/// <summary>
/// 初始化 <see cref="ColumnExpressionVisitor"/> 类的新实例
/// </summary>
/// <param name="provider">查询语义提供者</param>
/// <param name="aliases">表别名集合</param>
/// <param name="dbQuery">查询语义</param>
public ColumnExpressionVisitor(IDbQueryProvider provider, TableAlias aliases, IDbQueryableInfo_Select dbQuery)
: base(provider, aliases, dbQuery.Select.Expressions != null ? dbQuery.Select.Expressions[0] : null)
{
_provider = provider;
_aliases = aliases;
_dbQuery = dbQuery;
_groupBy = dbQuery.GroupBy;
_include = dbQuery.Includes;
if (_pickColumns == null)
{
_pickColumns = new DbColumnCollection();
}
_navDescriptors = new NavDescriptorCollection();
_navDescriptorKeys = new List <string>(10);
}
/// <summary>
/// 生成实体映射委托
/// </summary>
/// <param name="type">实体类型</param>
/// <param name="reader">数据读取器</param>
/// <param name="columns">字段列描述</param>
/// <param name="start">开始索引</param>
/// <param name="end">结束索引</param>
/// <returns></returns>
public Func <IDataRecord, object> GetTypeDeserializer(Type type, IDataRecord reader, DbColumnCollection columns = null, int start = 0, int?end = null)
{
//// specify a new assembly name
//var assemblyName = new AssemblyName("TZM.Deserialize");
//// create assembly builder
//var assemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.RunAndSave);
//// create module builder
//var moduleBuilder = assemblyBuilder.DefineDynamicModule(assemblyName.Name, assemblyName.Name + ".dll", true);
//// create type builder for a class
//var typeBuilder = moduleBuilder.DefineType("TZM.Deserialize.Deserializer", TypeAttributes.Public);
//// create method builder
//var methodBuilder = typeBuilder.DefineMethod("GetModel",
// MethodAttributes.Public | MethodAttributes.Static,
// typeof(object),
// new Type[] { typeof(IDataRecord)
// });
TypeRuntimeInfo typeRuntime = TypeRuntimeInfoCache.GetRuntimeInfo(type);
DynamicMethod method = new DynamicMethod(string.Format("Deserialize{0}", Guid.NewGuid()), typeof(object), new Type[] { typeof(IDataRecord) }, true);
//ILGenerator il = methodBuilder.GetILGenerator();
ILGenerator il = method.GetILGenerator();
il.DeclareLocal(typeof(int)); // [0] int index
il.DeclareLocal(type); // [1] {type}
il.Emit(OpCodes.Ldc_I4_0);
il.Emit(OpCodes.Stloc_0);
// 有参构造函数
ConstructorInfo specializedConstructor = null;
if (type.IsValueType)
{
// 如果是值类型，则将值类型设置为空或者0
il.Emit(OpCodes.Ldloca_S, (byte)1);
il.Emit(OpCodes.Initobj, type);
}
else
{
var ctor = typeRuntime.Constructor.Constructor;
if (ctor.GetParameters().Length > 0)
{
specializedConstructor = ctor;
}
else
{
// 如果不是匿名类或者只有无参构造函数，则new一个对象
il.Emit(OpCodes.Newobj, ctor);
il.Emit(OpCodes.Stloc_1); // [1] {type}=new {type}
}
}
// try #####
il.BeginExceptionBlock();
if (specializedConstructor == null)
{
il.Emit(OpCodes.Ldloc_1); // [target]
}
// stack is now [target]
Label finishLabel = il.DefineLabel();
Label loadNullLabel = il.DefineLabel();
int enumDeclareLocal = -1;
if (end == null)
{
end = reader.FieldCount;
}
for (int index = start; index < end; index++)
{
// 找出对应DataReader中的字段名
string memberName = reader.GetName(index);
if (columns != null)
{
DbColumn column = null;
columns.TryGetValue(memberName, out column);
memberName = column != null ? column.Name : string.Empty;
}
// 本地变量赋值
il.Emit(OpCodes.Ldc_I4, index); // [target][index]
il.Emit(OpCodes.Stloc_0); // [target]
// 如果导航属性分割列=DbNull，那么此导航属性赋空值
if (memberName == Constant.NAVIGATION_SPLITON_NAME)
{
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Ldc_I4, index);
il.Emit(OpCodes.Callvirt, _isDBNull);
il.Emit(OpCodes.Brtrue_S, loadNullLabel);
}
var m = typeRuntime.GetMember(memberName);
if (m == null)
{
continue;
}
if (specializedConstructor == null)
{
il.Emit(OpCodes.Dup); // stack is now [target][target]
}
// 数据字段类型
Type myFieldType = reader.GetFieldType(index);
Type myFieldType2 = myFieldType;
// 实体属性类型
Type memberType = m.DataType;
MethodInfo getFieldValue = this.GetReaderMethod(myFieldType, memberType, ref myFieldType2);
if (myFieldType != myFieldType2)
{
myFieldType = myFieldType2;
}
Label isDbNullLabel = il.DefineLabel();
Label nextLoopLabel = il.DefineLabel();
// 判断字段是否是 DbNull
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Ldc_I4, index);
il.Emit(OpCodes.Callvirt, _isDBNull);
il.Emit(OpCodes.Brtrue, isDbNullLabel);
// =>DataReader.Getxx(index)
il.Emit(OpCodes.Ldarg_0); // stack is now [target][target][reader]
if (getFieldValue.DeclaringType != typeof(IDataRecord))
{
il.Emit(OpCodes.Castclass, getFieldValue.DeclaringType); // (SqlDataReader)IDataReader
}
il.Emit(OpCodes.Ldc_I4, index); // stack is now [target][target][reader][index]
il.Emit(OpCodes.Callvirt, getFieldValue); // stack is now [target][target][value-or-object]
if (memberType == typeof(char) || memberType == typeof(char?))
