private static DynamicMethod CreateClassDeserializerDynamicMethod(Type type, IDataReader reader, IRecordStructure structure, int startColumn, int columnCount, bool createNewObject, bool isRootObject, bool allowBindChild)
{
// if there are no columns detected for the class, then the deserializer is null
if (columnCount == 0 && !isRootObject)
{
return(null);
}
var mappings = MapColumns(type, reader, startColumn, columnCount, structure, allowBindChild && isRootObject);
// need to know the constructor for the object (except for structs)
bool isStruct = type.GetTypeInfo().IsValueType;
ConstructorInfo constructor = createNewObject ? SelectConstructor(type) : null;
// the method can either be:
// createNewObject => Func<IDataReader, T>
// !createNewObject => Func<IDataReader, T, T>
// create a new anonymous method that takes an IDataReader and returns the given type
var dm = new DynamicMethod(
String.Format(CultureInfo.InvariantCulture, "Deserialize-{0}-{1}", type.FullName, Guid.NewGuid()),
type,
createNewObject ? new[] { typeof(IDataReader) } : new[] { typeof(IDataReader), type },
true);
// get the il generator and put some local variables on the stack
var il = dm.GetILGenerator();
var localIndex = il.DeclareLocal(typeof(int));
var localResult = il.DeclareLocal(type);
var localValue = il.DeclareLocal(typeof(object));
var localIsNotAllDbNull = il.DeclareLocal(typeof(bool));
// initialization
il.Emit(OpCodes.Ldc_I4_0);
il.Emit(OpCodes.Stloc, localIndex);
/////////////////////////////////////////////////////////////////////
// read all of the values into local variables
/////////////////////////////////////////////////////////////////////
il.BeginExceptionBlock();
var localValues = new LocalBuilder[mappings.Count];
for (int index = 0; index < columnCount; index++)
{
var mapping = mappings[index];
if (mapping == null)
{
continue;
}
var member = mapping.Member;
localValues[index] = il.DeclareLocal(member.MemberType);
// need to call IDataReader.GetItem to get the value of the field
il.Emit(OpCodes.Ldarg_0);
IlHelper.EmitLdInt32(il, index + startColumn);
// before we call it, put the current index into the index local variable
il.Emit(OpCodes.Dup);
il.Emit(OpCodes.Stloc, localIndex);
// now call it
il.Emit(OpCodes.Callvirt, _iDataReaderGetItem);
// if handling a subobject, we check to see if the value is null
if (startColumn > 0)
{
var afterNullCheck = il.DefineLabel();
il.Emit(OpCodes.Dup);
il.Emit(OpCodes.Ldsfld, typeof(DBNull).GetField("Value"));
il.Emit(OpCodes.Ceq);
il.Emit(OpCodes.Brtrue, afterNullCheck);
il.Emit(OpCodes.Ldc_I4_1);
il.Emit(OpCodes.Stloc, localIsNotAllDbNull);
il.MarkLabel(afterNullCheck);
}
// store the value as a local variable in case type conversion fails
il.Emit(OpCodes.Dup);
il.Emit(OpCodes.Stloc, localValue);
// convert the value and store it locally
Type sourceType = reader.GetFieldType(index + startColumn);
TypeConverterGenerator.EmitConvertValue(il, member.Name, sourceType, member.MemberType, mapping.Serializer);
il.Emit(OpCodes.Stloc, localValues[index]);
}
/////////////////////////////////////////////////////////////////////
// catch translation exceptions and rethrow
/////////////////////////////////////////////////////////////////////
il.BeginCatchBlock(typeof(Exception)); // stack => [Exception]
il.Emit(OpCodes.Ldloc, localIndex); // push loc.0, stack => [Exception][index]
il.Emit(OpCodes.Ldarg_0); // push arg.0, stack => [Exception][index][reader]
il.Emit(OpCodes.Ldloc, localValue); // push loc.3, stack => [Exception][index][reader][value]
il.Emit(OpCodes.Call, TypeConverterGenerator.CreateDataExceptionMethod);
il.Emit(OpCodes.Throw); // stack => DataException
il.EndExceptionBlock();
/////////////////////////////////////////////////////////////////////
// if this was a subobject and all of the values are null, then return the default for the object
/////////////////////////////////////////////////////////////////////
if (startColumn > 0)
{
var afterNullExit = il.DefineLabel();
il.Emit(OpCodes.Ldloc, localIsNotAllDbNull);
il.Emit(OpCodes.Brtrue, afterNullExit);
TypeHelper.EmitDefaultValue(il, type);
il.Emit(OpCodes.Ret);
il.MarkLabel(afterNullExit);
}
/////////////////////////////////////////////////////////////////////
// call the constructor
/////////////////////////////////////////////////////////////////////
if (createNewObject)
{
if (isStruct)
{
il.Emit(OpCodes.Ldloca_S, localResult);
il.Emit(OpCodes.Initobj, type);
if (constructor != null)
{
il.Emit(OpCodes.Ldloca_S, localResult);
}
}
// if there is a constructor, then populate the values
if (constructor != null)
{
foreach (var p in constructor.GetParameters())
{
var mapping = mappings.Where(m => m != null).SingleOrDefault(m => m.Member.Name.IsIEqualTo(p.Name));
if (mapping != null)
{
il.Emit(OpCodes.Ldloc, localValues[mappings.IndexOf(mapping)]);
}
else
{
TypeHelper.EmitDefaultValue(il, p.ParameterType);
}
}
}
if (isStruct)
{
if (constructor != null)
{
il.Emit(OpCodes.Call, constructor);
}
}
else
{
il.Emit(OpCodes.Newobj, constructor);
il.Emit(OpCodes.Stloc, localResult);
}
}
else
{
il.Emit(OpCodes.Ldarg_1);
il.Emit(OpCodes.Stloc, localResult);
}
/////////////////////////////////////////////////////////////////////
// for anything not passed to the constructor, copy the local values to the properties
/////////////////////////////////////////////////////////////////////
for (int index = 0; index < columnCount; index++)
{
var mapping = mappings[index];
if (mapping == null)
{
continue;
}
var member = mapping.Member;
if (!member.CanSetMember)
{
continue;
}
// don't set values that have already been set
if (constructor != null && constructor.GetParameters().Any(p => p.Name.IsIEqualTo(mapping.Member.Name)))
{
continue;
}
// load the address of the object we are working on
if (isStruct)
{
il.Emit(OpCodes.Ldloca_S, localResult);
}
else
{
il.Emit(OpCodes.Ldloc, localResult);
}
// for deep mappings, go to the parent of the field that we are trying to set
var nextLabel = il.DefineLabel();
if (mapping.IsDeep)
{
ClassPropInfo.EmitGetValue(type, mapping.Prefix, il);
// if the mapping parent is nullable, check to see if it is null.
