static Expression[] buildParameters(Type[] parameterTypes, ParameterExpression paramExp)
{
List <Expression> list = new List <Expression>();
for (int i = 0; i < parameterTypes.Length; i++)
{
var arg = BinaryExpression.ArrayIndex(paramExp, Expression.Constant(i));
var argCast = Expression.Convert(arg, parameterTypes[i]);
list.Add(argCast);
}
return(list.ToArray());
}
static Expression[] BuildParameters(Type[] parameterTypes, ParameterExpression paramExp)
{
List <Expression> list = new List <Expression>();
for (int i = 0; i < parameterTypes.Length; i++)
{
//从参数表达式（参数是：object[]）中取出参数
var arg = BinaryExpression.ArrayIndex(paramExp, Expression.Constant(i));
//把参数转化成指定类型
var argCast = Expression.Convert(arg, parameterTypes[i]);
list.Add(argCast);
}
return(list.ToArray());
}
/// <summary>
/// 搜索其参数与指定数组中的类型匹配的公共实例构造函数，并返加该构造函数的委托
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="type">类型</param>
/// <param name="parameterTypes">指定参数数组</param>
/// <returns></returns>
public static Func <object[], T> CreateInstanceDelegate <T>(this Type type, params Type[] parameterTypes)
{
//根据参数类型数组来获取构造函数
var constructor = type.GetConstructor(parameterTypes);
//创建lambda表达示参数
var lambdaParamsExp = Expression.Parameter(typeof(object[]), "_args");
//转换参数为构造函数可用的类型
var paramsExp = new Expression[parameterTypes.Length];
for (int i = 0; i < parameterTypes.Length; ++i)
{
var oneParamExp = BinaryExpression.ArrayIndex(lambdaParamsExp, Expression.Constant(i, typeof(int)));
paramsExp[i] = Expression.Convert(oneParamExp, parameterTypes[i]);
}
//创建构造函数表达式
var newExp = Expression.New(constructor, paramsExp);
//创建Func<object[],object>并返回
return(Expression.Lambda <Func <object[], T> >(newExp, lambdaParamsExp).Compile());
}
static Expression getMethodCallExpression(MethodInfo method, Type controllerType, Expression c, Expression ps)
{
var parameters = method.GetParameters();
Expression[] pExps = new Expression[parameters.Length];
for (int i = 0; i < parameters.Length; i++)
{
var pinfo = parameters[i];
var valExp = BinaryExpression.ArrayIndex(ps, Expression.Constant(i));
if (pinfo.ParameterType != typeof(object))
{
pExps[i] = Expression.Convert(valExp, pinfo.ParameterType);
}
else
{
pExps[i] = valExp;
}
}
var exp = Expression.Call(c, controllerType.GetMethod(method.Name), pExps);
return(exp);
}