildCompareExpression(Of T)(exp1 As Expression(Of Func(Of T, T, Integer)), exp2 As Expression(Of Func(Of T, T, Integer))) As Expression(Of Func(Of T, T, Integer))

        Dim parameters() = {Expression.Parameter(GetType(T)), Expression.Parameter(GetType(T))}

        Dim invoked = Expression.Invoke(exp1, parameters)
        Dim invoked2 = Expression.Invoke(exp2, parameters)
        Dim isTrue = Expression.Equal(Expression.Constant(0), invoked)
        Dim conditional = Expression.Condition(isTrue, invoked2, invoked)
        Dim lambda = Expression.Lambda(Of Func(Of T, T, Integer))(conditional, parameters)

       While lambda.CanReduce
            lambda = CType(lambda.Reduce,Expression(Of Global.System.Func(Of T, T, Integer)))
        End While
        Return lambda
    End Function

OBS！当然，在添加最后一个 Func（Of T，T，Integer）后，我会'lambda.Compile'



希望任何人都有更好/更快的选择。

提前致谢。



丹麦Jens。

OBS! Of course, upon adding the last Func(Of T, T, Integer) , I do 'lambda.Compile'

Hope anyone has some better/faster alternative.
Thanks in advance.

Jens, Denmark.

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