// if so, pop the parent off the stack and move to the next field
if (!ClassPropInfo.FindMember(type, mapping.Prefix).MemberType.GetTypeInfo().IsValueType)
{
var notNullLabel = il.DefineLabel();
il.Emit(OpCodes.Dup);
il.Emit(OpCodes.Brtrue, notNullLabel);
il.Emit(OpCodes.Pop);
il.Emit(OpCodes.Br, nextLabel);
il.MarkLabel(notNullLabel);
}
}
// load the value from the local and set it on the object
il.Emit(OpCodes.Ldloc, localValues[index]);
member.EmitSetValue(il);
il.MarkLabel(nextLabel);
/////////////////////////////////////////////////////////////////////
// stack should be [target] and ready for the next column
/////////////////////////////////////////////////////////////////////
}
/////////////////////////////////////////////////////////////////////
// load the return value from the local variable
/////////////////////////////////////////////////////////////////////
il.Emit(OpCodes.Ldloc, localResult); // ld loc.1 (target), stack => [target]
il.Emit(OpCodes.Ret);
// create the function
return(dm);
}
/// <summary>
/// Creates a converter from output parameters to an object of a given type.
/// </summary>
/// <param name="command">The command to analyze for the results.</param>
/// <param name="type">The type to put the values into.</param>
/// <returns>The converter method.</returns>
private static Action <IDbCommand, object> CreateClassOutputParameterConverter(IDbCommand command, Type type)
{
// get the parameters
List <IDataParameter> parameters = command.Parameters.Cast <IDataParameter>().ToList();
// if there are no output parameters, then return an empty method
if (!parameters.Cast <IDataParameter>().Any(p => p.Direction.HasFlag(ParameterDirection.Output)))
{
return (IDbCommand c, object o) => { }
}
;
// create a dynamic method
Type typeOwner = type.HasElementType ? type.GetElementType() : type;
// start creating a dynamic method
var dm = new DynamicMethod(String.Format(CultureInfo.InvariantCulture, "CreateOutputParameters-{0}", Guid.NewGuid()), null, new[] { typeof(IDbCommand), typeof(object) }, typeOwner, true);
var il = dm.GetILGenerator();
var localParameters = il.DeclareLocal(typeof(IDataParameterCollection));
// get the parameters collection from the command into loc.0
il.Emit(OpCodes.Ldarg_0); // push arg.0 (command), stack => [command]
il.Emit(OpCodes.Callvirt, _iDbCommandGetParameters); // call getparams, stack => [parameters]
il.Emit(OpCodes.Stloc, localParameters);
// go through all of the mappings
var mappings = ColumnMapping.MapParameters(type, command, parameters);
for (int i = 0; i < mappings.Count; i++)
{
var finishLabel = il.DefineLabel();
// if there is no parameter for this property, then skip it
var mapping = mappings[i];
if (mapping == null)
{
continue;
}
// if the property is readonly, then skip it
var prop = mapping.Member;
if (!prop.CanSetMember)
{
continue;
}
// if the parameter is not output, then skip it
IDataParameter parameter = parameters[i];
if (parameter == null || !parameter.Direction.HasFlag(ParameterDirection.Output))
{
continue;
}
// push the object on the stack. we will need it to set the value below
il.Emit(OpCodes.Ldarg_1);
// if this is a deep mapping, then get the parent object, and do a null test if its not a value type
if (mapping.IsDeep)
{
ClassPropInfo.EmitGetValue(type, mapping.Prefix, il);
if (!ClassPropInfo.FindMember(type, mapping.Prefix).MemberType.GetTypeInfo().IsValueType)
{
il.Emit(OpCodes.Dup);
var label = il.DefineLabel();
il.Emit(OpCodes.Brtrue, label);
il.Emit(OpCodes.Pop); // pop the object before finishing
il.Emit(OpCodes.Br, finishLabel);
il.MarkLabel(label);
}
}
// get the parameter out of the collection
il.Emit(OpCodes.Ldloc, localParameters);
il.Emit(OpCodes.Ldstr, parameter.ParameterName); // push (parametername)
il.Emit(OpCodes.Callvirt, _iDataParameterCollectionGetItem);
// get the value out of the parameter
il.Emit(OpCodes.Callvirt, _iDataParameterGetValue);
// emit the code to convert the value and set it on the object
TypeConverterGenerator.EmitConvertAndSetValue(il, _dbTypeToTypeMap[parameter.DbType], mapping);
il.MarkLabel(finishLabel);
}
il.Emit(OpCodes.Ret);
return((Action <IDbCommand, object>)dm.CreateDelegate(typeof(Action <IDbCommand, object>)));
}
