Expression拼接

public static class ExpressionHelp

{

///

/// Lambda表达式拼接

///

///

///

///

///

///

public static Expression Compose(this Expression first, Expression second, Func merge)

{

var map = first.Parameters.Select((f, i) => new { f, s = second.Parameters[i] }).ToDictionary(p => p.s, p => p.f);

var secondBody = ParameterRebinder.ReplaceParameters(map, second.Body);

return Expression.Lambda(merge(first.Body, secondBody), first.Parameters);

}

///

/// and扩展

///

///

///

///

///

public static Expression> And(this Expression> first, Expression> second)

{

return first.Compose(second, Expression.And);

}

public static Expression> And(this Expression> first, Expression> second)

{

return first.Compose(second, Expression.And);

}

///

/// or扩展

///

///

///

///

///

public static Expression> Or(this Expression> first, Expression> second)

{

return first.Compose(second, Expression.Or);

}

public static Expression> Or(this Expression> first, Expression> second)

{

return first.Compose(second, Expression.Or);

}

}

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