{
il.EmitCall(OpCodes.Call, memberType == typeof(char) ? _readChar : _readNullChar, null); // stack is now [target][target][typed-value]
}
else
{
// unbox nullable enums as the primitive, i.e. byte etc
var nullUnderlyingType = Nullable.GetUnderlyingType(memberType);
var unboxType = nullUnderlyingType != null && nullUnderlyingType.IsEnum ? nullUnderlyingType : memberType;
if (unboxType.IsEnum)
{
Type numericType = Enum.GetUnderlyingType(unboxType);
if (myFieldType != typeof(string))
{
ConvertBox(il, myFieldType, unboxType, numericType);
}
else
{
if (enumDeclareLocal == -1)
{
enumDeclareLocal = il.DeclareLocal(typeof(string)).LocalIndex;
}
il.Emit(OpCodes.Castclass, typeof(string)); // stack is now [target][target][string]
il.StoreLocal(enumDeclareLocal); // stack is now [target][target]
il.Emit(OpCodes.Ldtoken, unboxType); // stack is now [target][target][enum-type-token]
il.EmitCall(OpCodes.Call, _typeFromHandle, null); // stack is now [target][target][enum-type]
il.LoadLocal(enumDeclareLocal); // stack is now [target][target][enum-type][string]
il.Emit(OpCodes.Ldc_I4_1); // stack is now [target][target][enum-type][string][true]
il.EmitCall(OpCodes.Call, _enumParse, null); // stack is now [target][target][enum-as-object]
il.Emit(OpCodes.Unbox_Any, unboxType); // stack is now [target][target][typed-value]
}
// new Nullable<TValue>(TValue)
if (nullUnderlyingType != null)
{
EmitNewNullable(il, memberType); // stack is now [target][target][typed-value]
}
}
else if (memberType.FullName == _linqBinaryName)
{
var ctor = memberType.GetConstructor(new Type[] { typeof(byte[]) });
il.Emit(OpCodes.Unbox_Any, typeof(byte[])); // stack is now [target][target][byte-array]
il.Emit(OpCodes.Newobj, ctor); // stack is now [target][target][binary]
}
else
{
bool noBoxed = myFieldType == unboxType || myFieldType == nullUnderlyingType;
// myFieldType和实体属性类型一致， 如果用 DataReader.GetValue，则要强制转换{object}为实体属性定义的类型
bool useCast = noBoxed && getFieldValue == _getValue && unboxType != typeof(object);
if (useCast)
{
il.EmitCast(nullUnderlyingType ?? unboxType); // stack is now [target][target][typed-value]
}
// myFieldType和实体属性类型不一致，需要做类型转换
if (!noBoxed)
{
if (getFieldValue == _getValue && myFieldType.IsValueType)
{
il.Emit(OpCodes.Unbox_Any, myFieldType); // stack is now [target][target][value]
}
// not a direct match; need to tweak the unbox
ConvertBox(il, myFieldType, nullUnderlyingType ?? unboxType, null);
}
// new Nullable<TValue>(TValue)
if (nullUnderlyingType != null)
{
EmitNewNullable(il, memberType); // stack is now [target][target][typed-value]
}
}
}
if (specializedConstructor == null)
{
// Store the value in the property/field
if (m.MemberType == MemberTypes.Field)
{
il.Emit(OpCodes.Stfld, m.Member as FieldInfo); // stack is now [target]
}
else
{
MethodInfo setMethod = (m as PropertyAccessor).SetMethod;
il.Emit(type.IsValueType ? OpCodes.Call : OpCodes.Callvirt, setMethod);// stack is now [target]
}
}
il.Emit(OpCodes.Br_S, nextLoopLabel); // stack is now [target]
il.MarkLabel(isDbNullLabel); // incoming stack: [target][target]
if (specializedConstructor == null)
{
il.Emit(OpCodes.Pop); // stack is now [target]
}
else
{
// DbNull，将NULL或者0推到栈顶
if (!m.DataType.IsValueType)
{
il.Emit(OpCodes.Ldnull);
}
else
{
int localIndex = il.DeclareLocal(m.DataType).LocalIndex;
il.LoadLocalAddress(localIndex);
il.Emit(OpCodes.Initobj, m.DataType);
il.LoadLocal(localIndex);
}
}
il.MarkLabel(nextLoopLabel);
}
if (specializedConstructor != null)
{
il.Emit(OpCodes.Newobj, specializedConstructor);
}
il.Emit(OpCodes.Stloc_1); // stack is empty
// 直接跳到结束标签返回实体
il.Emit(OpCodes.Br, finishLabel);
// 将 null 赋值给实体
il.MarkLabel(loadNullLabel);
il.Emit(OpCodes.Pop);
il.Emit(OpCodes.Ldnull);
il.Emit(OpCodes.Stloc_1);
il.MarkLabel(finishLabel);
il.BeginCatchBlock(typeof(Exception)); // stack is Exception
il.Emit(OpCodes.Ldloc_0); // stack is Exception, index
il.Emit(OpCodes.Ldarg_0); // stack is Exception, index, reader
il.EmitCall(OpCodes.Call, _throwException, null);
il.EndExceptionBlock();
il.Emit(OpCodes.Ldloc_1); // stack is [rval]
il.Emit(OpCodes.Ret);
//// then create the whole class type
//typeBuilder.CreateType();
//// save assembly
//assemblyBuilder.Save(assemblyName.Name + ".dll");
return((Func <IDataRecord, object>)method.CreateDelegate(typeof(Func <IDataRecord, object>)));
}
