/// <summary>
/// 按Lambda创建对象
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="mapping"></param>
/// <returns></returns>
public static Func <DataContainer, T> CreateObjectGeneratorLambda <T>(IEnumerable <Attribute.FieldMapping> mapping)
{
var objectType = typeof(T);
var fields = TypeCache.GetProperties(objectType, true);
var parame = Expression.Parameter(typeof(DataContainer), "par");
var memberBindings = new List <MemberBinding>();
//按顺序生成Binding
int i = 0;
foreach (var mp in mapping)
{
if (!fields.ContainsKey(mp.MappingName))
{
continue;
}
var m = fields[mp.MappingName].GetPropertyInfo();
var method = DataContainer.GetMethod(m.PropertyType);
//Expression getValue = Expression.Call(method, parame);
var getValue = parame.Call(method.Name, Expression.Constant(i));
if (m.PropertyType.IsEnum)
{
getValue = Expression.Convert(getValue, m.PropertyType);
}
var bind = (MemberBinding)Expression.Bind(m, getValue);
memberBindings.Add(bind);
i += 1;
}
Expression expr = Expression.MemberInit(Expression.New(objectType), memberBindings);
var ret = Expression.Lambda <Func <DataContainer, T> >(expr, parame);
return(ret.Compile());
}
///// <summary>
///// 按Lambda创建对象
///// </summary>
///// <typeparam name="T"></typeparam>
///// <param name="mapping"></param>
///// <returns></returns>
//static Func<DataContainer, T> CreateObjectGeneratorLambda<T>(IEnumerable<Attribute.FieldMapping> mapping)
//{
// var objectType = typeof(T);
// var fields = TypeCache.GetProperties(objectType, true);
// var parame = Expression.Parameter(typeof(DataContainer), "par");
// var memberBindings = new List<MemberBinding>();
// //按顺序生成Binding
// int i = 0;
// foreach (var mp in mapping)
// {
// if (!fields.ContainsKey(mp.MemberName))
// {
// continue;
// }
// var m = fields[mp.MemberName].GetPropertyInfo();
// var method = DataContainer.GetMethod(m.PropertyType, true);
// //Expression getValue = Expression.Call(method, parame);
// var getValue = parame.Call(method.Name, Expression.Constant(i));
// if (m.PropertyType.IsEnum)
// {
// getValue = Expression.Convert(getValue, m.PropertyType);
// }
// var bind = (MemberBinding)Expression.Bind(m, getValue);
// memberBindings.Add(bind);
// i += 1;
// }
// Expression expr = Expression.MemberInit(Expression.New(objectType), memberBindings);
// var ret = Expression.Lambda<Func<DataContainer, T>>(expr, parame);
// return ret.Compile();
//}
/// <summary>
/// 使用EMIT
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="mapping"></param>
/// <param name="queryFields"></param>
/// <returns></returns>
public static Func <DataContainer, T> CreateObjectGeneratorEmit <T>(IEnumerable <Attribute.FieldMapping> mapping, Dictionary <string, ColumnType> queryFields)
{
var type = typeof(T);
var fields = TypeCache.GetProperties(type, true);
DynamicMethod method = new DynamicMethod("CreateObjectGeneratorEmit", type,
new Type[] { typeof(CRL.LambdaQuery.Mapping.DataContainer) }, type, true);
ILGenerator generator = method.GetILGenerator();
LocalBuilder result = generator.DeclareLocal(type);
generator.Emit(OpCodes.Newobj, type.GetConstructor(Type.EmptyTypes));
generator.Emit(OpCodes.Stloc, result);
//int i = 0;
//mapping顺序和语句查询不一致
foreach (var mp in mapping)
{
if (string.IsNullOrEmpty(mp.ResultName))
{
throw new CRLException("ResultName为空,请检查mapping创建" + mp);
}
if (!queryFields.ContainsKey(mp.ResultName.ToLower()))
{
continue;
}
if (!fields.ContainsKey(mp.ResultName))
{
continue;
}
var i = queryFields[mp.ResultName.ToLower()].index;
var pro = fields[mp.ResultName].GetPropertyInfo();
var endIfLabel = generator.DefineLabel();
generator.Emit(OpCodes.Ldloc, result);
generator.Emit(OpCodes.Ldarg_0);
generator.Emit(OpCodes.Ldc_I4, i);
var method2 = DataContainer.GetMethod(pro.PropertyType);
if (method2 == null)
{
throw new CRLException($"找不到对应类型的解析方法{pro.Name} {pro.PropertyType} ");
}
generator.Emit(OpCodes.Call, method2);
generator.Emit(OpCodes.Callvirt, pro.GetSetMethod());
generator.MarkLabel(endIfLabel);
//i += 1;
}
generator.Emit(OpCodes.Ldloc, result);
generator.Emit(OpCodes.Ret);
var handler = (Func <DataContainer, T>)method.CreateDelegate(typeof(Func <DataContainer, T>));
return(handler);
}
/// <summary>
/// 使用lambda匿名对象创建
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="constructor"></param>
/// <returns></returns>
static Func <DataContainer, T> CreateObjectGenerator <T>(ConstructorInfo constructor)
{
var parame = Expression.Parameter(typeof(DataContainer), "par");
ParameterInfo[] parameters = constructor.GetParameters();
List <Expression> arguments = new List <Expression>(parameters.Length);
int i = 0;
foreach (var parameter in parameters)
{
var method = DataContainer.GetMethod(parameter.ParameterType);
var getValue = parame.Call(method.Name, Expression.Constant(i));
//var getValue = Expression.Call(method, parame, Expression.Constant(i));
arguments.Add(getValue);
i += 1;
}
var body = Expression.New(constructor, arguments);
var ret = Expression.Lambda <Func <DataContainer, T> >(body, parame).Compile();
return(ret);
}
