public static Func <Expression, Expression, BinaryExpression> GetCombineExpressionDelegate(this ExpressionCombine combinor)
{
switch (combinor)
{
case ExpressionCombine.And:
return(Expression.And);
case ExpressionCombine.Or:
return(Expression.Or);
default:
throw new NotImplementedException();
}
}
public static Expression <Func <T1, T2> > Combine <T1, T2>(this Expression <Func <T1, T2> > first, Expression <Func <T1, T2> > second, ExpressionCombine combinor)
{
var param = Expression.Parameter(typeof(T1), "x");
var newFirst = first.ReplaceParameter(param);
var newSecond = second.ReplaceParameter(param);
var expressionCombinor = combinor.GetCombineExpressionDelegate();
var combinedExpression = expressionCombinor(newFirst.Body, newSecond.Body);
return(Expression.Lambda <Func <T1, T2> >(combinedExpression, param));
}
